Android自定义控件实现优雅的广告轮播图

前言

今天给大家带来一个新的控件–轮播图，网上已经有很多这类的博客来讲解如何实现的，那么我的这个有哪些特点呢？或是说有哪些不同呢？

满足了轮播图的基本要求，循环滑动，在最后一张切到第一张时可以平稳的过渡
简洁简洁简洁
扩展性强

如何使用

下面我们先展示两种效果图

1 默认效果

代码实现

//布局代码
<com.landptf.view.BannerM
  android:id="@+id/bm_banner"
  android:layout_width="match_parent"
  android:layout_height="200dp" />
//java代码
BannerM banner = (BannerM) findViewById(R.id.bm_banner);
if (banner != null) {
 banner.setBannerBeanList(bannerList).show();
}
//初始化数据
private void initData() {
 bannerList = new ArrayList<>(4);
 BannerBean banner1 = new BannerBean("测试图片1", url1, "");
 BannerBean banner2 = new BannerBean("测试图片2", url2, "");
 BannerBean banner3 = new BannerBean("测试图片3", url3, "");
 BannerBean banner4 = new BannerBean("测试图片4", url4, "");
 bannerList.add(banner1);
 bannerList.add(banner2);
 bannerList.add(banner3);
 bannerList.add(banner4);
}

其实关键代码就一行，这里面用到了BannerBean的实体类，有三个参数，分别是图片的描述文字，图片地址，点击后对应的链接

以上全部都是默认值，下面来看一下都哪些可以自定义

2 自定义效果

图1和图2主要有以下几点不同

1 指示器和文字的位置结构，这里面我只实现了两种，大家也可以下载源码后扩展
2 圆点指示器选中后的颜色
3 自动播放的时间间隔
4 支持图片未加载出来之前显示默认图片

自定义效果的代码实现

下面通过xml和java代码来分别演示一下图2的实现

1 xml

<com.landptf.view.BannerM
  android:id="@+id/bm_banner"
  android:layout_width="match_parent"
  android:layout_height="200dp"
  landptf:defaultImageDrawable="@drawable/default_image"
  landptf:intervalTime="3"
  landptf:indexPosition="bottom"
  landptf:indexColor="@color/colorPrimary"
  />
BannerM banner = (BannerM) findViewById(R.id.bm_banner);
if (banner != null) {
 banner.setBannerBeanList(bannerList)
   .setOnItemClickListener(new BannerM.OnItemClickListener() {
    @Override
    public void onItemClick(int position) {
     Log.e("landptf", "position = " + position);
    }
   })
   .show();
}

2 java

<com.landptf.view.BannerM
  android:id="@+id/bm_banner"
  android:layout_width="match_parent"
  android:layout_height="200dp" />
BannerM banner = (BannerM) findViewById(R.id.bm_banner);
if (banner != null) {
 banner.setBannerBeanList(bannerList)
   .setDefaultImageResId(R.drawable.default_image)
   .setIndexPosition(BannerM.INDEX_POSITION_BOTTOM)
   .setIndexColor(getResources().getColor(R.color.colorPrimary))
   .setIntervalTime(3)
   .setOnItemClickListener(new BannerM.OnItemClickListener() {
    @Override
    public void onItemClick(int position) {
     Log.e("landptf", "position = " + position);
    }
   })
   .show();
}

以上两种代码实现的效果完全等价，在java代码中都是通过链式调用，使代码看起来更加的简洁。
有木有很方便，大大的减少了代码量，而且是可以直接拿来用的。好了下面我们来看一下实现的代码。

实现

图片下载集成了Picasso，有对Picasso不熟悉的童鞋可以看一下我之前的博客图片加载利器之Picasso（二）基本用法

<?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.support.v4.view.ViewPager
  android:id="@+id/vp_banner"
  android:layout_width="match_parent"
  android:layout_height="match_parent" />
 <ViewStub
  android:id="@+id/vs_index_right"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:layout_alignParentBottom="true"
  android:layout="@layout/viewstub_banner_m_index_right" />
 <ViewStub
  android:id="@+id/vs_index_bottom"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:layout_alignParentBottom="true"
  android:layout="@layout/viewstub_banner_m_index_bottom" />
</RelativeLayout>

ViewStub的引用代码这里就不给出，大家可以访问我的git查看，文末会给出地址

package com.landptf.view;
import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.ColorStateList;
import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.GradientDrawable;
import android.os.Handler;
import android.os.Message;
import android.os.Parcelable;
import android.support.annotation.Nullable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.ViewStub;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import com.landptf.R;
import com.landptf.bean.BannerBean;
import com.landptf.util.ConvertM;
import com.squareup.picasso.MemoryPolicy;
import com.squareup.picasso.Picasso;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

public class BannerM extends RelativeLayout {
 
 public static final int INDEX_POSITION_RIGHT = 0x100;
 
 public static final int INDEX_POSITION_BOTTOM = 0x101;
 private static final int HANDLE_UPDATE_INDEX = 0;
 private Context mContext;
 private ViewPager vpBanner;
 private ViewPagerAdapter adapter;
 private OnItemClickListener mOnItemClickListener;
 //装载ImageView控件的list
 private List<ImageView> ivList;
 //圆点指示器控件
 private List<View> vList;
 //控制圆点View的形状，未选中的颜色
 private GradientDrawable gradientDrawable;
 //控制圆点View的形状，选中的颜色
 private GradientDrawable gradientDrawableSelected;
 //选中圆点的颜色值，默认为#FF3333
 private int indexColorResId;
 //图片对应的文字描述
 private TextView tvText;
 //自动滑动的定时器
 private ScheduledExecutorService scheduledExecutorService;
 //当前加载到第几页
 private int currentIndex = 0;
 //默认背景图
 private int defaultImageResId;
 private Drawable defaultImageDrawable = null;
 //自动轮播的时间间隔(s)
 private int intervalTime = 5;
 //轮播图需要的数据列表
 private List<BannerBean> bannerBeanList;
 //圆点指示器的位置，提供两种布局
 private int indexPosition = INDEX_POSITION_RIGHT;
 public BannerM(Context context) {
  this(context, null);
 }
 public BannerM(Context context, AttributeSet attrs) {
  this(context, attrs, 0);
 }
 public BannerM(Context context, AttributeSet attrs, int defStyleAttr) {
  super(context, attrs, defStyleAttr);
  init(context, attrs, defStyleAttr);
 }
 private void init(Context context, AttributeSet attrs, int defStyle) {
  mContext = context;
  LayoutInflater.from(context).inflate(R.layout.view_banner_m, this, true);
  vpBanner = (ViewPager) findViewById(R.id.vp_banner);
  TypedArray a = getContext().obtainStyledAttributes(
    attrs, R.styleable.bannerM, defStyle, 0);
  if (a != null) {
   defaultImageDrawable = a.getDrawable(R.styleable.bannerM_defaultImageDrawable);
   intervalTime = a.getInteger(R.styleable.bannerM_intervalTime, 5);
   indexPosition = a.getInteger(R.styleable.bannerM_indexPosition, INDEX_POSITION_RIGHT);
   ColorStateList indexColorList = a.getColorStateList(R.styleable.bannerM_indexColor);
   if (indexColorList != null) {
    indexColorResId = indexColorList.getColorForState(getDrawableState(), 0);
   }
   a.recycle();
  }
 }
 
 public BannerM setDefaultImageResId(int defaultImageResId) {
  this.defaultImageResId = defaultImageResId;
  return this;
 }
 
 public BannerM setDefaultImageDrawable(Drawable defaultImageDrawable) {
  this.defaultImageDrawable = defaultImageDrawable;
  return this;
 }
 
 public BannerM setIntervalTime(int intervalTime) {
  this.intervalTime = intervalTime;
  return this;
 }
 
 public BannerM setIndexPosition(int indexPosition) {
  this.indexPosition = indexPosition;
  return this;
 }
 
 public BannerM setIndexColor(int indexColor) {
  this.indexColorResId = indexColor;
  return this;
 }
 
 public BannerM setBannerBeanList(List<BannerBean> bannerBeanList) {
  this.bannerBeanList = bannerBeanList;
  return this;
 }
 
 public BannerM setOnItemClickListener(@Nullable OnItemClickListener listener) {
  mOnItemClickListener = listener;
  return this;
 }
 public void show() {
  if (bannerBeanList == null || bannerBeanList.size() == 0) {
   throw new IllegalArgumentException("bannerBeanList == null");
  }
  initImageViewList();
  initIndexList();
  vpBanner.addOnPageChangeListener(new OnPageChangeListener());
  adapter = new ViewPagerAdapter();
  vpBanner.setAdapter(adapter);
  //定时器开始工作
  startPlay();
 }
 
 private void initIndexList() {
  int count = bannerBeanList.size();
  vList = new ArrayList<>(count);
  LinearLayout llIndex;
  if (indexPosition == INDEX_POSITION_RIGHT) {
   ViewStub vsIndexRight = (ViewStub) findViewById(R.id.vs_index_right);
   vsIndexRight.inflate();
   llIndex = (LinearLayout) findViewById(R.id.ll_index_right);
   tvText = (TextView) findViewById(R.id.tv_text);
  } else {
   ViewStub vsIndexBottom = (ViewStub) findViewById(R.id.vs_index_bottom);
   vsIndexBottom.inflate();
   llIndex = (LinearLayout) findViewById(R.id.ll_index_bottom);
   tvText = (TextView) findViewById(R.id.tv_text);
  }
  //默认第一张图片的文字描述
  tvText.setText(bannerBeanList.get(0).getText());
  //使用GradientDrawable构造圆形控件
  gradientDrawable = new GradientDrawable();
  gradientDrawable.setShape(GradientDrawable.OVAL);
  gradientDrawable.setColor(mContext.getResources().getColor(R.color.text));
  gradientDrawableSelected = new GradientDrawable();
  gradientDrawableSelected.setShape(GradientDrawable.OVAL);
  if (indexColorResId != 0) {
   gradientDrawableSelected.setColor(indexColorResId);
  } else {
   gradientDrawableSelected.setColor(mContext.getResources().getColor(R.color.mainColor));
  }
  for (int i = 0; i < count; i++) {
   View view = new View(mContext);
   LinearLayout.LayoutParams lpView = new LinearLayout.LayoutParams(ConvertM.dp2px(mContext, 8), ConvertM.dp2px(mContext, 8));
   lpView.rightMargin = ConvertM.dp2px(mContext, 4);
   view.setLayoutParams(lpView);
   if (0 == i) {
    view.setBackgroundDrawable(gradientDrawableSelected);
   } else {
    view.setBackgroundDrawable(gradientDrawable);
   }
   view.bringToFront();
   vList.add(view);
   llIndex.addView(view);
  }
 }
 
 private void initImageViewList() {
  int count = bannerBeanList.size();
  ivList = new ArrayList<>(count);
  for (int i = 0; i < count; i++) {
   final ImageView imageView = new ImageView(mContext);
   imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
   ivList.add(imageView);
   imageView.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
     mOnItemClickListener.onItemClick(getPosition(imageView));
    }
   });
   if (defaultImageResId != 0) {
    Picasso.with(mContext)
      .load(bannerBeanList.get(i).getUrl())
      .placeholder(defaultImageResId)
      .memoryPolicy(MemoryPolicy.NO_CACHE, MemoryPolicy.NO_STORE)
      .into(imageView);
   } else if (defaultImageDrawable != null) {
    Picasso.with(mContext)
      .load(bannerBeanList.get(i).getUrl())
      .placeholder(defaultImageDrawable)
      .memoryPolicy(MemoryPolicy.NO_CACHE, MemoryPolicy.NO_STORE)
      .into(imageView);
   } else {
    Picasso.with(mContext)
      .load(bannerBeanList.get(i).getUrl())
      .memoryPolicy(MemoryPolicy.NO_CACHE, MemoryPolicy.NO_STORE)
      .into(imageView);
   }
  }
 }
 private void startPlay() {
  scheduledExecutorService = Executors.newSingleThreadScheduledExecutor();
  scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
   @Override
   public void run() {
    currentIndex++;
    handler.obtainMessage(HANDLE_UPDATE_INDEX).sendToTarget();
   }
  }, intervalTime, intervalTime, TimeUnit.SECONDS);
 }
 
 private int getPosition(ImageView item) {
  for (int i = 0; i < ivList.size(); i++) {
   if (item == ivList.get(i)) {
    return i;
   }
  }
  return -1;
 }
 @SuppressLint("HandlerLeak")
 private Handler handler = new Handler() {
  @Override
  public void handleMessage(Message msg) {
   switch (msg.what) {
    case HANDLE_UPDATE_INDEX:
     vpBanner.setCurrentItem(currentIndex);
     break;
    default:
     break;
   }
  }
 };
 private class OnPageChangeListener implements ViewPager.OnPageChangeListener {
  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
  }
  @Override
  public void onPageSelected(int position) {
   currentIndex = position;
   for (int i = 0; i < bannerBeanList.size(); i++) {
    if (position % ivList.size() == i) {
     vList.get(i).setBackgroundDrawable(gradientDrawableSelected);
    } else {
     vList.get(i).setBackgroundDrawable(gradientDrawable);
    }
    tvText.setText(bannerBeanList.get(position % ivList.size()).getText());
   }
  }
  @Override
  public void onPageScrollStateChanged(int state) {
  }
 }
 private class ViewPagerAdapter extends PagerAdapter {
  @Override
  public void destroyItem(View container, int position, Object object) {
  }
  @Override
  public Object instantiateItem(View container, int position) {
   position %= ivList.size();
   if (position<0){
    position = ivList.size()+position;
   }
   ImageView imageView = ivList.get(position);
   ViewParent vp =imageView.getParent();
   if (vp!=null){
    ViewGroup parent = (ViewGroup)vp;
    parent.removeView(imageView);
   }
   ((ViewPager) container).addView(imageView);
   return imageView;
  }
  @Override
  public int getCount() {
   return Integer.MAX_VALUE;
  }
  @Override
  public boolean isViewFromObject(View arg0, Object arg1) {
   return arg0 == arg1;
  }
  @Override
  public void restoreState(Parcelable arg0, ClassLoader arg1) {
  }
  @Override
  public Parcelable saveState() {
   return null;
  }
  @Override
  public void startUpdate(View arg0) {
  }
  @Override
  public void finishUpdate(View arg0) {
  }
 }
 public interface OnItemClickListener {
  void onItemClick(int position);
 }
}

这篇文章就介绍到这里了，点击这里查看源码

下面是测试用的图片：

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