Source Code Cross Referenced for Bean.java in  » J2EE » webwork-2.2.6 » com » opensymphony » webwork » components » Java Source Code / Java DocumentationJava Source Code and Java Documentation

001:        package com.opensymphony.webwork.components;
002:
003:        import com.opensymphony.util.ClassLoaderUtil;
004:        import com.opensymphony.xwork.ObjectFactory;
005:        import com.opensymphony.xwork.util.OgnlUtil;
006:        import com.opensymphony.xwork.util.OgnlValueStack;
007:        import org.apache.commons.logging.Log;
008:        import org.apache.commons.logging.LogFactory;
009:
010:        import java.io.Writer;
011:
012:        /**
013:         * <!-- START SNIPPET: javadoc -->
014:         * <p>Instantiates a class that conforms to the JavaBeans specification. This tag has a body which can contain
015:         * a number of {@link Param} elements to set any mutator methods on that class.</p>
016:         * <p/>
017:         * <p>If the id attribute is set on the BeanTag, it will place the instantiated bean into the
018:         * stack's Context.</p>
019:         * <p/>
020:         * <!-- END SNIPPET: javadoc -->
021:         *
022:         *
023:         * <!-- START SNIPPET: params -->
024:         * <ul>
025:         * 		<li>id - the stack's context id (if supplied) that the created bean will be store under</li>
026:         * 		<li>name* - the class name of the bean to be instantiated (must respect JavaBean specification)</li>
027:         * </ul>
028:         * <!-- END SNIPPET: params -->
029:         *
030:         *
031:         * <p>Examples:</p>
032:         * <p/>
033:         * <pre>
034:         * <!-- START SNIPPET: examples -->
035:         * &lt;-- in freemarker form --&gt;
036:         * [ww.bean name="com.opensymphony.webwork.example.counter.SimpleCounter" id="counter"]
037:         *   [ww:param name="foo" value="BAR"/]
038:         *   The value of foo is : [ww:property value="foo"/], when inside the bean tag.<br />
039:         * [/ww:bean]
040:         *
041:         * &lt;-- in jsp form --&gt;
042:         * &lt;ww:bean name="com.opensymphony.webwork.example.counter.SimpleCounter" id="counter"&gt;
043:         * 	 &lt;ww:param name="foo" value="BAR" /&gt;
044:         *   The value of foot is : &lt;ww:property value="foo"/&gt;, when inside the bean tag &lt;br /&gt;
045:         * &lt;/ww:bean&gt;
046:         * <!-- END SNIPPET: examples -->
047:         * </pre>
048:         * <p/>
049:         *
050:         * <!-- START SNIPPET: examplesdescription -->
051:         * <p>This example instantiates a bean called SimpleCounter and sets the foo property (setFoo('BAR')). The
052:         * SimpleCounter object is then pushed onto the Valuestack, which means that we can called its accessor methods (getFoo())
053:         * with the Property tag and get their values.</p>
054:         * <p/>
055:         * <p>In the above example, the id has been set to a value of <i>counter</i>. This means that the SimpleCounter class
056:         * will be placed into the stack's context. You can access the SimpleCounter class using WW's tag:</p>
057:         * <p/>
058:         * <pre>
059:         * &lt;-- jsp form --&gt;
060:         * &lt;ww:property value="#counter" /&gt;
061:         *
062:         * &lt;-- freemarker form --&gt;
063:         * [ww:property value="#counter.foo"/]
064:         * </pre>
065:         * <p/>
066:         * <p>In the property tag example, the <i>#</i> tells Ognl to search the context for the SimpleCounter class which has
067:         * an id(key) of <i>counter</i></p>
068:         * <!-- END SNIPPET: examplesdescription -->
069:         *
070:         * @author $author$
071:         * @author Rick Salsa (rsal@mb.sympatico.ca)
072:         * @author Brock Bulger
073:         * @author Rene Gielen
074:         * @version $Revision: 2468 $
075:         * @since 2.2
076:         *
077:         * @see Param
078:         *
079:         * @ww.tag name="bean" tld-body-content="JSP" tld-tag-class="com.opensymphony.webwork.views.jsp.BeanTag"
080:         * description="Instantiate a JavaBean and place it in the context."
081:         */
082:        public class Bean extends Component {
083:            protected static Log log = LogFactory.getLog(Bean.class);
084:
085:            protected Object bean;
086:            protected String name;
087:
088:            public Bean(OgnlValueStack stack) {
089:                super (stack);
090:            }
091:
092:            public boolean start(Writer writer) {
093:                boolean result = super .start(writer);
094:
095:                OgnlValueStack stack = getStack();
096:
097:                try {
098:                    String beanName = findString(name, "name",
099:                            "Bean name is required. Example: com.acme.FooBean");
100:                    bean = ObjectFactory.getObjectFactory().buildBean(
101:                            ClassLoaderUtil.loadClass(beanName, getClass()),
102:                            stack.getContext());
103:                } catch (Exception e) {
104:                    log.error("Could not instantiate bean", e);
105:
106:                    return false;
107:                }
108:
109:                // push bean on stack
110:                stack.push(bean);
111:
112:                // store for reference later
113:                if (getId() != null) {
114:                    getStack().getContext().put(getId(), bean);
115:                }
116:
117:                return result;
118:            }
119:
120:            public boolean end(Writer writer, String body) {
121:                OgnlValueStack stack = getStack();
122:                stack.pop();
123:
124:                return super .end(writer, body);
125:            }
126:
127:            public void addParameter(String key, Object value) {
128:                OgnlUtil.setProperty(key, value, bean, getStack().getContext());
129:            }
130:
131:            /**
132:             * the class name of the bean to be instantiated (must respect JavaBean specification)
133:             * @ww.tagattribute required="true" type="String"
134:             */
135:            public void setName(String name) {
136:                this.name = name;
137:            }
138:        }