android 常用小知识点 tips (一)
android 常用小知识点 tips (二)
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11、根据包名检测应用是否被安装
public static boolean isIntalled(Context context, String packageName) {
boolean exist = false;
PackageManager pm = context.getPackageManager();
Intent intent = new Intent(Intent.ACTION_MAIN, null);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
List<ResolveInfo> resolveInfoList = pm.queryIntentActivities(intent, 0);
for (ResolveInfo resolveInfo : resolveInfoList) {
if (resolveInfo.activityInfo.packageName.equals(packageName)) {
exist = true;
}
}
return exist;
}
12、RxJava防抖动
//引入依赖
compile 'com.jakewharton.rxbinding:rxbinding:0.4.0'
compile 'com.jakewharton.rxbinding:rxbinding-appcompat-v7:0.4.0'
compile 'com.jakewharton.rxbinding:rxbinding-design:0.4.0'
/**
*实现
*/
RxView.clicks(view.findViewById(R.id.weixin))
.throttleFirst(4, TimeUnit.SECONDS)
.subscribe(new Action1<Void>() {
@Override
public void call(Void aVoid) {
((LoginAndRegisterActivity) activity).doWXClick();
}
});
13、判断android 应用是否在前台运行
/**
* 程序是否在前台运行
*
* @return
*/
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<RunningAppProcessInfo> appProcesses = activityManager
.getRunningAppProcesses();
if (appProcesses == null)
return false;
for (RunningAppProcessInfo appProcess : appProcesses) {
// The name of the process that this object is associated with.
if (appProcess.processName.equals(packageName)
&& appProcess.importance == RunningAppProcessInfo.IMPORTANCE_FOREGROUND) {
return true;
}
}
return false;
}
@Override
protected void onResume() {
super.onResume();
Log.i(TAG, "onResume: ");
Log.i(TAG, "onResume2: "+isAppOnForeground(this));
}
@Override
protected void onPause() {
super.onPause();
Log.i(TAG, "onPause: ");
Log.i(TAG, "onPause2: "+isAppOnForeground(this));//true 所以进入后台时不要在onPause()方法监听，应该在onStop()里
}
@Override
protected void onStop() {
super.onStop();
Log.i(TAG, "onStop: ");
Log.i(TAG, "onStop2: "+isAppOnForeground(this));//false
}
14、java引用正则表达式
public static void main(String[] args) {
// 要验证的字符串
String str = "service@xsoftlab.net";
// 邮箱验证规则
String regEx = "[a-zA-Z_]{1,}[0-9]{0,}@(([a-zA-z0-9]-*){1,}\.){1,3}[a-zA-z\-]{1,}";
// 编译正则表达式
Pattern pattern = Pattern.compile(regEx);
// 忽略大小写的写法
// Pattern pat = Pattern.compile(regEx, Pattern.CASE_INSENSITIVE);
Matcher matcher = pattern.matcher(str);
// 字符串是否与正则表达式相匹配
boolean rs = matcher.matches();
System.out.println(rs);
}
15、android shape详解
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
<!-- 圆角 -->
<corners
android:radius="9dp"
android:topLeftRadius="2dp"
android:topRightRadius="2dp"
android:bottomLeftRadius="2dp"
android:bottomRightRadius="2dp"/><!-- 设置圆角半径 -->
<!-- 渐变 -->
<gradient
android:startColor="@android:color/white"
android:centerColor="@android:color/black"
android:endColor="@android:color/black"
android:useLevel="true"
android:angle="45"
android:type="radial"
android:centerX="0"
android:centerY="0"
android:gradientRadius="90"/>
<!-- 间隔 -->
<padding
android:left="2dp"
android:top="2dp"
android:right="2dp"
android:bottom="2dp"/><!-- 各方向的间隔 -->
<!-- 大小 -->
<size
android:width="50dp"
android:height="50dp"/><!-- 宽度和高度 -->
<!-- 填充 -->
<solid
android:color="@android:color/white"/><!-- 填充的颜色 -->
<!-- 描边 -->
<stroke
android:width="2dp"
android:color="@android:color/black"
android:dashWidth="1dp"
android:dashGap="2dp"/>
</shape>
填充：设置填充的颜色
间隔：设置四个方向上的间隔
大小：设置大小
圆角：同时设置五个属性，则Radius属性无效
android:Radius="20dp" 设置四个角的半径
android:topLeftRadius="20dp" 设置左上角的半径
android:topRightRadius="20dp" 设置右上角的半径
android:bottomLeftRadius="20dp" 设置右下角的半径
android:bottomRightRadius="20dp" 设置左下角的半径
描边：dashWidth和dashGap属性，只要其中一个设置为0dp，则边框为实现边框
android:width="20dp" 设置边边的宽度
android:color="@android:color/black" 设置边边的颜色
android:dashWidth="2dp" 设置虚线的宽度
android:dashGap="20dp" 设置虚线的间隔宽度
渐变：当设置填充颜色后，无渐变效果。angle的值必须是45的倍数（包括0），仅在type="linear"有效，不然会报错。android:useLevel 这个属性不知道有什么用。
16、android倒计时TextView
public class timerTask extends Activity{
private int recLen = 0;
private TextView txtView;
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.timertask);
txtView = (TextView)findViewById(R.id.txttime);
handler.postDelayed(runnable, 1000);
}
Handler handler = new Handler();
Runnable runnable = new Runnable() {
@Override
public void run() {
recLen++;
txtView.setText("" + recLen);
handler.postDelayed(this, 1000);
}
};
}
17、查看程序占用端口命令
打开cmd，输入
Windows：
netstat -ano | find "8081"
Linux：
netstat -ano | grep 8081
关闭这个进程 命令：tskill 'xxxx' 或者任务管理器中找到对应PID 结束任务
18、android 清空任务栈
Intent intent = new Intent();
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK |
Intent.FLAG_ACTIVITY_CLEAR_TASK);
intent.setClass(MainActivity.this, Activity2.class);
startActivity(intent);
FLAG_ACTIVITY_NEW_TASK 和 FLAG_ACTIVITY_CLEAR_TASK ，这两个Flag结合才能实现。
19、TabLayout添加分割线
#分割线shape
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#80c0c0c0"/>
<size android:width="1dp"/>
</shape>
# 代码
LinearLayout linearLayout = (LinearLayout) mTabLayout.getChildAt(0);
linearLayout.setShowDividers(LinearLayout.SHOW_DIVIDER_MIDDLE);
linearLayout.setDividerPadding(15);
linearLayout.setDividerDrawable(ContextCompat.getDrawable(this,
R.drawable.layout_divider_vertical));
20、华为手机logcat输出
华为手机设置日志输出：
拨号输入*#*#2846579#*#*，进入projectmenu--后台设置--LOG设置--LOG开关--打开；
21、RN Android Monitor调起调试面板
adb shell input keyevent 82
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