近期学习android总结

1.扫描全盘，刷新音乐视频列表：

（1）<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 <uses-permission android:name="android.permission.WRITE_SETTINGS"/>

（2）

/**
  * 扫描全盘
  **/
 public void allScan(){
        sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" 
                + Environment.getExternalStorageDirectory())));
    }

 

2.获取最近使用的4个应用：

（1） <uses-permission android:name="android.permission.GET_TASKS"/>

（2）

public class RecentAppActivity extends Activity {
 final ImageView[] mIcons = new ImageView[4];

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       
        mIcons[0]=(ImageView)findViewById(R.id.iv_01);
        mIcons[1]=(ImageView)findViewById(R.id.iv_02);
        mIcons[2]=(ImageView)findViewById(R.id.iv_03);
        mIcons[3]=(ImageView)findViewById(R.id.iv_04);
       
        getRecentApp();  
    }
   
    public void getRecentApp() {
     final PackageManager pm = this.getPackageManager();
        final ActivityManager am = (ActivityManager)
                this.getSystemService(Context.ACTIVITY_SERVICE);
        final List<ActivityManager.RecentTaskInfo> recentTasks =
                am.getRecentTasks(6, ActivityManager.RECENT_IGNORE_UNAVAILABLE);
       Log.e("listnum:",""+recentTasks.size());
       for(int i=2;i<recentTasks.size();i++){
        final ActivityManager.RecentTaskInfo info = recentTasks.get(i);
        Intent intent = new Intent(info.baseIntent);
        ResolveInfo resolveInfo = pm.resolveActivity(intent, 0);      
        if(resolveInfo!=null){
         final ActivityInfo activityInfo = resolveInfo.activityInfo;
            final String title = activityInfo.loadLabel(pm).toString();
            Log.e("rencentapp name:", title);
         mIcons[i-2].setImageDrawable(resolveInfo.loadIcon(pm));
        }
        mIcons[i-2].setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    Intent intent=new Intent(info.baseIntent);
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    RecentAppActivity.this.startActivity(intent);
   }
        
        });
       }
 }
}

 

3.获取所有应用：

/**
    * 获取所有机器上所有APK
    * @return APK数量
    */
   public int getAllApks() { 
  final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
  mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
  packageManager = this.getPackageManager();
  apps = packageManager.queryIntentActivities(mainIntent, 0);
  return apps.size();
 }

 

4.通过包名和类名获取应用图标和名字：

public void getData(){
  imgs.clear();
  names.clear();
  for(int i=0;i<cur.getCount();i++){
   cur.moveToPosition(i);
   String pkg=cur.getString(cur.getColumnIndex("_pkg"));
   String cls=cur.getString(cur.getColumnIndex("_cls"));
   ComponentName componentName = new ComponentName(pkg, cls);
   PackageManager pkm=data.getBaseContext().getPackageManager();
   try {
    Drawable img=pkm.getActivityInfo(componentName, ActivityInfo.FLAG_STATE_NOT_NEEDED).loadIcon(pkm);
    imgs.add(img);
    String label=pkm.getActivityInfo(componentName, ActivityInfo.FLAG_STATE_NOT_NEEDED).loadLabel(pkm)+"";
    names.add(label);
   } catch (NameNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
   }
  }
 }

 

5.列表item中checkbox，注意：由于checkbox的点击事件优先级比listview的高，所以要添加android:focusable="false"属性，使得checkbox初始的时候没有获取焦点。另外这里是点击ListView的item控制checkbox的状态改变，也就是让item接收clik事件，所以需要加android:focusableInTouchMode="false"这一属性。

<CheckBox
     android:id="@+id/box_lv"
        android:layout_width="30px"
        android:layout_height="30px"
        android:visibility="invisible"
        android:clickable="false"
        android:focusableInTouchMode="false"
        android:focusable="false"
        android:layout_gravity="center_vertical"/>

 

6.针对不同分辨率写不同layout文件

（1）<supports-screens
        android:anyDensity="true"
        android:largeScreens="true"
        android:normalScreens="true"
        android:smallScreens="true"
        android:xlargeScreens="true" />

（2）