Initial Contribution

1 files changed, 261 insertions, 0 deletions

diff --git a/src/org/apache/commons/logging/LogSource.java b/src/org/apache/commons/logging/LogSource.java
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+/*
+ * Copyright 2001-2004 The Apache Software Foundation.
+ * 
+ * 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 org.apache.commons.logging;
+
+
+import java.lang.reflect.Constructor;
+import java.util.Hashtable;
+
+import org.apache.commons.logging.impl.NoOpLog;
+
+
+/**
+ * <p>Factory for creating {@link Log} instances.  Applications should call
+ * the <code>makeNewLogInstance()</code> method to instantiate new instances
+ * of the configured {@link Log} implementation class.</p>
+ *
+ * <p>By default, calling <code>getInstance()</code> will use the following
+ * algorithm:</p>
+ * <ul>
+ * <li>If Log4J is available, return an instance of
+ *     <code>org.apache.commons.logging.impl.Log4JLogger</code>.</li>
+ * <li>If JDK 1.4 or later is available, return an instance of
+ *     <code>org.apache.commons.logging.impl.Jdk14Logger</code>.</li>
+ * <li>Otherwise, return an instance of
+ *     <code>org.apache.commons.logging.impl.NoOpLog</code>.</li>
+ * </ul>
+ *
+ * <p>You can change the default behavior in one of two ways:</p>
+ * <ul>
+ * <li>On the startup command line, set the system property
+ *     <code>org.apache.commons.logging.log</code> to the name of the
+ *     <code>org.apache.commons.logging.Log</code> implementation class
+ *     you want to use.</li>
+ * <li>At runtime, call <code>LogSource.setLogImplementation()</code>.</li>
+ * </ul>
+ *
+ * @deprecated Use {@link LogFactory} instead - The default factory
+ *  implementation performs exactly the same algorithm as this class did
+ *
+ * @author Rod Waldhoff
+ * @version $Id: LogSource.java 155426 2005-02-26 13:10:49Z dirkv $
+ */
+public class LogSource {
+
+    // ------------------------------------------------------- Class Attributes
+
+    static protected Hashtable logs = new Hashtable();
+
+    /** Is log4j available (in the current classpath) */
+    static protected boolean log4jIsAvailable = false;
+
+    /** Is JDK 1.4 logging available */
+    static protected boolean jdk14IsAvailable = false;
+
+    /** Constructor for current log class */
+    static protected Constructor logImplctor = null;
+
+
+    // ----------------------------------------------------- Class Initializers
+
+    static {
+
+        // Is Log4J Available?
+        try {
+            if (null != Class.forName("org.apache.log4j.Logger")) {
+                log4jIsAvailable = true;
+            } else {
+                log4jIsAvailable = false;
+            }
+        } catch (Throwable t) {
+            log4jIsAvailable = false;
+        }
+
+        // Is JDK 1.4 Logging Available?
+        try {
+            if ((null != Class.forName("java.util.logging.Logger")) &&
+                (null != Class.forName("org.apache.commons.logging.impl.Jdk14Logger"))) {
+                jdk14IsAvailable = true;
+            } else {
+                jdk14IsAvailable = false;
+            }
+        } catch (Throwable t) {
+            jdk14IsAvailable = false;
+        }
+
+        // Set the default Log implementation
+        String name = null;
+        try {
+            name = System.getProperty("org.apache.commons.logging.log");
+            if (name == null) {
+                name = System.getProperty("org.apache.commons.logging.Log");
+            }
+        } catch (Throwable t) {
+        }
+        if (name != null) {
+            try {
+                setLogImplementation(name);
+            } catch (Throwable t) {
+                try {
+                    setLogImplementation
+                            ("org.apache.commons.logging.impl.NoOpLog");
+                } catch (Throwable u) {
+                    ;
+                }
+            }
+        } else {
+            try {
+                if (log4jIsAvailable) {
+                    setLogImplementation
+                            ("org.apache.commons.logging.impl.Log4JLogger");
+                } else if (jdk14IsAvailable) {
+                    setLogImplementation
+                            ("org.apache.commons.logging.impl.Jdk14Logger");
+                } else {
+                    setLogImplementation
+                            ("org.apache.commons.logging.impl.NoOpLog");
+                }
+            } catch (Throwable t) {
+                try {
+                    setLogImplementation
+                            ("org.apache.commons.logging.impl.NoOpLog");
+                } catch (Throwable u) {
+                    ;
+                }
+            }
+        }
+
+    }
+
+
+    // ------------------------------------------------------------ Constructor
+
+
+    /** Don't allow others to create instances */
+    private LogSource() {
+    }
+
+
+    // ---------------------------------------------------------- Class Methods
+
+
+    /**
+     * Set the log implementation/log implementation factory
+     * by the name of the class.  The given class
+     * must implement {@link Log}, and provide a constructor that
+     * takes a single {@link String} argument (containing the name
+     * of the log).
+     */
+    static public void setLogImplementation(String classname) throws
+            LinkageError, ExceptionInInitializerError,
+            NoSuchMethodException, SecurityException,
+            ClassNotFoundException {
+        try {
+            Class logclass = Class.forName(classname);
+            Class[] argtypes = new Class[1];
+            argtypes[0] = "".getClass();
+            logImplctor = logclass.getConstructor(argtypes);
+        } catch (Throwable t) {
+            logImplctor = null;
+        }
+    }
+
+
+    /**
+     * Set the log implementation/log implementation factory
+     * by class.  The given class must implement {@link Log},
+     * and provide a constructor that takes a single {@link String}
+     * argument (containing the name of the log).
+     */
+    static public void setLogImplementation(Class logclass) throws
+            LinkageError, ExceptionInInitializerError,
+            NoSuchMethodException, SecurityException {
+        Class[] argtypes = new Class[1];
+        argtypes[0] = "".getClass();
+        logImplctor = logclass.getConstructor(argtypes);
+    }
+
+
+    /** Get a <code>Log</code> instance by class name */
+    static public Log getInstance(String name) {
+        Log log = (Log) (logs.get(name));
+        if (null == log) {
+            log = makeNewLogInstance(name);
+            logs.put(name, log);
+        }
+        return log;
+    }
+
+
+    /** Get a <code>Log</code> instance by class */
+    static public Log getInstance(Class clazz) {
+        return getInstance(clazz.getName());
+    }
+
+
+    /**
+     * Create a new {@link Log} implementation, based
+     * on the given <i>name</i>.
+     * <p>
+     * The specific {@link Log} implementation returned
+     * is determined by the value of the
+     * <tt>org.apache.commons.logging.log</tt> property.
+     * The value of <tt>org.apache.commons.logging.log</tt> may be set to
+     * the fully specified name of a class that implements
+     * the {@link Log} interface.  This class must also
+     * have a public constructor that takes a single
+     * {@link String} argument (containing the <i>name</i>
+     * of the {@link Log} to be constructed.
+     * <p>
+     * When <tt>org.apache.commons.logging.log</tt> is not set,
+     * or when no corresponding class can be found,
+     * this method will return a Log4JLogger
+     * if the log4j Logger class is
+     * available in the {@link LogSource}'s classpath, or a
+     * Jdk14Logger if we are on a JDK 1.4 or later system, or
+     * NoOpLog if neither of the above conditions is true.
+     *
+     * @param name the log name (or category)
+     */
+    static public Log makeNewLogInstance(String name) {
+
+        Log log = null;
+        try {
+            Object[] args = new Object[1];
+            args[0] = name;
+            log = (Log) (logImplctor.newInstance(args));
+        } catch (Throwable t) {
+            log = null;
+        }
+        if (null == log) {
+            log = new NoOpLog(name);
+        }
+        return log;
+
+    }
+
+
+    /**
+     * Returns a {@link String} array containing the names of
+     * all logs known to me.
+     */
+    static public String[] getLogNames() {
+        return (String[]) (logs.keySet().toArray(new String[logs.size()]));
+    }
+
+
+}