Ionic 3 Post Camera Image to API With cordova-plugin-file
我已经成功地使用cordova-plugin-file-transfer将图像文件从设备相机发布到API,例如fileTransfer.upload(fileUrl,url,options)。
但是,不建议使用cordova-plugin-file-transfer:
"通过XMLHttpRequest中引入的新功能,该插件不再需要。从此插件迁移到使用XMLHttpRequest的新功能,将在此Cordova博客文章中进行解释。"
https://github.com/apache/cordova-plugin-file-transfer
建议的新方法是使用cordova-plugin-file和XMLHttpRequest。
https://cordova.apache.org/blog/2017/10/18/from-filetransfer-to-xhr2.html
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, function (fs) { console.log('file system open: ' + fs.name); fs.root.getFile('bot.png', { create: true, exclusive: false }, function (fileEntry) { fileEntry.file(function (file) { var reader = new FileReader(); reader.onloadend = function() { // Create a blob based on the FileReader"result", which we asked to be retrieved as an ArrayBuffer var blob = new Blob([new Uint8Array(this.result)], { type:"image/png" }); var oReq = new XMLHttpRequest(); oReq.open("POST","http://mysweeturl.com/upload_handler", true); oReq.onload = function (oEvent) { // all done! }; // Pass the blob in to XHR's send method oReq.send(blob); }; // Read the file as an ArrayBuffer reader.readAsArrayBuffer(file); }, function (err) { console.error('error getting fileentry file!' + err); }); }, function (err) { console.error('error getting file! ' + err); }); }, function (err) { console.error('error getting persistent fs! ' + err); }); |
在上面的示例中,我们可以将XMLHttpRequest替换为Angular 5 HttpClient,例如
1 | this.http.post(path, body, options); |
cordova-plugin-camera文档建议使用DestinationType = FILE_URI或NATIVE_URI,它们均返回类似于以下内容的路径/文件:content:// media / external / images / media / 1249。他们特别警告不要返回base64编码的字符串。
"返回base64编码的字符串。DATA_URL可能占用大量内存,并导致应用程序崩溃或内存不足错误。如果可能,请使用FILE_URI或NATIVE_URI。"
https://github.com/apache/cordova-plugin-camera#module_Camera.DestinationType
似乎这里的新方法/正确方法是使用cordova-plugin-file获取文件,将此文件转换为blob,然后将其发布到API。
首先,我认为我需要使用cordova-plugin-file中的resolveLocalFilesystemUrl转换照相机localFile:https://ionicframework.com/docs/native/file/。
1 2 3 | this.file.resolveLocalFilesystemUrl(localFile).then((entry) => { console.log(entry.fullPath); }); |
Android示例:
1 2 | localFile: content://media/external/images/media/1249 resolvedLocalFile: content://media/external/images/media/1827 |
但是,我一直无法使用带有cordova-plugin-file的resolveLocalFile来获取文件并转换为blob(然后最终发布到API)。
这是正确的方法吗?如果是这样,那么这是一个有效的代码示例。如果没有,正确的方法是什么?请注意,我已经看到了一些示例,这些示例发布了base64编码的字符串,但是cordova-plugin-camera明确警告了这一点。
以下是基于此方法的有效Stubbing:使用cordova-plugin-file获取文件,将文件转换为blob,将blob发布到API。这篇文章对创建此Stubbing也非常有帮助:https://golb.hplar.ch/2017/02/Uploading-pictures-from-Ionic-2-to-Spring-Boot.html
主例程:
1 2 3 4 5 6 7 | this.cameraProvider.getPicture() .flatMap(imageData => { return this.cameraProvider.imageDataToBlob(imageData); }) .flatMap(blob => { return this.workerProvider.updateImage(blob); }).subscribe(); |
使用cordova-plugin-camera获取文件:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | public getPicture(): Observable { const options: CameraOptions = { destinationType: this.camera.DestinationType.FILE_URI, encodingType: this.camera.EncodingType.JPEG, mediaType: this.camera.MediaType.PICTURE, sourceType: this.camera.PictureSourceType.PHOTOLIBRARY } return Observable.fromPromise( this.platform.ready().then(() => { if (this.platform.is('cordova')) { return this.camera.getPicture(options).then((imageData: any) => { // Android DestinationType.FILE_URI returns a local image url in this form: content://media/external/images/media/1249 // iOS DestinationType.FILE_URI returns a local image url in this form: file:///var/mobile/Containers/Data/Application/25A3F622-38DB-4701-AB20-90AAE9AC02C8/tmp/cdv_photo_002.jpg return imageData; }).catch((error) => { // Handle error. }) } else { return Observable.of(null); } }) ) } |
将文件转换为blob:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 | public imageDataToBlob(imageData): Observable { return Observable.fromPromise(this.file.resolveLocalFilesystemUrl(imageData)) .flatMap((fileEntry: FileEntry) => { // Cast entry to fileEntry. return this.fileEntryToObservable(fileEntry) }) .flatMap((file) => { return this.fileReaderToObservable(file) }); } public fileEntryToObservable(fileEntry: any): Observable { return Observable.create(observer => { // Success. fileEntry.file(function(file) { observer.next(file); }, // Error. function (error) { observer.error(error) }) }); } public fileReaderToObservable(file: any): Observable { const fileReader = new FileReader(); fileReader.readAsArrayBuffer(file); return Observable.create(observer => { // Success. fileReader.onload = ev => { let formData = new FormData(); let imgBlob = new Blob([fileReader.result], { type: file.type }); observer.next(imgBlob); } // Error. fileReader.onerror = error => observer.error(error); }); } |
将Blob发布到API:
1 2 3 4 5 6 7 8 | // Do NOT add Content-Type multipart/form-data to header. let headers = new HttpHeaders() const formData = new FormData(); formData.append('file', blob, 'image'); let options = { headers: headers }; return this.http.post(url, formData, options); |