文件上传 | daidaiwo'blog

文件上传要素：

1	<form action="提交地址" method="post" enctype="multipart/form-data">

1	<input type="file" name="pic"> <!--name值随便写>

后台Servlet上必须加上注解 @MultipartConfig

代码实现：

UploadListener类：

package org.fkjava.listener;

import java.io.File;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class UploadListener implements ServletContextListener {

  
    public UploadListener() {
        // TODO Auto-generated constructor stub
    }

    public void contextDestroyed(ServletContextEvent arg0)  { 
         // TODO Auto-generated method stub
    }

    public void contextInitialized(ServletContextEvent event)  { 
         // 初始化创建一个上传的文件夹，如果文件夹存在就不再重复创建
    	
    	// 获得ServletContext
    	ServletContext context = event.getServletContext();
   	 	
    	// 获得web项目的根路径下的upload的路径
    	String realPath = context.getRealPath("/upload");
    	System.out.println("realPath:"+realPath);
    	// 构造一个File
    	File file = new File(realPath);
    	// 判断该File是否存在
    	if(!file.exists()){
    		// 如果不存在，创建
    		file.mkdirs();
    		System.out.println("创建上传文件夹成功!");
    	}else{
    		System.out.println("上传文件夹已经存在!");
    	}
    }
	
}

UploadServlet类：

package org.fkjava.servlet;

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

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

/**
 * 文件上传的要素
 * 1、页面中请求方式必须是  post请求
 * 2、form表单必须加上属性 enctype="multipart/form-data"
 * 3、后台Servlet上必须加上注解   @MultipartConfig
 */
@WebServlet("/upload")
@MultipartConfig
public class UploadServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	public UploadServlet() {
		super();
		// TODO Auto-generated constructor stub
	}

	protected void service(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
		
		request.setCharacterEncoding("UTF-8");
		
		String username = request.getParameter("username");
		System.out.println("username：" + username);
		
		Part part = request.getPart("pic");
		/*常用方法*/
		 System.out.println("name：" + part.getName());
		System.out.println("size：" + part.getSize());
		System.out.println("SubmittedFileName：" + part.getSubmittedFileName());
		System.out.println("ContentType：" + part.getContentType());
		
		// 获得上传的文件的原来的名称 1.jpg   ==  >  434343fdfdffd.jpg
		String fileName = part.getSubmittedFileName();
		
		//通过UUID生成随机数
		String fn = UUID.randomUUID().toString();
				
		// 获得上传的文件夹路径
		String filePath = this.getServletContext().getRealPath("/upload");
		System.out.println("filePath:"+filePath);
		
		// 上传        File.separator 用于获取文件分隔符       d:upload/4343434334343.jpg
		part.write(filePath + File.separator + fn+fileName.substring(fileName.lastIndexOf("."), fileName.length()));
		System.out.println("上传文件成功!");
	}
	
}

index.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
  
       <form action='fileUpload' method= 'post' enctype='multipart/form-data'>
        选择文件：<input type="file" name='pic' /><br>
        <input type="submit" value="提交">
       </form>

</body>
</html>