android实现ViewPager的Indicator的实例代码

虽然在android5.0中design中有了TabLayout来实现ViewPager的Indicator，简单好用。但这个是我自己实现的，学习了很多，记录在这里。效果图：

第一步

新建一个类继承LinearLayout，用来绘制指示器，及提供Viewpager滑动时重绘指示器的方法：

public class ViewPagerIndicator extends LinearLayout{

  //画笔
  private Paint mPaint;
   //用来画一条线
  private Path mPath;
  //绘制线的宽度
  private int mLineWidth;
  //线的初始位置
  private int mInitTranslationX;
  //移动位置
  private int mTranslationX;
  //子控件
  private View mChildView;

  public ViewPagerIndicator(Context context) {
    super(context,null);
  }

  public ViewPagerIndicator(Context context, AttributeSet attrs) {

    super(context, attrs);
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setColor(Color.parseColor("#ffba00"));
    mPaint.setStrokeWidth(3);
    mPaint.setStyle(Paint.Style.STROKE);
  }

  //完成布局后获取子控件
  @Override
  protected void onFinishInflate() {
    super.onFinishInflate();
    mChildView = getChildAt(0);
  }
//在onSizeChanged中获取宽和初始位置，并根据位置初始化线
  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    mTranslationX = 0;
    mLineWidth = mChildView.getMeasuredWidth();
    mInitTranslationX = (w/getChildCount()-mLineWidth)/2;

    initLine();
  }
//初始化线
  private void initLine(){
    mPath = new Path();
    mPath.moveTo(0,0);
    mPath.lineTo(mLineWidth,0);

  }
//绘制线
  @Override
  protected void dispatchDraw(Canvas canvas) {
    canvas.save();
    //移动到该坐标后开始绘制
    canvas.translate(mInitTranslationX + mTranslationX,getHeight());
    canvas.drawPath(mPath,mPaint);
    canvas.restore();
    super.dispatchDraw(canvas);
  }

  ////在viewpager的onPageScrolled监听方法中调用此方法。viewPager滑动时mTranslationX的距离跟着变化，实现线的滑动，position，offset由onPageScrolled传值
  public void scroll(int position ,float offset){
    int tabWidth = getWidth()/getChildCount();
    mTranslationX =(int) (tabWidth * offset +tabWidth * position);
    //请求重绘，调用dispatchDraw方法
    invalidate();
  }
}

第二步

在布局中使用该类：

layoutorderpicking

第三步

在activity中完成ViewPagerIndicator与Viewpager的关联

public class OrderPickingActivity extends FragmentActivity implements View.onClickListener {
  TextView forPicking;
  TextView hasBeenPicking;
  TextView hasBeenPicking;
  ViewPagerIndicator mIndicator;
  ViewPager orderPickingDate;
  private List mFragmentList;
  private FragmentPagerAdapter orderPickingAdapter;
  private ViewPager.onPageChangeListener onPageChangeListener;
  //当前选中的indicator
  private TextView currentItem;

   protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.orderpicking);
     init();
     orderPickingDate.setAdapter(orderPickingAdapter);
     orderPickingDate.addonPageChangeListener();
     orderPickingDate.setCurrentItem(0);
currentItem = forPicking;
  currentItem.setTextColor(Color.parseColor("#ffba00"));
  }
  private void init(){
    forPicking = (TextView) findViewById(R.id.for_picking);
    hasBeenPicking = (TextView) findViewById(R.id.has_been_picking);
    all = (TextView) findViewById(R.id.all);
    mIndicator=(ViewPagerIndicator)findViewById(R.id.indicator);
    orderPickingDate = (ViewPager)findViewById(R.id.orderpicking_date);
    //初始化viewpager的item，并添加到list中
      mFragmentList = new ArrayList<>();
      OrderPickingFragmentForPicking orderPickingFragmentForPicking = 
      new OrderPickingFragmentForPicking();
      OrderPickingFragmentHasBeenPicking orderPickingFragmentHasBeenPicking =
 new OrderPickingFragmentHasBeenPicking();
      OrderPickingFragmentAll orderPickingFragmentAll =
 new OrderPickingFragmentAll();
      mFragmentList.add(orderPickingFragmentForPicking);
      mFragmentList.add(orderPickingFragmentHasBeenPicking);
      mFragmentList.add(orderPickingFragmentAll);
      //设置viewpager的适配器；
      orderPickingAdapter = new FragmentPagerAdapter(getSupportFragmentManager()) {
 @Override
 public int getCount() {
   return mFragmentList.size();
 }
 @Override
 public Fragment getItem(int i) {
   return mFragmentList.get(i);
 }
      };
      //设置ViewPager监听事件
      onPageChangeListener = new ViewPager.onPageChangeListener(){
 //滑动时，indicator下面的横线跟着滑动
 @Override
 public void onPageScrolled(int i, float v, int i1) {
   mIndicator.scroll(i, v);
 }
 //选中监听，改变indicator文字颜色
 @Override
 public void onPageSelected(int i) {
   switch (i) {
     case 0:
if (currentItem == forPicking)
  return;
forPicking.setTextColor(Color.parseColor("#ffba00"));
currentItem.setTextColor(Color.parseColor("#646464"));
currentItem = forPicking;
break;
     case 1:
if (currentItem == hasBeenPicking)
  return;
hasBeenPicking.setTextColor(Color.parseColor("#ffba00"));
currentItem.setTextColor(Color.parseColor("#646464"));
currentItem = hasBeenPicking;
break;
     case 2:
if (currentItem == all)
  return;
all.setTextColor(Color.parseColor("#ffba00"));
currentItem.setTextColor(Color.parseColor("#646464"));
currentItem = all;
   }
 }
 @Override
 public void onPageScrollStateChanged(int i) {}
      });
  }
  @Override
  public void onClick(View v) {
 switch (v.getId()) {
 case R.id.for_picking:
   orderPickingDate.setCurrentItem(0);
   break;
 case R.id.has_been_picking:
   orderPickingDate.setCurrentItem(1);
   break;
 case R.id.all:
   orderPickingDate.setCurrentItem(2);
   break;
 default:
   break;
  }
}

这就完成了。

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。