1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123
/* * @(#)CommandInfo.java 1.12 05/11/17 * * Copyright 2006 Sun Microsystems, Inc. All Rights Reserved. * * This software is the proprietary information of Sun Microsystems, Inc. * Use is subject to license terms. * */ package javax.activation; import java.io.*; import java.beans.Beans; /** * The CommandInfo class is used by CommandMap implementations to * describe the results of command requests. It provides the requestor * with both the verb requested, as well as an instance of the * bean. There is also a method that will return the name of the * class that implements the command but <i>it is not guaranteed to * return a valid value</i>. The reason for this is to allow CommandMap * implmentations that subclass CommandInfo to provide special * behavior. For example a CommandMap could dynamically generate * JavaBeans. In this case, it might not be possible to create an * object with all the correct state information solely from the class * name. * * @since 1.6 */ public class CommandInfo { private String verb; private String className; /** * The Constructor for CommandInfo. * @param verb The command verb this CommandInfo decribes. * @param className The command's fully qualified class name. */ public CommandInfo(String verb, String className) { this.verb = verb; this.className = className; } /** * Return the command verb. * * @return the command verb. */ public String getCommandName() { return verb; } /** * Return the command's class name. <i>This method MAY return null in * cases where a CommandMap subclassed CommandInfo for its * own purposes.</i> In other words, it might not be possible to * create the correct state in the command by merely knowing * its class name. <b>DO NOT DEPEND ON THIS METHOD RETURNING * A VALID VALUE!</b> * * @return The class name of the command, or <i>null</i> */ public String getCommandClass() { return className; } /** * Return the instantiated JavaBean component. * <p> * Begin by instantiating the component with * <code>Beans.instantiate()</code>. * <p> * If the bean implements the <code>javax.activation.CommandObject</code> * interface, call its <code>setCommandContext</code> method. * <p> * If the DataHandler parameter is null, then the bean is * instantiated with no data. NOTE: this may be useful * if for some reason the DataHandler that is passed in * throws IOExceptions when this method attempts to * access its InputStream. It will allow the caller to * retrieve a reference to the bean if it can be * instantiated. * <p> * If the bean does NOT implement the CommandObject interface, * this method will check if it implements the * java.io.Externalizable interface. If it does, the bean's * readExternal method will be called if an InputStream * can be acquired from the DataHandler.<p> * * @param dh The DataHandler that describes the data to be * passed to the command. * @param loader The ClassLoader to be used to instantiate the bean. * @return The bean * @see java.beans.Beans#instantiate * @see javax.activation.CommandObject */ public Object getCommandObject(DataHandler dh, ClassLoader loader) throws IOException, ClassNotFoundException { Object new_bean = null; // try to instantiate the bean new_bean = java.beans.Beans.instantiate(loader, className); // if we got one and it is a CommandObject if (new_bean != null) { if (new_bean instanceof CommandObject) { ((CommandObject)new_bean).setCommandContext(verb, dh); } else if (new_bean instanceof Externalizable) { if (dh != null) { InputStream is = dh.getInputStream(); if (is != null) { ((Externalizable)new_bean).readExternal( new ObjectInputStream(is)); } } } } return new_bean; } }