Android利用ViewPager实现带小圆球的图片滑动

package com.android.circleforimage;
 
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
 
public class MyPagerAdapter extends FragmentPagerAdapter {
 
 private static Activity activity;
 
 private static final int[] IMAGES = { R.drawable.x01, R.drawable.x02,
 R.drawable.x03, R.drawable.x04, R.drawable.x05 };
 public static int sum = IMAGES.length;
 
 public MyPagerAdapter(FragmentManager fm) {
 super(fm);
 }
 
 /**
 * 为了获得 MainActivity 中的 activity
 */
 public void setForActivity(Activity activity) {
 this.activity = activity;
 }
 
 public Activity getForActivity() {
 return activity;
 }
 
 @Override
 public int getCount() {
 return IMAGES.length;
 }
 
 @Override
 public Fragment getItem(final int position) {
 return MyFragment.newInstance(position);
 }
 
 public static class MyFragment extends Fragment {
 
 private int mBaseIndex;
 
 // 使用工厂模式创建 Fragment
 static MyFragment newInstance(int baseIndex) {
 MyFragment fragment = new MyFragment();
 fragment.setBaseIndex(baseIndex);
 return fragment;
 }
 
 public MyFragment() {
 super();
 }
 
 @Override
 public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 }
 
 @Override
 public View onCreateView(LayoutInflater inflater, ViewGroup container,
 Bundle savedInstanceState) {
 // 最后一张图片上有 button 按钮
 if (getBaseIndex() == IMAGES.length - 1) {
 return initForButton(inflater);
 } else {
 return showImages(inflater);
 }
 }
 
 /**
 * 在全局列表中保存一个索引，记录页面开始的地方
 */
 public void setBaseIndex(int index) {
 mBaseIndex = index;
 }
 
 /**
 * 在全局列表中检索索引，可以找到页面开始的地方
 */
 public int getBaseIndex() {
 return mBaseIndex;
 }
 
 public View initForButton(LayoutInflater inflater){
 
 View view = inflater.inflate(R.layout.item_two, null);
 
 Button button = (Button) view.findViewById(R.id.button);
 button.setOnClickListener(new OnClickListener() {
 
 @Override
 public void onClick(View v) {
  Intent intent = new Intent(activity,
  SecondActivity.class);
  startActivity(intent);
  activity.finish();
 }
 });
 return view;
 }
 
 public View showImages(LayoutInflater inflater){
 View view = inflater.inflate(R.layout.item_one, null);
 ImageView imageView = (ImageView) view.findViewById(R.id.imageView);
 imageView.setImageResource(IMAGES[getBaseIndex()]);
 imageView.setScaleType(ImageView.ScaleType.FIT_XY);
 
 return view;
 }
 }
 
}

package com.android.circleforimage;
 
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
 
public class Circle extends View {
 
 private Paint paint;
 
 private int radius = 16;
 // 页数和小圆球的数量相等
 private int count = MyPagerAdapter.sum;
 // 被选中的位置
 private int choosePosition = 0;
 // 两个小圆之间的中心距
 private int gap = 70;
 
 /**
 * 共外部的类调用
 */
 public void choose(int pos) {
 choosePosition = pos;
 // 通知重绘
 this.invalidate();
 }
 
 public Circle(Context context) {
 this(context, null);
 }
 
 public Circle(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
 }
 
 public Circle(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);
 
 paint = new Paint();
 paint.setAntiAlias(true);
 }
 
 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 
 int width = getWidth();
 int height = getHeight();
 // 居中显示时，小圆球的起始位置
 int startPx = (width - (count - 1) * gap) / 2;
 
 for (int i = 0; i < count; i++) {
 if (choosePosition == i) {
 paint.setColor(Color.RED);
 canvas.drawCircle(startPx + i * gap, height - 50, radius + 4,
  paint);
 } else {
 paint.setColor(Color.WHITE);
 canvas.drawCircle(startPx + i * gap, height - 50, radius, paint);
 }
 }
 }
}

package com.android.circleforimage;
 
import com.android.circleforimageutils.Words;
 
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.view.Window;
import android.view.WindowManager;
 
public class MainActivity extends FragmentActivity {
 
 private ViewPager viewPager;
 private MyPagerAdapter mAdapter;
 private Circle circle;
 
 private Activity activity = null;
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 initActivity();
 setContentView(R.layout.activity_main);
 
 activity = this;
 showForSecondActivity();
 
 viewPager = (ViewPager) findViewById(R.id.viewPager);
 circle = (Circle) findViewById(R.id.circle);
 
 scrollPager();
 
 mAdapter = new MyPagerAdapter(getSupportFragmentManager());
 /* 调用 MyPagerAdapter 的方法*/
 mAdapter.setForActivity(activity);
 
 viewPager.setAdapter(mAdapter);
 }
 
 /**
 * 对界面的处理
 */
 private void initActivity() {
 // 去标题
 requestWindowFeature(Window.FEATURE_NO_TITLE);
 // 全屏
 getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
 WindowManager.LayoutParams.FLAG_FULLSCREEN);
 }
 
 /**
 * 第一次安装启动时，会加载开始的页面，第二次启动时，会跳过加载页面
 */
 private void showForSecondActivity() {
 // PreferenceManager:Used to help create Preference hierarchies from activities or XML.
 SharedPreferences mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
 SharedPreferences.Editor editor = mSharedPreferences.edit();
 
 boolean b = mSharedPreferences.getBoolean(Words.KEY_ONE, true);
 if (b) {
 editor.putBoolean(Words.KEY_ONE, false);
 editor.commit();
 } else {
 Intent intent = new Intent(this, SecondActivity.class);
 startActivity(intent);
 finish();
 }
 }
 
 /**
 * viewPager 滚动时，提示 Circle 类重绘
 */
 private void scrollPager() {
 viewPager.addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
 @Override
 public void onPageSelected(int position) {
 super.onPageSelected(position);
 
 circle.choose(position);
 }
 });
 }
 
}

package com.android.circleforimageutils;
 
public class Words {
 public static String KEY_ONE = "key_for_main";
}

package com.android.circleforimage;
 
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Gravity;
import android.widget.TextView;
 
public class SecondActivity extends Activity{
 
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 
 TextView textView = new TextView(this);
 textView.setText("欢迎来到我的博客：\n http://blog.csdn.net/antimage08");
 textView.setTextSize(25);
 textView.setTextColor(Color.BLUE);
 textView.setGravity(Gravity.CENTER);
 
 setContentView(textView);
 }
}

<FrameLayout 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"
 android:orientation="vertical"
 tools:context="com.android.circleforimage.MainActivity" >
 
 <android.support.v4.view.ViewPager
  android:id="@+id/viewPager"
  android:layout_width="match_parent"
  android:layout_height="match_parent" />
 
 <com.android.circleforimage.Circle 
  android:id="@+id/circle"
  android:layout_width="match_parent"
  android:layout_height="match_parent"/>
</FrameLayout>

<?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" >
 
 <ImageView 
  android:id="@+id/imageView"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  /> 
 
</LinearLayout>

<?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:orientation="vertical" >
 
 <ImageView 
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:src="@drawable/x05"/>
 
 <Button 
  android:id="@+id/button"
  android:layout_alignParentBottom="true"
  android:layout_alignParentRight="true"
  android:text="点击进入"
  android:textSize="20sp"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"/>
 
</RelativeLayout>

<activity android:name=".SecondActivity" />