Created
February 8, 2014 05:28
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利用xhr2得到文件,转为bolb存储到localstorage中
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// Getting a file through XMLHttpRequest as an arraybuffer and creating a Blob | |
var rhinoStorage = localStorage.getItem("rhino"), | |
rhino = document.getElementById("rhino"); | |
if (rhinoStorage) { | |
// Reuse existing Data URL from localStorage | |
rhino.setAttribute("src", rhinoStorage); | |
} | |
else { | |
// Create XHR, Blob and FileReader objects | |
var xhr = new XMLHttpRequest(), | |
blob, | |
fileReader = new FileReader(); | |
xhr.open("GET", "rhino.png", true); | |
// Set the responseType to arraybuffer. "blob" is an option too, rendering manual Blob creation unnecessary, but the support for "blob" is not widespread enough yet | |
xhr.responseType = "arraybuffer"; | |
xhr.addEventListener("load", function () { | |
if (xhr.status === 200) { | |
// Create a blob from the response | |
blob = new Blob([xhr.response], {type: "image/png"}); | |
// onload needed since Google Chrome doesn't support addEventListener for FileReader | |
fileReader.onload = function (evt) { | |
// Read out file contents as a Data URL | |
var result = evt.target.result; | |
// Set image src to Data URL | |
rhino.setAttribute("src", result); | |
// Store Data URL in localStorage | |
try { | |
localStorage.setItem("rhino", result); | |
} | |
catch (e) { | |
console.log("Storage failed: " + e); | |
} | |
}; | |
// Load blob as Data URL | |
fileReader.readAsDataURL(blob); | |
} | |
}, false); | |
// Send XHR | |
xhr.send(); | |
} |
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