Servlet上传

最新推荐文章于 2022-08-17 16:56:56 发布

流浪的面包树丶

最新推荐文章于 2022-08-17 16:56:56 发布

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文章标签： ajax java servlet jsp

本文链接：https://blog.youkuaiyun.com/qq_31462011/article/details/73823082

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1 写上传的jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>上传</title>
</head>
<body>
<!-- image/*     text/css   text/javascript   -->
	<form action="upload.do" method="post" enctype="multipart/form-data">
		<input type="text" name="username"/>
		<!-- name是用来在后台servlet中获取当前文件内容，name的命名可以随意 -->
		<input type="file" name="file"/><br/>
		<!-- 是一个隐藏的控件 -->
		<input type="hidden" id="token" name="token"/>
		<input id="submit_btn" type="button" value="提交" οnclick="submit1()"/>
	</form>
	<script type="text/javascript" src="js/jquery-3.1.1.js"></script>
	<script type="text/javascript">
		$.get("token.do",function(data,status){$("#token").val(data);});
		
		function submit1(){
			
			$("#submit_btn").hide();
			alert("--");
			$("form").submit();
		}
	</script>
</body>
</html>

其中，利用Ajax来实现异步请求，获取token，之所以要用到token是为了防止用户重复提交。
2 写UploadServlet

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.Random;

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

import com.mysql.fabric.xmlrpc.base.Data;

@MultipartConfig
public class UploadServlet extends HttpServlet{
	
	private Random random = new Random();
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//---
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//		System.out.println("---" + req.getParameter("file"));
		
		String username = req.getParameter("username");
		String token = req.getParameter("token");
		Object defaultToken = req.getSession().getAttribute("token");
		System.out.println(token + "---" + defaultToken);
		//比较用户提交的Token和系统本身的TOken是否一致
		if (token != null && defaultToken!=null && token.equals(defaultToken.toString())){
			//一旦匹配成功，将系统中的Token销毁
			req.getSession().removeAttribute("token");
			System.out.println("---" + username);
			//获取从页面上传递过来的文件
			Part part = req.getPart("file");
			String name = part.getSubmittedFileName();
			System.out.println(part.getSubmittedFileName());
			System.out.println(part.getName());
			//获取当前时间的毫秒
			long time = new Date().getTime();
			int randomNum = random.nextInt(Integer.MAX_VALUE);
			name = time+"_"+randomNum+"_"+name;
			//创建输出流，用来在服务器磁盘上输出文件
			File file = new File("E:\\"+name);
			FileOutputStream fos = new FileOutputStream(file);
			//获取输入流
			InputStream is = part.getInputStream();
			byte[] buffer = new byte[1024];
			int len=0;
			while((len=is.read(buffer)) != -1){
				//将文件写入服务器磁盘
				fos.write(buffer, 0, len);
			}
			fos.flush();
			fos.close();
			is.close();
		} 
		
	}

}

3 写TokenServlet

import java.io.IOException;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 制造Token的一个类
 */
public class TokenServlet extends HttpServlet{
	private Random random = new Random(); 
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//制造Token
		int token = random.nextInt(Integer.MAX_VALUE);
		req.getSession().setAttribute("token", token);
		resp.getWriter().write(String.valueOf(token));
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doGet(req,resp);
	}

}