base64转换字符串作为PhoneGap的PDF格式 [英] Convert base64 string as pdf in phonegap
问题描述
在我的应用我收到一个base64字符串,再presents的PDF文件。我希望用户能够以base64保存为PDF格式,以他的电话。我一直在寻找到科尔多瓦文件传输插件,但该需要(服务器)文件所在的路径能下载,而不是转换成一个base64字符串。
In my app I have received a base64 string that represents a PDF. I want the user to be able to save the base64 as a pdf to his phone. I have been looking in to the cordova-file-transfer plugin but that requires a (server)path where the file can be downloaded from, instead of converting a base64 string.
有没有人成功地使用base64字符串中的PhoneGap下载一个PDF?
Has anybody succeeded in downloading a pdf in phonegap using a base64 string?
推荐答案
在一些更多的搜索和尝试,我发现一些工作。
After some more searching and trying I found something that worked.
<一个href=\"http://stackoverflow.com/questions/16245767/creating-a-blob-from-a-base64-string-in-javascript\">Converting BASE64为PDF BLOB
//Helper function that converts base64 to blob
function b64toBlob(b64Data, contentType, sliceSize) {
var input = b64Data.replace(/\s/g, ''),
byteCharacters = atob(input),
byteArrays = [],
offset, slice, byteNumbers, i, byteArray, blob;
contentType = contentType || '';
sliceSize = sliceSize || 512;
for (offset = 0; offset < byteCharacters.length; offset += sliceSize) {
slice = byteCharacters.slice(offset, offset + sliceSize);
byteNumbers = new Array(slice.length);
for (i = 0; i < slice.length; i++) {
byteNumbers[i] = slice.charCodeAt(i);
}
byteArray = new Uint8Array(byteNumbers);
byteArrays.push(byteArray);
}
//Convert to blob.
try {
blob = new Blob(byteArrays, { type: contentType });
}
catch (e) {
// TypeError old chrome, FF and Android browser
window.BlobBuilder = window.BlobBuilder ||
window.WebKitBlobBuilder ||
window.MozBlobBuilder ||
window.MSBlobBuilder;
if (e.name == 'TypeError' && window.BlobBuilder) {
var bb = new BlobBuilder();
for (offset = 0; offset < byteArrays.length; offset += 1) {
bb.append(byteArrays[offset].buffer);
}
blob = bb.getBlob(contentType);
}
else if (e.name == "InvalidStateError") {
blob = new Blob(byteArrays, {
type: contentType
});
}
else {
return null;
}
}
return blob;
};
然后把下载本身我们需要科尔多瓦文件插件:
var fileToSave= b64toBlob(fileData, 'application/pdf');
writeFile();
function writeFile() {
console.log("request file system");
window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, onFileSystemRetrieved, onFileSystemFail);
}
function onFileSystemRetrieved(fileSystem) {
console.log("file system retrieved");
fileSystem.root.getFile(fileName, { create: true }, onFileEntryRetrieved, onFileSystemFail);
}
function onFileEntryRetrieved(fileEntry) {
console.log("file entry retrieved");
fileEntry.createWriter(gotFileWriter, onFileSystemFail);
}
function gotFileWriter(writer) {
console.log("write to file");
writer.onwrite = function (evt) {
alert('done');
}
writer.write(fileToSave);
window.open(fileName, '_blank');
}
function onFileSystemFail(error) {
console.log(error.code);
alert(error.code)
}
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