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某些时候你想要知道某个APP是否有注册了一个明确的intent，比如说你想要检查某个receiver是否存在，然后根据是否存在来这个receiver来在你的AP里面enable某些功能。我们可以通过PackageManager来check它。
public boolean isIntentAvailable(Context context, String action) { final PackageManager packageManager = context.getPackageManager(); final Intent intent = new Intent(action); List<ResolveInfo> resolveInfo = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY); if (resolveInfo.size() > 0) { return true; } return false; }
一般APP的manifest里面要设置为launcher的activity总是要设置intent-filter：
<intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter>
可以通过queryIntentActivities来获得有哪些launcher：
private void loadApps() { Intent mainIntent = new Intent(Intent.ACTION_MAIN, null); mainIntent.addCategory(Intent.CATEGORY_LAUNCHER); mApps = getPackageManager().queryIntentActivities(mainIntent, 0); }
我们可以在自己的app上用一个gridview显示出当前手机有哪些app：
import java.util.List; import android.app.Activity; import android.content.Intent; import android.content.pm.ResolveInfo; import android.os.Bundle; import android.view.View; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.GridView; import android.widget.ImageView; public class MyHome extends Activity { GridView mGrid; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); loadApps(); setContentView(R.layout.main); mGrid = (GridView) findViewById(R.id.apps_list); mGrid.setAdapter(new AppsAdapter()); } private List<ResolveInfo> mApps; private void loadApps() { Intent mainIntent = new Intent(Intent.ACTION_MAIN, null); mainIntent.addCategory(Intent.CATEGORY_LAUNCHER); mApps = getPackageManager().queryIntentActivities(mainIntent, 0); } public class AppsAdapter extends BaseAdapter { public AppsAdapter() { } public View getView(int position, View convertView, ViewGroup parent) { ImageView i; if (convertView == null) { i = new ImageView(MyHome.this); i.setScaleType(ImageView.ScaleType.FIT_CENTER); i.setLayoutParams(new GridView.LayoutParams(50, 50)); } else { i = (ImageView) convertView; } ResolveInfo info = mApps.get(position); i.setImageDrawable(info.activityInfo.loadIcon(getPackageManager())); return i; } public final int getCount() { return mApps.size(); } public final Object getItem(int position) { return mApps.get(position); } public final long getItemId(int position) { return position; } } }
可以设置点击监听器去开启app：
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,long id) { ResolveInfo info = mApps.get(position); //该应用的包名 String pkg = info.activityInfo.packageName; //应用的主activity类 String cls = info.activityInfo.name; ComponentName componet = new ComponentName(pkg, cls); Intent i = new Intent(); i.setComponent(componet); startActivity(i); }
Android -- queryIntentActivities
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原文地址：http://www.cnblogs.com/yydcdut/p/4287077.html
