拦截器与文件上传
作者：互联网
文章目录
1.三种上传方案
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
这里我使用了第二种1、利用struts拦截器完成文件上传功能，接下来和大家讲解下。
2.文件上传
首先写一个文件上传的方法
classAction.java
/**
* 跳转文件上传页面
* @return
*/
public String preUpload() {
try {
Clazz c =this.clzDao.list(clz, null).get(0);
request.setAttribute("clz",c );
} catch (InstantiationException | IllegalAccessException | SQLException e) {
e.printStackTrace();
}
return "toUpload";
}
/**
* 跳转新增修改页面的公用方法
* @return
*/
public String preSave() {
if(clz.getCid()!=0) {
try {
Clazz c =this.clzDao.list(clz, null).get(0);
request.setAttribute("clz",c );
} catch (InstantiationException | IllegalAccessException | SQLException e) {
e.printStackTrace();
}
}
return "preSave";
}
第二步：配置一下
struts-sy.xml
<action name="/clz_*" class="com.crud.web.ClazzAction" method="{1}">
<!-- <interceptor-ref name="one"></interceptor-ref>
<interceptor-ref name="two"></interceptor-ref> -->
<result name = "list">/clzList.jsp</result>
<result name = "preSave">/clzEdit.jsp</result>
<result name = "toList" type="redirectAction">clz_list</result>
<result name = "toUpload">/upload.jsp</result>
</action>
最后写jsp界面
clzList.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib uri="/zrh" prefix="z" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>目录</h2>
<form action="${pageContext.request.contextPath }/sy/clz_list.action" method="post">
<!-- <input type="hidden" name="paginaction" value="false"> -->
班级名：<input type="text" name="cname">
<input type="submit" value="确定">
</form>
<a href="${pageContext.request.contextPath }/sy/clz_preSave.action">增加</a>
<table border="1px" width="90%">
<tr>
<td>编号</td>
<td>班级名</td>
<td>教员</td>
<td>图片</td>
<td>操作</td>
</tr>
<c:forEach items="${clzList }" var="c">
<tr>
<td>${c.cid }</td>
<td>${c.cname }</td>
<td>${c.cteacher }</td>
<td>
<img alt="" style="width: 60px;height:60px" src="${pageContext.request.contextPath }/${c.pic }">
</td>
<td>
<a href="${pageContext.request.contextPath }/sy/clz_preSave.action?cid=${c.cid}">修改</a>
<a href="${pageContext.request.contextPath }/sy/clz_del.action?cid=${c.cid}">删除</a>
<a href="${pageContext.request.contextPath }/sy/clz_preUpload.action?cid=${c.cid}">上传</a>
</td>
</tr>
</c:forEach>
</table>
<z:page pageBean="${pageBean }"/>
</body>
</html>
upload.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
<form action="${pageContext.request.contextPath }/sy/clz_upload.action" method="post" enctype="multipart/form-data" >
<input type="hidden" name="cid" value="${clz.cid }">
<input type="hidden" name="cname" value="${clz.cname }">
<input type="hidden" name="cteacher" value="${clz.cteacher }">
<input type="file" name="file">
<input type="submit" >
</form>
</body>
</html>
在你的本地servers的server.xml加一条代码
<Context path="struts/upload" docBase="E:/temp/T224/"/>
这样就写完了
效果为：
3、拦截器原理
文件上传的底层原理
首先自己定义一个带缓冲区流对象
/**
* FileUtils.copyFile的底层并且通过缓冲区进行了增强
* @param source
* @param target
* @throws Exception
*/
public void copyBufFile(File source,File target) throws Exception{
BufferedInputStream in = new BufferedInputStream(new FileInputStream(source));//带缓冲区流对象
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(target));
byte[] bbuf = new byte[1024];
int len = 0;
while((len = in.read(bbuf))!=-1) {
out.write(bbuf,0,len);
}
in.close();
out.close();
}
// 将这个注释 FileUtils.copyFile(file, new File(targeDir+"/"+fileFileName));
替换为自己写的 copyBufFile(file, new File(targeDir+"/"+fileFileName));
然后写两个拦截器
OneInterceptor拦截器
package com.crud.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class OneInterceptor implements Interceptor{
//实现OneInterceptor的三个方法
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public void init() {
// TODO Auto-generated method stub
}
@Override
public String intercept(ActionInvocation arg0) throws Exception {
System.out.println("=========OneInterceptor===========1");
String invoke = arg0.invoke();
System.out.println("=========OneInterceptor===========2");
return invoke;
}
}
TwoInterceptor拦截器
package com.crud.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;
public class TwoInterceptor implements Interceptor{
//实现TwoInterceptor的三个方法
@Override
public void destroy() {
// TODO Auto-generated method stub
}
@Override
public void init() {
// TODO Auto-generated method stub
}
@Override
public String intercept(ActionInvocation arg0) throws Exception {
System.out.println("=========TwoInterceptor===========1");
String invoke = arg0.invoke();
System.out.println("=========TwoInterceptor===========2");
return invoke;
}
}
第三步：
<!-- 定义拦截器 -->
<interceptors>
<interceptor name="oneInterceptor" class="com.javaxl.interceptor.OneInterceptor"></interceptor>
<interceptor name="twoInterceptor" class="com.javaxl.interceptor.TwoInterceptor"></interceptor>
</interceptors>
<!-- 应用拦截器 -->
<action name="/clz_*" class="com.crud.web.ClazzAction" method="{1}">
<interceptor-ref name="one"></interceptor-ref>
<interceptor-ref name="two"></interceptor-ref>
<result name = "list">/clzList.jsp</result>
<result name = "preSave">/clzEdit.jsp</result>
<result name = "toList" type="redirectAction">clz_list</result>
<result name = "toUpload">/upload.jsp</result>
</action>
最后运行，结果为
标签：文件,拦截器,jsp,clz,new,上传,public 来源： https://blog.csdn.net/Zhangrunhong/article/details/95744979