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diff --git a/docs/html/guide/topics/clipboard/copy-paste.jd b/docs/html/guide/topics/clipboard/copy-paste.jd new file mode 100644 index 0000000..9a50a35 --- /dev/null +++ b/docs/html/guide/topics/clipboard/copy-paste.jd @@ -0,0 +1,1094 @@ +page.title=Copying and Pasting +@jd:body +<div id="qv-wrapper"> + <div id="qv"> + <h2>Quickview</h2> + <ul> + <li> + A clipboard-based framework for copying and pasting data. + </li> + <li> + Supports both simple and complex data, including text strings, complex data + structures, text and binary stream data, and application assets. + </li> + <li> + Copies and pastes simple text directly to and from the clipboard. + </li> + <li> + Copies and pastes complex data using a content provider. + </li> + <li> + Requires API 11. + </li> + </ul> + <h2>In this document</h2> + <ol> + <li> + <a href="#Clipboard">The Clipboard Framework</a> + </li> + <li> + <a href="#ClipboardClasses">Clipboard Classes</a> + <ol> + <li> + <a href="#ClipboardManager">ClipboardManager</a> + </li> + <li> + <a href="#ClipClasses"> + ClipData, ClipDescription, and ClipData.Item + </a> + </li> + <li> + <a href="#ClipDataMethods">ClipData convenience methods</a> + </li> + <li> + <a href="#CoerceToText">Coercing the clipboard data to text</a> + </li> + </ol> + </li> + <li> + <a href="#Copying">Copying to the Clipboard</a> + </li> + <li> + <a href="#Pasting">Pasting from the Clipboard</a> + <ol> + <li> + <a href="#PastePlainText">Pasting plain text</a> + </li> + <li> + <a href="#PasteContentUri">Pasting data from a content URI</a> + </li> + <li> + <a href="#PasteIntent">Pasting an Intent</a> + </li> + </ol> + </li> + <li> + <a href="#Provider">Using Content Providers to Copy Complex Data</a> + <ol> + <li> + <a href="#Encoding">Encoding an identifier on the URI</a> + </li> + <li> + <a href="#Records">Copying data structures</a> + </li> + <li> + <a href="#Streams">Copying data streams</a> + </li> + </ol> + </li> + <li> + <a href="#DataDesign">Designing Effective Copy/Paste Functionality</a> + </li> + </ol> + <h2>Key classes</h2> + <ol> + <li> + {@link android.content.ClipboardManager ClipboardManager} + </li> + <li> + {@link android.content.ClipData ClipData} + </li> + <li> + {@link android.content.ClipData.Item ClipData.Item} + </li> + <li> + {@link android.content.ClipDescription ClipDescription} + </li> + <li> + {@link android.net.Uri Uri} + </li> + <li> + {@link android.content.ContentProvider} + </li> + <li> + {@link android.content.Intent Intent} + </li> + </ol> + <h2>Related Samples</h2> + <ol> + <li> + <a href="{@docRoot}resources/samples/NotePad/index.html"> + Note Pad sample application</a> + </li> + </ol> + <h2>See also</h2> + <ol> + <li> + <a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a> + </li> + </ol> + </div> +</div> +<p> + Android provides a powerful clipboard-based framework for copying and pasting. It + supports both simple and complex data types, including text strings, complex data + structures, text and binary stream data, and even application assets. Simple text data is stored + directly in the clipboard, while complex data is stored as a reference that the pasting + application resolves with a content provider. Copying and pasting works both within an + application and between applications that implement the framework. +</p> + +<p> + Since a part of the framework uses content providers, this topic assumes some + familiarity with the Android Content Provider API, which is described in the topic + <a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a>. +</p> +<h2 id="Clipboard">The Clipboard Framework</h2> +<p> + When you use the clipboard framework, you put data into a clip object, and then + put the clip object on the system-wide clipboard. The clip object can take one of three forms: +</p> + <dl> + <dt>Text</dt> + <dd> + A text string. You put the string directly into the clip object, which you then put onto + the clipboard. To paste the string, you get the clip object from the clipboard and copy + the string to into your application's storage. + </dd> + <dt>URI</dt> + <dd> + A {@link android.net.Uri} object representing any form of URI. This is primarily for + copying complex data from a content provider. To copy data, you put a + {@link android.net.Uri} object into a clip object and put the clip object onto + the clipboard. To paste the data, you get the clip object, get the + {@link android.net.Uri} object, resolve it to a data source such as a content provider, + and copy the data from the source into your application's storage. + </dd> + <dt>Intent</dt> + <dd> + An {@link android.content.Intent}. This supports copying application shortcuts. To copy + data, you create an Intent, put it into a clip object, and put the clip object onto the + clipboard. To paste the data, you get the clip object and then copy the Intent object + into your application's memory area. + </dd> + </dl> +<p> + The clipboard holds only one clip object at a time. When an application puts a clip object on + the clipboard, the previous clip object disappears. +</p> +<p> + If you want to allow users to paste data into your application, you don't have to handle all + types of data. You can examine the data on the clipboard before you give users the option to + paste it. Besides having a certain data form, the clip object also contains metadata that tells + you what MIME type or types are available. This metadata helps you decide if your application + can do something useful with the clipboard data. For example, if you have an application that + primarily handles text you may want to ignore clip objects that contain a URI or Intent. +</p> +<p> + You may also want to allow users to paste text regardless of the form of data on the + clipboard. To do this, you can force the clipboard data into a text representation, and then + paste this text. This is described in the section <a href="#CoerceToText">Coercing the + clipboard to text</a>. +</p> +<h2 id="ClipboardClasses">Clipboard Classes</h2> +<p> + This section describes the classes used by the clipboard framework. +</p> +<h3 id="ClipboardManager">ClipboardManager</h3> +<p> + In the Android system, the system clipboard is represented by the global + {@link android.content.ClipboardManager} class. You do not instantiate this + class directly; instead, you get a reference to it by invoking + {@link android.content.Context#getSystemService(String) getSystemService(CLIPBOARD_SERVICE)}. +</p> +<h3 id="ClipClasses">ClipData, ClipData.Item, and ClipDescription</h3> +<p> + To add data to the clipboard, you create a {@link android.content.ClipData} object that + contains both a description of the data and the data itself. The clipboard holds only one + {@link android.content.ClipData} at a time. A {@link android.content.ClipData} contains a + {@link android.content.ClipDescription} object and one or more + {@link android.content.ClipData.Item} objects. +</p> +<p> + A {@link android.content.ClipDescription} object contains metadata about the clip. In + particular, it contains an array of available MIME types for the clip's data. When you put a + clip on the clipboard, this array is available to pasting applications, which can examine it to + see if they can handle any of available the MIME types. +</p> +<p> + A {@link android.content.ClipData.Item} object contains the text, URI, or Intent data: +</p> +<dl> + <dt>Text</dt> + <dd> + A {@link java.lang.CharSequence}. + </dd> + <dt>URI</dt> + <dd> + A {@link android.net.Uri}. This usually contains a content provider URI, although any + URI is allowed. The application that provides the data puts the URI on the clipboard. + Applications that want to paste the data get the URI from the clipboard and use it to + access the content provider (or other data source) and retrieve the data. + </dd> + <dt>Intent</dt> + <dd> + An {@link android.content.Intent}. This data type allows you to copy an application shortcut + to the clipboard. Users can then paste the shortcut into their applications for later use. + </dd> +</dl> +<p> + You can add more than one {@link android.content.ClipData.Item} object to a clip. This allows + users to copy and paste multiple selections as a single clip. For example, if you have a list + widget that allows the user to select more than one item at a time, you can copy all the items + to the clipboard at once. To do this, you create a separate + {@link android.content.ClipData.Item} for each list item, and then you add the + {@link android.content.ClipData.Item} objects to the {@link android.content.ClipData} object. +</p> +<h3 id="ClipDataMethods">ClipData convenience methods</h3> +<p> + The {@link android.content.ClipData} class provides static convenience methods for creating + a {@link android.content.ClipData} object with a single {@link android.content.ClipData.Item} + object and a simple {@link android.content.ClipDescription} object: +</p> +<dl> + <dt> +{@link android.content.ClipData#newPlainText(CharSequence,CharSequence) newPlainText(label, text)} + </dt> + <dd> + Returns a {@link android.content.ClipData} object whose single + {@link android.content.ClipData.Item} object contains a text string. The + {@link android.content.ClipDescription} object's label is set to <code>label</code>. + The single MIME type in {@link android.content.ClipDescription} is + {@link android.content.ClipDescription#MIMETYPE_TEXT_PLAIN}. + <p> + Use +{@link android.content.ClipData#newPlainText(CharSequence,CharSequence) newPlainText()} + to create a clip from a text string. + </dd> + <dt> +{@link android.content.ClipData#newUri(ContentResolver, CharSequence, Uri) newUri(resolver, label, URI)} + </dt> + <dd> + Returns a {@link android.content.ClipData} object whose single + {@link android.content.ClipData.Item} object contains a URI. The + {@link android.content.ClipDescription} object's label is set to <code>label</code>. + If the URI is a content URI ({@link android.net.Uri#getScheme() Uri.getScheme()} returns + <code>content:</code>), the method uses the {@link android.content.ContentResolver} object + provided in <code>resolver</code> to retrieve the available MIME types from the + content provider and store them in {@link android.content.ClipDescription}. For a URI that + is not a <code>content:</code> URI, the method sets the MIME type to + {@link android.content.ClipDescription#MIMETYPE_TEXT_URILIST}. + <p> + Use +{@link android.content.ClipData#newUri(ContentResolver, CharSequence, Uri) newUri()} + to create a clip from a URI, particularly a <code>content:</code> URI. + </p> + </dd> + <dt> + {@link android.content.ClipData#newIntent(CharSequence, Intent) newIntent(label, intent)} + </dt> + <dd> + Returns a {@link android.content.ClipData} object whose single + {@link android.content.ClipData.Item} object contains an {@link android.content.Intent}. + The {@link android.content.ClipDescription} object's label is set to <code>label</code>. + The MIME type is set to {@link android.content.ClipDescription#MIMETYPE_TEXT_INTENT}. + <p> + Use +{@link android.content.ClipData#newIntent(CharSequence, Intent) newIntent()} + to create a clip from an Intent object. + </dd> +</dl> +<h3 id="CoerceToText">Coercing the clipboard data to text</h3> +<p> + Even if your application only handles text, you can copy non-text data from the + clipboard by converting it with the method + {@link android.content.ClipData.Item#coerceToText(Context) ClipData.Item.coerceToText()}. +</p> +<p> + This method converts the data in {@link android.content.ClipData.Item} to text and + returns a {@link java.lang.CharSequence}. The value that + {@link android.content.ClipData.Item#coerceToText(Context) ClipData.Item.coerceToText()} + returns is based on the form of data in {@link android.content.ClipData.Item}: +</p> +<dl> + <dt><em>Text</em></dt> + <dd> + If {@link android.content.ClipData.Item} is text + ({@link android.content.ClipData.Item#getText()} is not null), + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} returns the + text. + </dd> + <dt><em>URI</em></dt> + <dd> + If {@link android.content.ClipData.Item} is a URI + ({@link android.content.ClipData.Item#getUri()} is not null), + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} tries to use + it as a content URI: + <ul> + <li> + If the URI is a content URI and the provider can return a text stream, + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} returns + a text stream. + </li> + <li> + If the URI is a content URI but the provider does not offer a text stream, + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} returns + a representation of the URI. The representation is the same as that returned by + {@link android.net.Uri#toString() Uri.toString()}. + </li> + <li> + If the URI is not a content URI, + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} returns + a representation of the URI. The representation is the same as that returned by + {@link android.net.Uri#toString() Uri.toString()}. + </li> + </ul> + </dd> + <dt><em>Intent</em></dt> + <dd> + If {@link android.content.ClipData.Item} is an Intent + ({@link android.content.ClipData.Item#getIntent()} is not null), + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} converts it to + an Intent URI and returns it. The representation is the same as that returned by + {@link android.content.Intent#toUri(int) Intent.toUri(URI_INTENT_SCHEME)}. + </dd> +</dl> +<p> + The clipboard framework is summarized in Figure 1. To copy data, an application puts a + {@link android.content.ClipData} object on the {@link android.content.ClipboardManager} global + clipboard. The {@link android.content.ClipData} contains one or more + {@link android.content.ClipData.Item} objects and one + {@link android.content.ClipDescription} object. To paste data, an application gets the + {@link android.content.ClipData}, gets its MIME type from the + {@link android.content.ClipDescription}, and gets the data either from + the {@link android.content.ClipData.Item} or from the content provider referred to by + {@link android.content.ClipData.Item}. +</p> + <a name="framework"></a> + <img + src="{@docRoot}images/ui/clipboard/copy_paste_framework.png" + alt="A block diagram of the copy and paste framework" height="400px" id="figure1" /> +<p class="img-caption"> + <strong>Figure 1.</strong> The Android clipboard framework +</p> +<h2 id="Copying">Copying to the Clipboard</h2> +<p> + As described previously, to copy data to the clipboard you get a handle to the global + {@link android.content.ClipboardManager} object, create a {@link android.content.ClipData} + object, add a {@link android.content.ClipDescription} and one or more + {@link android.content.ClipData.Item} objects to it, and add the finished + {@link android.content.ClipData} object to the {@link android.content.ClipboardManager} object. + This is described in detail in the following procedure: +</p> +<ol> + <li> + If you are copying data using a content URI, set up a content + provider. + <p> + The <a href="{@docRoot}resources/samples/NotePad/index.html"> + Note Pad</a> sample application is an example of using a content provider for + copying and pasting. The +<a href="{@docRoot}resources/samples/NotePad/src/com/example/android/notepad/NotePadProvider.html"> + NotePadProvider</a> class implements the content provider. The +<a href="{@docRoot}resources/samples/NotePad/src/com/example/android/notepad/NotePad.html"> + NotePad</a> class defines a contract between the provider and other applications, + including the supported MIME types. + </p> + </li> + <li> + Get the system clipboard: +<pre> + +... + +// if the user selects copy +case R.id.menu_copy: + +// Gets a handle to the clipboard service. +ClipboardManager clipboard = (ClipboardManager) + getSystemService(Context.CLIPBOARD_SERVICE); +</pre> + </li> + <li> + <p> + Copy the data to a new {@link android.content.ClipData} object: + </p> + <ul> + <li> + <h4>For text</h4> +<pre> +// Creates a new text clip to put on the clipboard +ClipData clip = ClipData.newPlainText("simple text","Hello, World!"); +</pre> + </li> + <li> + <h4>For a URI</h4> + <p> + This snippet constructs a URI by encoding a record ID onto the content URI + for the provider. This technique is covered in more detail + in the section <a href="#Encoding">Encoding an identifier on the URI</a>: + </p> +<pre> +// Creates a Uri based on a base Uri and a record ID based on the contact's last name +// Declares the base URI string +private static final String CONTACTS = "content://com.example.contacts"; + +// Declares a path string for URIs that you use to copy data +private static final String COPY_PATH = "/copy"; + +// Declares the Uri to paste to the clipboard +Uri copyUri = Uri.parse(CONTACTS + COPY_PATH + "/" + lastName); + +... + +// Creates a new URI clip object. The system uses the anonymous getContentResolver() object to +// get MIME types from provider. The clip object's label is "URI", and its data is +// the Uri previously created. +ClipData clip = ClipData.newUri(getContentResolver(),"URI",copyUri); +</pre> + </li> + <li> + <h4>For an Intent</h4> + <p> + This snippet constructs an Intent for an application + and then puts it in the clip object: + </p> +<pre> +// Creates the Intent +Intent appIntent = new Intent(this, com.example.demo.myapplication.class); + +... + +// Creates a clip object with the Intent in it. Its label is "Intent" and its data is +// the Intent object created previously +ClipData clip = ClipData.newIntent("Intent",appIntent); +</pre> + </li> + </ul> + </li> + <li> + Put the new clip object on the clipboard: +<pre> +// Set the clipboard's primary clip. +clipboard.setPrimaryClip(clip); +</pre> + </li> +</ol> +<h2 id="Pasting">Pasting from the Clipboard</h2> +<p> + As described previously, you paste data from the clipboard by getting the global clipboard + object, getting the clip object, looking at its data, and if possible copying the data from + the clip object to your own storage. This section describes in detail how to do this for + the three forms of clipboard data. +</p> +<h3 id="PastePlainText">Pasting plain text</h3> +<p> + To paste plain text, first get the global clipboard and verify that it can return plain text. + Then get the clip object and copy its text to your own storage using + {@link android.content.ClipData.Item#getText()}, as described in the following procedure: +</p> +<ol> + <li> + Get the global {@link android.content.ClipboardManager} object using + {@link android.content.Context#getSystemService(String) getSystemService(CLIPBOARD_SERVICE)}. Also + declare a global variable to contain the pasted text: +<pre> +ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE); + +String pasteData = ""; + +</pre> + </li> + <li> + Next, determine if you should enable or disable the "paste" option in the + current Activity. You should verify that the clipboard contains a clip and that you + can handle the type of data represented by the clip: +<pre> +// Gets the ID of the "paste" menu item +MenuItem mPasteItem = menu.findItem(R.id.menu_paste); + +// If the clipboard doesn't contain data, disable the paste menu item. +// If it does contain data, decide if you can handle the data. +if (!(clipboard.hasPrimaryClip())) { + + mPasteItem.setEnabled(false); + + } else if (!(clipboard.getPrimaryClipDescription().hasMimeType(MIMETYPE_TEXT_PLAIN))) { + + // This disables the paste menu item, since the clipboard has data but it is not plain text + mPasteItem.setEnabled(false); + } else { + + // This enables the paste menu item, since the clipboard contains plain text. + mPasteItem.setEnabled(true); + } +} +</pre> + </li> + <li> + Copy the data from the clipboard. This point in the program is only reachable if the + "paste" menu item is enabled, so you can assume that the clipboard contains + plain text. You do not yet know if it contains a text string or a URI that points to plain + text. The following snippet tests this, but it only shows the code for handling plain text: +<pre> +// Responds to the user selecting "paste" +case R.id.menu_paste: + +// Examines the item on the clipboard. If getText() does not return null, the clip item contains the +// text. Assumes that this application can only handle one item at a time. + ClipData.Item item = clipboard.getPrimaryClip().getItemAt(0); + +// Gets the clipboard as text. +pasteData = item.getText(); + +// If the string contains data, then the paste operation is done +if (pasteData != null) { + return; + +// The clipboard does not contain text. If it contains a URI, attempts to get data from it +} else { + Uri pasteUri = item.getUri(); + + // If the URI contains something, try to get text from it + if (pasteUri != null) { + + // calls a routine to resolve the URI and get data from it. This routine is not + // presented here. + pasteData = resolveUri(Uri); + return; + } else { + + // Something is wrong. The MIME type was plain text, but the clipboard does not contain either + // text or a Uri. Report an error. + Log.e("Clipboard contains an invalid data type"); + return; + } +} +</pre> + </li> +</ol> +<h3 id="PasteContentUri">Pasting data from a content URI</h3> +<p> + If the {@link android.content.ClipData.Item} object contains a content URI and you + have determined that you can handle one of its MIME types, create a + {@link android.content.ContentResolver} and then call the appropriate content provider + method to retrieve the data. +</p> +<p> + The following procedure describes how to get data from a content provider based on a + content URI on the clipboard. It checks that a MIME type that the application can use + is available from the provider: +</p> +<ol> + <li> + Declare a global variable to contain the MIME type: +<pre> +// Declares a MIME type constant to match against the MIME types offered by the provider +public static final String MIME_TYPE_CONTACT = "vnd.android.cursor.item/vnd.example.contact" +</pre> + </li> + <li> + Get the global clipboard. Also get a content resolver so you can access the content + provider: +<pre> +// Gets a handle to the Clipboard Manager +ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE); + +// Gets a content resolver instance +ContentResolver cr = getContentResolver(); +</pre> + </li> + <li> + Get the primary clip from the clipboard, and get its contents as a URI: +<pre> +// Gets the clipboard data from the clipboard +ClipData clip = clipboard.getPrimaryClip(); + +if (clip != null) { + + // Gets the first item from the clipboard data + ClipData.Item item = clip.getItemAt(0); + + // Tries to get the item's contents as a URI + Uri pasteUri = item.getUri(); +</pre> + </li> + <li> + Test to see if the URI is a content URI by calling + {@link android.content.ContentResolver#getType(Uri) getType(Uri)}. This method returns + null if <code>Uri</code> does not point to a valid content provider: +<pre> + // If the clipboard contains a URI reference + if (pasteUri != null) { + + // Is this a content URI? + String uriMimeType = cr.getType(pasteUri); +</pre> + </li> + <li> + Test to see if the content provider supports a MIME type that the current application + understands. If it does, call + {@link android.content.ContentResolver#query(Uri, String[], String, String[], String) + ContentResolver.query()} to get the data. The return value is a + {@link android.database.Cursor}: +<pre> + // If the return value is not null, the Uri is a content Uri + if (uriMimeType != null) { + + // Does the content provider offer a MIME type that the current application can use? + if (uriMimeType.equals(MIME_TYPE_CONTACT)) { + + // Get the data from the content provider. + Cursor pasteCursor = cr.query(uri, null, null, null, null); + + // If the Cursor contains data, move to the first record + if (pasteCursor != null) { + if (pasteCursor.moveToFirst()) { + + // get the data from the Cursor here. The code will vary according to the + // format of the data model. + } + } + + // close the Cursor + pasteCursor.close(); + } + } + } +} +</pre> + </li> +</ol> +<h3 id="PasteIntent">Pasting an Intent</h3> +<p> + To paste an Intent, first get the global clipboard. Examine the + {@link android.content.ClipData.Item} object to see if it contains an Intent. Then call + {@link android.content.ClipData.Item#getIntent()} to copy the Intent to your own storage. + The following snippet demonstrates this: +</p> +<pre> +// Gets a handle to the Clipboard Manager +ClipboardManager clipboard = (ClipboardManager) getSystemService(Context.CLIPBOARD_SERVICE); + +// Checks to see if the clip item contains an Intent, by testing to see if getIntent() returns null +Intent pasteIntent = clipboard.getPrimaryClip().getItemAt(0).getIntent(); + +if (pasteIntent != null) { + + // handle the Intent + +} else { + + // ignore the clipboard, or issue an error if your application was expecting an Intent to be + // on the clipboard +} +</pre> +<h2 id="Provider">Using Content Providers to Copy Complex Data</h2> +<p> + Content providers support copying complex data such as database records or file streams. + To copy the data, you put a content URI on the clipboard. Pasting applications then get this + URI from the clipboard and use it to retrieve database data or file stream descriptors. +</p> +<p> + Since the pasting application only has the content URI for your data, it needs to know which + piece of data to retrieve. You can provide this information by encoding an identifier for the + data on the URI itself, or you can provide a unique URI that will return the data you want to + copy. Which technique you choose depends on the organization of your data. +</p> +<p> + The following sections describe how to set up URIs, how to provide complex data, and how to + provide file streams. The descriptions assume that you are familiar with the general principles + of content provider design. +</p> +<h3 id="Encoding">Encoding an identifier on the URI</h3> +<p> + A useful technique for copying data to the clipboard with a URI is to encode an identifier for + the data on the URI itself. Your content provider can then get the identifier from the URI and + use it to retrieve the data. The pasting application doesn't have to know that the identifier + exists; all it has to do is get your "reference" (the URI plus the identifier) from + the clipboard, give it your content provider, and get back the data. +</p> +<p> + You usually encode an identifier onto a content URI by concatenating it to the end of the URI. + For example, suppose you define your provider URI as the following string: +</p> +<pre> +"content://com.example.contacts" +</pre> +<p> + If you want to encode a name onto this URI, you would use the following snippet: +</p> +<pre> +String uriString = "content://com.example.contacts" + "/" + "Smith" + +// uriString now contains content://com.example.contacts/Smith. + +// Generates a uri object from the string representation +Uri copyUri = Uri.parse(uriString); +</pre> +<p> + If you are already using a content provider, you may want to add a new URI path that indicates + the URI is for copying. For example, suppose you already have the following URI paths: +</p> +<pre> +"content://com.example.contacts"/people +"content://com.example.contacts"/people/detail +"content://com.example.contacts"/people/images +</pre> +<p> + You could add another path that is specific to copy URIs: +</p> +<pre> +"content://com.example.contacts/copying" +</pre> +<p> + You could then detect a "copy" URI by pattern-matching and handle it with code that + is specific for copying and pasting. +</p> +<p> + You normally use the encoding technique if you're already using a content provider, internal + database, or internal table to organize your data. In these cases, you have multiple pieces of + data you want to copy, and presumably a unique identifier for each piece. In response to a + query from the pasting application, you can look up the data by its identifier and return it. +</p> +<p> + If you don't have multiple pieces of data, then you probably don't need to encode an identifier. + You can simply use a URI that is unique to your provider. In response to a query, your provider + would return the data it currently contains. +</p> +<p> + Getting a single record by ID is used in the + <a href="{@docRoot}resources/samples/NotePad/index.html">Note Pad</a> sample application to + open a note from the notes list. The sample uses the <code>_id</code> field from an SQL + database, but you can have any numeric or character identifier you want. +</p> +<h3 id="Records">Copying data structures</h3> +<p> + You set up a content provider for copying and pasting complex data as a subclass of the + {@link android.content.ContentProvider} component. You should also encode the URI you put on + the clipboard so that it points to the exact record you want to provide. In addition, you + have to consider the existing state of your application: +</p> +<ul> + <li> + If you already have a content provider, you can add to its functionality. You may only + need to modify its +{@link android.content.ContentResolver#query(Uri, String[], String, String[], String) query()} + method to handle URIs coming from applications that want to paste data. You will + probably want to modify the method to handle a "copy" URI pattern. + </li> + <li> + If your application maintains an internal database, you may + want to move this database into a content provider to facilitate copying from it. + </li> + <li> + If you are not currently using a database, you can implement a simple content provider + whose sole purpose is to offer data to applications that are pasting from the + clipboard. + </li> +</ul> +<p> +In the content provider, you will want to override at least the following methods: +</p> +<dl> + <dt> +{@link android.content.ContentResolver#query(Uri, String[], String, String[], String) query()} + </dt> + <dd> + Pasting applications will assume that they can get your data by using this method with + the URI you put on the clipboard. To support copying, you should have this method + detect URIs that contain a special "copy" path. Your application can then + create a "copy" URI to put on the clipboard, containing the copy path and + a pointer to the exact record you want to copy. + </dd> + <dt> + {@link android.content.ContentProvider#getType(Uri) getType()} + </dt> + <dd> + This method should return the MIME type or types for the data you intend to copy. The method + {@link android.content.ClipData#newUri(ContentResolver, CharSequence, Uri) newUri()} calls + {@link android.content.ContentProvider#getType(Uri) getType()} in order to put the MIME + types into the new {@link android.content.ClipData} object. + <p> + MIME types for complex data are described in the topic + <a href="{@docRoot}guide/topics/providers/content-providers.html">Content Providers</a>. + </p> + </dd> +</dl> +<p> + Notice that you don't have to have any of the other content provider methods such as + {@link android.content.ContentProvider#insert(Uri, ContentValues) insert()} or + {@link android.content.ContentProvider#update(Uri, ContentValues, String, String[]) update()}. + A pasting application only needs to get your supported MIME types and copy data from your + provider. If you already have these methods, they won't interfere with copy operations. +</p> +<p> + The following snippets demonsrate how to set up your application to copy complex data: +</p> +<ol> + <li> + <p> + In the global constants for your application, + declare a base URI string and a path that identifies URI strings you are + using to copy data. Also declare a MIME type for the copied data: + </p> +<pre> +// Declares the base URI string +private static final String CONTACTS = "content://com.example.contacts"; + +// Declares a path string for URIs that you use to copy data +private static final String COPY_PATH = "/copy"; + +// Declares a MIME type for the copied data +public static final String MIME_TYPE_CONTACT = "vnd.android.cursor.item/vnd.example.contact" +</pre> + </li> + <li> + In the Activity from which users copy data, + set up the code to copy data to the clipboard. In response to a copy request, put + the URI on the clipboard: +<pre> +public class MyCopyActivity extends Activity { + + ... + +// The user has selected a name and is requesting a copy. +case R.id.menu_copy: + + // Appends the last name to the base URI + // The name is stored in "lastName" + uriString = CONTACTS + COPY_PATH + "/" + lastName; + + // Parses the string into a URI + Uri copyUri = Uri.parse(uriString); + + // Gets a handle to the clipboard service. + ClipboardManager clipboard = (ClipboardManager) + getSystemService(Context.CLIPBOARD_SERVICE); + + ClipData clip = ClipData.newUri(getContentResolver(), "URI", copyUri); + + // Set the clipboard's primary clip. + clipboard.setPrimaryClip(clip); +</pre> + </li> + + <li> + <p> + In the global scope of your content provider, create a URI matcher and add a URI + pattern that will match URIs you put on the clipboard: + </p> +<pre> +public class MyCopyProvider extends ContentProvider { + + ... + +// A Uri Match object that simplifies matching content URIs to patterns. +private static final UriMatcher sURIMatcher = new UriMatcher(UriMatcher.NO_MATCH); + +// An integer to use in switching based on the incoming URI pattern +private static final int GET_SINGLE_CONTACT = 0; + +... + +// Adds a matcher for the content URI. It matches +// "content://com.example.contacts/copy/*" +sUriMatcher.addURI(CONTACTS, "names/*", GET_SINGLE_CONTACT); +</pre> + </li> + <li> + <p> + Set up the + {@link android.content.ContentProvider#query(Uri, String[], String, String[], String) query()} + method. This method can handle different URI patterns, depending on how you code it, but + only the pattern for the clipboard copying operation is shown: + </p> +<pre> +// Sets up your provider's query() method. +public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, + String sortOrder) { + + ... + + // Switch based on the incoming content URI + switch (sUriMatcher.match(uri)) { + + case GET_SINGLE_CONTACT: + + // query and return the contact for the requested name. Here you would decode + // the incoming URI, query the data model based on the last name, and return the result + // as a Cursor. + + ... + +} +</pre> + </li> + <li> + <p> + Set up the {@link android.content.ContentProvider#getType(Uri) getType()} method to + return an appropriate MIME type for copied data: + </p> +<pre> +// Sets up your provider's getType() method. +public String getType(Uri uri) { + + ... + + switch (sUriMatcher.match(uri)) { + + case GET_SINGLE_CONTACT: + + return (MIME_TYPE_CONTACT); +</pre> + </li> +</ol> +<p> + The section <a href="#PasteContentUri">Pasting data from a content URI</a> + describes how to get a content URI from the clipboard and use it to get and paste data. +</p> +<h3 id="Streams">Copying data streams</h3> +<p> + You can copy and paste large amounts of text and binary data as streams. The data can have + forms such as the following: +</p> + <ul> + <li> + Files stored on the actual device. + </li> + <li> + Streams from sockets. + </li> + <li> + Large amounts of data stored in a provider's underlying database system. + </li> + </ul> +<p> + A content provider for data streams provides access to its data with a file descriptor object + such as {@link android.content.res.AssetFileDescriptor} instead of a + {@link android.database.Cursor} object. The pasting application reads the data stream using + this file descriptor. +</p> +<p> + To set up your application to copy a data stream with a provider, follow these steps: +</p> +<ol> + <li> + Set up a content URI for the data stream you are putting on the clipboard. Options + for doing this include the following: + <ul> + <li> + Encode an identifier for the data stream onto the URI, + as described in the section + <a href="#Encoding">Encoding an identifier on the URI</a>, and then maintain a + table in your provider that contains identifiers and the corresponding stream name. + </li> + <li> + Encode the stream name directly on the URI. + </li> + <li> + Use a unique URI that always returns the current stream from the provider. If you + use this option, you have to remember to update your provider to point to a + different stream whenever you copy the stream to the clipboard via the URI. + </li> + </ul> + </li> + <li> + Provide a MIME type for each type of data stream you plan to offer. Pasting applications + need this information to determine if they can paste the data on the clipboard. + </li> + <li> + Implement one of the {@link android.content.ContentProvider} methods that returns + a file descriptor for a stream. If you encode identifiers on the content URI, use this + method to determine which stream to open. + </li> + <li> + To copy the data stream to the clipboard, construct the content URI and place it + on the clipboard. + </li> +</ol> +<p> + To paste a data stream, an application gets the clip from the clipboard, gets the URI, and + uses it in a call to a {@link android.content.ContentResolver} file descriptor method that + opens the stream. The {@link android.content.ContentResolver} method calls the corresponding + {@link android.content.ContentProvider} method, passing it the content URI. Your provider + returns the file descriptor to {@link android.content.ContentResolver} method. The pasting + application then has the responsibility to read the data from the stream. +</p> +<p> + The following list shows the most important file descriptor methods for a content provider. + Each of these has a corresponding {@link android.content.ContentResolver} method with the + string "Descriptor" appended to the method name; for example, the + {@link android.content.ContentResolver} analog of + {@link android.content.ContentProvider#openAssetFile(Uri, String) openAssetFile()} is +{@link android.content.ContentResolver#openAssetFileDescriptor(Uri, String) openAssetFileDescriptor()}: +</p> +<dl> + <dt> +{@link android.content.ContentProvider#openTypedAssetFile(Uri,String,Bundle) openTypedAssetFile()} + </dt> + <dd> + This method should return an asset file descriptor, but only if the provided MIME type is + supported by the provider. The caller (the application doing the pasting) provides a MIME + type pattern. The content provider (of the application that has copied a URI to the + clipboard) returns an {@link android.content.res.AssetFileDescriptor} file handle if it + can provide that MIME type, or throws an exception if it can not. + <p> + This method handles subsections of files. You can use it to read assets that the + content provider has copied to the clipboard. + </p> + </dd> + <dt> + {@link android.content.ContentProvider#openAssetFile(Uri, String) openAssetFile()} + </dt> + <dd> + This method is a more general form of +{@link android.content.ContentProvider#openTypedAssetFile(Uri,String,Bundle) openTypedAssetFile()}. + It does not filter for allowed MIME types, but it can read subsections of files. + </dd> + <dt> + {@link android.content.ContentProvider#openFile(Uri, String) openFile()} + </dt> + <dd> + This is a more general form of + {@link android.content.ContentProvider#openAssetFile(Uri, String) openAssetFile()}. It can't + read subsections of files. + </dd> +</dl> +<p> + You can optionally use the +{@link android.content.ContentProvider#openPipeHelper(Uri, String, Bundle, T, ContentProvider.PipeDataWriter) openPipeHelper()} + method with your file descriptor method. This allows the pasting application to read the + stream data in a background thread using a pipe. To use this method, you need to implement the + {@link android.content.ContentProvider.PipeDataWriter} interface. An example of doing this is + given in the <a href="{@docRoot}resources/samples/NotePad/index.html">Note Pad</a> sample + application, in the <code>openTypedAssetFile()</code> method of + <code>NotePadProvider.java</code>. +</p> +<h2 id="DataDesign">Designing Effective Copy/Paste Functionality</h2> +<p> + To design effective copy and paste functionality for your application, remember these + points: +</p> + <ul> + <li> + At any time, there is only one clip on the clipboard. A new copy operation by + any application in the system overwrites the previous clip. Since the user may + navigate away from your application and do a copy before returning, you can't assume + that the clipboard contains the clip that the user previously copied in <em>your</em> + application. + </li> + <li> + The intended purpose of multiple {@link android.content.ClipData.Item} + objects per clip is to support copying and pasting of multiple selections rather than + different forms of reference to a single selection. You usually want all of the + {@link android.content.ClipData.Item} objects in a clip to have the same form, that is, + they should all be simple text, content URI, or {@link android.content.Intent}, but not + a mixture. + </li> + <li> + When you provide data, you can offer different MIME representations. Add the MIME types + you support to the {@link android.content.ClipDescription}, and then + implement the MIME types in your content provider. + </li> + <li> + When you get data from the clipboard, your application is responsible for checking the + available MIME types and then deciding which one, if any, to use. Even if there is a + clip on the clipboard and the user requests a paste, your application is not required + to do the paste. You <em>should</em> do the paste if the MIME type is compatible. You + may choose to coerce the data on the clipboard to text using + {@link android.content.ClipData.Item#coerceToText(Context) coerceToText()} if you + choose. If your application supports more than one of the available MIME types, you can + allow the user to choose which one to use. + </li> + </ul> |