Activity生命週期應用實例

 瞭解了Activity的生命週期，下面我們寫一個實例更進一步的學習怎麼使用生命週期。

一  需求：

（1）有兩個Activity，MainActivity和ActivityTwo  ，其中MainActivity中有一個按鈕btnSkip，

（2）啓動MainActivity之後播放音樂

（3）點擊btnSkip跳轉到ActivityTwo  ，此時音樂播放暫停

（4）按Back返回MainActivity，音樂開始播放

（5）再按Back退出MainActivity，銷燬播放器

二  實現

（1）首先我們需要在工程目錄的res文件夾下面新建一raw文件夾，然後把一個音頻文件粘貼到此文件夾下，如圖所示

（2）正式編寫代碼 主要是MainActivity.java

package com.example.activitytest;

import android.app.Activity;

import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends Activity {
	private Button  btnSkip;
	private MediaPlayer mediaPlayer;
	private int position;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        btnSkip = (Button)this.findViewById(R.id.btnButton);
        if(savedInstanceState!=null){
        	String str = savedInstanceState.getString("name");
        }
        Log.e("TAG", "MainActivity onCreate() method is executed");
        mediaPlayer = MediaPlayer.create(this,R.raw.huoyuanjia);//獲取了音頻文件的地址信息
        mediaPlayer.start();
        btnSkip.setOnClickListener(new OnClickListener() {
			
			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				Intent intent = new Intent(MainActivity.this,ActivityTwo.class);
				startActivity(intent);
			}
		});
    }
    
    @Override
    protected void onSaveInstanceState(Bundle outState) {
    	// TODO Auto-generated method stub
    	super.onSaveInstanceState(outState);
    	outState.putString("name", "zhuminquan");
    	Log.e("TAG", "MainActivity onSaveInstanceState() method is executed");
    }
    
    
    @Override
	protected void onStart() {
		// TODO Auto-generated method stub
		super.onStart();
		Log.e("TAG", "MainActivity onStart() method is executed");
	}
    
    @Override
    protected void onRestart() {
    	// TODO Auto-generated method stub
    	if(position!=0){
    		mediaPlayer.seekTo(position);
    		mediaPlayer.start();
    	}
    	super.onRestart();
    	Log.e("TAG", "MainActivity onRestart() method is executed");
    }
    
    @Override
    protected void onPause() {
    	// TODO Auto-generated method stub
    	if(mediaPlayer.isPlaying()){
    		mediaPlayer.pause();
    		position = mediaPlayer.getCurrentPosition();
    	}
    	super.onPause();
    	Log.e("TAG", "MainActivity onPause() method is executed");
    }
    
    @Override
    protected void onResume() {
    	// TODO Auto-generated method stub
    	super.onResume();
    	Log.e("TAG", "MainActivity onResume() method is executed");
    }
    
    @Override
    protected void onStop() {
    	// TODO Auto-generated method stub
    	super.onStop();
    	Log.e("TAG", "MainActivity onStop() method is executed");
    }
    
    @Override
    protected void onDestroy() {
    	// TODO Auto-generated method stub
    	super.onDestroy();
    	Log.e("TAG", "MainActivity onDestroy() method is executed");
    	if(mediaPlayer!=null){
    		mediaPlayer.release();
    		mediaPlayer = null;
    	}
    }


}