文件的上传

package com.neuedu.servlet;
import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.UUID;
import javax.servlet.ServletContext;
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.FileUploadBase.FileSizeLimitExceededException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

@WebServlet("/FileUpLoad")
public class FileUpLoad extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	    //获取项目
		ServletContext servletContext = request.getServletContext();
		//获取项目路径及文件
		String realPath = servletContext.getRealPath("/upload");
	    File file = new File(realPath);
		//判断文件是否存在---不存在则创建出来
	    if (!file.exists()) {
			file.mkdir();
		}
		//创建一个工厂类
		DiskFileItemFactory factory=new DiskFileItemFactory();
	    //创建对象，完成上传
		ServletFileUpload fileUpload =new ServletFileUpload(factory);
		//单文件大小限制  1024b*50
		fileUpload.setFileSizeMax(1024*50);
		//上传所有文件限制大小
		fileUpload.setSizeMax(1024*150);
		//用这个对象解析request请求
		try {
			List<FileItem> fileList = fileUpload.parseRequest(request);
		    for(FileItem item:fileList){
		    	//isFormField()用于判断当前表单项是否是一个普通表单项，true是普通表单项， false是文件表单项
		        if (item.isFormField()) {
					//代表普通表单项----能获取普通表单的参数
		        	String fieldName = item.getFieldName(); //获取表单项的name属性值
		        	String value = item.getString("utf-8"); //获取表单项的value属性值，需要接受一个编码作为参数。
				   //输出参数
		        	System.out.println(fieldName+":"+value);
		        }else {
		        	
					//代表上传的文件----能获取普通表单的参数
					long size = item.getSize();       //获取文件的大小
				    if (size==0) {
						continue;
					}
					String contentType = item.getContentType();  // 返回的是文件的类型，是MIME值
				    String name2 = item.getName();        // 获取上传的文件的名字
				    String prName = UUID.randomUUID().toString();//利用时间戳，制作唯一标示
				    prName=prName.replaceAll("-", "");    //字符串操作，去掉时间戳的-
				    String reaName=prName+"_"+name2;       //对文件名进行拼串，创造出唯一文件名，防止文件名相同而覆盖
				    String fieldName = item.getFieldName();   //获取表单项的name属性值
				    //输出参数
				    System.out.println(size+":"+fieldName+":"+contentType+":"+name2);
				    //item.write(new File("C:/Users/000/Desktop/234.jpg"));  // 将表单项中的内容写入到磁盘中
				     item.write(new File(realPath+"\\"+reaName));// 将表单项中的内容写入到磁盘中
		        }
		    }
		} catch(FileSizeLimitExceededException e){
			System.out.println("文件过大");
		}catch (SizeLimitExceededException e) {
			System.out.println("超处上传文件最大限制");
		}catch ( Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}