如何将图像从本地计算机加载到JS对象，避免加载到服务器 [英] How to load images from the local machine to JS object avoiding loading to the server

问题描述

我想将图像文件从计算机直接加载到任何js对象，而不使用任何服务器端组件.例如，我想从本地计算机上选择一张图片并将其显示在网页上.有没有办法避免文件上传到服务器?

I want to load an image file from the computer directly to any js object without using any server-side component. For example, I want to select a picture from the local machine and display it on a webpage. Is there a way to avoid file upload to the server?

事实上，我想编写一种多图像加载器，但是在加载到服务器之前，我想旋转一些图像，创建一个包含一些数据的xml文件，例如用户ID，图像文件名列表并压缩所有图像和这个xml，然后将其发送到服务器.我该如何在客户端上做到这一点?

In fact I want to write a kind of multiple image loader, but before loading to the server I want to rotate some images, create an xml-file with some data like user id, image file names list and to zip all images and this xml and then send it to the server. How can I do that on the client side?

推荐答案

HTML5有一种方法，但是它要求用户将文件拖放到放置目标中或使用<input type="file"/>框，否则将会是一个安全问题.

There is a way with HTML5, but it requires the user to have dropped the file into a drop target or used a <input type="file"/> box, since otherwise it would be a security issue.

使用File API可以读取文件，特别是可以使用FileReader.readAsDataURL方法将内容设置为图像标签的data: URL.

Using the File API you can read files, and specifically you can use the FileReader.readAsDataURL method to set the content as a data: URL for the image tag.

这是一个例子:

$('#f').on('change', function(ev) {
    var f = ev.target.files[0];
    var fr = new FileReader();

    fr.onload = function(ev2) {
        console.dir(ev2);
        $('#i').attr('src', ev2.target.result);
    };

    fr.readAsDataURL(f);
});​

http://jsfiddle.net/alnitak/Qszjg/

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