Android利用ViewPager实现带小圆球的图片滑动

在上文实现的带小圆球的图片滑动的通用性较好，但是较复杂。

现在也是利用 ViewPager ，但是却没有利用 ShapeDrawable 来实现带小圆球的图片滑动。如有些播放器一样，在开始安装 app 时，都会出现引导界面，然后才进入主界面，但是在重新启动 app 时却不会再出现该引导界面。

下面实现的就是该类似的功能，只是把引导界面都做成了图片显示，这样更能够体现不同的做法（和上一篇博客）。

本例主要主要：在小圆点的绘制和 viewpager 相关联起来。

如下效果：

MyPagerAdapter主要用于创建适配器；

MyPagerAdapter.java  :

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);
 }
 
 
 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);
 }
 }
 
 
 public void setbaseIndex(int index) {
 mbaseIndex = index;
 }
 
 
 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;
 }
 }
 
}

Circle 类主要用于绘制小圆球：

Circle.java :

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;
 
 
 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);
 }
 }
 }
}

MainActivity.java :

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());
 
 mAdapter.setForActivity(activity);
 
 viewPager.setAdapter(mAdapter);
 }
 
 
 private void initActivity() {
 // 去标题
 requestWindowFeature(Window.FEATURE_NO_TITLE);
 // 全屏
 getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
 WindowManager.LayoutParams.FLAG_FULLSCREEN);
 }
 
 
 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();
 }
 }
 
 
 private void scrollPager() {
 viewPager.addonPageChangeListener(new ViewPager.SimpleonPageChangeListener() {
 @Override
 public void onPageSelected(int position) {
 super.onPageSelected(position);
 
 circle.choose(position);
 }
 });
 }
 
}

另外新建一个常量类 Words，用于存放存量，不在一个包中；

Words.java :

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

SecondActivity.java :

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);
 }
}

activity_main.xml （一般情况下，有 viewpager 和其他占界面较少的组件一起时，效果和本例相似时，可以选用 frameLayout）:

item_one.xml :

item_two.xml （ImageView 中 src 指定的是用于在有 button 按钮时有图片显示才加载的，在代码中没有添加有 button 按钮界面时的图片） :

最后不能忘了在 AndroidManifest.xml 中为 SecondActivity 注册，最好在刚刚建好该类时就注册，这样不易遗忘：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。