利用Struts拦截器完成文件上传功能

Struts2的图片上传以及页面展示图片

在上次的CRUD基础上加上图片上传功能（https://www.cnblogs.com/liuwenwu9527/p/11108611.html）

文件上传：
三种上传方案
1、上传到tomcat服务器
2、上传到指定文件目录，添加服务器与真实目录的映射关系，从而解耦上传文件与tomcat的关系
文件服务器
3、在数据库表中建立二进制字段，将图片存储到数据库(现在基本不用了)

我们使用第二种方法实现图片上传实现效果如下：

首先是展示页面 clzList.jsp

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3     <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
 4     <%@taglib prefix="z" uri="/zking" %>
 5 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 6 <html>
 7 <head>
 8 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 9 <title>Insert title here</title>
10 </head>
11 <body>
12 <h2>班级</h2><br>
13     <form action="${pageContext.request.contextPath }/sy/clz_list.action" method="post">
14         班级名：<input type="text" name="cname">
15               <input type="submit" value="确定">
16     </form>
17     <a href="${pageContext.request.contextPath }/sy/clz_preSave.action">新增</a>
18     <table border="1" width="100%">
19         <tr>
20             <td>编号</td>
21             <td>班级名</td>
22             <td>教员</td>
23             <td>图片</td>
24             <td>操作</td> 
25         </tr>    
26         <c:forEach items="${clzList }" var="c">
27         <tr>
28             <td>${c.cid }</td>
29             <td>${c.cname }</td>
30             <td>${c.cteacher}</td>
31             <td>
32                 <img alt="" style=" 60px;height: 60px" src="${pageContext.request.contextPath }${c.pic }">
33             </td>
34             <td>
35                 <a href="${pageContext.request.contextPath }/sy/clz_preSave.action?cid=${c.cid}">修改</a>&nbsp;&nbsp;
36                 <a href="${pageContext.request.contextPath }/sy/clz_del.action?cid=${c.cid}">删除</a>&nbsp;&nbsp;
37                 <a href="${pageContext.request.contextPath }/sy/clz_preUpload.action?cid=${c.cid}">图片上传</a>&nbsp;&nbsp;
38             </td>
39         </tr>    
40         </c:forEach>
41     </table>
42     <z:page pageBean="${pageBean }"></z:page>
43     
44 </body>
45 </html>

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3     <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
 4     <%@taglib prefix="z" uri="/zking" %>
 5 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 6 <html>
 7 <head>
 8 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 9 <title>Insert title here</title>
10 </head>
11 <body>
12 <h2>班级</h2><br>
13     <form action="${pageContext.request.contextPath }/sy/clz_list.action" method="post">
14         班级名：<input type="text" name="cname">
15               <input type="submit" value="确定">
16     </form>
17     <a href="${pageContext.request.contextPath }/sy/clz_preSave.action">新增</a>
18     <table border="1" width="100%">
19         <tr>
20             <td>编号</td>
21             <td>班级名</td>
22             <td>教员</td>
23             <td>图片</td>
24             <td>操作</td> 
25         </tr>    
26         <c:forEach items="${clzList }" var="c">
27         <tr>
28             <td>${c.cid }</td>
29             <td>${c.cname }</td>
30             <td>${c.cteacher}</td>
31             <td>
32                 <img alt="" style=" 60px;height: 60px" src="${pageContext.request.contextPath }${c.pic }">
33             </td>
34             <td>
35                 <a href="${pageContext.request.contextPath }/sy/clz_preSave.action?cid=${c.cid}">修改</a>&nbsp;&nbsp;
36                 <a href="${pageContext.request.contextPath }/sy/clz_del.action?cid=${c.cid}">删除</a>&nbsp;&nbsp;
37                 <a href="${pageContext.request.contextPath }/sy/clz_preUpload.action?cid=${c.cid}">图片上传</a>&nbsp;&nbsp;
38             </td>
39         </tr>    
40         </c:forEach>
41     </table>
42     <z:page pageBean="${pageBean }"></z:page>
43     
44 </body>
45 </html>

图片上传界面 upload.jsp

 1 <%@ page language="java" contentType="text/html; charset=UTF-8"
 2     pageEncoding="UTF-8"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 <form action="${pageContext.request.contextPath}/sy/clz_upload.action" method="post" enctype="multipart/form-data">
11     <input type="hidden" name="cid" value="${clz.cid }"><br>
12     <input type="hidden" name="cname" value="${clz.cname }"><br>
13     <input type="hidden" name="cteacher" value="${clz.cteacher }"><br>
14     <!-- 注意：name对应的值决定了，子控制器action属性的命名  -->
15     <input type="file" name="file" >
16     <input type="submit" >
17 </form>
18 </body>
19 </html>

ClazzAction类

  1 package com.liuwenwu.crud.web;
  2 
  3 import java.io.BufferedInputStream;
  4 import java.io.BufferedOutputStream;
  5 import java.io.File;
  6 import java.io.FileInputStream;
  7 import java.io.FileNotFoundException;
  8 import java.io.FileOutputStream;
  9 import java.io.IOException;
 10 import java.sql.SQLException;
 11 import java.util.List;
 12 
 13 import org.apache.commons.io.FileUtils;
 14 
 15 import com.liuwenwu.crud.dao.ClazzDao;
 16 import com.liuwenwu.crud.entity.Clazz;
 17 import com.liuwenwu.crud.util.PageBean;
 18 import com.opensymphony.xwork2.ModelDriven;
 19 
 20 public class ClazzAction extends BaseAction implements ModelDriven<Clazz>{
 21     
 22     private ClazzDao clzDao=new ClazzDao();
 23     private Clazz clz=new Clazz();
 24 //    img/img/imgContentType/imgFileName
 25     private File file;
 26     private String fileContentType;
 27     private String fileFileName;
 28     
 29     public String list() {
 30         PageBean pageBean=new PageBean();
 31         pageBean.setRequest(request);
 32         try {
 33             List<Clazz> list= this.clzDao.list(clz, pageBean);
 34 //            this.result=this.clzDao.list(clz, pageBean);
 35             request.setAttribute("clzList", list);
 36             request.setAttribute("pageBean", pageBean);
 37         } catch (Exception e) {
 38             e.printStackTrace();
 39         } 
 40         return "list";
 41     }
 42 
 43     /**
 44      * 直接上传图片
 45      * @return
 46      */
 47     public String upload() {
 48         try {
 49 //            注意：在linux下是没有F盘的，linux下只有一个盘符，那么意味着，当打包到linux服务器的时候需要改动代码
 50 //            这个时候通常是这么解决的，将targetPath对应的目录串，配置到资源文件中，通过Properties类进行动态读取
 51 //            那么当需要将项目发布到linux服务器的时候，只需要改变xxx.properties文件中的targetPath=/zking/T224/img
 52 //            实际图片存储的位置
 53             String targetDir="F:/zz";
 54 //            存储到数据库中的地址
 55             String serverPath="/upload";
 56             FileUtils.copyFile(file, new File(targetDir+"/"+fileFileName));    
 57 //            注意：数据库存放的是网络请求地址 ，而不是本地图片存放地址
 58             clz.setPic(serverPath+"/"+fileFileName);
 59             this.clzDao.edit(clz);
 60             } catch (Exception e) {
 61                 // TODO Auto-generated catch block
 62                 e.printStackTrace();
 63         } 
 64         return "toList";
 65     }
 66 
 67     /**
 68      * 跳转文件上传页面
 69      * @return
 70      */
 71     public String preUpload() {
 72         try {
 73             Clazz c = this.clzDao.list(clz, null).get(0);
 74             request.setAttribute("clz", c);
 75         } catch (Exception e) {
 76             e.printStackTrace();
 77         }
 78         return "toUpload";
 79     }
 80     
 81     /**
 82      * 跳转新增修改页面的公用方法
 83      * @return
 84      */
 85     public String preSave() {
 86         if(clz.getCid()!=0) {
 87             try {
 88                 Clazz c = this.clzDao.list(clz, null).get(0);
 89                 request.setAttribute("clz", c);
 90             } catch (Exception e) {
 91                 e.printStackTrace();
 92             }
 93         }
 94         return "preSave";
 95     }
 96     /**
 97      * 新增
 98      * @return
 99      */
100     public String add() {
101         try {
102             result=this.clzDao.add(clz);
103         } catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException
104                 | SQLException e) {
105             // TODO Auto-generated catch block
106             e.printStackTrace();
107         }
108         return "toList";
109     }
110     /**
111      * 修改
112      * @return
113      */
114     public String edit() {
115         try {
116             this.clzDao.edit(clz);
117         } catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException
118                 | SQLException e) {
119             // TODO Auto-generated catch block
120             e.printStackTrace();
121         }
122         return "toList";
123     }
124     /**
125      * 删除
126      * @return
127      */
128     public String del() {
129         try {
130             this.clzDao.del(clz);
131         } catch (NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException
132                 | SQLException e) {
133             // TODO Auto-generated catch block
134             e.printStackTrace();
135         }
136         return "toList";
137     }
138     
139     @Override
140     public Clazz getModel() {
141         // TODO Auto-generated method stub
142         return clz;
143     }
144 
145     public File getFile() {
146         return file;
147     }
148 
149     public void setFile(File file) {
150         this.file = file;
151     }
152 
153     public String getFileContentType() {
154         return fileContentType;
155     }
156 
157     public void setFileContentType(String fileContentType) {
158         this.fileContentType = fileContentType;
159     }
160 
161     public String getFileFileName() {
162         return fileFileName;
163     }
164 
165     public void setFileFileName(String fileFileName) {
166         this.fileFileName = fileFileName;
167     }
168 }

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE struts PUBLIC
 3     "-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
 4     "http://struts.apache.org/dtds/struts-2.5.dtd">
 5 <struts>
 6     <!-- /user/bookAction?methodName=list 
 7         /sy/bookAction?methodName=list
 8     -->
 9     <package name="sy" extends="base" namespace="/sy">
10         <action name="/demo_*" class="com.liuwenwu.web.HelloAction" method="{1}">
11             <result name="rs">/rs.jsp</result>
12         </action>
13         
14         <action name="/stack_*" class="com.liuwenwu.test.DemoAction" method="{1}">
15             <result name="rs">/rs.jsp</result>
16         </action>
17 
18         <action name="/clz_*" class="com.liuwenwu.crud.web.ClazzAction" method="{1}">
19             <result name="list">/clzList.jsp</result>
20             <result name="preSave">/clzEdit.jsp</result>
21             <result name="toList" type="redirectAction">/clz_list</result>
22             <result name="toUpload">/upload.jsp</result>
23         </action>
24     </package>
25 </struts>

eclipse中修改Tomcat服务器配置文件添加服务器与真实目录映射关系

<Context path="/T224_struts/upload" docBase="F:/zz/"/>

path是指服务器路径 docBase是指服务器本地映射地址

理解图片上传的原理自己写一个通过缓冲区增强的图片上传方法

 1 /**
 2      * FileUtils.copyFile的底层，并且通过缓冲区进行了增强
 3      * @param source
 4      * @param target
 5      * @throws Exception
 6      */
 7     public void conpyBufFile(File source,File target) throws Exception{
 8         //读取
 9         BufferedInputStream in=new BufferedInputStream(new FileInputStream(source));
10         //写入
11         BufferedOutputStream out=new BufferedOutputStream(new FileOutputStream(target));
12         byte[] bbuf=new byte[1024];
13         int len=0;
14         while((len=in.read(bbuf))!=-1){
15             out.write(bbuf, 0, len);
16         }
17         in.close();
18         out.close();
19     }

拦截器 Interceptor：

实现的2种方法：
implements Interceptor
extends AbstractInterceptor

 1 package com.liuwenwu.crud.interceptor;
 2 
 3 import com.opensymphony.xwork2.ActionInvocation;
 4 import com.opensymphony.xwork2.interceptor.Interceptor;
 5 
 6 public class OneInterceptor implements Interceptor{
 7 
 8     @Override
 9     public void destroy() {
10         // TODO Auto-generated method stub
11         
12     }
13 
14     @Override
15     public void init() {
16         // TODO Auto-generated method stub
17         
18     }
19 
20     @Override
21     public String intercept(ActionInvocation invocation) throws Exception {
22         // TODO Auto-generated method stub
23         System.out.println("=======OneInterceptor==========1");
24         String invoke = invocation.invoke();
25         System.out.println("=======OneInterceptor==========2");
26         return invoke;
27     }
28 }

package com.liuwenwu.crud.interceptor;

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

public class TwoInterceptor implements Interceptor{

    @Override
    public void destroy() {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void init() {
        // TODO Auto-generated method stub
        
    }

    @Override
    public String intercept(ActionInvocation invocation) throws Exception {
        // TODO Auto-generated method stub
        System.out.println("=======TwoInterceptor==========1");
        String invoke = invocation.invoke();
        System.out.println("=======TwoInterceptor==========2");
        return invoke;
    }
}

拦截器的工作原理：

先定义两个拦截器

在struts-sy.xml中配置拦截器

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <!DOCTYPE struts PUBLIC
 3     "-//Apache Software Foundation//DTD Struts Configuration 2.5//EN"
 4     "http://struts.apache.org/dtds/struts-2.5.dtd">
 5 <struts>
 6     <package name="sy" extends="base" namespace="/sy">
 7      <interceptors>
 8         <interceptor name="one" class="com.liuwenwu.crud.interceptor.OneInterceptor"></interceptor>
 9         <interceptor name="two" class="com.liuwenwu.crud.interceptor.TwoInterceptor"></interceptor>
10     </interceptors> 
11         <action name="/demo_*" class="com.liuwenwu.web.HelloAction" method="{1}">
12             <result name="rs">/rs.jsp</result>
13         </action>
14         
15         <action name="/stack_*" class="com.liuwenwu.test.DemoAction" method="{1}">
16             <result name="rs">/rs.jsp</result>
17         </action>
18         
19         <action name="/clz_*" class="com.liuwenwu.crud.web.ClazzAction" method="{1}">
20             <interceptor-ref name="one"></interceptor-ref>
21             <interceptor-ref name="two"></interceptor-ref>
22             <result name="list">/clzList.jsp</result>
23             <result name="preSave">/clzEdit.jsp</result>
24             <result name="toList" type="redirectAction">/clz_list</result>
25             <result name="toUpload">/upload.jsp</result>
26         </action>
27     </package>
28 </struts>

当拦截器起作用：

相关阅读:
10-12
8-10
5.2-5.3
四则运算测试与封装
 第5-7章
 汉堡包
 1-5章
 实验二
 实验一
 Controller方法是如何与请求匹配上的及参数如何填充的
原文地址：https://www.cnblogs.com/hyfl/p/11224742.html