Android WebView 上传文件支持全解析
jopen
8年前
默认情况下情况下，使用Android的WebView是不能够支持上传文件的。而这个，也是在我们的前端工程师告知之后才了解的。因为 Android的每个版本WebView的实现有差异，因此需要对不同版本去适配。花了一点时间，参考别人的代码，这个问题已经解决，这里把我踩过的坑分享出来。
主要思路是重写WebChromeClient，然后在WebViewActivity中接收选择到的文件Uri，传给页面去上传就可以了。
创建一个WebViewActivity的内部类
public class XHSWebChromeClient extends WebChromeClient { // For Android 3.0+ public void openFileChooser(ValueCallback<Uri> uploadMsg) { CLog.i("UPFILE", "in openFile Uri Callback"); if (mUploadMessage != null) { mUploadMessage.onReceiveValue(null); } mUploadMessage = uploadMsg; Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); i.setType("*/*"); startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE); } // For Android 3.0+ public void openFileChooser(ValueCallback uploadMsg, String acceptType) { CLog.i("UPFILE", "in openFile Uri Callback has accept Type" + acceptType); if (mUploadMessage != null) { mUploadMessage.onReceiveValue(null); } mUploadMessage = uploadMsg; Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); String type = TextUtils.isEmpty(acceptType) ? "*/*" : acceptType; i.setType(type); startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE); } // For Android 4.1 public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) { CLog.i("UPFILE", "in openFile Uri Callback has accept Type" + acceptType + "has capture" + capture); if (mUploadMessage != null) { mUploadMessage.onReceiveValue(null); } mUploadMessage = uploadMsg; Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); String type = TextUtils.isEmpty(acceptType) ? "*/*" : acceptType; i.setType(type); startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE); } //Android 5.0+ @Override @SuppressLint("NewApi") public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) { if (mUploadMessage != null) { mUploadMessage.onReceiveValue(null); } CLog.i("UPFILE", "file chooser params：" + fileChooserParams.toString()); mUploadMessage = filePathCallback; Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); if (fileChooserParams != null && fileChooserParams.getAcceptTypes() != null && fileChooserParams.getAcceptTypes().length > 0) { i.setType(fileChooserParams.getAcceptTypes()[0]); } else { i.setType("*/*"); } startActivityForResult(Intent.createChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE); return true; } }上面openFileChooser是系统未暴露的接口，因此不需要加Override的注解，同时不同版本有不同的参数，其中的参数，第一个 ValueCallback用于我们在选择完文件后，接收文件回调到网页内处理，acceptType为接受的文件mime type。在Android 5.0之后，系统提供了onShowFileChooser来让我们实现选择文件的方法，仍然有ValueCallback，在 FileChooserParams参数中，同样包括acceptType。我们可以根据acceptType，来打开系统的或者我们自己创建文件选择器。当然如果需要打开相机拍照，也可以自己去使用打开相机拍照的Intent去打开即可。
处理选择的文件
以上是打开响应的选择文件的界面，我们还需要处理接收到文件之后，传给网页来响应。因为我们前面是使用startActivityForResult来打开的选择页面，我们会在onActivityResult中接收到选择的结果。Show code：
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == FILECHOOSER_RESULTCODE) { if (null == mUploadMessage) return; Uri result = data == null || resultCode != RESULT_OK ? null : data.getData(); if (result == null) { mUploadMessage.onReceiveValue(null); mUploadMessage = null; return; } CLog.i("UPFILE", "onActivityResult" + result.toString()); String path = FileUtils.getPath(this, result); if (TextUtils.isEmpty(path)) { mUploadMessage.onReceiveValue(null); mUploadMessage = null; return; } Uri uri = Uri.fromFile(new File(path)); CLog.i("UPFILE", "onActivityResult after parser uri:" + uri.toString()); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { mUploadMessage.onReceiveValue(new Uri[]{uri}); } else { mUploadMessage.onReceiveValue(uri); } mUploadMessage = null; } }以上代码主要就是调用ValueCallback的onReceiveValue方法，将结果传回web。
注意，其他要说的，重要
由于不同版本的差别，Android 5.0以下的版本，ValueCallback 的onReceiveValue接收的参数类型是Uri, 5.0及以上版本接收的是Uri数组，在传值的时候需要注意。
选择文件会使用系统提供的组件或者其他支持的app，返回的uri有的直接是文件的url，有的是contentprovider的uri，因此我们需要统一处理一下，转成文件的uri，可参考以下代码（获取文件的路径）。
调用getPath可以将Uri转成真实文件的Path，然后可以自己生成文件的Uri
public class FileUtils { /** * @param uri The Uri to check. * @return Whether the Uri authority is ExternalStorageProvider. */ public static boolean isExternalStorageDocument(Uri uri) { return "com.android.externalstorage.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is DownloadsProvider. */ public static boolean isDownloadsDocument(Uri uri) { return "com.android.providers.downloads.documents".equals(uri.getAuthority()); } /** * @param uri The Uri to check. * @return Whether the Uri authority is MediaProvider. */ public static boolean isMediaDocument(Uri uri) { return "com.android.providers.media.documents".equals(uri.getAuthority()); } /** * Get the value of the data column for this Uri. This is useful for * MediaStore Uris, and other file-based ContentProviders. * * @param context The context. * @param uri The Uri to query. * @param selection (Optional) Filter used in the query. * @param selectionArgs (Optional) Selection arguments used in the query. * @return The value of the _data column, which is typically a file path. */ public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) { Cursor cursor = null; final String column = "_data"; final String[] projection = { column }; try { cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null); if (cursor != null && cursor.moveToFirst()) { final int column_index = cursor.getColumnIndexOrThrow(column); return cursor.getString(column_index); } } finally { if (cursor != null) cursor.close(); } return null; } /** * Get a file path from a Uri. This will get the the path for Storage Access * Framework Documents, as well as the _data field for the MediaStore and * other file-based ContentProviders. * * @param context The context. * @param uri The Uri to query. * @author paulburke */ @SuppressLint("NewApi") public static String getPath(final Context context, final Uri uri) { final boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT; // DocumentProvider if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) { // ExternalStorageProvider if (isExternalStorageDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; if ("primary".equalsIgnoreCase(type)) { return Environment.getExternalStorageDirectory() + "/" + split[1]; } // TODO handle non-primary volumes } // DownloadsProvider else if (isDownloadsDocument(uri)) { final String id = DocumentsContract.getDocumentId(uri); final Uri contentUri = ContentUris.withAppendedId( Uri.parse("content://downloads/public_downloads"), Long.valueOf(id)); return getDataColumn(context, contentUri, null, null); } // MediaProvider else if (isMediaDocument(uri)) { final String docId = DocumentsContract.getDocumentId(uri); final String[] split = docId.split(":"); final String type = split[0]; Uri contentUri = null; if ("image".equals(type)) { contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI; } else if ("video".equals(type)) { contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI; } else if ("audio".equals(type)) { contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; } final String selection = "_id=?"; final String[] selectionArgs = new String[] { split[1] }; return getDataColumn(context, contentUri, selection, selectionArgs); } } // MediaStore (and general) else if ("content".equalsIgnoreCase(uri.getScheme())) { return getDataColumn(context, uri, null, null); } // File else if ("file".equalsIgnoreCase(uri.getScheme())) { return uri.getPath(); } return null; } }再有，即使获取的结果为null，也要传给web，即直接调用mUploadMessage.onReceiveValue(null),否则网页会阻塞。
最后，在打release包的时候，因为我们会混淆，要特别设置不要混淆WebChromeClient子类里面的openFileChooser方法，由于不是继承的方法，所以默认会被混淆，然后就无法选择文件了。
就这样吧。
原文地址：http://blog.isming.me/2015/12/21/android-webview-upload-file/，转载请注明出处。