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;

/**
* Created by landptf on 2017/03/06.
* 轮播图控件
*/
public class BannerM extends RelativeLayout {
/**
 * 圆点指示器的位置，文字在左，圆点在右
 */
public static final int INDEX_POSITION_RIGHT = 0x100;
/**
 * 圆点指示器的位置，文字在上，圆点在下
 */
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();
 }
}

/**
 * 设置图片加载之前默认显示的图片
 *
 * @param defaultImageResId
 * @return BannerM
 */
public BannerM setDefaultImageResId(int defaultImageResId) {
 this.defaultImageResId = defaultImageResId;
 return this;
}

/**
 * 设置图片加载之前默认显示的图片
 *
 * @param defaultImageDrawable
 * @return BannerM
 */
public BannerM setDefaultImageDrawable(Drawable defaultImageDrawable) {
 this.defaultImageDrawable = defaultImageDrawable;
 return this;
}

/**
 * 设置轮播的时间间隔，单位为s，默认为5s
 *
 * @param intervalTime
 * @return BannerM
 */
public BannerM setIntervalTime(int intervalTime) {
 this.intervalTime = intervalTime;
 return this;
}

/**
 * 设置圆点指示器的位置
 * #BannerM.INDEX_POSITION_RIGHT or #BannerM.INDEX_POSITION_BOTTOM
 *
 * @param indexPosition
 * @return BannerM
 */
public BannerM setIndexPosition(int indexPosition) {
 this.indexPosition = indexPosition;
 return this;
}

/**
 * 选中圆点的颜色值，默认为#FF3333
 *
 * @param indexColor
 * @return BannerM
 */
public BannerM setIndexColor(int indexColor) {
 this.indexColorResId = indexColor;
 return this;
}

/**
 * 设置轮播图需要的数据列表
 *
 * @param bannerBeanList
 * @return BannerM
 */
public BannerM setBannerBeanList(List<BannerBean> bannerBeanList) {
 this.bannerBeanList = bannerBeanList;
 return this;
}

/**
 * 设置图片的点击事件
 * @param listener
 */
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();
}

/**
 * 初始化圆点指示器，根据indexPosition来加载不同的布局
 */
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);
 }
}

/**
 * 初始化ImageView，使用Picasso下载图片，只在SdCard中缓存
 */
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);
}

/**
 * 获取点击图片的位置
 * @param item
 * @return int
 */
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);
}
}

下面是测试用的图片：

来源：http://blog.csdn.net/wangjihuanghun/article/details/60785267