如何检查某个活动是否可以处理意图？

到目前为止，我已经有了这种方法，但是好像缺少了一些东西

例如，我有一个文件/sdcard/sound.3ga返回false（例如没有活动可以处理这种类型的文件），但是当我从文件管理器中打开它时，它可以与媒体播放器一起正常打开

我认为这个意图还不完整，我需要做更多的事情来确保只有没有活动可以处理这个意图时，handlerExists变量才会为false。

PackageManager pm = getPackageManager();
Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
String extension = android.webkit.MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(new File(uriString)).toString());
String mimetype = android.webkit.MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension);
intent.setDataAndType(Uri.fromFile(new File(uriString)),mimetype);
boolean handlerExists = intent.resolveActivity(pm) != null;

edwardxu的解决方案非常适合我。

只是澄清一下：

PackageManager packageManager = getActivity().getPackageManager();
if (intent.resolveActivity(packageManager) != null) {
    startActivity(intent);
} else {
    Log.d(TAG, "No Intent available to handle action");
}

PackageManager manager = context.getPackageManager();
List<ResolveInfo> infos = manager.queryIntentActivities(intent, 0);
if (infos.size() > 0) {
    //Then there is an Application(s) can handle your intent
} else {
    //No Application can handle your intent
}

您是否尝试过此意图？

Intent intent = new Intent(Intent.ACTION_VIEW, Uri.fromFile(yourFileHere));

if (intent.resolveActivity(getPackageManager()) == null) {
    // No Activity found that can handle this intent. 
}
else{
    // There is an activity which can handle this intent. 
}

您可以使用：

public static boolean isAvailable(Context ctx, Intent intent) {
   final PackageManager mgr = ctx.getPackageManager();
   List<ResolveInfo> list =
      mgr.queryIntentActivities(intent, 
         PackageManager.MATCH_DEFAULT_ONLY);
   return list.size() > 0;
}

使用Kotlin如果您在意图不可用时需要做一些事情，

fun isIntentAvailable(
                context: Context,
                action: String?
            ): Boolean {
                val packageManager = context.packageManager
                val intent = Intent(action)
                val resolveInfo: List<*> = packageManager.queryIntentActivities(
                    intent,
                    PackageManager.MATCH_DEFAULT_ONLY
                )
                return resolveInfo.isNotEmpty()
            }

将此方法实现为

private const val SAMPLE_INTENT = "com.realwear.barcodereader.intent.action.SCAN_BARCODE"



 if(isIntentAvailable(this,SAMPLE_INTENT)){
  //Do Stuff
 }

如果你没事做

Intent(SAMPLE_INTENT).also { barcodeReaderIntent ->
            barcodeReaderIntent.resolveActivity(packageManager)?.also {
                barcodeReaderIntent.putExtra(EXTRA_CODE_128, false)
                startActivityForResult(barcodeReaderIntent, BARCODE_REQUEST_CODE)
            }
    }

使用Kotlin扩展的另一种方法

 fun Context.isIntentAvailable(intent: Intent): Boolean {
    val resolveInfo: List<*> = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY)
    return resolveInfo.isNotEmpty()
 }

片段内的用法

val available = requireContext().isIntentAvailable(this)

活动中的用法

val available = this.isIntentAvailable(this)