android-Android 自動旋轉屏幕快捷開關，系統會發送廣播嗎？

Android 自動旋轉屏幕快捷開關，系統會發送廣播嗎？

就是下圖這裡的自動旋轉屏幕開關，開啟和關閉自動旋轉系統會發送廣播嗎？什麼廣播？怎麼監聽它的狀態改變？

最佳回答：

屏幕旋轉開關：
1). 屏幕旋轉開關設置主要調用android.provider.Settings.System的putInt和getInt方法實現。

  2). 通過ContentObserver來動態觀察屏幕旋轉設置的改變。

     示例代碼如下：

package com.example.srs;

import android.app.Activity;

import android.content.ContentResolver;

import android.content.Context;

import android.database.ContentObserver;

import android.net.Uri;

import android.os.Bundle;

import android.os.Handler;

import android.provider.Settings;

import android.provider.Settings.SettingNotFoundException;

import android.util.Log;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.Toast;

public class ScreenRotationSwitch extends Activity implements OnClickListener

{

private Button mRotationButton;

private RotationObserver mRotationObserver;  
/** Called when the activity is first created. */  
@Override  
public void onCreate(Bundle savedInstanceState)  
{  
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.main);  
    //創建觀察類對象  
    mRotationObserver = new RotationObserver(new Handler());  

    mRotationButton = (Button) findViewById(R.id.rotation);  
    refreshButton();  
    mRotationButton.setOnClickListener(this);  
}  


@Override  
protected void onDestroy() {  
    // TODO Auto-generated method stub  
    super.onDestroy();  
    //解除觀察變化  
    mRotationObserver.stopObserver();  
}  


@Override  
protected void onResume() {  
    // TODO Auto-generated method stub  
    super.onResume();  
    //注冊觀察變化  
    mRotationObserver.startObserver();  
}  


//更新按鈕狀態  
private void refreshButton()  
{  
    if (getRotationStatus(this) == 1)  
    {  
        mRotationButton.setText(R.string.rotation_off);  
    }  
    else  
    {  
        mRotationButton.setText(R.string.rotation_on);  
    }  
}  

//得到屏幕旋轉的狀態  
private int getRotationStatus(Context context)  
{  
    int status = 0;  
    try  
    {  
        status = android.provider.Settings.System.getInt(context.getContentResolver(),  
                android.provider.Settings.System.ACCELEROMETER_ROTATION);  
    }  
    catch (SettingNotFoundException e)  
    {  
        // TODO Auto-generated catch block  
        e.printStackTrace();  
    }  
    return status;  
}  

private void setRotationStatus(ContentResolver resolver, int status)  
{  
    //得到uri  
    Uri uri = android.provider.Settings.System.getUriFor("accelerometer_rotation");  
    //溝通設置status的值改變屏幕旋轉設置  
    android.provider.Settings.System.putInt(resolver, "accelerometer_rotation", status);  
    //通知改變  
    resolver.notifyChange(uri, null);  
}  

@Override  
public void onClick(View v)  
{  
    // TODO Auto-generated method stub  

    if (getRotationStatus(this) == 1)  
    {  

        setRotationStatus(getContentResolver(), 0);  
    }  
    else  
    {  
        setRotationStatus(getContentResolver(), 1);  
    }  
}  

//觀察屏幕旋轉設置變化，類似於注冊動態廣播監聽變化機制  
private class RotationObserver extends ContentObserver  
{  
    ContentResolver mResolver;  

    public RotationObserver(Handler handler)   
    {  
        super(handler);  
        mResolver = getContentResolver();  
        // TODO Auto-generated constructor stub  
    }  

    //屏幕旋轉設置改變時調用  
    @Override  
    public void onChange(boolean selfChange)   
    {  
        // TODO Auto-generated method stub  
        super.onChange(selfChange);  
        //更新按鈕狀態  
        refreshButton();  
        Toast.makeText(ScreenRotationSwitch.this, "旋轉屏幕設置有變化",  
                Toast.LENGTH_SHORT).show();  
    }  

    public void startObserver()  
    {  
        mResolver.registerContentObserver(Settings.System  
                .getUriFor(Settings.System.ACCELEROMETER_ROTATION), false,  
                this);  
    }  

    public void stopObserver()  
    {  
        mResolver.unregisterContentObserver(this);  
    }  
}  

}

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