struts2学习笔记十（第10讲.Struts2的核心 拦截器）

Struts2的核心 拦截器

一、修改RegisterAction.java类，在validate方法中添加一条错误信息语句this.addFieldError("username", "aaaaaaaaaaaaaaa");：

package com.test.action;

import java.util.Calendar;
import java.util.Date;

import com.opensymphony.xwork2.ActionSupport;

public class RegisterAction extends ActionSupport {
	
	private String username;
	
	private String password;
	
	private String repassword;
	
	private int age;
	
	private Date birthday;
	
	private Date graduation;

	public String getUsername() {
		return username;
	}

	public void setUsername(String username) {
		this.username = username;
	}

	public String getPassword() {
		return password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

	public String getRepassword() {
		return repassword;
	}

	public void setRepassword(String repassword) {
		this.repassword = repassword;
	}

	public int getAge() {
		return age;
	}

	public void setAge(int age) {
		this.age = age;
	}

	public Date getBirthday() {
		return birthday;
	}

	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}

	public Date getGraduation() {
		return graduation;
	}

	public void setGraduation(Date graduation) {
		this.graduation = graduation;
	}

	@Override
	public String execute() throws Exception {
		
		return SUCCESS;
	}
//	public String abc() throws Exception {
//		
//		System.out.println("abc() method invoked");
//		return SUCCESS;
//	}
//	
//	public void validateAbc(){
//		
//		System.out.println("validateAbc() invoked");
//	}

	@Override
	public void validate() {
		
		System.out.println("validate~~~~~~~~~~~~~~");
		
		this.addFieldError("username", "aaaaaaaaaaaaaaa");
		
//		if(null == username || username.length() < 6 || username.length() > 10){
//			this.addActionError("username invalid");
//		}
//		if(null == password || password.length() <6 || password.length() > 10){
//			this.addActionError("password invalid");
//		}
//		else if(null == repassword || repassword.length() < 6 || repassword.length() > 10){
//			this.addActionError("repassword invalid");
//		}
//		else if(!password.equals(repassword)){
//			this.addFieldError("password", "two passwords not the same");
//		}
//		if(age <= 0 || age > 150){
//			this.addActionError("age should be between 1 and 150");
//		}
//
//		if(null != birthday && null != graduation){
//			Calendar c1 = Calendar.getInstance();
//			c1.setTime(birthday);
//			
//			Calendar c2 = Calendar.getInstance();
//			c2.setTime(graduation);
//			
//			if(!c1.before(c2)){
//				this.addActionError("birthday should be before graduation");
//			}
//		}
	}
}

当表单所有的输入都为空，会出现下面的效果：


说明：不管是何种验证方式，最终的错误信息都会放到fielderror里面去，最终出现验证重复的现象。
笔记：
1、真正存放field级别的错误信息的对象是LinkedHashMap
2、该LinkedHashMap的key是String类型的，value是ArrayList类型的
3、对于Action级别的错误信息实际上是放置在ArrayList中的
4、拦截器：Interceptor
功能：拦截器的实现机制：
二、在src下创建com.interceptor包，并在这个包下创建一个Target类和一个TargetInterface接口：
Target.java:

package com.interceptor;

public class Target implements TargetInterface{
	public void doSomething(){
		System.out.println("do something");
	}
}

TargetInterface.java:

package com.interceptor;

public interface TargetInterface {
	public void doSomething();
}

三、在同一目录下创建一个拦截器Interceptor.java:

package com.interceptor;

public class Intercepoter {
	public void before(){
		System.out.println("before");
	}
	public void after(){
		System.out.println("after");
	}
}

四、在同一目录下再创建一个处理器类MyHandker.java:

package com.interceptor;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

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;
	}

}

五、再创建一个代理类MyProxy.java类（作用是为了产生一个代理）：

package com.interceptor;

import java.lang.reflect.Proxy;

public class MyProxy {
	public Object getProxy(Object object){
		MyHandler myHandler = new MyHandler();
		
		myHandler.setObject(object);
		
		return Proxy.newProxyInstance(Target.class.getClassLoader(), 
				object.getClass().getInterfaces(), myHandler);
	}
}

六、再创建一个Client.java类：

package com.interceptor;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

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;
	}
}