android自定义滑动开关控件，适合所有的android系统

我们都知道Android4.0以上才带有滑动开关Switch，那么在4.0以下呢，很多人会选择用CheckBox，放两张图片，但是这样子只能点击，效果不太好，所以我就自定义了滑动开关WiperSwitch这么一个控件，下面先把截图贴上吧，这蹩脚的图片真戳啊，大家可以自己换三张图片

package com.example.wiperswitch;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

/**
 * 
 * @author xiaanming
 *
 */
public class WiperSwitch extends View implements OnTouchListener{
	private Bitmap bg_on, bg_off, slipper_btn;
	/**
	 * 按下时的x和当前的x
	 */
	private float downX, nowX;
	
	/**
	 * 记录用户是否在滑动
	 */
	private boolean onSlip = false;
	
	/**
	 * 当前的状态
	 */
	private boolean nowStatus = false;
	
	/**
	 * 监听接口
	 */
	private OnChangedListener listener;
	
	
	public WiperSwitch(Context context) {
		super(context);
		init();
	}

	public WiperSwitch(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}
	
	public void init(){
		//载入图片资源
		bg_on = BitmapFactory.decodeResource(getResources(), R.drawable.on_btn);
		bg_off = BitmapFactory.decodeResource(getResources(), R.drawable.off_btn);
		slipper_btn = BitmapFactory.decodeResource(getResources(), R.drawable.white_btn);
		
		setOnTouchListener(this);
	}
	
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		Matrix matrix = new Matrix();
		Paint paint = new Paint();
		float x = 0;
		
		//根据nowX设置背景，开或者关状态
		if (nowX < (bg_on.getWidth()/2)){
			canvas.drawBitmap(bg_off, matrix, paint);//画出关闭时的背景
		}else{
			canvas.drawBitmap(bg_on, matrix, paint);//画出打开时的背景 
		}
		
		if (onSlip) {//是否是在滑动状态,  
			if(nowX >= bg_on.getWidth())//是否划出指定范围,不能让滑块跑到外头,必须做这个判断
				x = bg_on.getWidth() - slipper_btn.getWidth()/2;//减去滑块1/2的长度
			else
				x = nowX - slipper_btn.getWidth()/2;
		}else {
			if(nowStatus){//根据当前的状态设置滑块的x值
				x = bg_on.getWidth() - slipper_btn.getWidth();
			}else{
				x = 0;
			}
		}
		
		//对滑块滑动进行异常处理，不能让滑块出界
		if (x < 0 ){
			x = 0;
		}
		else if(x > bg_on.getWidth() - slipper_btn.getWidth()){
			x = bg_on.getWidth() - slipper_btn.getWidth();
		}
		
		//画出滑块
		canvas.drawBitmap(slipper_btn, x , 0, paint); 
	}

	@Override
	public boolean onTouch(View v, MotionEvent event) {
		switch(event.getAction()){
		case MotionEvent.ACTION_DOWN:{
			if (event.getX() > bg_off.getWidth() || event.getY() > bg_off.getHeight()){
				return false;
			}else{
				onSlip = true;
				downX = event.getX();
				nowX = downX;
			}
			break;
		}
		case MotionEvent.ACTION_MOVE:{
			nowX = event.getX();
			break;
		}
		case MotionEvent.ACTION_UP:{
			onSlip = false;
			if(event.getX() >= (bg_on.getWidth()/2)){
				nowStatus = true;
				nowX = bg_on.getWidth() - slipper_btn.getWidth();
			}else{
				nowStatus = false;
				nowX = 0;
			}
			
			if(listener != null){
				listener.OnChanged(WiperSwitch.this, nowStatus);
			}
			break;
		}
		}
		//刷新界面
		invalidate();
		return true;
	}
	
	
	
	/**
	 * 为WiperSwitch设置一个监听，供外部调用的方法
	 * @param listener
	 */
	public void setOnChangedListener(OnChangedListener listener){
		this.listener = listener;
	}
	
	
	/**
	 * 设置滑动开关的初始状态，供外部调用
	 * @param checked
	 */
	public void setChecked(boolean checked){
		if(checked){
			nowX = bg_off.getWidth();
		}else{
			nowX = 0;
		}
		nowStatus = checked;
	}

	
    /**
     * 回调接口
     * @author len
     *
     */
	public interface OnChangedListener {
		public void OnChanged(WiperSwitch wiperSwitch, boolean checkState);
	}


}

用法是，先定义XML文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.example.wiperswitch.WiperSwitch
        android:id="@+id/wiperSwitch1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />


</RelativeLayout>

新建一个Activity

package com.example.wiperswitch;


import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

import com.example.wiperswitch.WiperSwitch.OnChangedListener;

public class MainActivity extends Activity implements OnChangedListener {

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		//实例化WiperSwitch
		WiperSwitch wiperSwitch = (WiperSwitch)findViewById(R.id.wiperSwitch1);
		
		//设置初始状态为false
		wiperSwitch.setChecked(false);
		
		//设置监听
		wiperSwitch.setOnChangedListener(this);
	}


	@Override
	public void OnChanged(WiperSwitch wiperSwitch, boolean checkState) {
		Log.e("log", "" + checkState);
	}


}

代码全部上完了，写的不好的地方欢迎大牛指点！

哦，忘记了还有三张蹩脚的图片没传