BaseActivity

1.新建BaseActivity继承FragmenytActivity。由于我习惯在Activity里用些公共的方法，所以将此类建为abstract 

public abstract class BaseActivity extends FragmentActivity {

}

2.重写onCreate()方法

public abstract class BaseActivity extends FragmentActivity {

             @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_base_activity);

    }
}

3.编写必要的属性

public abstract class BaseActivity extends FragmentActivity {
    
    protected int mScreenWidth;
    protected int mScreenHeight;
    protected float mDensity;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_base_activity);
        
        
        DisplayMetrics metrics =new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(metrics);
        mScreenHeight = metrics.heightPixels;
        mScreenWidth = metrics.widthPixels;
        mDensity = metrics.density;
        
    }
}

4.编写子类公共的方法

protected void showShortToast(int resId){
        Toast.makeText(this, getString(resId), Toast.LENGTH_SHORT).show();
    }
    protected void showShortToast(String text){
        Toast.makeText(this, text, Toast.LENGTH_SHORT).show();
    }
    
    protected void showLongToast(int resId){
        Toast.makeText(this, getString(resId), Toast.LENGTH_LONG).show();
    }
    
    protected void showLongToast(String text){
        Toast.makeText(this, text, Toast.LENGTH_LONG).show();
    }
    
    protected void showLogDebug(String tag,String msg){
        Log.d(tag, msg);
    }

    protected void showLogError(String tag,String msg){
        Log.e(tag, msg);
    }
    
    
    protected void startActivity(Class<?> cls, Bundle bundle){
        Intent intent = new Intent();
        intent.setClass(this, cls);
        if(bundle != null){
            intent.putExtras(bundle);
        }
        startActivity(intent);
    }
    
    protected void startActivity(Class<?> cls){
        startActivity(cls,null);
    }
    
    
    protected AlertDialog showAlertDialog(String title,String message){
        AlertDialog alertDialog = new AlertDialog.Builder(this)
        .setTitle(title)
        .setMessage(message)
        .show();
        return alertDialog;
    }
    
    protected AlertDialog showAlertDialog(String title,String message
            ,String posistiveText
            ,DialogInterface.OnClickListener onPositiveClickListener
            ,String negativeText
            ,DialogInterface.OnClickListener onNegativeClickListener){
        AlertDialog alertDialog = new AlertDialog.Builder(this)
        .setTitle(title)
        .setMessage(message)
        .setPositiveButton(posistiveText, onPositiveClickListener)
        .setNegativeButton(negativeText, onNegativeClickListener)
        .show();
        return alertDialog;
    }
    
    
    protected void defaultFinish(){
        super.finish();
    }
    
    
    abstract void initView();
    abstract void initEvent();