Android应用开发—知识点汇总

1
2
3
4
   getActivity().getApplicationContext()或者getActivity()
   You can use getActivity(), which returns the activity associated with a fragment.
   The activity is a context (since Activity extends Context).

1
2
3
 setTextColor(0xff999faa);
 setTextColor(Color.parseColor("#999faa"))

1
2
3
4
setTextSize(TypedValue.COMPLEX_UNIT_PX,22); 
setTextSize(TypedValue.COMPLEX_UNIT_SP,22); 
setTextSize(TypedValue.COMPLEX_UNIT_DIP,22);

1
2
ArrayList<String> list = new ArrayList<String>() {{add("string1"); add("string2"); add("string3");}}

1
2
3
4
5
6
7
8
setBackgroundXXX的用处，设置View背景。
setBackgroundDrawable的参数为Drawable对象。
setBackgroundColor的参数为Color对象，比如说Color.Red为红色或  Color.rgb(255,0,0)来指定一个红色
setBackgroundResource的参数为资源ID，比如说R.drawable.icon

对于ImageView类有类似 setImageXXX
道理同上，setImageBitmap的参数为Bitmap对象，同时ImageView还支持矩阵对象，比如setImageMatrix的参数为Matrix对象。

1
2
3
4
5
6
7
new Handler().postDelayed(new Runnable(){
    @Override
    public void run() {
        func();
    }
}, 250);

1
2
adb shell service list

1
2
3
4
5
6
public static String removePunct(String s) {
    String str = s.replaceAll("[`~!@#$%^&*()+=|{}':;',\[\].<>/?~！@#￥%……& amp;*（）——+|{}【】‘；：”“’。，、？|-]", "");
    str = str.replace(""", "");
    return str;
}

1
2
3
4
5
6
7
public static boolean isChinese(String string) {
      String regex = "^[u4E00-u9FA5]+$";
      Pattern pattern = Pattern.compile(regex);
      Matcher match = pattern.matcher(string);
      return match.matches();
  }

1
2
3
4
5
6
7
8
9
10
11
XXXX info = mXXXXList.get(position);
if (info == null) {
    return;
}
Intent intent = new Intent(XXXXActivity.this, XXXXActivity.class);
intent.putExtra(XXX.KEY_SOUND_INFO, info);

if (intent != null) {
    mXXXX = (XXXX) intent.getSerializableExtra(XXX.KEY_SOUND_INFO);
}

1
2
android:layout_centerVertical="true"

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
xxx.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">

    <item>
        <shape>
            <gradient
                android:angle="0"
                android:endColor="#28d5fa"
                android:startColor="#0083fa"
                android:type="linear" />
        </shape>
    </item>

</layer-list>

1
2
3
4
5
6
7
8
<RelativeLayout
                android:id="@+id/va_voice_print_step_ll"
                android:layout_width="match_parent"
                android:layout_height="149dp"
                android:background="@drawable/xxx">
</RelativeLayout>

1
2
3
4
public static boolean isInMainThread() {
      return Looper.myLooper() == Looper.getMainLooper();
}

1
2
android:hint="请输入xx"

1
2
3
adb shell dumpsys activity activities
adb shell dumpsys activity top

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
public void openNotificationSettings() {
    try {
        Intent intent = new Intent();
        intent.setAction("android.settings.APP_NOTIFICATION_SETTINGS");
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.N_MR1) {
            intent.putExtra("android.provider.extra.APP_PACKAGE", context.getPackageName());
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            intent.putExtra("app_package", context.getPackageName());
            intent.putExtra("app_uid", context.getApplicationInfo().uid);
        }
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

1
2
~/.gradle/caches/modules-2/files-2.1/com.ali*

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
 public boolean isAppOnForeground() {
    // Returns a list of application processes that are running on the
    // device

    ActivityManager activityManager = (ActivityManager) getApplicationContext().getSystemService(Context.ACTIVITY_SERVICE);
    String packageName = getApplicationContext().getPackageName();

    List<ActivityManager.RunningAppProcessInfo> appProcesses = activityManager
            .getRunningAppProcesses();
    if (appProcesses == null)
        return false;

    for (ActivityManager.RunningAppProcessInfo appProcess : appProcesses) {
        // The name of the process that this object is associated with.
        if (appProcess.processName.equals(packageName)
                && appProcess.importance == ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
            return true;
        }
    }
    return false;
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
private BroadcastReceiver mSearchRequestReceiver = new BroadcastReceiver() {
      @Override
      public void onReceive(Context context, Intent intent) {
          //do somethings
          }
      }
  };

  @Override
  public void onResume() {
      super.onResume();
      LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
      lbm.registerReceiver(mSearchRequestReceiver, new IntentFilter(SEARCH_REQUEST_BROADCAST_ACTION));
  }

  @Override
  protected void onPause() {
      super.onPause();
      LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
      lbm.unregisterReceiver(mSearchRequestReceiver);
  }

1
2
3
4
public static boolean isMainThread() {
        return Thread.currentThread() == Looper.getMainLooper().getThread();
}

1
2
3
4
5
6
with(Context context)：使用Application上下文，Glide请求将不受Activity/Fragment生命周期控制。
with(Activity activity)：使用Activity作为上下文，Glide的请求会受到Activity生命周期控制。
with(FragmentActivity activity)：Glide的请求会受到FragmentActivity生命周期控制。
with(android.app.Fragment fragment)：Glide的请求会受到Fragment 生命周期控制。
with(android.support.v4.app.Fragment fragment)：Glide的请求会受到Fragment生命周期控制。

1
2
3
4
5
6
Map<String, String> map = new HashMap<String, String>();
for (Entry<String, String> entry : map.entrySet()) {
	entry.getKey();
	entry.getValue();
}

1
2
3
4
5
Map<String, String> map = new HashMap<String, String>();
for (String key : map.keySet()) {
	// key process
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
public XXXX(Context context) {
    super(context);
}

/**
 * 自定义View时,如果自定义View有属性,这个方法一定要覆写!!
 *
 * @param context
 * @param attrs
 */
public XXXX(Context context, AttributeSet attrs) {
    super(context, attrs);
}

1
2
 Android 中 FileLock 只支持进程间死锁，同一进程不同线程是无效的。

1
2
3
4
5
6
7
8
9
10
11
12
/**
 * 判断当前应用是否是debug状态
 */
public static boolean isApkInDebug(Context context) {
    try {
        ApplicationInfo info = context.getApplicationInfo();
        return (info.flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0;
    } catch (Exception e) {
        return false;
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
    public static String getTopActivityPackageName(@NonNull Context context) {
        final UsageStatsManager usageStatsManager = (UsageStatsManager)context.getSystemService(Context.USAGE_STATS_SERVICE);
        if(usageStatsManager == null) {
            return PACKAGE_NAME_UNKNOWN;
        }

        String topActivityPackageName = PACKAGE_NAME_UNKNOWN;
        long time = System.currentTimeMillis();
        // 查询最后十秒钟使用应用统计数据
        List<UsageStats> usageStatsList = usageStatsManager.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000*10, time);
        // 以最后使用时间为标准进行排序
        if(usageStatsList != null) {
            SortedMap<Long,UsageStats> sortedMap = new TreeMap<Long,UsageStats>();
            for (UsageStats usageStats : usageStatsList) {
                sortedMap.put(usageStats.getLastTimeUsed(),usageStats);
            }
            if(sortedMap.size() != 0) {
                topActivityPackageName =  sortedMap.get(sortedMap.lastKey()).getPackageName();
                Log.d(TAG,"Top activity package name = " + topActivityPackageName);
            }
        }

        return topActivityPackageName;
    }
    ```