android自定義回調接口

這是流傳已久的故事：

某天，我打電話向你請教問題，當然是個難題，你一時想不出解決方法，我又不能拿着電話在那裏傻等，於是我們約定：等你想出辦法後打手機通知我，這樣，我就掛掉電話辦其它事情去了。過了XX分鐘，我的手機響了，你興高采烈的說問題已經搞定，應該如此這般處理。

初學者，這篇文章，第一次理解自定義回調接口，可以說這是寫給自己看的。。。

直接上碼

一個自定義的View：（別急，往下看）

package ivo_chuanzhi.myapplication_bluetooth_zhongli;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.PorterDuff.Mode;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.SurfaceHolder.Callback;

@SuppressLint("ViewConstructor")
public class AppSingleRocker extends SurfaceView implements Callback{
	private SurfaceHolder mHolder;
	private Paint mPaint;
	public Point mRockerPosition; // 搖桿位置
	private Point mCtrlPoint;// 搖桿起始位置
	private int mRudderRadius = 25;// 搖桿半徑
	private int mWheelRadius = 80;// 搖桿活動範圍半徑
	private int batmapHW = 160;
	private int batmap2HW = 40;
	int isHide = 0;
	Bitmap bitmap,bitmap2;
	float scale;

	public SingleRudderListener listener = null; //事件回調接口

	public static final int ACTION_RUDDER = 1, ACTION_ATTACK_DEVICEMOVE = 2, ACTION_STOP = 3,  ACTION_ATTACK_CAMERAMOVE = 4;
	public AppSingleRocker(Context context, AttributeSet attrs) {
		super(context, attrs);
		this.setKeepScreenOn(true);
		scale = context.getResources().getDisplayMetrics().density;
		mRudderRadius = dip2px(15);// 搖桿半徑
		mWheelRadius = dip2px(45);// 搖桿活動範圍半徑
		mCtrlPoint = new Point((mRudderRadius + mWheelRadius), (mRudderRadius + mWheelRadius));// 搖桿起始位置
		batmapHW = (mWheelRadius+mRudderRadius) * 2;
		batmap2HW = mRudderRadius * 2;
        mHolder = getHolder();
        mHolder.addCallback(this);
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        setFocusable(true);
        setFocusableInTouchMode(true);
        mRockerPosition = new Point(mCtrlPoint);
        setZOrderOnTop(true);
        mHolder.setFormat(PixelFormat.TRANSPARENT);//設置背景透明
        bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.joystick_l_pad);
        bitmap = Bitmap.createScaledBitmap(bitmap, batmapHW, batmapHW, false);
        bitmap2 = BitmapFactory.decodeResource(getResources(), R.drawable.print2);
        bitmap2 = Bitmap.createScaledBitmap(bitmap2,batmap2HW,batmap2HW, false);
	}

	//獲取屏幕的寬度，高度和密度以及dp / px
	 public void getDisplayMetrics() {
 		
	}
	public int dip2px(float dpValue) {  
        return (int)(dpValue * scale + 0.5f);
    }


	//public SingleRudderListener listener = null; //事件回調接口
	//回調接口
    public interface SingleRudderListener {
        void onSteeringWheelChanged(int action, int angle);
    }
    
	//設置回調接口
    public void setSingleRudderListener(SingleRudderListener rockerListener) {
        listener = rockerListener;
    }


    
    int len;
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		try {
			if (isHide == 0) {
				switch (event.getAction()) {
				case MotionEvent.ACTION_DOWN:
					len = MathUtils.getLength(mCtrlPoint.x, mCtrlPoint.y, event.getX(), event.getY());
					 //如果屏幕接觸點不在搖桿揮動範圍內,則不處理
		            if(len > mWheelRadius) {
		                return true;
		            }
					break;
				case MotionEvent.ACTION_MOVE:
					len = MathUtils.getLength(mCtrlPoint.x, mCtrlPoint.y, event.getX(), event.getY());
					if(len <= mWheelRadius) {
		                //如果手指在搖桿活動範圍內，則搖桿處於手指觸摸位置
		                mRockerPosition.set((int)event.getX(), (int)event.getY());
		            }else{
		                //設置搖桿位置，使其處於手指觸摸方向的 搖桿活動範圍邊緣
		                mRockerPosition = MathUtils.getBorderPoint(mCtrlPoint, new Point((int)event.getX(), (int)event.getY()), mWheelRadius);
		            }




		            if(listener != null) {
		                float radian = MathUtils.getRadian(mCtrlPoint, new Point((int)event.getX(), (int)event.getY()));
		                listener.onSteeringWheelChanged(ACTION_RUDDER, getAngleCouvert(radian));
		            }



					break;
				case MotionEvent.ACTION_UP:
					 mRockerPosition = new Point(mCtrlPoint);
					 if (listener != null) {
						 listener.onSteeringWheelChanged(ACTION_STOP, 0);
					}
					break;
				}
				Canvas_OK();
				Thread.sleep(60);
			}else {
				Thread.sleep(200);
			}
		} catch (Exception e) {

		}
		return true;
	}

	public void singleRockerUp(){
		 mRockerPosition = new Point(mCtrlPoint);
		 listener.onSteeringWheelChanged(ACTION_STOP, 0);
	}
	//獲取搖桿偏移角度 0-360°
    private int getAngleCouvert(float radian) {
        int tmp = (int)Math.round(radian/Math.PI * 180);
        if(tmp < 0) {
            return -tmp;
        }else{
            return 180 + (180 - tmp);
        }
    }

	public void surfaceCreated(SurfaceHolder holder) {
		Canvas_OK();
	}

	public void surfaceChanged(SurfaceHolder holder, int format, int width,
			int height) {
		
	}

	public void surfaceDestroyed(SurfaceHolder holder) {
		
	}
	// 設置是否隱藏
	public void Hided(int opt)
	{
		isHide = opt;
		Canvas_OK();
	}
	
	public void setHided(int opt){
		isHide = opt;
	}
	/**
	 * 返回圓盤是否隱藏
	 * @return
	 */
	public int getIsHided(){
		return isHide;
	}
	//繪製圖像
	public void Canvas_OK(){
		 Canvas canvas = null;
		 try {
			 if (isHide == 0) {
				 canvas = mHolder.lockCanvas();
	             canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);//清除屏幕
	             canvas.drawBitmap(bitmap, mCtrlPoint.x - mWheelRadius - mRudderRadius, mCtrlPoint.y - mWheelRadius - mRudderRadius, mPaint);
	             canvas.drawBitmap(bitmap2, mRockerPosition.x - mRudderRadius, mRockerPosition.y - mRudderRadius, mPaint);
			}else {
				 canvas = mHolder.lockCanvas();
	             canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);//清除屏幕
			}
         } catch (Exception e) {
             e.printStackTrace();
         } finally {
             if(canvas != null) {
                 mHolder.unlockCanvasAndPost(canvas);
             }
         }
	 }
}

這個自定義的View裏面，設置了，回調接口，但具體的方法未實現：

public SingleRudderListener listener = null; //事件回調接口
	//回調接口
    public interface SingleRudderListener {
        void onSteeringWheelChanged(int action, int angle);//具體的方法
    }
    
	//設置回調接口
    public void setSingleRudderListener(SingleRudderListener rockerListener) {
        listener = rockerListener;
    }

在這個例子裏，在

onTouchEvent(MotionEvent event){xxxx}方法裏使用了這個回調接口的方法，但具體實現任然沒有

具體的實現這個接口，是在另一個類裏面（一般是UI線程）

MainActivity：

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

        if(D) Log.v(TAG2, "+++ ON CREATE +++");
        System.out.println("+++ ON CREATE +++");


      //  seekBar1 = (SeekBar) findViewById(R.id.seekBar1);

     //   textView1 = (TextView) findViewById(R.id.textView1);
        textView2 = (TextView) findViewById(R.id.textView2);
        textView3 = (TextView) findViewById(R.id.textView3);
        textView_test = (TextView) findViewById(R.id.textView_test);
        textView_test2 = (TextView) findViewById(R.id.textView_test2);

        /*//兩種方式監聽
        seekBar1.setOnSeekBarChangeListener(this);*/

        initOpenBluetooth();



        initWebView();


        AppSingleRocker appSingleRocker_one = (AppSingleRocker) findViewById(R.id.YaoGan_one);
        AppSingleRocker appSingleRocker_two = (AppSingleRocker) findViewById(R.id.YaoGan_two);

//兩種方式，有this的，是這樣的<pre style="background-color:#2b2b2b;color:#a9b7c6;font-family:'Monospac821 BT';font-size:11.3pt;"><span style="color:#cc7832;">public class </span>MainActivity <span style="color:#cc7832;">extends </span>ActionBarActivity <span style="color:#cc7832;">implements </span>AppSingleRocker.SingleRudderListener {}

appSingleRocker_one.setSingleRudderListener(this);//自定義接口，實現該接口 appSingleRocker_two.setSingleRudderListener(new AppSingleRocker.SingleRudderListener() { @Override public void onSteeringWheelChanged(int action, int angle) {//具體實現 textView_test.setText("x = " + action + " " + "y = " + angle ); } }); } @Override public void onSteeringWheelChanged(int action, int angle) { textView_test2.setText("x = " + action + " " + "y = " + angle ); }

總結：第一次理解自定義回調接口，可以說這是寫給自己看的。。。