Android实现自定义轮播图片控件示例

2019-12-12 04:51:17

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要完成一个轮播图片，首先想到的应该是使用ViewPager来实现。ViewPager已经有了滑动的功能，我们只要让它自己滚动。再加上下方的小圆点就行了。所以我们本次的自定义控件就是由ViewPager和LinearLayout叠加起来组成的。

直接先上效果图：

创建一个自定义的ViewPager

先上完整的代码

package com.kcode.autoscrollviewpager.view;import android.content.Context;import android.os.Message;import android.support.v4.view.ViewPager;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import java.util.Timer;import java.util.TimerTask;/** * Created by caik on 2016/10/10. */public class AutoViewPager extends ViewPager {  private static final String TAG = "AutoViewPager";  private int currentItem;  private Timer mTimer;  private AutoTask mTask;  private boolean isFirst = true;  public AutoViewPager(Context context) {    super(context);  }  public AutoViewPager(Context context, AttributeSet attrs) {    super(context, attrs);  }  public void start(){    if (mTimer == null) {      mTimer = new Timer();    }    mTimer.schedule(new AutoTask(),3000,3000);  }  private Runnable runnable = new Runnable() {    @Override    public void run() {      currentItem = getCurrentItem();      if(currentItem == getAdapter().getCount() - 1){        currentItem = 0 ;      }else {        currentItem++ ;      }      setCurrentItem(currentItem);    }  };  private AutoHandler mHandler = new AutoHandler();  public void updatePointView(int size) {    if (getParent() instanceof AutoScrollViewPager){      AutoScrollViewPager pager = (AutoScrollViewPager) getParent();      pager.initPointView(size);    }else {      Log.e(TAG,"parent view not be AutoScrollViewPager");    }  }  public void onPageSelected(int position) {    AutoScrollViewPager pager = (AutoScrollViewPager) getParent();    pager.updatePointView(position);  }  private class AutoTask extends TimerTask{    @Override    public void run() {      mHandler.post(runnable);    }  }  private final static class AutoHandler extends android.os.Handler{    @Override    public void handleMessage(Message msg) {      super.handleMessage(msg);    }  }  public void onStop(){    //先取消定时器    if (mTimer != null) {      mTimer.cancel();      mTimer = null;    }  }  public void onDestroy(){    onStop();  }  public void onResume(){    start();  }  @Override  public boolean onTouchEvent(MotionEvent ev) {    switch (ev.getAction()){      case MotionEvent.ACTION_DOWN:        Log.i(TAG,"down");        onStop();        break;      case MotionEvent.ACTION_MOVE:        Log.i(TAG,"move");        break;      case MotionEvent.ACTION_UP:        Log.i(TAG,"up");        onResume();        break;    }    return super.onTouchEvent(ev);  }}

AutoViewPager 继承至ViewPager，我们通过Timer来启动一个定时器。

public void start(){    if (mTimer == null) {      mTimer = new Timer();    }    mTimer.schedule(new AutoTask(),3000,3000);  }  private Runnable runnable = new Runnable() {    @Override    public void run() {      currentItem = getCurrentItem();      if(currentItem == getAdapter().getCount() - 1){        currentItem = 0 ;      }else {        currentItem++ ;      }      setCurrentItem(currentItem);    }  };

每隔三秒去更新一下页面。这样就能起到一个自己滚动的效果。

设置Adapter

要实现无限循环，只要把Adapter中的getCount()方法返回无限大，直接返回Integer.MAX_VALUE就可以了。

完整的Adapter代码：

package com.kcode.autoscrollviewpager.view;import android.content.Context;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import com.kcode.autoscrollviewpager.R;import java.util.ArrayList;import java.util.List;/** * Created by caik on 2016/10/11. */public abstract class BaseViewPagerAdapter<T> extends PagerAdapter implements ViewPager.OnPageChangeListener{  private List<T> data = new ArrayList<>();  private Context mContext;  private AutoViewPager mView;  private OnAutoViewPagerItemClickListener listener;  public BaseViewPagerAdapter(List<T> t) {    this.data = t;  }  public BaseViewPagerAdapter(Context context, AutoViewPager viewPager) {    this.mContext = context;    mView = viewPager;    mView.setAdapter(this);    mView.addOnPageChangeListener(this);    mView.setCurrentItem(0);  }  public BaseViewPagerAdapter(Context context, AutoViewPager viewPager,OnAutoViewPagerItemClickListener listener) {    this.mContext = context;    mView = viewPager;    this.listener = listener;    mView.setAdapter(this);    mView.addOnPageChangeListener(this);    mView.setCurrentItem(0);  }  public BaseViewPagerAdapter(Context context, List<T> data,AutoViewPager viewPager,OnAutoViewPagerItemClickListener listener) {    this.mContext = context;    mView = viewPager;    this.data = data;    this.listener = listener;    mView.setAdapter(this);    mView.addOnPageChangeListener(this);    mView.setCurrentItem(0);    mView.start();    mView.updatePointView(getRealCount());  }  public void add(T t){    data.add(t);    notifyDataSetChanged();    mView.updatePointView(getRealCount());  }  @Override  public int getCount() {    return data == null ? 0 : Integer.MAX_VALUE;  }  public int getRealCount(){    return data == null ? 0 : data.size();  }  @Override  public void destroyItem(ViewGroup container, int position, Object object) {    container.removeView((ImageView) object);  }  @Override  public Object instantiateItem(ViewGroup container, final int position) {    ImageView view = (ImageView) LayoutInflater.from(mContext)        .inflate(R.layout.imageview,container,false);    view.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View view) {        if (listener != null) {          listener.onItemClick(position % getRealCount(),data.get(position % getRealCount()));        }      }    });    loadImage(view,position, data.get(position % getRealCount()));    container.addView(view);    return view;  }  public abstract void loadImage(ImageView view,int position,T t);  @Override  public boolean isViewFromObject(View view, Object object) {    return view == object;  }  @Override  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {  }  @Override  public void onPageSelected(int position) {    mView.onPageSelected(position % getRealCount());  }  @Override  public void onPageScrollStateChanged(int state) {  }  public interface OnAutoViewPagerItemClickListener<T> {    void onItemClick(int position,T t);  }}

这里我们使用了泛型，因为有时候我们可能只传一个url集合进来，也可能是对象集合，方便拓展。加载图片的方法也是一个抽象方法

public abstract void loadImage(ImageView view,int position,T t);

因为每个App使用的图片加载框架都不一样，所以这里的加载就留个App自己实现。使用的时候创建Adapter只要继承这里的BaseViewPagerAdapter，然后重写loadImage(ImageView view,int position,T t)方法，在这里进行图片的加载就行了。

如果你需不要底部的小圆点标示的话，这里就已经完成了。使用的时候，直接使用

  <com.kcode.autoscrollviewpager.view.AutoViewPager    android:layout_width="match_parent"    android:layout_height="200dp">      </com.kcode.autoscrollviewpager.view.AutoViewPager>

代替

  <android.support.v4.view.ViewPager    android:layout_width="match_parent"    android:layout_height="match_parent">  </android.support.v4.view.ViewPager>

就可以了。需要底部的小圆点标示的话，继续往下

添加小圆点标示

需要添加小圆点标示的话。其实就是在ViewPager上再加一层。我们新建一个View，继承至RelativeLayout

完整代码如下：

package com.kcode.autoscrollviewpager.view;import android.content.Context;import android.util.AttributeSet;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.RelativeLayout;import com.kcode.autoscrollviewpager.R;import static android.view.Gravity.CENTER;/** * Created by caik on 2016/10/17. */public class AutoScrollViewPager extends RelativeLayout{  private AutoViewPager mViewPager;  private Context mContext;  private LinearLayout layout;  public AutoScrollViewPager(Context context) {    super(context);    init(context);  }  public AutoScrollViewPager(Context context, AttributeSet attrs) {    super(context, attrs);    init(context);  }  private void init(Context context){    mContext = context;    mViewPager = new AutoViewPager(context);    layout = new LinearLayout(mContext);    addView(mViewPager);  }  public AutoViewPager getViewPager() {    return mViewPager;  }  public void initPointView(int size){    layout = new LinearLayout(mContext);    for (int i = 0; i < size; i++) {      ImageView imageView = new ImageView(mContext);      LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(20,20);      params.leftMargin = 8;      params.gravity = CENTER;      imageView.setLayoutParams(params);      if (i == 0) {        imageView.setBackgroundResource(R.drawable.point_checked);      }else {        imageView.setBackgroundResource(R.drawable.point_normal);      }      layout.addView(imageView);    }    LayoutParams layoutParams = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);    layoutParams.addRule(ALIGN_PARENT_BOTTOM);    layoutParams.addRule(ALIGN_PARENT_RIGHT);    layoutParams.setMargins(12,20,12,20);    layout.setLayoutParams(layoutParams);    addView(layout);  }  public void updatePointView(int position) {    int size = layout.getChildCount();    for (int i = 0; i < size; i++) {      ImageView imageView = (ImageView) layout.getChildAt(i);      if (i == position){        imageView.setBackgroundResource(R.drawable.point_checked);      }else {        imageView.setBackgroundResource(R.drawable.point_normal);      }    }  }}

初始化的时候创建一个ViewPager,一个LinearLayout（用来放小圆点）

 public AutoScrollViewPager(Context context) {    super(context);    init(context);  }  public AutoScrollViewPager(Context context, AttributeSet attrs) {    super(context, attrs);    init(context);  }  private void init(Context context){    mContext = context;    mViewPager = new AutoViewPager(context);    layout = new LinearLayout(mContext);    addView(mViewPager);  }

再通过addView(mViewPager);添加。

需要准备两张图片，这里用Shape进行绘制,Shape的使用可以查看Android Shape使用.

初始化小圆点：

 public void initPointView(int size){    layout = new LinearLayout(mContext);    for (int i = 0; i < size; i++) {      ImageView imageView = new ImageView(mContext);      LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(20,20);      params.leftMargin = 8;      params.gravity = CENTER;      imageView.setLayoutParams(params);      if (i == 0) {        imageView.setBackgroundResource(R.drawable.point_checked);      }else {        imageView.setBackgroundResource(R.drawable.point_normal);      }      layout.addView(imageView);    }    LayoutParams layoutParams = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);    layoutParams.addRule(ALIGN_PARENT_BOTTOM);    layoutParams.addRule(ALIGN_PARENT_RIGHT);    layoutParams.setMargins(12,20,12,20);    layout.setLayoutParams(layoutParams);    addView(layout);  }

更新小圆点：

 public void updatePointView(int position) {    int size = layout.getChildCount();    for (int i = 0; i < size; i++) {      ImageView imageView = (ImageView) layout.getChildAt(i);      if (i == position){        imageView.setBackgroundResource(R.drawable.point_checked);      }else {        imageView.setBackgroundResource(R.drawable.point_normal);      }    }  }

带小圆点的使用以下控件

<com.kcode.autoscrollviewpager.view.AutoScrollViewPager    android:id="@+id/viewPager"    android:layout_width="match_parent"    android:layout_height="220dp">  </com.kcode.autoscrollviewpager.view.AutoScrollViewPager>

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武林网。

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