版权声明：本文为博主原创文章，遵循 CC 4.0 BY-SA 版权协议，转载请附上原文出处链接和本声明。
我们使用开源项目Commons FileUpload最常用ServletFileUpload上传
项目结构：
pom.xml
这里就是用到了javax.servlet-api-3.0.1.jar、commons-fileupload-1.3.2.jar、commons-io-2.2.jar
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.citywy</groupId>
<artifactId>upload-03</artifactId>
<packaging>war</packaging>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.0.1</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.2</version>
</dependency>
</dependencies>
<build>
<finalName>upload-03</finalName>
</build>
</project>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<display-name>Archetype Created Web Application</display-name>
<servlet>
<description></description>
<display-name>Upload01</display-name>
<servlet-name>Upload01</servlet-name>
<servlet-class>com.citywy.servlet.Upload01</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Upload01</servlet-name>
<url-pattern>/upload01</url-pattern>
</servlet-mapping>
</web-app>Upload01.java
package com.citywy.servlet;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletContext;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
public class Upload01 extends HttpServlet {
private static final long serialVersionUID = 1L;
public Upload01() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
//Check that we have a file upload request 检查是否有文件上传请求
boolean isMultipart=ServletFileUpload.isMultipartContent(request);
if(isMultipart){
// Create a factory for disk-based file items 创建DiskFileItemFactory对象，设置缓冲区大小和临时文件目录
DiskFileItemFactory factory=new DiskFileItemFactory();
//System.out.println(System.getProperty("java.io.tmpdir"));//默认临时文件夹
// Set factory constraints
/*factory.setSizeThreshold(yourMaxMemorySize);
factory.setRepository(yourTempDirectory);*/
//Create a new file upload handler创建ServletFileUpload对象，并设置上传文件的大小限制
ServletFileUpload upload=new ServletFileUpload(factory);
upload.setSizeMax(10 * 1024 * 1024);// 以byte为单位 不能超过10M 1024byte
// Set overall request size constraint
// upload.setSizeMax(yourMaxRequestSize);
// Parse the request 调用ServletFileUpload.parseRequest方法解析request对象，得到一个保存了所有上传内容的List对象
try {
List<FileItem> items = upload.parseRequest(request);
// Process the uploaded items
Iterator<FileItem> iter=items.iterator();
while(iter.hasNext()){
FileItem item=iter.next();
//遍历list，每迭代一个FileItem对象，调用其isFormField方法判断是否是上传文件
if(item.isFormField()==true){// 普通表单元素
String name=item.getFieldName();// name属性值
String value=item.getString();// name对应的value值
System.out.println("form field："+name+"--"+value);
}else{
String fieldName = item.getFieldName();
String fileName = item.getName();// 文件名称
String contentType = item.getContentType();
boolean isInMemory = item.isInMemory();
long sizeInBytes = item.getSize();
System.out.println("file upload："+fieldName+"--"+fileName+"--"+contentType+"--"+isInMemory+"--"+sizeInBytes);
}
// Process a file upload
if(!item.isFormField()){
//1.获取真实地址,这里保存在Tomcat运行的项目upload目录中,这要在src/main/webapp下新建upload文件夹
/*ServletContext sctx = getServletContext();
String path=sctx.getRealPath("/upload");
String fileName = item.getName();
File uploadedFile=new File(path+"\\"+fileName);
item.write(uploadedFile);*/
//2.保存到指定盘符
String fileName=item.getName();
File uploadedFile=new File("d:/tmp/"+fileName);
item.write(uploadedFile);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'upload.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form action="/upload-03/upload01" method="post" enctype="multipart/form-data">
请选择上传的图片或文件:
<!-- 这个是item.isFormField()==false -->
<input type="file" name="fileName"/>
<!-- 这个走的就是item.isFormField()==true -->
<input type="text" name="hello" value="taray">
<input type="submit" value="上传"/>
</form>
</body>
</html>