利用commons-fileupload组件实现文件上传-实例

最新推荐文章于 2020-08-23 19:11:33 发布

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#Servlet #Java #JavaEE #Apache #Web

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本文介绍了一个使用Java Servlet实现的文件上传示例，包括所需的commons-fileupload和commons-io库，展示了如何配置表单以便进行文件上传，并提供了完整的Servlet代码及web.xml配置。

一、所需要的包：

1、commons-fileupload-1.2.1.jar：

下载地址
http://commons.apache.org/downloads/download_fileupload.cgi

2、commons-io-1.4.jar：

下载地址
http://commons.apache.org/downloads/download_io.cgi

二、注意事项：

form表单里面要加上enctype="multipart/form-data"

三、代码示例

1、jsp代码：

<%@ 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>upload</title>
</head>
<body>
<form action="uploadServlet" method="post" enctype="multipart/form-data">
	<table>
	<caption>上传实例</caption>
		<tr>
			<td>姓名</td>
			<td>
				<input type="text" name="name">
			</td>
		</tr>
		<tr>
			<td>年龄</td>
			<td>
				<input type="text" name="age">
			</td>
		</tr>
		<tr>
			<td>照片</td>
			<td>
				<input type="file" name="image">
			</td>
		</tr>
		<tr>
			<td></td>
			<td>
				<input type="submit" value="提交">
			</td>
		</tr>
	</table>
</form>
</body>
</html>

2、UploadServlet代码

package servlet;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.Writer;
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.FileUploadException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import org.apache.commons.fileupload.util.Streams;

/**
 * 上传servlet
 * @author lisanlai
 *
 */
public class UploadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public UploadServlet() {
        super();
    }

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		this.doPost(request, response);
	}

	@SuppressWarnings("unchecked")
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		response.setContentType("text/html");   
        // 设置字符编码为UTF-8, 这样支持汉字显示   
        response.setCharacterEncoding("UTF-8");
        Writer o = response.getWriter();
		
		/**
		 * 首先判断form的enctype是不是multipart/form-data
		 * 同时也判断了form的提交方式是不是post
		 * 方法：isMultipartContent(request)
		 */
	
		if(ServletFileUpload.isMultipartContent(request)){
			request.setCharacterEncoding("utf-8");
			
			// 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload   
			DiskFileItemFactory factory =  new DiskFileItemFactory();
			
			//设置文件存放的临时文件夹，这个文件夹要真实存在
			File fileDir = new File("../webapps/fileupload/tmp/");
			if(fileDir.isDirectory() && fileDir.exists()==false){
				fileDir.mkdir();
			}
			factory.setRepository(fileDir);
			
			//设置最大占用的内存
			factory.setSizeThreshold(1024000);
			
			//创建ServletFileUpload对象
			ServletFileUpload sfu = new ServletFileUpload(factory);
			sfu.setHeaderEncoding("utf-8");
			
			//设置单个文件最大值byte 
			sfu.setFileSizeMax(102400000);
			
			//所有上传文件的总和最大值byte   
			sfu.setSizeMax(204800000);
			
			List<FileItem> items =  null;
			
			try {
				items = sfu.parseRequest(request);
			}catch (SizeLimitExceededException e) {   
                System.out.println("文件大小超过了最大值");   
            } catch(FileUploadException e) {   
                e.printStackTrace();   
            } 
            
            //取得items的迭代器
            Iterator<FileItem> iter = items==null?null:items.iterator();
            
            //图片上传后存放的路径目录
            File images = new File("D:/upload/images/");
			if(images.exists()==false){
				images.mkdirs();
			}
            //迭代items
            while(iter!=null && iter.hasNext()){
            	FileItem item = (FileItem) iter.next();
            	
            	//如果传过来的是普通的表单域
            	if(item.isFormField()){
            		System.out.print("普通的表单域:");   
                    System.out.print(new String(item.getFieldName()) + "  ");   
                    System.out.println(new String(item.getString("UTF-8")));   
            	}
            	//文件域
            	else if(!item.isFormField()){
            		System.out.println("源图片:" + item.getName());   
            		String fileName = item.getName().substring(item.getName().lastIndexOf("\\"));
            		BufferedInputStream in = new BufferedInputStream(item.getInputStream());
            		//文件存储在D:/upload/images目录下,这个目录也得存在 
                    BufferedOutputStream out = new BufferedOutputStream(   
                            new FileOutputStream(new File(images.getAbsolutePath()+ fileName))); 
                    Streams.copy(in, out, true);   
                    o.write("文件上传成功");
            	}
            }
		}else {   
            System.out.println("表单的enctype 类型错误");   
        } 
	}

}

3、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">
  <display-name>UploadTest</display-name>
  <welcome-file-list>
    <welcome-file>upload.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <description></description>
    <display-name>UploadServlet</display-name>
    <servlet-name>UploadServlet</servlet-name>
    <servlet-class>servlet.UploadServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>UploadServlet</servlet-name>
    <url-pattern>/uploadServlet</url-pattern>
  </servlet-mapping>
</web-app>