Jsf 对managedbean调用的taglib调用

我有这样一个托管bean（会话范围）：

class Home {// as homeBean
  public void doSomething(ActionEvent ae, int a, int b){
    System.out.println("result="+(a+b));
  }
}

我喜欢称之为

<a4j:commandLink actionListener="#{homeBean:doSomething(1,2)}"/>

---

动态调用它怎么样？使用bcel或URLClassLoader？

此EL表达式语法仅用于静态方法，必须在标记库中定义，并在视图中定义命名空间：

 #{namespacePrefix:fn(arg)}

此EL表达式调用对象实例上的：

#{someInstance.method(arg)}

第二种形式在或更高版本（JavaEE6）中提供。在此之前，一些第三方JSF库支持类似的表达式

只要托管bean在JSF上下文中执行，就可以从静态方法中查找它：

FacesContext context = FacesContext.getCurrentInstance();
SomeBean someBean = context.getApplication()
                           .evaluateExpressionGet(context, 
                                                  "#{someBean}", SomeBean.class);

然而，这不是理想的方法。这段代码是针对JSF2编写的；以前的版本使用不同的动态查找调用

如果需要静态方法中的bean，请使用以下形式的表达式：

#{namespacePrefix:fn(someBean, 1, 2)}

---

哦，酷，我找到了一种工作方式：

public class ... implements TagLibrary {

@Override
public Method createFunction(String taglib, String functionName) {
    if (!map.containsKey(functionName)) {

        String classname = "de.Test" + functionName;
        ClassGen _cg = new ClassGen(classname,
                "java.lang.Object", "Test.java", ACC_PUBLIC | ACC_SUPER,
                new String[] {});
        ConstantPoolGen _cp = _cg.getConstantPool();
        InstructionFactory _factory = new InstructionFactory(_cg, _cp);

        Method meth = find(functionName, getNavigation());
        Class<?>[] parameterTypes = meth.getParameterTypes();
        int countParams = parameterTypes.length;
        Type[] types = new Type[countParams];
        String[] names = new String[countParams];
        for (int i = 0; i < countParams; i++) {
            types[i] = new ObjectType(parameterTypes[i].getName());
            names[i] = "arg" + i;
        }

        InstructionList il = new InstructionList();

        MethodGen staticMethod = new MethodGen(ACC_PUBLIC | ACC_STATIC,
                Type.OBJECT, types, names, functionName, getClass()
                        .getName(), il, _cp);

        InstructionHandle ih_1 = il.append(new PUSH(_cp, functionName));
        il.append(new PUSH(_cp, countParams));

        il.append(_factory.createNewArray(Type.OBJECT, (short) 1));
        il.append(InstructionConstants.DUP);

        for (int i = 0; i < countParams; i++) {
            il.append(new PUSH(_cp, i));

            il.append(_factory.createLoad(Type.OBJECT, i));
            il.append(InstructionConstants.AASTORE);
            if (i != countParams - 1)
                il.append(InstructionConstants.DUP);
        }

        il.append(_factory.createInvoke(getClass().getName(),
                "call", Type.OBJECT, new Type[] { Type.STRING,
                        new ArrayType(Type.OBJECT, 1) },
                Constants.INVOKESTATIC));
        InstructionHandle ih_25 = il.append(_factory
                .createReturn(Type.OBJECT));
        staticMethod.setMaxStack();
        staticMethod.setMaxLocals();
        _cg.addMethod(staticMethod.getMethod());
        il.dispose();

        try {

            byte[] bytes = _cg.getJavaClass().getBytes();

            InjectingClassLoader icl = new InjectingClassLoader();

            Method find = 
                    find(functionName, icl.load(classname, bytes));

            map.put(functionName, find);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    Method method = map.get(functionName);
    return method;

}

public static Object call(String functionname, Object[] arguments) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
    Navigation myTargetBean = getNavigation();
    Method proxyMethod = find(functionname,myTargetBean);

    Object result = proxyMethod.invoke(myTargetBean, arguments);

    return result;
}

公共类。。。实现标记库{
@凌驾
公共方法createFunction（字符串taglib、字符串functionName）{
if（！map.containsKey（functionName））{
字符串classname=“de.Test”+函数名；
ClassGen _cg=新的ClassGen（classname，
“java.lang.Object”、“Test.java”、ACC|u PUBLIC | ACC|u SUPER、，
新字符串[]{}）；
ConstantPoolGen _cp=_cg.getConstantPool（）；
指令工厂_工厂=新指令工厂（_cg，_cp）；
方法meth=find（functionName，getNavigation（））；
类[]parameterTypes=meth.getParameterTypes（）；
int countParams=参数类型.length；
类型[]类型=新类型[countParams]；
字符串[]名称=新字符串[countParams]；
for（int i=0；i

---

现在，我可以调用#{cms:doSomething（1,2）}

您有JSF1.2的“简单”方法吗？“简单”对我来说意味着不需要所有这些getter-setter-header。如果您碰巧运行Servlet 2.5，您可以安装JBoss EL来实现类似EL 2.2的增强。

public class ... implements TagLibrary {

@Override
public Method createFunction(String taglib, String functionName) {
    if (!map.containsKey(functionName)) {

        String classname = "de.Test" + functionName;
        ClassGen _cg = new ClassGen(classname,
                "java.lang.Object", "Test.java", ACC_PUBLIC | ACC_SUPER,
                new String[] {});
        ConstantPoolGen _cp = _cg.getConstantPool();
        InstructionFactory _factory = new InstructionFactory(_cg, _cp);

        Method meth = find(functionName, getNavigation());
        Class<?>[] parameterTypes = meth.getParameterTypes();
        int countParams = parameterTypes.length;
        Type[] types = new Type[countParams];
        String[] names = new String[countParams];
        for (int i = 0; i < countParams; i++) {
            types[i] = new ObjectType(parameterTypes[i].getName());
            names[i] = "arg" + i;
        }

        InstructionList il = new InstructionList();

        MethodGen staticMethod = new MethodGen(ACC_PUBLIC | ACC_STATIC,
                Type.OBJECT, types, names, functionName, getClass()
                        .getName(), il, _cp);

        InstructionHandle ih_1 = il.append(new PUSH(_cp, functionName));
        il.append(new PUSH(_cp, countParams));

        il.append(_factory.createNewArray(Type.OBJECT, (short) 1));
        il.append(InstructionConstants.DUP);

        for (int i = 0; i < countParams; i++) {
            il.append(new PUSH(_cp, i));

            il.append(_factory.createLoad(Type.OBJECT, i));
            il.append(InstructionConstants.AASTORE);
            if (i != countParams - 1)
                il.append(InstructionConstants.DUP);
        }

        il.append(_factory.createInvoke(getClass().getName(),
                "call", Type.OBJECT, new Type[] { Type.STRING,
                        new ArrayType(Type.OBJECT, 1) },
                Constants.INVOKESTATIC));
        InstructionHandle ih_25 = il.append(_factory
                .createReturn(Type.OBJECT));
        staticMethod.setMaxStack();
        staticMethod.setMaxLocals();
        _cg.addMethod(staticMethod.getMethod());
        il.dispose();

        try {

            byte[] bytes = _cg.getJavaClass().getBytes();

            InjectingClassLoader icl = new InjectingClassLoader();

            Method find = 
                    find(functionName, icl.load(classname, bytes));

            map.put(functionName, find);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    Method method = map.get(functionName);
    return method;

}

public static Object call(String functionname, Object[] arguments) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException {
    Navigation myTargetBean = getNavigation();
    Method proxyMethod = find(functionname,myTargetBean);

    Object result = proxyMethod.invoke(myTargetBean, arguments);

    return result;
}