javaEE开发之文件上传

package com.example.web;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.UUID;

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;
import org.apache.commons.io.IOUtils;

public class FileUpload extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		request.setCharacterEncoding("UTF-8");
		response.setContentType("text/html;charset=utf-8");
		PrintWriter out=response.getWriter();
		//指定文件存放目录
		String storePath=getServletContext().getRealPath("WEB-INF/files");
		File file=new File(storePath);
		//如果目录不存在，需要创建
		if(!file.exists()){
			file.mkdirs();
		}
		//要检查是不是enctype=multipart/form-data提交过来的数据
		boolean isMultipart=ServletFileUpload.isMultipartContent(request);
		//如果不是，需要处理
		if(!isMultipart){
			out.write("请将enctype设置成multipart/form-data类型");
			response.setHeader("Refresh", "1;URL="+request.getContextPath());
			return;
		}
		//去生成一个文件上传的FileUpload对象
		DiskFileItemFactory factory=new DiskFileItemFactory();
		//设置一个临时目录
		//factory.setRepository(new File("E:/temp"));temp文件需要临时创建，我已经删掉了
		
		ServletFileUpload upload=new ServletFileUpload(factory);
		//将用户的请求转化为List<FileItem>
		try {
			List<FileItem> items=upload.parseRequest(request);
			//遍历List<FileItem>中的数据
			for (FileItem item : items) {
				//如果部分文件没有上传
				if("".equals(item.getName())){
					continue;
				}
				//判断是普通字段
				if(item.isFormField()){
					String fieldName=item.getFieldName();
					String fieldValue=item.getString("UTF-8");
					System.out.println(fieldName+":"+fieldValue);
				}else{
					//是上传的文件
					//需要获取文件名,有可能是路径
					String fileName=item.getName();
					fileName=fileName.substring(fileName.lastIndexOf(File.separator)+1);
					//文件名同名问题
					fileName=UUID.randomUUID().toString()+"_"+fileName;
					//解决一个文件夹下的文件过多的问题
					//用时间来生成子目录
					//String childPath=generateDir(storePath);
					//用hashcode来生成子目录
					String childPath=generateDir(storePath,fileName);
					//获取上传文件的数据
					InputStream is=item.getInputStream();
					OutputStream os=new FileOutputStream(storePath+File.separator+childPath+File.separator+fileName);
					IOUtils.copy(is, os);
					os.close();
					is.close();
					//item.delete();//清空临时文件
				}
			}
			out.write("文件上传成功<a href='"+request.getContextPath()+"'>继续上传</a>");
		} catch (FileUploadException e) {
			e.printStackTrace();
		}
	}

	private String generateDir(String storePath, String fileName) {
		int hashcode=fileName.hashCode();
		int dir1=hashcode &  0xf;
		int dir2=(hashcode & 0xf0)>>4;
		String childPath=dir1+File.separator+dir2;
		File file=new File(storePath,childPath);
		if(!file.exists()){
			file.mkdirs();
		}
		return childPath;
	}

	private String generateDir(String storePath) {
		DateFormat df=new SimpleDateFormat("yyyyMMddhhmmss");
		String childPath=df.format(new Date());
		File file=new File(storePath, childPath);
		if(!file.exists()){
			file.mkdirs();
		}
		return childPath;
	}

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

	}

}