- 表单 enctype 属性应该设置为 multipart/form-data.
- 需要引入的 jar 文件：commons-fileupload-1.3.2、commons-io-2.5.jar。
upload.jsp : 文件上传表单
<%@ 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>文件上传</title>
</head>
<body>
<form action="UploadServlet" method="post" enctype="multipart/form-data">
选择一个文件:
<input type="file" name="uploadFile"/>
<br/><br/>
<input type="submit" value="上传"/>
</form>
</body>
</html>
message.jsp : 上传成功后跳转页面。
<%@ 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>文件上传结果</title>
</head>
<body>
<center>
<h2>${message}</h2>
</center>
</body>
</html>
web.xml
<?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>
<display-name>UploadServlet</display-name>
<servlet-name>UploadServlet</servlet-name>
<servlet-class>com.tanlei.test.UploadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>UploadServlet</servlet-name>
<url-pattern>/UploadServlet</url-pattern>
</servlet-mapping>
</web-app>
UploadServlet.java : 上传处理 Servlet。
package com.tanlei.test;
import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
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 = 1L;
//上传文件存储目录
private static final String UPLOAD_DIRECTORY="upload";
//上传配置
private static final int MEMORY_THRESHOLD=1024*1024*3;//3MB
private static final int MAX_FILE_SIZE= 1024 * 1024 * 40; // 40MB
private static final int MAX_REQUEST_SIZE= 1024 * 1024 * 50; // 50MB
/**
* 上传数据及保存文件
*/
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//检测是否为多媒体上传
if(!ServletFileUpload.isMultipartContent(req)) {
//如果不是则停止
PrintWriter writer=resp.getWriter();
writer.println("Error: 表单必须包含 enctype=multipart/form-data");
writer.flush();
return;
}
//配置上传参数
DiskFileItemFactory factory=new DiskFileItemFactory();
//设置内存临界值-超过后将产生临时文件并存储于临时目录中
factory.setSizeThreshold(MEMORY_THRESHOLD);
//设置临时存储目录
factory.setRepository(new File(System.getProperty("java.io.tmpdir")));
ServletFileUpload upload=new ServletFileUpload(factory);
//设置最大文件上传值
upload.setFileSizeMax(MAX_FILE_SIZE);
//设置最大请求值(包含文件和表单数据)
upload.setFileSizeMax(MAX_REQUEST_SIZE);
//中文处理
upload.setHeaderEncoding("UTF-8");
//构造临时路径来存储上传的文件
//这个路径相对当前应用的目录
String uploadPath=getServletContext().getRealPath("/")+ File.separator + UPLOAD_DIRECTORY;
//如果目录不存在则创建
File uploadDir=new File(uploadPath);
if(uploadDir.exists()) {
uploadDir.mkdir();
}
try {
// 解析请求的内容提取文件数据
@SuppressWarnings("unchecked")
List<FileItem> formItems = upload.parseRequest(req);
if (formItems != null && formItems.size() > 0) {
// 迭代表单数据
for (FileItem item : formItems) {
// 处理不在表单中的字段
if (!item.isFormField()) {
String fileName = new File(item.getName()).getName();
String filePath = uploadPath + File.separator + fileName;
File storeFile = new File(filePath);
// 在控制台输出文件的上传路径
System.out.println(filePath);
// 保存文件到硬盘
item.write(storeFile);
req.setAttribute("message",
"文件上传成功!");
}
}
}
} catch (Exception ex) {
req.setAttribute("message",
"错误信息: " + ex.getMessage());
}
// 跳转到 message.jsp
getServletContext().getRequestDispatcher("/message.jsp").forward(
req, resp);
}
}