最近公司項(xiàng)目需要在WebView上調(diào)用手機(jī)系統(tǒng)相冊來上傳圖片，開發(fā)過程中發(fā)現(xiàn)在很多機(jī)器上無法正常喚起系統(tǒng)相冊來選擇圖片。
解決問題之前我們先來說說WebView上傳文件的邏輯：當(dāng)我們在Web頁面上點(diǎn)擊選擇文件的控件(<input type="file">)時(shí)，會回調(diào)WebChromeClient下的openFileChooser()（5.0及以上系統(tǒng)回調(diào)onShowFileChooser()）。這個(gè)時(shí)候我們在openFileChooser方法中通過Intent打開系統(tǒng)相冊或者支持該Intent的第三方應(yīng)用來選擇圖片。like this：
public void openFileChooser(ValueCallback<Uri> valueCallback, String acceptType, String capture) { uploadMessage = valueCallback; openImageChooserActivity();}private void openImageChooserActivity() { Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); i.setType("image/*"); startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILE_CHOOSER_RESULT_CODE);}最后我們在onActivityResult()中將選擇的圖片內(nèi)容通過ValueCallback的onReceiveValue方法返回給WebView，然后通過js上傳。代碼如下：
@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == FILE_CHOOSER_RESULT_CODE) { Uri result = data == null || resultCode != RESULT_OK ? null : data.getData(); if (uploadMessage != null) { uploadMessage.onReceiveValue(result); uploadMessage = null; } }}PS:ValueCallbacks是WebView組件通過openFileChooser()或者onShowFileChooser()提供給我們的，它里面包含了一個(gè)或者一組Uri,然后我們在onActivityResult()里將Uri傳給ValueCallbacks的onReceiveValue()方法，這樣WebView就知道我們選擇了什么文件。
webview.setWebChromeClient(new WebChromeClient() { // For Android < 3.0 public void openFileChooser(ValueCallback<Uri> valueCallback) { *** } // For Android >= 3.0 public void openFileChooser(ValueCallback valueCallback, String acceptType) { *** } //For Android >= 4.1 public void openFileChooser(ValueCallback<Uri> valueCallback, String acceptType, String capture) { *** } // For Android >= 5.0 @Override public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) { *** return true; } });到這里你可能要問了，說了這么多還是沒解釋為什么在很多機(jī)型上無法喚起系統(tǒng)相冊或者第三方app來選擇圖片啊？！這是因?yàn)闉榱俗钋笸昝赖腉oogle攻城獅們對openFileChooser做了多次修改，在5.0上更是將回調(diào)方法該為了onShowFileChooser。所以為了解決這一問題，兼容各個(gè)版本，我們需要對openFileChooser()進(jìn)行重載，同時(shí)針對5.0及以上系統(tǒng)提供onShowFileChooser()方法：
webview.setWebChromeClient(new WebChromeClient() { // For Android < 3.0 public void openFileChooser(ValueCallback<Uri> valueCallback) { *** } // For Android >= 3.0 public void openFileChooser(ValueCallback valueCallback, String acceptType) { *** } //For Android >= 4.1 public void openFileChooser(ValueCallback<Uri> valueCallback, String acceptType, String capture) { *** } // For Android >= 5.0 @Override public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) { *** return true; } });大家應(yīng)該注意到onShowFileChooser()中的ValueCallback包含了一組Uri(Uri[]),所以針對5.0及以上系統(tǒng)，我們還需要對onActivityResult()做一點(diǎn)點(diǎn)處理。這里不做描述，最后我再貼上完整代碼。
當(dāng)處理完這些后你以為就萬事大吉了？！當(dāng)初我也這樣天真，但當(dāng)我們打好release包測試的時(shí)候卻又發(fā)現(xiàn)沒法選擇圖片了！！！真是坑了個(gè)爹啊！！！無奈去翻WebChromeClient的源碼，發(fā)現(xiàn)openFileChooser()是系統(tǒng)API，我們的release包是開啟了混淆的，所以在打包的時(shí)候混淆了openFileChooser()，這就導(dǎo)致無法回調(diào)openFileChooser()了。
/** * 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. */@SystemApi@Deprecatedpublic void openFileChooser(ValueCallback<Uri> uploadFile, String acceptType, String capture) { uploadFile.onReceiveValue(null);}解決方案也很簡單，直接不混淆openFileChooser()就好了。
-keepclassmembers class * extends android.webkit.WebChromeClient{ public void openFileChooser(...);}支持關(guān)于上傳文件的所有坑都填完了，最后附上完整源碼：
public class MainActivity extends AppCompatActivity { private ValueCallback<Uri> uploadMessage; private ValueCallback<Uri[]> uploadMessageAboveL; private final static int FILE_CHOOSER_RESULT_CODE = 10000; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); WebView webview = (WebView) findViewById(R.id.web_view); assert webview != null; WebSettings settings = webview.getSettings(); settings.setUseWideViewPort(true); settings.setLoadWithOverviewMode(true); settings.setJavaScriptEnabled(true); webview.setWebChromeClient(new WebChromeClient() { // For Android < 3.0 public void openFileChooser(ValueCallback<Uri> valueCallback) { uploadMessage = valueCallback; openImageChooserActivity(); } // For Android >= 3.0 public void openFileChooser(ValueCallback valueCallback, String acceptType) { uploadMessage = valueCallback; openImageChooserActivity(); } //For Android >= 4.1 public void openFileChooser(ValueCallback<Uri> valueCallback, String acceptType, String capture) { uploadMessage = valueCallback; openImageChooserActivity(); } // For Android >= 5.0 @Override public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) { uploadMessageAboveL = filePathCallback; openImageChooserActivity(); return true; } }); String targetUrl = "file:///android_asset/up.html"; webview.loadUrl(targetUrl); } private void openImageChooserActivity() { Intent i = new Intent(Intent.ACTION_GET_CONTENT); i.addCategory(Intent.CATEGORY_OPENABLE); i.setType("image/*"); startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILE_CHOOSER_RESULT_CODE); } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { super.onActivityResult(requestCode, resultCode, data); if (requestCode == FILE_CHOOSER_RESULT_CODE) { if (null == uploadMessage && null == uploadMessageAboveL) return; Uri result = data == null || resultCode != RESULT_OK ? null : data.getData(); if (uploadMessageAboveL != null) { onActivityResultAboveL(requestCode, resultCode, data); } else if (uploadMessage != null) { uploadMessage.onReceiveValue(result); uploadMessage = null; } } } @TargetApi(Build.VERSION_CODES.LOLLIPOP) private void onActivityResultAboveL(int requestCode, int resultCode, Intent intent) { if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null) return; Uri[] results = null; if (resultCode == Activity.RESULT_OK) { if (intent != null) { String dataString = intent.getDataString(); ClipData clipData = intent.getClipData(); if (clipData != null) { results = new Uri[clipData.getItemCount()]; for (int i = 0; i < clipData.getItemCount(); i++) { ClipData.Item item = clipData.getItemAt(i); results[i] = item.getUri(); } } if (dataString != null) results = new Uri[]{Uri.parse(dataString)}; } } uploadMessageAboveL.onReceiveValue(results); uploadMessageAboveL = null; }}源碼地址: http://xiazai.VeVB.COm/201701/yuanma/WebViewSample_jb51.rar
以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持武林網(wǎng)。
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