Struts2学习笔记11:Struts2的拦截器
第十讲
真正存放field级别错误信息对象是LinkedHashMap |
该LinkedHashMap的key是String类型的,value是ArrayList类型的 |
addFiled(String fieldName,String errorMessage) fieldName的存放容器类型是String errorMessage的存放容器类型是ArrayList |
XML文件先实行,完毕后 再执行validate()方法 |
对于Action级别的错误信息,实际上是放置在ArrayList中的 |
拦截器的基础应用
建立文件
Target.java
TargetInterface.java
Interceptor.java
MyHandler.java
MyProxy.java
Client.java
Target.java文件内容:
package test;
/*
* 目标对象
*/
public class Target implements TargetInterface {
public void doSomething() {
System.out.println("dosomething");
}
}
TargetInterface.java文件内容:
package test;
public interface TargetInterface {
public void doSomething();
}
Interceptor.java文件内容:
package test;
/*
* 拦截器
*/
public class Interceptor {
public void before(){
System.out.println("before");
}
public void after(){
System.out.println("after");
}
}
MyHandler.java文件内容:
package test;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
/*
* 反射处理器类
*/
public class MyHandler implements InvocationHandler{
private Object object;
private Interceptor interceptor = new Interceptor();
public void setObject(Object object) {
this.object = object;
}
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable {
Object result = null;
interceptor.before();
result = method.invoke(object, args);
interceptor.after();
return result;
}
}
MyProxy.java文件内容:
package test;
import java.lang.reflect.Proxy;
/*
* 代理类
*/
public class MyProxy {
public Object getObject( Object object ){
//代理是动态生成的
MyHandler myHandler = new MyHandler();
myHandler.setObject( object );
return Proxy.newProxyInstance(
Target.class.getClassLoader(),
object.getClass().getInterfaces(),
myHandler);
}
}
Client.java文件内容:
package test;
public class Client {
/**
* @param args
*/
public static void main(String[] args) {
TargetInterface target = new Target();
MyProxy myProxy = new MyProxy();
TargetInterface proxy = (TargetInterface)myProxy.getObject(target);
proxy.doSomething();
}
}
运行结果:
before
dosomething
after