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Implementation steps for file upload using js and servlet in h5

php中世界最好的语言Original: 2017-12-04 10:45:042469browse

This time I will teach you how to use JS and servlet to implement file upload in H5, but there is a prerequisite, it must be h5 and jsp3.0 version, because New attributes are used to obtain the file object and the part object in the background.

Let me show you a case

Front-end jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "https://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript" src="jquery-3.2.1.min.js"></script>
</head>
<body>
    <p>
        name:<input type="text" id="name"/>
        文件：<input type="file" id="file"/>
        <br>
        <button id="btu" onclick="btu()">提交</button>
    </p>
</body>
 
<script>
    function btu(){
            var name=$("#name").val();
            var file=$("#file")[0].files[0];//新特性，获取文件对象
            var fordata=new FormData();//新特性，得到formData对象，把获取的值扔进去，相当于map
            fordata.append("name",name);
            fordata.append("file",file);
            console.log(file)
            $.ajax({
                url:"/war-2/UpdataFile",
                data:fordata,
                cache:false,
                processData:false, //必须写
                contentType:false, //必须写
                type:"post",
                success:function(data){
 
                }
            })
    }
</script>
</html>

Back-end java

package up;
 
import java.io.File;
import java.io.IOException;
import java.util.Collection;
 
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;
 
/**
 * Servlet implementation class UpdataFile
 */
@MultipartConfig(location="E:/")
@WebServlet("/UpdataFile")
public class UpdataFile extends HttpServlet {
    private static final long serialVersionUID = 1L;
 
    private File file;
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
            System.out.println("1111111111");
    }
 
    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        //得到part对象，这个对象有write的方法，直接写到指定位置。但是千万别忘了写@MultipartConfig(location="E:/")注解，不指定位置默认是写到注解指定的位置。
        Part part = request.getPart("file");
        //普通的字段可以采用常规的getparamter的方法得到。
        System.out.println(new String(request.getParameter("name").getBytes("iso-8859-1"),"utf-8"));
        System.out.println(part.getName());
        System.out.println(part.getHeader("Content-Disposition"));
        System.out.println(part.getSize());
        String fileName = getFileNameFromPart(part);  
        part.write(fileName); 
    }
     //截取文件名  
    public String getFileNameFromPart(Part part) {  
        String header = part.getHeader("Content-Disposition");  
        String fileName = header.substring(header.indexOf("filename=\"")+10, header.lastIndexOf("\""));  
        return fileName;  
    } 
}

Believe it After reading these cases, you have mastered the methods. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

Implementation steps for file upload using js and servlet in h5

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