重寫view實現viewpager下導航圓點

佈局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/white"
    android:orientation="vertical" >
    <android.support.v4.view.ViewPager
        android:id="@+id/welcome_pager"
        android:background="@color/light_gray"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <cn.com.util.StateChange
        android:id="@+id/zhishi"
        android:layout_width="fill_parent"
        android:layout_height="30dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="71dp"
        android:background="@color/white" />

</RelativeLayout>

自定義導航圓點：

package cn.com.util;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.view.View;
/**
 * viewpager下導航欄圓點
 * @author ML  2015-05-29
 *
 */
public class StateChange extends View {
	public StateChange(Context context, AttributeSet attrs) {
		super(context, attrs);
		// TODO Auto-generated constructor stub
	}

	private int size, current;

	@SuppressLint("NewApi")
	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		super.onDraw(canvas);
		Paint p = new Paint();
		p.setAntiAlias(true);

		int item_width = 30;
		int center_x = (getWidth() - item_width * size) / 2;

		for (int i = 0; i < size; i++) {
			p.setColor(Color.BLACK);
			p.setStyle(Style.STROKE);
			if (i == current) {
				p.setStyle(Style.FILL);
				p.setColor(Color.RED);
			}
			canvas.drawCircle(center_x + item_width / 2 + i * item_width,
					getHeight() / 2, 10, p);
		}
		canvas.save();
 	}

	public void drawCicle(int size, int current) {
		this.size = size;
		this.current = current;
		invalidate();
	}

}

主界面：

package cn.com.jdsc;

import java.util.ArrayList;

import android.app.Activity;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
import cn.com.util.StateChange;

public class welcome extends Activity {
	ViewPager viewpager;	StateChange zhi;
	ArrayList<ImageView> viewList = new ArrayList<ImageView>();

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.welcome);
		viewpager = (ViewPager) this.findViewById(R.id.welcome_pager);
		 zhi=(StateChange) this.findViewById(R.id.zhishi);

		int[] welImg = { R.drawable.wel1, R.drawable.wel2, R.drawable.wel3 };

		for (int i = 0; i < welImg.length; i++) {
			ImageView image = new ImageView(welcome.this);
			image.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT,
					LayoutParams.MATCH_PARENT));
			// image.setImageResource(welImg[i]);
			image.setImageBitmap(BitmapFactory.decodeResource(getResources(),
					welImg[i]));
			image.setVisibility(View.VISIBLE);
			viewList.add(image);
		}
		  PagerAdapter pagerAdapter = new PagerAdapter() {  
              
	            @Override  
	            public boolean isViewFromObject(View arg0, Object arg1) {  
	                // TODO Auto-generated method stub  
	                return arg0 == arg1;  
	            }  
	              
	            @Override  
	            public int getCount() {  
	                // TODO Auto-generated method stub  
	                return viewList.size();  
	            }  
	              
	            @Override  
	            public void destroyItem(ViewGroup container, int position,  
	                    Object object) {  
	                // TODO Auto-generated method stub  
	                container.removeView(viewList.get(position));  
	                System.out.println("destroyItem="+position);
	            }  
	              
	            @Override  
	            public Object instantiateItem(ViewGroup container, int position) {  
	                // TODO Auto-generated method stub  
	                container.addView(viewList.get(position));  
	                 System.out.println("instantiateItem="+position);
	                  
	                return viewList.get(position);  
	            }  
	        };  
	          
		viewpager.setAdapter(pagerAdapter);
		viewpager.setOnPageChangeListener(new OnPageChangeListener() {
			
			@Override
			public void onPageSelected(int arg0) {
				// TODO Auto-generated method stub
				zhi.drawCicle(viewList.size(),arg0);

			}
			
			@Override
			public void onPageScrolled(int arg0, float arg1, int arg2) {
				// TODO Auto-generated method stub
				System.out.println("onPageScrolled="+arg0);
			}
			
			@Override
			public void onPageScrollStateChanged(int arg0) {
				// TODO Auto-generated method stub
				System.out.println("onPageScrollStateChanged="+arg0);

			}
		});
		zhi.drawCicle(viewList.size(),0);
	}
     
	 
 }