1 files changed, 199 insertions, 0 deletions
diff --git a/core/java/android/webkit/StreamLoader.java b/core/java/android/webkit/StreamLoader.java
new file mode 100644
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+++ b/core/java/android/webkit/StreamLoader.java
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+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.webkit;
+
+import android.net.http.EventHandler;
+import android.net.http.Headers;
+import android.os.Handler;
+import android.os.Message;
+import android.util.Config;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+
+/**
+ * This abstract class is used for all content loaders that rely on streaming
+ * content into the rendering engine loading framework.
+ *
+ * The class implements a state machine to load the content into the frame in
+ * a similar manor to the way content arrives from the network. The class uses
+ * messages to move from one state to the next, which enables async. loading of
+ * the streamed content.
+ *
+ * Classes that inherit from this class must implement two methods, the first
+ * method is used to setup the InputStream and notify the loading framework if
+ * it can load it's content. The other method allows the derived class to add
+ * additional HTTP headers to the response.
+ *
+ * By default, content loaded with a StreamLoader is marked with a HTTP header
+ * that indicates the content should not be cached.
+ *
+ */
+abstract class StreamLoader extends Handler {
+
+    public static final String NO_STORE       = "no-store";
+
+    private static final int MSG_STATUS = 100;  // Send status to loader
+    private static final int MSG_HEADERS = 101; // Send headers to loader
+    private static final int MSG_DATA = 102;  // Send data to loader
+    private static final int MSG_END = 103;  // Send endData to loader
+
+    protected LoadListener mHandler; // loader class
+    protected InputStream mDataStream; // stream to read data from
+    protected long mContentLength; // content length of data
+    private byte [] mData; // buffer to pass data to loader with.
+
+    /**
+     * Constructor. Although this class calls the LoadListener, it only calls
+     * the EventHandler Interface methods. LoadListener concrete class is used
+     * to avoid the penality of calling an interface.
+     *
+     * @param loadlistener The LoadListener to call with the data.
+     */
+    StreamLoader(LoadListener loadlistener) {
+        mHandler = loadlistener;
+    }
+
+    /**
+     * This method is called when the derived class should setup mDataStream,
+     * and call mHandler.status() to indicate that the load can occur. If it
+     * fails to setup, it should still call status() with the error code.
+     *
+     * @return true if stream was successfully setup
+     */
+    protected abstract boolean setupStreamAndSendStatus();
+
+    /**
+     * This method is called when the headers are about to be sent to the
+     * load framework. The derived class has the opportunity to add addition
+     * headers.
+     *
+     * @param headers Map of HTTP headers that will be sent to the loader.
+     */
+    abstract protected void buildHeaders(Headers headers);
+
+
+    /**
+     * Calling this method starts the load of the content for this StreamLoader.
+     * This method simply posts a message to send the status and returns
+     * immediately.
+     */
+    public void load() {
+        if (!mHandler.isSynchronous()) {
+            sendMessage(obtainMessage(MSG_STATUS));
+        } else {
+            // Load the stream synchronously.
+            if (setupStreamAndSendStatus()) {
+                // We were able to open the stream, create the array
+                // to pass data to the loader
+                mData = new byte[8192];
+                sendHeaders();
+                while (!sendData());
+                closeStreamAndSendEndData();
+                mHandler.loadSynchronousMessages();
+            }
+        }
+    }
+
+    /* (non-Javadoc)
+     * @see android.os.Handler#handleMessage(android.os.Message)
+     */
+    public void handleMessage(Message msg) {
+        if (Config.DEBUG && mHandler.isSynchronous()) {
+            throw new AssertionError();
+        }
+        switch(msg.what) {
+            case MSG_STATUS:
+                if (setupStreamAndSendStatus()) {
+                    // We were able to open the stream, create the array
+                    // to pass data to the loader
+                    mData = new byte[8192];
+                    sendMessage(obtainMessage(MSG_HEADERS));
+                }
+                break;
+            case MSG_HEADERS:
+                sendHeaders();
+                sendMessage(obtainMessage(MSG_DATA));
+                break;
+            case MSG_DATA:
+                if (sendData()) {
+                    sendMessage(obtainMessage(MSG_END));
+                } else {
+                    sendMessage(obtainMessage(MSG_DATA));
+                }
+                break;
+            case MSG_END:
+                closeStreamAndSendEndData();
+                break;
+            default:
+                super.handleMessage(msg);
+                break;
+        }
+    }
+
+    /**
+     * Construct the headers and pass them to the EventHandler.
+     */
+    private void sendHeaders() {
+        Headers headers = new Headers();
+        if (mContentLength > 0) {
+            headers.setContentLength(mContentLength);
+        }
+        headers.setCacheControl(NO_STORE);
+        buildHeaders(headers);
+        mHandler.headers(headers);
+    }
+
+    /**
+     * Read data from the stream and pass it to the EventHandler.
+     * If an error occurs reading the stream, then an error is sent to the
+     * EventHandler, and moves onto the next state - end of data.
+     * @return True if all the data has been read. False if sendData should be
+     *         called again.
+     */
+    private boolean sendData() {
+        if (mDataStream != null) {
+            try {
+                int amount = mDataStream.read(mData);
+                if (amount > 0) {
+                    mHandler.data(mData, amount);
+                    return false;
+                }
+            } catch (IOException ex) {
+                mHandler.error(EventHandler.FILE_ERROR,
+                               ex.getMessage());
+            }
+        }
+        return true;
+    }
+
+    /**
+     * Close the stream and inform the EventHandler that load is complete.
+     */
+    private void closeStreamAndSendEndData() {
+        if (mDataStream != null) {
+            try {
+                mDataStream.close();
+            } catch (IOException ex) {
+                // ignore.
+            }
+        }
+        mHandler.endData();
+    }
+
+}