1 /*
2 * Copyright (c) 2002-2007 by OpenSymphony
3 * All rights reserved.
4 */
5 package com.opensymphony.xwork2.interceptor;
6
7 import com.opensymphony.xwork2.ActionInvocation;
8 import com.opensymphony.xwork2.Preparable;
9 import com.opensymphony.xwork2.util.logging.Logger;
10 import com.opensymphony.xwork2.util.logging.LoggerFactory;
11
12 import java.lang.reflect.InvocationTargetException;
13
14
15 /**
16 * <!-- START SNIPPET: description -->
17 *
18 * This interceptor calls <code>prepare()</code> on actions which implement
19 * {@link Preparable}. This interceptor is very useful for any situation where
20 * you need to ensure some logic runs before the actual execute method runs.
21 *
22 * <p/> A typical use of this is to run some logic to load an object from the
23 * database so that when parameters are set they can be set on this object. For
24 * example, suppose you have a User object with two properties: <i>id</i> and
25 * <i>name</i>. Provided that the params interceptor is called twice (once
26 * before and once after this interceptor), you can load the User object using
27 * the id property, and then when the second params interceptor is called the
28 * parameter <i>user.name</i> will be set, as desired, on the actual object
29 * loaded from the database. See the example for more info.
30 *
31 * <p/>
32 * <b>Note:</b> Since XWork 2.0.2, this interceptor extends {@link MethodFilterInterceptor}, therefore being
33 * able to deal with excludeMethods / includeMethods parameters. See [Workflow Interceptor]
34 * (class {@link DefaultWorkflowInterceptor}) for documentation and examples on how to use this feature.
35 *
36 * <p/><b>Update</b>: Added logic to execute a prepare{MethodName} and conditionally
37 * the a general prepare() Method, depending on the 'alwaysInvokePrepare' parameter/property
38 * which is by default true. This allows us to run some logic based on the method
39 * name we specify in the {@link com.opensymphony.xwork2.ActionProxy}. For example, you can specify a
40 * prepareInput() method that will be run before the invocation of the input method.
41 *
42 * <!-- END SNIPPET: description -->
43 *
44 * <p/> <u>Interceptor parameters:</u>
45 *
46 * <!-- START SNIPPET: parameters -->
47 *
48 * <ul>
49 *
50 * <li>alwaysInvokePrepare - Default to true. If true, prepare will always be invoked,
51 * otherwise it will not.</li>
52 *
53 * </ul>
54 *
55 * <!-- END SNIPPET: parameters -->
56 *
57 * <p/> <u>Extending the interceptor:</u>
58 *
59 * <p/>
60 *
61 * <!-- START SNIPPET: extending -->
62 *
63 * There are no known extension points to this interceptor.
64 *
65 * <!-- END SNIPPET: extending -->
66 *
67 * <p/> <u>Example code:</u>
68 *
69 * <pre>
70 * <!-- START SNIPPET: example -->
71 * <!-- Calls the params interceptor twice, allowing you to
72 * pre-load data for the second time parameters are set -->
73 * <action name="someAction" class="com.examples.SomeAction">
74 * <interceptor-ref name="params"/>
75 * <interceptor-ref name="prepare"/>
76 * <interceptor-ref name="basicStack"/>
77 * <result name="success">good_result.ftl</result>
78 * </action>
79 * <!-- END SNIPPET: example -->
80 * </pre>
81 *
82 * @author Jason Carreira
83 * @author Philip Luppens
84 * @author tm_jee
85 * @see com.opensymphony.xwork2.Preparable
86 */
87 public class PrepareInterceptor extends MethodFilterInterceptor {
88
89 private static final long serialVersionUID = -5216969014510719786L;
90
91 private static final Logger LOG = LoggerFactory.getLogger(PrepareInterceptor.class);
92
93 private final static String PREPARE_PREFIX = "prepare";
94 private final static String ALT_PREPARE_PREFIX = "prepareDo";
95
96 private boolean alwaysInvokePrepare = true;
97
98 /**
99 * Sets if the <code>preapare</code> method should always be executed.
100 * <p/>
101 * Default is <tt>true</tt>.
102 *
103 * @param alwaysInvokePrepare if <code>prepare</code> should always be executed or not.
104 */
105 public void setAlwaysInvokePrepare(String alwaysInvokePrepare) {
106 this.alwaysInvokePrepare = Boolean.parseBoolean(alwaysInvokePrepare);
107 }
108
109 @Override
110 public String doIntercept(ActionInvocation invocation) throws Exception {
111 Object action = invocation.getAction();
112
113 if (action instanceof Preparable) {
114 try {
115 PrefixMethodInvocationUtil.invokePrefixMethod(invocation,
116 new String[]{PREPARE_PREFIX, ALT_PREPARE_PREFIX});
117 }
118 catch (InvocationTargetException e) {
119 // just in case there's an exception while doing reflection,
120 // we still want prepare() to be able to get called.
121 LOG.warn("an exception occured while trying to execute prefixed method", e);
122 }
123 catch (IllegalAccessException e) {
124 // just in case there's an exception while doing reflection,
125 // we still want prepare() to be able to get called.
126 LOG.warn("an exception occured while trying to execute prefixed method", e);
127 } catch (Exception e) {
128 // just in case there's an exception while doing reflection,
129 // we still want prepare() to be able to get called.
130 LOG.warn("an exception occured while trying to execute prefixed method", e);
131 }
132
133 if (alwaysInvokePrepare) {
134 ((Preparable) action).prepare();
135 }
136 }
137
138 return invocation.invoke();
139 }
140
141 }
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