Android自定義View時添加自己的監聽器

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

關鍵代碼實現

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纔會響應
        } 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);
    }

    // 爲每個接口設置監聽器
    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);
            }
        });
    }
}

打印消息

說明我們自定義的監聽器已經起作用了。

原帖地址：

http://blog.csdn.net/deng0zhaotai/article/details/21456791?utm_source=tuicool