Android8.0 Settings数据库监听的一个通用工具类

当Settings数据库某个字段的值发生变化，要监听怎么办，就用下面这个类。我是从qs settigns中发现的。

/** Helper for managing a global setting. **/
public abstract class GlobalSetting extends ContentObserver implements Listenable {
private final Context mContext;
private final String mSettingName;

protected abstract void handleValueChanged(int value);

public GlobalSetting(Context context, Handler handler, String settingName) {
super(handler);
mContext = context;
mSettingName = settingName;
}

public int getValue() {
return Global.getInt(mContext.getContentResolver(), mSettingName, 0);
}

public void setValue(int value) {
Global.putInt(mContext.getContentResolver(), mSettingName, value);
}

@Override
public void setListening(boolean listening) {
if (listening) {
mContext.getContentResolver().registerContentObserver(Global.getUriFor(mSettingName)
, false, this); 198
} else {
mContext.getContentResolver().unregisterContentObserver(this);
}
}

@Override
public void onChange(boolean selfChange) {
handleValueChanged(getValue());
}
}

/** Common interface for components with an active listening state. **/
public interface Listenable {
void setListening(boolean listening);
}

这么用

Looper looper = this.getPrefContext().getMainLooper();
mHandler = new Handler(looper);
mSetting = new GlobalSetting(this.getPrefContext(), mHandler, Global.xxx) {
//global.xxx就是要监听的字段
@Override
protected void handleValueChanged(int value) {
//value就是监听的值
}
}

}
};

mSetting.setListening(true);

mSetting.setListening(true);就是设置监听，不需要的时候就设false.