文件上传备录（使用servlet）

/*1、来自 
    [菜鸟教程](http://www.runoob.com/servlet/servlet-file-uploading.html)
*/

package com.runoob.test;

import java.io.File;import java.io.IOException;import java.io.PrintWriter;import java.util.List;

import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;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;


/**
 * Servlet implementation class UploadServlet
 */@WebServlet("/UploadServlet")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
     */
    protected void doPost(HttpServletRequest request,
                HttpServletResponse response) throws ServletException, IOException {
                // 检测是否为多媒体上传
                if (!ServletFileUpload.isMultipartContent(request)) {
                    // 如果不是则停止
                    PrintWriter writer = response.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.setSizeMax(MAX_REQUEST_SIZE);

        // 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 = request.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 formItems = upload.parseRequest(request);

            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);
                        request.setAttribute("message",
                            "文件上传成功!");
                    }
                }
            }
        } catch (Exception ex) {
            request.setAttribute("message",
                    "错误信息: " + ex.getMessage());
        }
        // 跳转到 message.jsp
        request.getServletContext().getRequestDispatcher("/message.jsp").forward(
                request, response);
    }}
m

2、另一种方法，不需要使用commons，来自李刚老师的轻量级企业应用开发SSH框架

package tool.utils;

import java.io.IOException;
import java.util.Collection;
import java.util.UUID;

import javax.servlet.ServletException;
import javax.servlet.annotation.MultipartConfig;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.Part;

/** 基于servlet3.0以上的上传，本身可作为一个servlet服务 */
@MultipartConfig
public class Upload {
    public String upload(HttpServlet ser,HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException{
        Part part=request.getPart("file");//servlet3.0直接支持通过request传递二进制文件，获取文件上传域
        System.out.println("文件上传类型："+part.getContentType());
        System.out.println("文件上传大小："+part.getSize());
        //该文件上传域的Header Name
        Collection headerNames=part.getHeaderNames();
        for(String str:headerNames){
            System.out.println("headerName "+str+"-----"+part.getHeader(str));
        }
        //获取包含原始文件名的字符串
        String fileNameInfo = part.getHeader("content-disposition");
        System.out.println("获取包含原始文件名的字符串"+fileNameInfo);
        //提取上传文件的原始文件名
        String fileName=fileNameInfo.substring(fileNameInfo.indexOf("filename=\"")+10,fileNameInfo.length()-1);
        System.out.println("提取上传文件的原始文件名"+fileName);
        System.out.println("重新命名");
//        fileName=request.getParameter("name")+fileNameInfo.substring(fileNameInfo.indexOf("\\."));
        fileName = UUID.randomUUID().toString().replace("-", "")+fileName.substring(fileName.lastIndexOf("."));
        System.out.println("上传文件的文件名"+fileName);
        //将文件写入服务器
        part.write(ser.getServletContext().getRealPath("/upload")+"/"+fileName);
        return "upload/"+fileName;
    }
}