FormData and Spring MVC implement Ajax file download function

This time I will bring you FormData and Spring MVC to implement the Ajax file download function. What are the precautions for FormData and Spring MVC to implement the Ajax file download function. The following is a practical case. , let’s take a look.

Ajax file download

Using the FormData object and Spring MVC to implement the Ajax file upload function:

Steps

1. Import components and prepare static scripts

<dependency>
 <groupId>commons-fileupload</groupId>
 <artifactId>commons-fileupload</artifactId>
 <version>1.3.2</version>
</dependency>
  <h1>Ajax 文件上载</h1>
  <input type="file" id="file1"> <br>
  <input type="file" id="file2"> <br>
  <input type="button" id="upload" value="上载" >
  <p id="result"></p>

1. Bind events to buttons

$("upload").click(ajaxUpload);

2. Get files

var file1 = $("#file1")[0].files[0];
var file2 = $("#file2")[0].files[0];

3. Create the form object in memory and add the data transmitted to the server

//创建内存中的表单对象
var form = new FormData();
//向其中添加要传输的数据
form.append("userfile1", file1);
form.append("userfile2", file2);

4.ajax() upload object

$.ajax({
  url:'user/upload.do',//请求地址
  data: form,   //请求参数
  type: 'POST',  //请求类型
  dataType: 'json',//服务器返回的数据类型
  contentType: false,//没有设置任何内容类型头信息
  processData: false, //见jQuery_api详解
  success: function(obj){ //成功时回调函数,obj表示服务器返回的数据
    if(obj.state==0){
      $('#result').html("成功!"); 
    }
  }
});

5.Spring-MVC presentation layer

@RequestMapping("/upload.do")
@ResponseBody
public JsonResult upload( 
    MultipartFile userfile1, 
    MultipartFile userfile2) throws Exception{
  //Spring MVC 中可以利用 MultipartFile 
  //接收 上载的文件! 文件中的一切数据
  //都可以从 MultipartFile 对象中找到
  //获取上再是原始文件名
  String file1 = 
    userfile1.getOriginalFilename();
  String file2 = 
    userfile2.getOriginalFilename();
  System.out.println(file1);
  System.out.println(file2);
  //保存文件的3种方法:
  //1. transferTo(目标文件)
  //  将文件直接保存到目标文件, 可以处理大文件
  //2. userfile1.getBytes() 获取文件的全部数据
  //  将文件全部读取到内存, 适合处理小文件!!
  //3. userfile1.getInputStream()
  //  获取上载文件的流, 适合处理大文件
  //保存的目标文件夹: /home/soft01/demo
  File dir = new File("D:/demo");
  dir.mkdir();
  File f1 = new File(dir, file1);
  File f2 = new File(dir, file2);
  //第一种保存文件
  //userfile1.transferTo(f1);
  //userfile2.transferTo(f2);
  //第三种 利用流复制数据
  InputStream in1 = userfile1.getInputStream();
  FileOutputStream out1 = 
    new FileOutputStream(f1);
  int b;
  while((b=in1.read())!=-1){
    out1.write(b);
  }
  in1.close();
  out1.close();
  InputStream in2 = userfile2.getInputStream();
  FileOutputStream out2=
      new FileOutputStream(f2);
  byte[] buf= new byte[8*1024];
  int n;
  while((n=in2.read(buf))!=-1){
    out2.write(buf, 0, n);
  }
  in2.close();
  out2.close();
  return new JsonResult(true);
  }

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

Recommended reading:

How to implement WebApi Ajax cross-domain requests using CORS

How to implement dynamic loading of combo boxes with Ajax (With code)

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