文件上传

package com.ecc.servlet;

import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
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.DiskFileUpload;
import org.apache.commons.fileupload.FileItem;

public class FileUploadServlet extends HttpServlet {
	
	private String uploadBasePath = null; // 用于存放上传文件的目录
    private String tempPath = null; //
	/**
	 * Constructor of the object.
	 */
	public FileUploadServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setCharacterEncoding("GBK");
		
		try {
			//创建基本目录
			createBaseDir(request.getSession().getServletContext().getRealPath("/"));
			String subDir = genSubDir();
			String uploadPath = uploadBasePath + subDir;
			
        	if( !(new File(uploadPath).isDirectory()) ){
        		new File(uploadPath).mkdirs();
        	}
        	
	        DiskFileUpload fu = new DiskFileUpload();
	        // 设置最大文件尺寸，这里是4MB
	        fu.setSizeMax(4194304);
	        // 设置缓冲区大小，这里是4kb
	        fu.setSizeThreshold(4096);
	        // 设置临时目录：
	        fu.setRepositoryPath(tempPath);
	        // 得到所有的文件：
	        List fileItems = fu.parseRequest(request);
	        Iterator i = fileItems.iterator();
	        String[] result = new String[fileItems.size()];
	        
	        // 依次处理每一个文件：
	        while(i.hasNext()) {
	            FileItem fi = (FileItem)i.next();
	            String fileName = fi.getName();
	            
	            if(fileName!=null) {
	                // 在这里可以记录用户和文件信息
	                // ...
	                // 写入文件a.txt，你也可以从fileName中提取文件名：
	                fi.write(new File(uploadPath + rename(fileName)));
	            }
	        }
	        // 跳转到上传成功提示页面
	        response.getWriter().println("上传成功！ upload success!");
	    }
	    catch(Exception e) {
	        // 可以跳转出错页面
	    	response.getWriter().println(e.getMessage());
	    }

	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occure
	 */
	public void init() throws ServletException {
	}
	
	//生成子目录 
	private String genSubDir(){
		Calendar calendar = Calendar.getInstance();
		
		StringBuffer subDir = new StringBuffer(File.separatorChar)
			.append(calendar.get(Calendar.YEAR))
			.append(File.separatorChar)
			.append(calendar.get(Calendar.MONTH))
			.append(File.separatorChar)
			.append(calendar.get(Calendar.DATE))
			.append(File.separatorChar);
		
		return subDir.toString();
	}
	
	//创建基本目录
	private void createBaseDir(String appRootPath){
		if(uploadBasePath == null){
			uploadBasePath = appRootPath + "\\upload\\";
			if( !(new File(uploadBasePath).isDirectory()) ){
				new File(uploadBasePath).mkdirs();
			}
		}
		
		if(tempPath == null){
			tempPath = appRootPath + "\\upload\\temp\\";
			if( !(new File(tempPath).isDirectory()) ){
				new File(tempPath).mkdirs();
			}
		}
	}
	
	//重命名文件
	private String rename(String fileName){
		Date date = new Date();
    	SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");
    	return sdf.format(date) + fileName.substring(fileName.lastIndexOf('.'));
	}
	
}