Java(Servlet)上传文件的小demo

最新推荐文章于 2021-03-03 18:11:19 发布

转载最新推荐文章于 2021-03-03 18:11:19 发布 · 66 阅读

1 ·

CC 4.0 BY-SA版权

原文链接：http://blog.51cto.com/leamonlee/949638

写在前面：简单的上传文件的小demo，拿过来就可以用。有什么疑问可以加版主交流，共同学习。QQ：70747053。

之前在网上找了很多小例子，好多都有错，调试一段时间也烦了，索性自己写点。本来因为自己懒不是很想写，呵呵。就当温习了。

实现上传文件需要apache提供的两个jar包：

commons-fileupload-1.2.2.jar:http://commons.apache.org/fileupload/

commons-io-2.4.jar:http://commons.apache.org/io/

然后是简单的JSP页面:

需要注意的是：form表单里面有个属性enctype="multipart/form-data"，这是必须写的。具体参考文档：http://www.w3school.com.cn/tags/att_form_enctype.asp

<%@ 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>
<script type="text/javascript">
function reFun(msg) {
alert(msg);
}
</script>
<script type="text/javascript" src="js/jquery-1.4.2.min.js"></script>
<script type="text/javascript">
function uploads() {
$("#frmUpload")[0].submit();
}
</script>
<style type="text/css">
#load{
background:url('img/loading.gif') no-repeat;
height:80px;
border:1px solid red;
}
</style>
</head>
<body>
<div id="load"> </div>
<form id="frmUpload" target="uploadframe" enctype="multipart/form-data"
action="uploadFile" method="post">
<input type="file" name="file" id="file" /> <input type="button"
value="上传" id="uload" onclick="uploads()" />
</form>
<iframe id="uploadframe" name="uploadframe" style="display: none"></iframe>
</body>
</html>

这里面有些锦上添花的东西，各位看官各凭所好自己添或删。

然后就是Java类，处理发来的请求：

package cn.upload.servlet;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class UploadServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = -3159753144050260701L;
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
req.setCharacterEncoding("UTF-8");
DiskFileItemFactory fac = new DiskFileItemFactory();
ServletFileUpload fu = new ServletFileUpload(fac);
resp.setCharacterEncoding("utf-8");
resp.setContentType("text/html");
try {
//上传文件，并解析出所有的表单字段，包括普通字段和文件字段
List list = fu.parseRequest(req);
//下面对每个字段进行处理，分普通字段和文件字段
Iterator i = list.iterator();
while (i.hasNext()) {
FileItem fileItem = (FileItem) i.next();
if (!fileItem.isFormField()) {
String name = fileItem.getName();
InputStream is = fileItem.getInputStream();
String p="D:/uploads/";
File file = new File(p);
if(!file.exists()){
file.mkdirs();
}
OutputStream os = new FileOutputStream(p + name);
try {
byte[] b = new byte[2048];
int index = is.read(b, 0, b.length);
while (index != -1) {
os.write(b, 0, index);
index = is.read(b, 0, b.length);
}
resp.getWriter().println(
"<script>window.parent.reFun('ok')</script>");
} catch (Exception e) {
e.printStackTrace();
resp.getWriter()
.println(
"<script>window.parent.reFun('error')</script>");
} finally {
os.close();
is.close();
}
}
}
} catch (Exception e) {
e.printStackTrace();
resp.getWriter().println(
"<script>window.parent.reFun('error')</script>");
}
}
}

有些注释没加，大家应该都可以看得懂，真心懒得加了。

还有就是web.xml里面的配置:

<?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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<servlet>
<servlet-name>uploadFile</servlet-name>
<servlet-class>cn.upload.servlet.UploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>uploadFile</servlet-name>
<url-pattern>/uploadFile</url-pattern>
</servlet-mapping>
</web-app>