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。

code

public boolean isIntentAvailable(Context context, String action) {      final PackageManager packageManager = context.getPackageManager();      final Intent intent = new Intent(action);      List
     
       resolveInfo = packageManager.queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);     if (resolveInfo.size() > 0) {          return true;      }     return false;  }
     

干货

一般APP的manifest里面要设置为launcher的activity总是要设置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
     
       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);          }

我是天王盖地虎的分割线