struts2

struts2:是一个按MVC模式设计的Web层框架,
 MVC是一个设计模式，它强制性的使应用程序的输入、处理和输出分开。使用MVC应用程序被分成三个核心部件：模型、视图、控制器。它们各自处理自己的任务。
　　  (1)视图是用户看到并与之交互的界面.
  (2)模型表示企业数据和业务规则.
  (3)控制器接受用户的输入并调用模型和视图去完成用户的需求.
 1:
  加入struts2能力
 2:
  加入请求
 3:
  描述回应类Action类
   public class TestAction{
    public String execute(){
     return "success";
    }
   }  
 4:
  在/struts.xml文件中
   <!-- 修改默认尾椎(尾椎默认为action).改变常量struts.action.extension的属性值 -->
   <constant name="struts.action.extension" value="do"></constant>
  
   <!-- 包配置,一般一个模块写在一个包中 .
   name:代表包名,如果配置文件中出现多个包,包名不能相同
   extends:代表继承struts的默认包,继承默认包中所有默认的增强方式
   namespace:代表请求模块的名称
   action中的method:不写时默认执行execute方法.可以使用method指定本次执行哪个方法
   -->
   <package name="test" extends="struts-default" namespace="/">
    <action name="testAction" class="action.TestAction" method="execute">
     <!-- type不写时默认为dispatcher:内部转  redirect:重定向
      重动向的访问方式:"${pageContext.request.contextPath}/testAction!query.action?test.id="+id+"&test.name="+name;
     -->
     <result name="success" type="dispatcher">test/result.jsp</result>
     <result name="fail" type="redirect">testAction!test.action</result>
    </action>
   </package>
   
 5:
  加入web能力:对象的获得方式
   1.
    public class TestAction implements ServletRequestAware,ServletResponseAware{
     private HttpServletRequest request;
     private HttpServletResponse response;
     public void setServletRequest(HttpServletRequest request) {
      this.request=request;
     }
     public void setServletResponse(HttpServletResponse response) {
      this.response=response;
     }
    }
   2.
    HttpServletRequest request = ServletActionContext.getRequest();
    HttpServletResponse response = ServletActionContext.getResponse();
    HttpSession session = ServletActionContext.getRequest().getSession();
    session.setAttribute(key, value);
    ServletContext application=ServletActionContext.getServletContext();
    application.setAttribute(name, object);
    Map session2 = ActionContext.getContext().getSession();
    session2.put(key, value);
    Map application2 = ActionContext.getContext().getApplication();
    application2.put(key, value);
    
 6:
  拦截器:(interceptor)
   作用:对Action中方法的增强
   拦截器与拦截器栈:
    拦截器(interceptor):对某一方面的增强
    拦截器栈(interceptor-stack):一组拦截器的整体配置
   一个包中只能存在一个默认拦截器栈:default-interceptor-ref
   
   public class TestInterceptor implements Interceptor{
    public void destroy() {
     System.out.println("TestInterceptor被销毁");
    }
    public void init() {
     System.out.println("TestInterceptor被初始化");
    }
    public String intercept(ActionInvocation arg0) throws Exception {
     System.out.println("TestInterceptor_前置增强");
     String result = arg0.invoke();
     System.out.println("TestInterceptor_后置增强");
     return result;
    }
   }
   
   <package name="test" extends="struts-default" namespace="/">
    <interceptors>
     <interceptor name="interceptor" class="interceptor.TestInterceptor"></interceptor>
    </interceptors>
   
    <action name="testAction" class="action.TestAction">
     <interceptor-ref name="interceptor"></interceptor-ref>
     <result name="success" type="dispatcher">test/result.jsp</result>
    </action>
   </package>
   
 7:
  文件上传:
   页面部分:注意--表单form中的method=post enctype=multipart/form-data
       <form action="${pageContext.request.contextPath }/uploadAction!upload.action" method="post" enctype="multipart/form-data" >
        <table border="5" align="center">
         <tr>
          <td>文件名</td>
          <td>
           <input type="text" name="fileName"/>
          </td>
         </tr>
         <tr>
          <td>上传组件</td>
          <td>
           <input type="file" name="theFile"/>
          </td>
         </tr>
         <tr>
          <td colspan="2" align="center">
        <input type="submit" value="上传" />
          </td>
         </tr>
        </table>
       </form>
   
   后台Action中:
    //定义属性.需要set方法
    private String fileName;
    private File theFile;
    private String theFileFileName;//文件原始名称
    
    public String upload(){
     this.uploadFile(fileName,theFile,theFileFileName);
     return "success";
    }
    //文件上传方法
    public void uploadFile(String fileName,File file,String protoFileName){
     HttpServletRequest request = ServletActionContext.getRequest();
     String path = "";
     if(fileName==null){
      path = request.getRealPath("/upload")+File.separator+UUID.randomUUID().toString()+protoFileName.substring(protoFileName.lastIndexOf("."));
     }else{
      path = request.getRealPath("/upload")+File.separator+fileName+protoFileName.substring(protoFileName.lastIndexOf("."));
     }
     
     FileOutputStream fos = null;
     FileInputStream fis = null;
     try {
      fos = new FileOutputStream(new File(path));
      fis = new FileInputStream(file);
      byte[] buff = new byte[1024*1024];
      int i = 0;
      while((i=fis.read(buff)) != -1){
       fos.write(buff, 0, i);
       fos.flush();
      }
     } catch (FileNotFoundException e) {
      e.printStackTrace();
     } catch (IOException e) {
      e.printStackTrace();
     } finally{
      try {
       if(fis!=null){
        fis.close();
       }
       if(fos!=null){
        fos.close();
       }
      } catch (IOException e) {
       e.printStackTrace();
      }
     }
    }
     
 8:解决文件上传过大问题:
  文件上传默认大小为:1024*1024*2(2M)
  (1)在struts.xml文件中加入标签<constant name="struts.multipart.maxSize" value="104857600"></constant> 
  
  (2)文件上传异常捕捉:<exception></exception>标签
   <action name="uploadAction" class="action.UploadAction">
    <exception-mapping result="exception" exception="java.lang.Exception"></exception-mapping>
    <result name="exception">file/exception.jsp</result>
   </action> 
   
   exception.jsp页面:
    <script type="text/javascript">
     function exception(){
      alert("文件过大..请选择小于2M文件上传");
      window.location="${pageContext.request.contextPath}/file/upload.jsp";
     }
    </script>
     <body onload="exception()"></body>