Struts2（三）

以下内容是基于导入struts2-2.3.32.jar包来讲的

1.全局视图配置

xml标签：
<global-results>
    <result name="error">/error.jsp</result>
</global-results>

package com.ronng.web.action;

public class TwoAction {
    public String show(){
        return "error";
    }
    
    public String look(){
        return "error";
    }
}

<?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="com.rong.web.action" namespace="/" extends="struts-default">
        <!-- 全局视图。当action标签里面不包含result标签时，就会寻找全局的global-results结果视图 -->
        <global-results>
            <result name="error">/error.jsp</result>
        </global-results>
        <action name="error1" class="com.ronng.web.action.TwoAction" method="show">
        </action>
        <action name="error2" class="com.ronng.web.action.TwoAction" method="look">
        </action>
    </package>
    
</struts>

访问路径：

http://localhost:8080/struts/error1

http://localhost:8080/struts/error2

返回的都是同一个error.jsp页面

2.全局的异常配置

package com.ronng.web.action;

public class TwoAction {
    public String show() throws Exception{
        //抛出异常，无法返回"error"字符串
        int number=1/0;
        return "error";
    }
    
    public String look()throws Exception{
        return "error";
    }
}

struts.xml配置是有顺序的：全局结果视图需要放在全局异常的前面

<?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="com.rong.web.action" namespace="/" extends="struts-default">
        
        <!-- 全局视图。当action标签里面不包含result标签时，就会寻找全局的global-results结果视图 -->
        <global-results>
            <result name="error">/error.jsp</result>
            <result name="exception">/exception.jsp</result>
        </global-results>
        <!-- 全局异常配置 。result对应全局视图的result的name-->
        <global-exception-mappings>
            <exception-mapping result="exception" exception="java.lang.Exception"></exception-mapping>
        </global-exception-mappings>
        <action name="error1" class="com.ronng.web.action.TwoAction" method="show">
        </action>
        <action name="error2" class="com.ronng.web.action.TwoAction" method="look">
        </action>
    </package>
    
</struts>

以上的方法不能处理类似404的错误，若要处理404错误，则只需要修改web.xml配置文件

<error-page>标签配置

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>struts</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <filter>
      <filter-name>struts2</filter-name>
      <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  <filter-mapping>
      <filter-name>struts2</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <error-page>
      <error-code>404</error-code>
      <location>/404.jsp</location>
  </error-page>
</web-app>

3.最简单的action配置

<?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="com.rong.web.action" namespace="/" extends="struts-default">
        <!-- 最简单的action
            class 默认是struts-default.xml的  
                <default-class-ref class="com.opensymphony.xwork2.ActionSupport" />
            默认执行的method 是 execute
            方法默认的返回值是什么 "success"
         -->
        <!-- 对于最简单的action也就是
        没有配置class的action要执行的哪个action,
        可以不使用默认的，重新配置 ,但是依然会使用默认的 execute方法-->
        <default-class-ref class="com.ronng.web.action.OneAction"></default-class-ref>
        <action name="simple">
            <result>/index.jsp</result>
        </action>
    </package>
    
</struts>

4.路径访问搜索顺序

<?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>
    <!-- 
        资源路径
        http://localhost:8080/struts/search
        http://localhost:8080/struts/aa/bb/cc/search
        以上两种方式均可访问到同一页面
        其中http://localhost:8080/struts是服务器以及项目信息
            主要看这段：/aa/bb/cc/search
            搜索顺序：没找到时继续往前找，由于search是action里面的name路径，所以最后才判断
            先判断package，最后才判断action
                namespace是/aa/bb/cc
                namespace是/aa/bb
                namespace是/aa
                namespace是/
                有这个/的命名空间了
                    那就在这个命名空间的action里找search
     -->
    <!-- namespace命名空间不写时，默认是斜杠"/" -->
    <package name="com.rong.web.action" namespace="/" extends="struts-default">
        <action name="search" class="com.ronng.web.action.OneAction">
            <result>/index.jsp</result>
        </action>
    </package>
    
</struts>

 5.获取域对象以及ActionContext上下文

A.第一种方式（通过ServletActionContext获取）

package com.ronng.web.action;

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

import org.apache.struts2.ServletActionContext;

/**
 * 普通类获取域对象
 * 通过ServletActionContext获取
 * @author Rong
 *
 */
public class TwoAction {
    public String show() throws Exception{
        //使用原生API,耦合度高，很少使用
        PageContext pageContext = ServletActionContext.getPageContext();
        //可通过pageContext获取其余域对象
//        ServletRequest request = pageContext.getRequest();
//        HttpSession session = pageContext.getSession();
//        ServletContext application = pageContext.getServletContext();
        HttpServletRequest request = ServletActionContext.getRequest();
        //获取前台传过来的值
        String parameter = request.getParameter("name");
        System.out.println(parameter);
        HttpSession session = request.getSession();
        ServletContext application = ServletActionContext.getServletContext();
        request.setAttribute("name", "rong");
        session.setAttribute("name", "jie");
        application.setAttribute("name", "long");
        return "success";
    }
}

<body>
    通用的域： ${name }<br/>
    request域:${requestScope.name }<br/>
    session域：${sessionScope.name }<br/>
    application域：${applicationScope.name }<br/>
</body>

<?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="com.rong.web.action" namespace="/" extends="struts-default">
        <action name="search" class="com.ronng.web.action.TwoAction" method="show">
            <result>/two.jsp</result>
        </action>
    </package>
</struts>

B.第二种方式（ActionContext上下文的get方式）

package com.ronng.web.action;

import org.apache.struts2.dispatcher.ApplicationMap;
import org.apache.struts2.dispatcher.RequestMap;
import org.apache.struts2.dispatcher.SessionMap;

import com.opensymphony.xwork2.ActionContext;

/**
 * 普通类获取域对象
 * 通过ActionContext上下文get方式获取
 * 松耦合
 * @author Rong
 */
public class TwoAction {
    public String show() throws Exception{
        //获取ActionContext上下文。ActionContext在请求最开始的时候封装了所有数据。
        ActionContext actionContext = ActionContext.getContext();
        //通过get方法获取域对象。其中get里面的字符串是唯一指定的。
        RequestMap requestMap = (RequestMap) actionContext.get("request");
        SessionMap<String, Object> sessionMap = (SessionMap<String, Object>) actionContext.get("session");
        ApplicationMap applicationMap = (ApplicationMap) actionContext.get("application");
        requestMap.put("name", "rong");
        sessionMap.put("name", "jie");
        applicationMap.put("name", "long");
        return "success";
    }
}

C.第三种方式（ActionContext上下文的getXxx方式）

package com.ronng.web.action;

import java.util.Map;

import com.opensymphony.xwork2.ActionContext;

/**
 * 普通类获取域对象
 * 通过ActionContext上下文getXxx方式获取
 * 松耦合
 * @author Rong
 */
public class TwoAction {
    public String show() throws Exception{
        //获取ActionContext上下文。ActionContext在请求最开始的时候封装了所有数据。
        ActionContext actionContext = ActionContext.getContext();
        Map<String, Object> request = actionContext.getContextMap();
        Map<String, Object> session = actionContext.getSession();
        Map<String, Object> application = actionContext.getApplication();
        request.put("name", "rong");
        session.put("name", "jie");
        application.put("name", "long");
        return "success";
    }
}

D.第四种方式（实现XxxAware接口）

根据需要实现不同域的接口

package com.ronng.web.action;

import java.util.Map;

import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;


/**
 * 实现接口方式获取域对象
 * 松耦合
 * @author Rong
 * 这里列举了实现多种域接口，实际根据自己需要实现接口
 */
public class TwoAction implements RequestAware,SessionAware,ApplicationAware{
    //需要自己去声明成员变量（域对象）
    private Map<String, Object> request;
    private Map<String, Object> session;
    private Map<String, Object> applicaton;
    public String show() throws Exception{
        request.put("name", "r");
        session.put("name", "j");
        applicaton.put("name", "l");
        return "success";
    }
    //域对象赋值
    @Override
    public void setApplication(Map<String, Object> arg0) {
        this.applicaton=arg0;
    }

    @Override
    public void setSession(Map<String, Object> arg0) {
        this.session=arg0;
    }

    @Override
    public void setRequest(Map<String, Object> arg0) {
        this.request=arg0;
    }
}