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）