package com.liuxianglin.demo

 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.widget.Button;  

 public class LifeCycleActivity extends Activity {  

     private static final String TAG = "LifeCycleActivity";
     private Context context = this;
     private int param = 1;  

     //Activity创建时被调用
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         Log.i(TAG, "onCreate called.");  

         setContentView(R.layout.lifecycle);  

         Button btn = (Button) findViewById(R.id.btn);
         btn.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 Intent intent = new Intent(context, TargetActivity.class);
                 startActivity(intent);
             }
         });
     }  

     //Activity创建或者从后台重新回到前台时被调用
     @Override
     protected void onStart() {
         super.onStart();
         Log.i(TAG, "onStart called.");
     }  

     //Activity从后台重新回到前台时被调用
     @Override
     protected void onRestart() {
         super.onRestart();
         Log.i(TAG, "onRestart called.");
     }  

     //Activity创建或者从被覆盖、后台重新回到前台时被调用
     @Override
     protected void onResume() {
         super.onResume();
         Log.i(TAG, "onResume called.");
     }  

     //Activity窗口获得或失去焦点时被调用,在onResume之后或onPause之后
     /*@Override
     public void onWindowFocusChanged(boolean hasFocus) {
         super.onWindowFocusChanged(hasFocus);
         Log.i(TAG, "onWindowFocusChanged called.");
     }*/  

     //Activity被覆盖到下面或者锁屏时被调用
     @Override
     protected void onPause() {
         super.onPause();
         Log.i(TAG, "onPause called.");
         //有可能在执行完onPause或onStop后,系统资源紧张将Activity杀死,所以有必要在此保存持久数据
     }  

     //退出当前Activity或者跳转到新Activity时被调用
     @Override
     protected void onStop() {
         super.onStop();
         Log.i(TAG, "onStop called.");
     }  

     //退出当前Activity时被调用,调用之后Activity就结束了
     @Override
     protected void onDestroy() {
         super.onDestroy();
         Log.i(TAG, "onDestory called.");
     }  

     /**
      * Activity被系统杀死时被调用.
      * 例如:屏幕方向改变时,Activity被销毁再重建;当前Activity处于后台,系统资源紧张将其杀死.
      * 另外,当跳转到其他Activity或者按Home键回到主屏时该方法也会被调用,系统是为了保存当前View组件的状态.
      * 在onPause之前被调用.
      */
     @Override
     protected void onSaveInstanceState(Bundle outState) {
         outState.putInt("param", param);
         Log.i(TAG, "onSaveInstanceState called. put param: " + param);
         super.onSaveInstanceState(outState);
     }  

     /**
      * Activity被系统杀死后再重建时被调用.
      * 例如:屏幕方向改变时,Activity被销毁再重建;当前Activity处于后台,系统资源紧张将其杀死,用户又启动该Activity.
      * 这两种情况下onRestoreInstanceState都会被调用,在onStart之后.
      */
     @Override
     protected void onRestoreInstanceState(Bundle savedInstanceState) {
         param = savedInstanceState.getInt("param");
         Log.i(TAG, "onRestoreInstanceState called. get param: " + param);
         super.onRestoreInstanceState(savedInstanceState);
     }
 }