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;
     }
 }