使用PHP和HTML5 FormData实现无刷新文件上传教程

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使用PHP和HTML5 FormData实现无刷新文件上传教程_PHP

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May 31, 2016 pm 07:29 PM

formdatahtml5php

无刷新文件上传是一个常见而又有点复杂的问题，常见的解决方案是构造 iframe 方式实现。

在 HTML5 中提供了一个 FormData 对象 API，通过 FormData 可以方便地构造一个表单请求，并通过 XMLHttpRequest 来发送。通过 FormData 对象发送文件也是可以的，如此则无刷新上传就变的非常简单了。

那么 FormData 怎么使用呢？下面对此进行简单的介绍。

1. 构造 FormData 对象

想得到一个FormData对象，很简单：

var fd = new FormData();

FormData 对象只提供了一个方法 append ，用于向对象中添加表单请求参数。
在当前主流浏览器中，可通过如下两种方式获取或修改FormData。
方法一：创建一个空的FormData对象，然后再用append方法逐个添加键值对。示例：

var fd = new FormData();
fd.append("name", "");
fd.append("blog", "http://bitsCN.com");
fd.append("file", document.getElementById("file"));

这种方法可以不需要 HTML 的表单对象存在。
方法二：取得form元素对象，将它作为参数传入FormData对象中。示例：

var formobj = document.getElementById("form");
var fd = new FormData(formobj);

当然，这里还可以使用 append 方法继续向 fd 中添加其他参数。

2. FormData 发送请求

得到 FormData 对象了，如何发送请求呢？ FormData 对象主要用于增强型的 XMLHttpRequest 对象的 send 方法中。参考如下示例：

var xhr = new XMLHttpRequest();    
xhr.open("POST" ,"http://bitsCN.com" , true);
xhr.send(fd);
xhr.onload = function(e) {
  if (this.status == 200) {
    alert(this.responseText);
  }
};

3. jquery 中使用 FormData

在 jQuery 的 ajax 方法中，也可使用 FormData 方式实现无刷新上传。但要注意参数的设置，参考如下：

$.ajax({
  url: "http://bitsCN.com",
  type: 'POST',
  data: fd,
  /**
   *必须false才会自动加上正确的Content-Type
   */
  contentType:false,
  /**
   * 必须false才会避开jQuery对 formdata 的默认处理
   * XMLHttpRequest会对 formdata 进行正确的处理
   */
  processData:false
}).done(function(result){
  console.log(result);
}).fail(function(err){
  console.log(err);
});

4. 一个完整的示例（包含PHP处理示例）：

<&#63;php
//php 接收表单提交信息并打印
if( isset( $_REQUEST['do']) ){
  var_dump($_REQUEST);
  var_dump($_FILES);
  die();
}

&#63;>
<!DOCTYPE HTML>
<html>
  <head>
    <meta charset="utf-8">
    <title>FormData Test - bitsCN.com</title>
    <script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
  </head>
  <body>
    <form id="form">
      <input type="file" name="file" id="file" />
      <input type="text" name="name" id="" value="" />
      <input type="text" name="blog" id="" value="http://bitsCN.com" />
      <input type="submit" name="do" id="do" value="submit" />
    </form>
    <script>
    $("form").submit(function(e){
      e.preventDefault();
      
      //空对象然后添加
      var fd = new FormData();
      fd.append("name", "");
      fd.append("blog", "http://bitsCN.com");
      fd.append("file", document.getElementById("file"));
      //fd.append("file", $(":file")[0].files[0]); //jQuery 方式
      fd.append("do", "submit");
      
      //通过表单对象创建 FormData
      var fd = new FormData(document.getElementById("form"));
      //var fd = new FormData($("form:eq(0)")[0]); //jquery 方式
      
      //XMLHttpRequest 原生方式发送请求
      var xhr = new XMLHttpRequest();    
      xhr.open("POST" ,"" , true);
      xhr.send(fd);
      xhr.onload = function(e) {
        if (this.status == 200) {
          alert(this.responseText);
        };
      };
      return;
      //jQuery 方式发送请求
      $.ajax({
        type:"post",
        //url:"",
        data: fd,
        processData: false,
        contentType: false
      }).done(function(res){
        console.log(res);
      });
      
      return false;
    });
    </script>
  </body>
</html>

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