struts2学习笔记十二（第12讲.Struts2的文件上传和下载）

Struts2的文件上传和下载
接上节的拦截器未完成的部分。
功能：简单介绍监听器。用struts2的拦截器做一个关于权限校验的简单例子。
一、在src下创建一个包com.test.listener,然后在此包下创建一个监听器类MyListener.java继承自接口PreResultListener:

package com.test.interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;

public class MyInterceptor3 extends MethodFilterInterceptor {

	public void init(){
		System.out.println("init3");
	}
	
	@Override
	protected String doIntercept(ActionInvocation invocation) throws Exception {

		
		
		System.out.println("my interceptor3");
		
		String result = invocation.invoke();
		
		return result;
	}
}

二、将这个监听器注册到MyIntercepoter3拦截器里面去：

package com.test.interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
import com.test.listener.MyListener;

public class MyInterceptor3 extends MethodFilterInterceptor {

	public void init(){
		System.out.println("init3");
	}
	
	@Override
	protected String doIntercept(ActionInvocation invocation) throws Exception {

		invocation.addPreResultListener(new MyListener());
		
		System.out.println("my interceptor3");
		
		String result = invocation.invoke();
		
		System.out.println("after my interceptor3 finished");
		
		return result;
	}
}

说明：监听器的执行时机是在Action的execute方法（或者自己定义的方法如test()方法）执行之后，但是在返回结果之前执行。
功能：使用拦截器进行一个权限校验,用户输入用户名和密码之后跳转到register.jsp页面，不允许用户直接通过register2.jsp进行提交，如果通过register2.jsp提交的话会直接的跳转到login2.jsp页面，模拟一下。
三、在之前做的login2.jsp页面为例子，在struts.xml中修改输入成功之后跳转到register2.jsp：

<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/register2.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>

四、在com.test.interceptor中创建一个权限验证的拦截器AuthInterceptor.java继承自AbstractInterceptor类：

package com.test.interceptor;

import java.util.Map;

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

public class AuthInterceptor extends AbstractInterceptor {

	@Override
	@SuppressWarnings("unchecked")
	public String intercept(ActionInvocation invocation) throws Exception {

		Map map = invocation.getInvocationContext().getSession();
		
		if(map.get("user") == null){
			
			return Action.LOGIN;
		}
		else
		{
			return invocation.invoke();
		}
	}
}

五、修改LoginAction.java类，把用户信息存放到Session中：

package com.test.action;

import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport
{
	private String username;
	private String password;
	
	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;
	}
	
	@SuppressWarnings("unchecked")
	public String execute() throws Exception
	{
		if("zly".equals(this.getUsername().trim()) && "zly".equals(this.getPassword().trim()))
		{
			Map map = ActionContext.getContext().getSession();
			
			map.put("user", "valid");
			
			return "success";
		}
		else
		{
			this.addFieldError("username", "username or password error");
			return "failer";
		}
	}
	
	@Override
	public void validate() 
	{
		if(null == this.getUsername() || "".equals(this.getUsername().trim()))
		{
			this.addFieldError("username", "username required");
		}
		if(null == this.getPassword() || "".equals(this.getPassword().trim()))
		{
			this.addFieldError("password", "password required");
		}
	}
}

六、在struts.xml中注册拦截器，并且添加一个全局的转向global-results，设置type属性类型为重定向redirect：

<package name="struts2" extends="struts-default">
		
		<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				<param name="hello">world</param>
			</interceptor>
			
			<interceptor name="myInterceptor2" class="com.test.interceptor.MyInterceptor2">
			</interceptor>
			
			<interceptor name="myInterceptor3" class="com.test.interceptor.MyInterceptor3">
			</interceptor>
			
			<interceptor name="auth" class="com.test.interceptor.AuthInterceptor">
			</interceptor>
			
			<interceptor-stack name="myStack">
			
			<!-- 
				<interceptor-ref name="myInterceptor"></interceptor-ref>
				<interceptor-ref name="myInterceptor2"></interceptor-ref> 
			-->
				
				<interceptor-ref name="defaultStack"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
	
		<default-interceptor-ref name="myStack"></default-interceptor-ref>
	
		<global-results>
			<result name="login" type="redirect">/login2.jsp</result>
		</global-results>
		
		<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/register2.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>
		
		<action name="pointConverter" class="com.test.action.PointAction">
			<result name="success">/output.jsp</result>
		</action>
		
		<action name="register" class="com.test.action.RegisterAction" method="test">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
			<interceptor-ref name="auth"></interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
			
			<!-- 
			<interceptor-ref name="myInterceptor3">
				<param name="excludeMethods">test,execute</param>
				<param name="includeMethods">test</param>
			</interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
			 -->
		</action>
		
	</package>

关于拦截器的部分完成。
功能：struts2的上传和下载。
七、在WebRoot下创建一个文件夹upload,并且创建一个upload.jsp:

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>

	<form action="result.jsp" method="post" enctype="application/x-www-form-urlencoded">
		Information:<input type="text" name="info"><br>
		File:<input type="file" name="file"><br>
		
		<input type="submit" name="submit" value=" submit ">
		
	</form>

</body>
</html>

八、接着在创建一个结果页面result.jsp：

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<%@ page import="java.io.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>

<%
	InputStream is = request.getInputStream();

	BufferedReader br = new BufferedReader(new InputStreamReader(is));
	
	String buffer = null;
	
	while((buffer = br.readLine()) != null){
		out.print(buffer + "<br>");
	}
%>
</body>
</html>

说明：form中使用的是enctype="application/x-www-form-urlencoded"，这样是会出现编码错误的问题，所以要改成enctype="multipart/form-data"，还会出现下面的错误：

修改的方法是不加载关于struts2的内容，所以要先注销了web.xml中的下面代码：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" 
	xmlns="http://java.sun.com/xml/ns/j2ee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

	<!-- 
	<filter>
		<filter-name>struts2</filter-name>
		<filter-class>
			org.apache.struts2.dispatcher.FilterDispatcher
		</filter-class>
	</filter>

	<filter-mapping>
		<filter-name>struts2</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>
	 -->
	 <!--表示客服端发送过来的所有请求都必须由FilterDispatcher过滤器来过滤-->
</web-app>

说明：这样会把上传文件中的信息都显示出来，未完待续。