WebView中打开相机,文件选择器的问题和解决方法
Posted 不积跬步-无以至千里
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了WebView中打开相机,文件选择器的问题和解决方法相关的知识,希望对你有一定的参考价值。
近几年前端开发真是越来越火,H5页面开发的移动端页面甚至有夺我原生开发半壁江山的意思,忧伤忧伤。不过从实际情况考虑,H5一套代码到处跑的特性,我们的android, ios ...也就只能呵呵了。然而我还是比较喜欢原生应用,对网络质量要求低,经过H5页面加载不出来一片空白就不受得抓狂!吐槽归吐槽,正事不能落下。
上一篇意图调相机的2方式种以及那些你知道的不状语从句:知道的坑中完成了对意向调起系统相机,结果处理以及一些问题的应对。其实上篇文章还是因为今天的主题web视图中调用相机系统-而起,因为涉及到调用相机本身的一些问题之前不是很明确,所以专门搞了一下,记录下来,所以如果调用相机操作本身有什么疑问或问题,请点击跳转到上一篇电子邮件寻找答案,本篇不再重复。接下来们看看在WebView中调用相机的一些问题。
问题说明
最近有个需求是要上传身份证正反照,说来简单,可偏偏这部分业务是H5页面处理的,所以只能通过H5页面去拍照或选取本地图片了,然而问题来了 - 这段H5代码在用浏览器打开可以实现功能,但是放在WebView中却没有动作。
<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>相机调用</title> <script type="text/javascript"> function previewPhoto(sourceId, targetId) { var url; if (navigator.userAgent.indexOf("MSIE") >= 1) { // IE url = document.getElementById(sourceId).value; } else if(navigator.userAgent.indexOf("Firefox") > 0) { // Firefox url = window.URL.createObjectURL(document.getElementById(sourceId).files.item(0)); } else if(navigator.userAgent.indexOf("Chrome") > 0) { // Chrome url = window.URL.createObjectURL(document.getElementById(sourceId).files.item(0)); } else if(navigator.userAgent.indexOf("Opera") > 0 || navigator.userAgent.indexOf("Oupeng") > 0) { // Oupeng url = window.URL.createObjectURL(document.getElementById(sourceId).files.item(0)); } else { url = "flower_err.jpg"; } <!--window.alert("address:" + url);--> window.alert("address:" + navigator.userAgent); var imgPre = document.getElementById(targetId); imgPre.src = url; } </script> </head> <body> <a href="http://www.baidu.com">去百度</a> <br><br> <img id="img" width="200px" height="300px" alt="图片预览区"> <br> <input type="file" id="pic" name="camera" accept="image/*" onchange="previewPhoto(this.id, \'img\');"/> <br><br> <input type="file" accept="image/*" multiple> </body> </html>
在浏览器中正常运行:
根据前人描述,是因为Android源码中将这部分屏蔽了,需要在webView.setWebChromeClient(new WebChromeClient())中重写WebChromeClient的openFileChooser()等方法,接下来我们就打开源码看看。
源码分析
遇到问题看源码是最直接也是最有效的办法,虽然通常情况下阅读源码比看网上一些帖子难度要大点,但却是问题的根本所在。可能有时候遇到很多问题不知道专门从源码下手,这时候就只能用问题去百度,谷歌去了,看看前辈们是怎么解决这个问题的,遇到涉及源码时再回头追本溯源,这样便会对问题本身理解深刻;久而久之,可见成效。说到这里,一个推荐用英语查看各版本源码的地址,毕竟你不会下载了所有版本的源码。闲话少叙,据说不同版本还不一样,那就一个一个看(WebChromeClient.java在\\机器人\\ WebKit的包下):
(Android 2.2)8 <= API <= 10(Android 2.3)
以Version 2.3.7_r1(API 10)为例(API <8时就没有这个方法):
可以看到,openFileChooser()方法用来告诉客户端打开一个文件选择器,只有一个入参ValueCallback对象uploadMsg,uploadMsg是一个回调值,用来设置待上传文件的Uri,用onReceiveValue()方法来唤醒等待线程(英语不好,莫见怪);并且该方法被隐藏了。
(Android 3.0)11 <= API <= 15(Android 4.0.3)
以Version 2.3.7_r1(API 15)为例:
可以看到,该方法也是被隐藏了;不过openFileChooser()方法比上一版多了一个字符串入参acceptType,H5页面中输入标签声明的文件选择器设置的接受属性值,就是上边H5代码中这一行:
<input type="file" id="pic" name="camera" accept="image/*" onchange="previewPhoto(this.id, \'img\');"/>
(Android 4.1.2)16 <= API <= 20(Android 4.4W.2)
以版本4.4W(API 20)为例:
/** * Tell the client to open a file chooser. * @param uploadFile A ValueCallback to set the URI of the file to upload. * onReceiveValue must be called to wake up the thread.a * @param acceptType The value of the \'accept\' attribute of the input tag * associated with this file picker. * @param capture The value of the \'capture\' attribute of the input tag * associated with this file picker. * @hide */ public void openFileChooser(ValueCallback<Uri> uploadFile, String acceptType, String capture) { uploadFile.onReceiveValue(null); }
同样有@hide标签;又比上一版多了一个String入参捕获,同样是输入标签的同名属性值(用来指定设备比如capture =“camera”,不过好像用的很少了)。
API> = 21(Android 5.0.1)
以版本5.0(API 21)为例:
/** * Tell the client to open a file chooser. * @param uploadFile A ValueCallback to set the URI of the file to upload. * onReceiveValue must be called to wake up the thread.a * @param acceptType The value of the \'accept\' attribute of the input tag * associated with this file picker. * @param capture The value of the \'capture\' attribute of the input tag * associated with this file picker. * * @deprecated Use {@link #showFileChooser} instead. * @hide This method was not published in any SDK version. */ @Deprecated public void openFileChooser(ValueCallback<Uri> uploadFile, String acceptType, String capture) { uploadFile.onReceiveValue(null); }
之前的@hide干嘛用的,之前不知道,但是这里就有说明了 - 这个方法没有在任何SDK版本发布,也就是说这个方法没有公开,所以不会像别的普通方法那样Override,那要怎么搞?后边说。
还有,这个方法被@deprecated标记了,用新方法showFileChooser()替换了,那我再找找showFileChooser:
/** * Tell the client to show a file chooser. * * This is called to handle HTML forms with \'file\' input type, in response to the * user pressing the "Select File" button. * To cancel the request, call <code>filePathCallback.onReceiveValue(null)</code> and * return true. * * @param webView The WebView instance that is initiating the request. * @param filePathCallback Invoke this callback to supply the list of paths to files to upload, * or NULL to cancel. Must only be called if the * <code>showFileChooser</code> implementations returns true. * @param fileChooserParams Describes the mode of file chooser to be opened, and options to be * used with it. * @return true if filePathCallback will be invoked, false to use default handling. * * @see FileChooserParams */ public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) { return false; }
看,这个注释就很用心了.onShowFileChooser()方法和openFileChooser()同样的作用,但是有更详细的解释 -
- 这个方法用来处理HTML表单中声明type =“file”的输入标签,响应的时机用户按下“选择文件”按钮
- 如果要取消该操作(选择文件操作),需要调用filePathCallback.onReceiveValue(空); 返回true;
- 返回值的含义:返回true表示认可再该方法中重写的对filePathCallback的操作,返回false表示使用默认处理(即空方法,不做任何处理)
参数filePathCallback泛型由原来的一个Uri变为Uri [],说明可以支持一次选取多个文件(当然,调用系统相机直接拍照的话还是只能一张一拍,此时Uri []中之只有1个人素,若从相册或文件系统选,应该可以多选(本人没有现现,不敢说肯定可以));
参数FileChooserParams fileChooserParams应该和原来的是一个道理,就是输入标签的属性集合,可以看一下源码:
/** * Parameters used in the {@link #onShowFileChooser} method. */ public static abstract class FileChooserParams { /** Open single file. Requires that the file exists before allowing the user to pick it. */ public static final int MODE_OPEN = 0; /** Like Open but allows multiple files to be selected. */ public static final int MODE_OPEN_MULTIPLE = 1; /** Like Open but allows a folder to be selected. The implementation should enumerate all files selected by this operation. This feature is not supported at the moment. @hide */ public static final int MODE_OPEN_FOLDER = 2; /** Allows picking a nonexistent file and saving it. */ public static final int MODE_SAVE = 3; /** * Parse the result returned by the file picker activity. This method should be used with * {@link #createIntent}. Refer to {@link #createIntent} for how to use it. * * @param resultCode the integer result code returned by the file picker activity. * @param data the intent returned by the file picker activity. * @return the Uris of selected file(s) or null if the resultCode indicates * activity canceled or any other error. */ public static Uri[] parseResult(int resultCode, Intent data) { return WebViewFactory.getProvider().getStatics().parseFileChooserResult(resultCode, data); } /** * Returns file chooser mode. */ public abstract int getMode(); /** * Returns an array of acceptable MIME types. The returned MIME type * could be partial such as audio/*. The array will be empty if no * acceptable types are specified. */ public abstract String[] getAcceptTypes(); /** * Returns preference for a live media captured value (e.g. Camera, Microphone). * True indicates capture is enabled, false disabled. * * Use <code>getAcceptTypes</code> to determine suitable capture devices. */ public abstract boolean isCaptureEnabled(); /** * Returns the title to use for this file selector, or null. If null a default * title should be used. */ public abstract CharSequence getTitle(); /** * The file name of a default selection if specified, or null. */ public abstract String getFilenameHint(); /** * Creates an intent that would start a file picker for file selection. * The Intent supports choosing files from simple file sources available * on the device. Some advanced sources (for example, live media capture) * may not be supported and applications wishing to support these sources * or more advanced file operations should build their own Intent. * * <pre> * How to use: * 1. Build an intent using {@link #createIntent} * 2. Fire the intent using {@link android.app.Activity#startActivityForResult}. * 3. Check for ActivityNotFoundException and take a user friendly action if thrown. * 4. Listen the result using {@link android.app.Activity#onActivityResult} * 5. Parse the result using {@link #parseResult} only if media capture was not requested. * 6. Send the result using filePathCallback of {@link WebChromeClient#onShowFileChooser} * </pre> * * @return an Intent that supports basic file chooser sources. */ public abstract Intent createIntent(); }
都有注释,不解释。
解决办法
看完源码一切都明了了,怎么做,重写上边这些方法就好。但是@hide方法不能Override怎么办 - 简单粗暴,直接写(没有代码提示是不是有点心虚?等运行完了就不心有)。为了兼容所有版本,最好把3个参数不同的openFileChooser()方法都写上,onShowFileChooser()正常Override就好:
webView.setWebChromeClient(new WebChromeClient() { /** * 8(Android 2.2) <= API <= 10(Android 2.3)回调此方法 */ public void openFileChooser(ValueCallback<Uri> uploadMsg) { Log.e("WangJ", "运行方法 openFileChooser-1"); // (2)该方法回调时说明版本API < 21,此时将结果赋值给 mUploadCallbackBelow,使之 != null mUploadCallbackBelow = uploadMsg; takePhoto(); } /** * 11(Android 3.0) <= API <= 15(Android 4.0.3)回调此方法 */ public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType) { Log.e("WangJ", "运行方法 openFileChooser-2 (acceptType: " + acceptType + ")"); openFileChooser(uploadMsg); } /** * 16(Android 4.1.2) <= API <= 20(Android 4.4W.2)回调此方法 */ public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) { Log.e("WangJ", "运行方法 openFileChooser-3 (acceptType: " + acceptType + "; capture: " + capture + ")"); openFileChooser(uploadMsg); } /** * API >= 21(Android 5.0.1)回调此方法 */ @Override public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) { Log.e("WangJ", "运行方法 onShowFileChooser"); // (1)该方法回调时说明版本API >= 21,此时将结果赋值给 mUploadCallbackAboveL,使之 != null mUploadCallbackAboveL = filePathCallback; takePhoto(); return true; } }); /* 省略其他内容 */ /** * 调用相机 */ private void takePhoto() { // 指定拍照存储位置的方式调起相机 String filePath = Environment.getExternalStorageDirectory() + File.separator + Environment.DIRECTORY_PICTURES + File.separator; String fileName = "IMG_" + DateFormat.format("yyyyMMdd_hhmmss", Calendar.getInstance(Locale.CHINA)) + ".jpg"; imageUri = Uri.fromFile(new File(filePath + fileName)); Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri); startActivityForResult(intent, REQUEST_CODE); // 选择图片(不包括相机拍照),则不用成功后发刷新图库的广播 // Intent i = new Intent(Intent.ACTION_GET_CONTENT); // i.addCategory(Intent.CATEGORY_OPENABLE); // i.setType("image/*"); // startActivityForResult(Intent.createChooser(i, "Image Chooser"), REQUEST_CODE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == REQUEST_CODE) { // 经过上边(1)、(2)两个赋值操作,此处即可根据其值是否为空来决定采用哪种处理方法 if (mUploadCallbackBelow != null) { chooseBelow(resultCode, data); } else if (mUploadCallbackAboveL != null) { chooseAbove(resultCode, data); } else { Toast.makeText(this, "发生错误", Toast.LENGTH_SHORT).show(); } } } /** * Android API < 21(Android 5.0)版本的回调处理 * @param resultCode 选取文件或拍照的返回码 * @param data 选取文件或拍照的返回结果 */ private void chooseBelow(int resultCode, Intent data) { Log.e("WangJ", "返回调用方法--chooseBelow"); if (RESULT_OK == resultCode) { updatePhotos(); if (data != null) { // 这里是针对文件路径处理 Uri uri = data.getData(); if (uri != null) { Log.e("WangJ", "系统返回URI:" + uri.toString()); mUploadCallbackBelow.onReceiveValue(uri); } else { mUploadCallbackBelow.onReceiveValue(null); } } else { // 以指定图像存储路径的方式调起相机,成功后返回data为空 Log.e("WangJ", "自定义结果:" + imageUri.toString()); mUploadCallbackBelow.onReceiveValue(imageUri); } } else { mUploadCallbackBelow.onReceiveValue(null); } mUploadCallbackBelow = null; } /** * Android API >= 21(Android 5.0) 版本的回调处理 * @param resultCode 选取文件或拍照的返回码 * @param data 选取文件或拍照的返回结果 */ private void chooseAbove(int resultCode, Intent data) { Log.e("WangJ", "返回调用方法--chooseAbove"); if (RESULT_OK == resultCode) { updatePhotos(); if (data != null) { // 这里是针对从文件中选图片的处理 Uri[] results; Uri uriData = data.getData(); if (uriData != null) { results = new Uri[]{uriData}; for (Uri uri : results) { Log.e("WangJ", "系统返回URI:" + uri.toString()); } mUploadCallbackAboveL.onReceiveValue(results); } else { mUploadCallbackAboveL.onReceiveValue(null); } } else { Log.e("WangJ", "自定义结果:" + imageUri.toString()); mUploadCallbackAboveL.onReceiveValue(new Uri[]{imageUri}); } } else { mUploadCallbackAboveL.onReceiveValue(null); } mUploadCallbackAboveL = null; } private void updatePhotos() { // 该广播即使多发(即选取照片成功时也发送)也没有关系,只是唤醒系统刷新媒体文件 Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE); intent.setData(imageUri); sendBroadcast(intent); }
为什么要分开chooseBelow(),chooseAbove()处理?
因为openFileChooser(),onShowFileChooser()方法参数中那个回调参数的泛型不同(一个开放的,一个开放的[]),分开处理明了一些。
看结果:
怎么样?看完这个结果,粗暴写那几个@hide的方法不心虚了吧?
为什么同样的HTML文件在浏览器中打开和我们做的不一样,浏览器节能拍照又能选文件呢?
那是因为我们写死了要么是使用拍照,要么是用文件选取,如果你愿意,可以根据openFileChooser(),onShowFileChooser()方法中的参数指定更个性化的响应,也可以做到像浏览器一样。
可能的问题
权限问题
再次提示,了别忘权限问题,别再这里被坑。
打包完成后不能工作
本来在demo中跑的好好的,但当我们打好释放包测试的时候却又发现没拍拍,没法选择图片了!!!真是坑了个爹啊!!!想想不奇怪,因为openFileChooser ()方法被系统隐藏,又不能Override,而我们的release包是开启了混淆的,所以在打包的时候混淆了openFileChooser(),这就导致无法回调openFileChooser()了。-
keepclassmembers class * extends android。 webkit.WebChromeClient {
public void openFileChooser(...);
}
当然作为良好的面向对象开发者,你可以用一个借口把这个过程写的更优美一点,我只求能把问题说明白,这里就不实现这一步了。
好像没什么了吧,想起了再加。水平有限,如有错,欢迎指正
照旧,Demo源码GitHub传送门,如有收获,欢迎Star
https://gitee.com/anan9303/CallCameraDemo
http://blog.csdn.net/a_running_wolf/article/details/77983739
以上是关于WebView中打开相机,文件选择器的问题和解决方法的主要内容,如果未能解决你的问题,请参考以下文章
有没有办法让颤动的 webview 使用 android 相机进行文件上传?如何在 webview_flutter 中打开文件选择器?
Android Webview 文件和相机上传 - Kotlin