Android編程自定義View時添加自己的監(jiān)聽器示例

更新時間：2018年01月18日 09:49:05 作者：dztai

這篇文章主要介紹了Android編程自定義View時添加自己的監(jiān)聽器,涉及Android自定義view中監(jiān)聽器的添加、設置與使用相關操作技巧,需要的朋友可以參考下

本文實例講述了Android編程自定義View時添加自己的監(jiān)聽器。分享給大家供大家參考，具體如下：

監(jiān)聽器在Java中非常常用，在自定義控件時可能根據自己的需要去監(jiān)聽一些數(shù)據的改變，這時就需要我們自己去寫監(jiān)聽器，Java中的監(jiān)聽器實際上就是C++中的回調函數(shù)，在初始化時設置了這個函數(shù)，由某個事件觸發(fā)這個函數(shù)被調用，兩個類之間的數(shù)據通信也可以通過監(jiān)聽器來實現(xiàn)。要定義監(jiān)聽器就要先定義一個接口，具體功能由設置監(jiān)聽器的類去實現(xiàn)

關鍵代碼實現(xiàn)

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;
/**
 * 在自定義的View中定義三個監(jiān)聽器
 */
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這個控件的move和up才會響應
    } 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);
  }
  // 為每個接口設置監(jiān)聽器
  public void setOnDownActionListener(OnDownActionListener down) {
    mDown = down;
  }
  public void setOnMoveActionListener(OnMoveActionListener move) {
    mMove = move;
  }
  public void setOnUpActionListener(OnUpActionListener up) {
    mUp = up;
  }
  // 定義三個接口
  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);
  }
}

自定義View在xml中的定義

<?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中設置監(jiān)聽器

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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