Android 常见问题二：创建MyApplication
一、MyApplication单例
java 常见单例模式单例模式
import android.util.Log;
public class Car {
/**
* 饿汉式
* 线程安全
*/
private static Car car=new Car();
public static Car getInstance(){
return car;
}
/**
* 懒汉式
* 线程安全，效率稍低
*/
private static Car car1;
public static synchronized Car getInstance1(){
if(car1==null){
car1=new Car();
}
return car1;
}
/**
* 双锁模式/双重校验
* 效率比懒汉式高，线程安全
* volatile修饰符：会将变量存到主存中，每次创建刷新，都会更新主存中的变量，相当于变量单例
* 无volatile修饰时，如果线程不同，变量会存到当前线程所在的栈中
*/
private volatile static Car car2;
public static Car getInstance2(){
if(car2==null){
synchronized (Car.class){
if(car2==null){
car2=new Car();
}
}
}
return car2;
}
public void drive(){
Log.i("DL","单例开车");
}
}
MyApplication单例
private static final MyApplication app=new MyApplication();
public static MyApplication getInstance(){
return app;
}
kotlin MyApplication单例
1、手动设置
companion object{
private var instance:MyApplication? = null
fun instance() = instance!!
//2、声明延迟初始化属性
// private lateinit var instance:MyApplication
// fun instance() = instance
}
override fun onCreate() {
super.onCreate()
instance=this
}
2、Delegates代理
kotlin提供了一个系统工具自动校验，这个工具便是Delegates的notNull方法。该方法返回非空校验的行为，只要将指定属性的读写行为委托给这个非空校验行为，那么开发者就无需手工进行非空判断了
companion object{
private var instance:MyApplication by Delegates.notNull()
fun instance() = instance
}
override fun onCreate() {
super.onCreate()
instance=this
}
二、界面管理
class MyApplication : Application() {
private val activitys = ArrayList()
fun addActivity(activity:Activity){
activitys.add(activity)
}
fun removeActivity(activity:Activity){
activitys.remove(activity)
}
fun removeAllActivity(){
activitys.map {
it.finish()
}
}
fun getCurrentActivity():Activity = activitys.get(activitys.size-1)
}
三、全局异常处理
1、MyApplication实现Thread.UncaughtExceptionHandler
2、oncreate 方法中 Thread.setDefaultUncaughtExceptionHandler(this)
3、重写方法uncaughtException
/**
* 全局未知异常处理
*/
override fun uncaughtException(t: Thread, e: Throwable) {
val b:Boolean = handException(e)
}
private fun handException(e: Throwable): Boolean {
if(e == null) return false
//写入错误日志
Thread{
var out: FileWriter? = null
try {
Looper.prepare()
Toast.makeText(applicationContext, e.toString(), Toast.LENGTH_LONG)
.show()
val file = File(getExternalFilesDir(null), "error.txt")
if(!file.exists()){
val createNewFile = file.createNewFile()
}
out = FileWriter(file, true)
out.write("\r\n") //换行
out.write(e.toString())
}catch (e: Exception){
}finally {
if(out!=null){
out.close()
}
}
try {
Thread.sleep(5000)
removeAllActivity()
restartApp()
} catch (e: InterruptedException) {
e.printStackTrace()
}
Looper.loop()
}.start()
return true
}
/**
* 重启app
*/
private fun restartApp() {
val intent = Intent(this, SplashActvity::class.java)
@SuppressLint("WrongConstant") val restartIntent = PendingIntent.getActivity(
applicationContext, 0, intent, Intent.FLAG_ACTIVITY_NEW_TASK
)
//退出程序
val mgr = getSystemService(ALARM_SERVICE) as AlarmManager
mgr[AlarmManager.RTC, System.currentTimeMillis() + 1000] = restartIntent // 1秒钟后重启应用
//结束进程之前可以把你程序的注销或者退出代码放在这段代码之前
Process.killProcess(Process.myPid())
}
MyApplication代码
package com.zqq.shell
import android.annotation.SuppressLint
import android.app.Activity
import android.app.AlarmManager
import android.app.Application
import android.app.PendingIntent
import android.content.Intent
import android.os.Looper
import android.os.Process
import android.widget.Toast
import com.zqq.shell.activity.SplashActvity
import java.io.File
import java.io.FileWriter
class MyApplication : Application(),Thread.UncaughtExceptionHandler {
private val activitys = ArrayList()
companion object{
private var instance:MyApplication? = null
fun instance() = instance!!
//2、声明延迟初始化属性
// private lateinit var instance:MyApplication
// fun instance() = instance
}
// companion object{
// private var instance:MyApplication by Delegates.notNull()
// fun instance() = instance
// }
override fun onCreate() {
super.onCreate()
instance=this
Thread.setDefaultUncaughtExceptionHandler(this)
}
fun addActivity(activity: Activity){
activitys.add(activity)
}
fun removeActivity(activity: Activity){
activitys.remove(activity)
}
fun removeAllActivity(){
activitys.map {
it.finish()
}
}
fun getCurrentActivity():Activity = activitys.get(activitys.size - 1)
/**
* 全局未知异常处理
*/
override fun uncaughtException(t: Thread, e: Throwable) {
val b:Boolean = handException(e)
}
private fun handException(e: Throwable): Boolean {
if(e == null) return false
//写入错误日志
Thread{
var out: FileWriter? = null
try {
Looper.prepare()
Toast.makeText(applicationContext, e.toString(), Toast.LENGTH_LONG)
.show()
val file = File(getExternalFilesDir(null), "error.txt")
if(!file.exists()){
val createNewFile = file.createNewFile()
}
out = FileWriter(file, true)
out.write("\r\n") //换行
out.write(e.toString())
}catch (e: Exception){
}finally {
if(out!=null){
out.close()
}
}
try {
Thread.sleep(5000)
removeAllActivity()
restartApp()
} catch (e: InterruptedException) {
e.printStackTrace()
}
Looper.loop()
}.start()
return true
}
/**
* 重启app
*/
private fun restartApp() {
val intent = Intent(this, SplashActvity::class.java)
@SuppressLint("WrongConstant") val restartIntent = PendingIntent.getActivity(
applicationContext, 0, intent, Intent.FLAG_ACTIVITY_NEW_TASK
)
//退出程序
val mgr = getSystemService(ALARM_SERVICE) as AlarmManager
mgr[AlarmManager.RTC, System.currentTimeMillis() + 1000] = restartIntent // 1秒钟后重启应用
//结束进程之前可以把你程序的注销或者退出代码放在这段代码之前
Process.killProcess(Process.myPid())
}
}
测试异常处理
