Struts2 基础总结

1 Struts2中获取Action的方式：

    可以通过继承ActionSupport的方式获取；

2 Struts2中常用 的传递参数方式：

    a:可以通过属性传递参数，表单的属性名称和javabean的属性名称相对应，在Action添加对应的属性，并设置get和set方法即可；

    b:可以通过javabean传递参数，Action中设置javabean类型的属性，添加get和set方法，表单中使用，对象.属性的形式作为属性名称；

3 struts2访问servletAPI:

    访问假的API(用Map模拟的ServletAPI):

     实例化ActionContext，由此获取;

package com.st.action;

import java.util.HashMap;
import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
import com.st.user.User;

public class LoginAction extends ActionSupport {
	private Map<String, Object> request=new HashMap<String, Object>();
	private Map<String, Object> session=new HashMap<String, Object>();
	private Map<String, Object> application=new HashMap<String, Object>();
	private User user;	
    public User getUser() {
		return user;
	}

	public void setUser(User user) {
		this.user = user;
	}


	public String checkLogin(){
		ActionContext actionContext=ActionContext.getContext();
		request=(Map<String, Object>) actionContext.get("request");
		session=actionContext.getSession();
		application=actionContext.getApplication();
		
		request.put("r", "request中的值");
		session.put("s", "session中的值");
		application.put("a", "application中的值");
		return "suc";
	}
}

        访问真的ServletAPI:

        用到ServletActionContext,来获取request;

package com.st.action;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
import com.st.user.User;

public class LoginAction extends ActionSupport {
	HttpServletRequest request=null;
	HttpSession session=null;
	ServletContext application=null;
	private User user;	
    public User getUser() {
		return user;
	}

	public void setUser(User user) {
		this.user = user;
	}


	public String checkLogin(){		
		request=ServletActionContext.getRequest();
		session=request.getSession();
		application=session.getServletContext();
		
		request.setAttribute("r", "request中的值");
		session.setAttribute("s", "session中的值");
		application.setAttribute("a", "application中的值");
		return "suc";
	}
}

 4 struts2中的拦截器：

     继承于AbstractInterceptor,在struts.xml声明拦截器，在Action配置拦截器；

package com.st.in;

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

public class LoginInterceptor extends AbstractInterceptor {

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		System.out.println("in Interceptor");
		String result=invocation.invoke();
		System.out.println("out Interceptor");
		return result;
	}

}

package com.st.in;

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

public class TwoIntercepto extends AbstractInterceptor {

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		System.out.println("in 2 Interceptor");
		String res=invocation.invoke();
		System.out.println("out 2 Interceptor");
		return res;
	}

}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
	"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
	"http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>	
	<package name="user" namespace="/user" extends="struts-default"> 

		<interceptors>
			<interceptor name="loginIn" class="com.st.in.LoginInterceptor"></interceptor>
			<interceptor name="twoIn" class="com.st.in.TwoIntercepto"></interceptor>
			<interceptor-stack name="allIn">
				<interceptor-ref name="defaultStack"></interceptor-ref>
				<interceptor-ref name="loginIn"></interceptor-ref>
				<interceptor-ref name="twoIn"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
        <action name="login" class="com.st.action.LoginAction" method="checkLogin">            	
        	<interceptor-ref name="allIn"></interceptor-ref>
        	<result name="suc">/success.jsp</result>         	       	
        </action>        
   </package>   
</struts>

说明 invocation.invoke();是执行下一个资源，进入下一个拦截器或者Action等；如果没有执行invocation.invoke()，将根据return的字符串在struts.xml匹配result。

拦截用户名 aaa，若出现，跳转到haha.jsp.没有出现最终执行action;

package com.st.in;

import java.util.Map;

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

public class LoginInterceptor extends AbstractInterceptor {

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		
		Map<String, Object> request=(Map<String, Object>) ActionContext.getContext().get("request");
		String uname=(String) request.get("user.uname");
		System.out.println(uname);
		if(uname.equals("aaa")){
        	return "haha";
        }	
		String result=invocation.invoke();
        	
		return result;
	}

}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
	"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
	"http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>	
	<package name="user" namespace="/user" extends="struts-default"> 

		<interceptors>
			<interceptor name="loginIn" class="com.st.in.LoginInterceptor"></interceptor>
			<interceptor name="twoIn" class="com.st.in.TwoIntercepto"></interceptor>
			<interceptor-stack name="allIn">
				<interceptor-ref name="defaultStack"></interceptor-ref>
				<interceptor-ref name="loginIn"></interceptor-ref>
				<interceptor-ref name="twoIn"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
        <action name="login" class="com.st.action.LoginAction" method="checkLogin">            	
        	<interceptor-ref name="allIn"></interceptor-ref>
        	<result name="suc">/success.jsp</result>         	       	
        	<result name="haha">/haha.jsp</result>         	       	
        </action>        
   </package>   
</struts>

5 struts2的路径问题：

   当struts2返回页面的路径含有namespace的时候，在该页面跳转到其他jsp页面会产生报错，原因是此时连接含有namespace，此时可以使用跟路径解决此问题。

   在返回的jsp页面加上：

 <%
  String path=request.getContextPath();
    String basePath=request.getScheme()+"://"+request.getServerName()+":"
  +request.getServerPort()+path+"/";
 %>

<base href="<%=basePath %>">

此时页面跳转默认是在basePath基础上的，可以避免命名空间带来的问题；

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
 <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
 <%
 	String path=request.getContextPath();
    String basePath=request.getScheme()+"://"+request.getServerName()+":"
 	+request.getServerPort()+path+"/";
 %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<base href="<%=basePath %>">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
${request.r}<br>
${session.s}<br>
${application.a}<br>
<a href="haha.jsp">haha</a>
</body>
</html>

Struts2 基础总结

原文：http://blog.csdn.net/liangwenmail/article/details/47403173