完整文件上传和下载（Servlet部分）

package Demo_1;


import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


public class doFile extends HttpServlet {


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


	public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
     
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		String method = request.getParameter("method");
		
		if(method.equals("upload")){
		
		FileItemFactory factory = new DiskFileItemFactory();
		
		ServletFileUpload upload = new ServletFileUpload(factory);
		
		upload.setFileSizeMax(30*1024*1024);
		
		upload.setSizeMax(100*1024*1024);
		
		if(upload.isMultipartContent(request)){
			//普通表单处理
			try {
				List<FileItem> list = upload.parseRequest(request);
				
				for(FileItem item : list){
					if(item.isFormField()){
						String filedName = item.getFieldName();//文本框民称   jsp页面中name中的值
						String content = item.getString("UTF-8");//文本框值  
						
					}else{
						//处理文江上传
						
						String id = UUID.randomUUID().toString();
						//获取文件名字
						
						String name = id+"#"+item.getName();
						
						//获取上传的目录路径
						String basePath = getServletContext().getRealPath("/upload");
					    File file = new File(basePath, name);	
					    item.write(file);
					    item.delete();
					}
				}
			} catch (FileUploadException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			
		}else{
			System.out.println("不是表单，不处理");
		}
		}
		if(method.equals("showList")){
			Map<String,String> fileNames = new HashMap<String, String>();
			String basePath = getServletContext().getRealPath("/upload");
			File file = new File(basePath);
			String list[] = file.list();
			if(list!=null && list.length>0){
				for(int i=0;i<list.length;i++){
					//全部名称
					String fileName = list[i];
					String shortName = list[i].substring(fileName.indexOf("#")+1, fileName.length());
					fileNames.put(fileName, shortName);
				}
			}
			request.setAttribute("fileNames", fileNames);
			request.getRequestDispatcher("/showList.jsp").forward(request, response);
		}
		if(method.equals("down")){
			//获取用户下载文件的名称
			String fileName = request.getParameter("fileName");
			//改变文件名称的编码
			fileName = new String(fileName.getBytes("ISO8859-1"),"UTF-8");
			//先获取上传目录路径
			String basePath = getServletContext().getRealPath("/upload");
			//获取一个文件流
			FileInputStream in = new FileInputStream(new File(basePath,fileName));
			//如果文件名是中文，需要进行url编码
			fileName = URLEncoder.encode(fileName, "utf-8");
			//设置下载的响应头
			response.setHeader("content-disposition", "attachment;fileName="+fileName);
			//获取response字节流
			OutputStream out = response.getOutputStream();
			byte[] b = new byte[1024];
			int len = -1;
			while((len = in.read(b))!=-1){
				out.write(b, 0, b.length);
			}
			out.close();
		    in.close();
		}
	}


}