Android编程自定义View时添加自己的监听器示例

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本文实例讲述了Android编程自定义View时添加自己的监听器。分享给大家供大家参考，具体如下：

监听器在Java中非常常用，在自定义控件时可能根据自己的需要去监听一些数据的改变，这时就需要我们自己去写监听器，Java中的监听器实际上就是C++中的回调函数，在初始化时设置了这个函数，由某个事件触发这个函数被调用，两个类之间的数据通信也可以通过监听器来实现。要定义监听器就要先定义一个接口，具体功能由设置监听器的类去实现

关键代码实现

package com.example.listviewitem.widgets;
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
/**
 * 在自定义的View中定义三个监听器
 */
public class MyView extends View {
  private OnDownActionListener mDown = null;
  private OnMoveActionListener mMove = null;
  private OnUpActionListener mUp = null;
  public MyView(Context context) {
    super(context);
  }
  public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
  }
  @Override
  protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    super.onDraw(canvas);
  }
  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    int x, y;
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
      x = (int) event.getX();
      y = (int) event.getY();
      if (mDown != null) {
        mDown.OnDown(x, y);
      }
      return true; // 只有返回true这个控件的move和up才会响应
    } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
      x = (int) event.getX();
      y = (int) event.getY();
      if (mMove != null) {
        mMove.OnMove(x, y);
      }
    } else if (event.getAction() == MotionEvent.ACTION_UP) {
      x = (int) event.getX();
      y = (int) event.getY();
      if (mUp != null) {
        mUp.OnUp(x, y);
      }
    }
    return super.onTouchEvent(event);
  }
  // 为每个接口设置监听器
  public void setOnDownActionListener(OnDownActionListener down) {
    mDown = down;
  }
  public void setOnMoveActionListener(OnMoveActionListener move) {
    mMove = move;
  }
  public void setOnUpActionListener(OnUpActionListener up) {
    mUp = up;
  }
  // 定义三个接口
  public interface OnDownActionListener {
    public void OnDown(int x, int y);
  }
  public interface OnMoveActionListener {
    public void OnMove(int x, int y);
  }
  public interface OnUpActionListener {
    public void OnUp(int x, int y);
  }
}

自定义View在xml中的定义

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:orientation="vertical" >
  <com.example.listviewitem.widgets.MyView
    android:id="@+id/my_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/area_point_bg" />
</LinearLayout>

Activity中设置监听器

package com.example.listviewitem;
import com.example.listviewitem.widgets.MyView;
import com.example.listviewitem.widgets.MyView.OnDownActionListener;
import com.example.listviewitem.widgets.MyView.OnMoveActionListener;
import com.example.listviewitem.widgets.MyView.OnUpActionListener;
import android.app.Activity;
import android.os.Bundle;
public class TestListener extends Activity {
  private MyView view;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.listener);
    view = (MyView) findViewById(R.id.my_view);
    view.setOnDownActionListener(new OnDownActionListener() {
      @Override
      public void OnDown(int x, int y) {
        // TODO Auto-generated method stub
        System.out.println("down x = " + x + " y = " + y);
      }
    });
    view.setOnMoveActionListener(new OnMoveActionListener() {
      @Override
      public void OnMove(int x, int y) {
        // TODO Auto-generated method stub
        System.out.println("move x = " + x + " y = " + y);
      }
    });
    view.setOnUpActionListener(new OnUpActionListener() {
      @Override
      public void OnUp(int x, int y) {
        // TODO Auto-generated method stub
        System.out.println("up x = " + x + " y = " + y);
      }
    });
  }
}

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