AndroidUI组件SlidingTabLayout实现ViewPager页滑动效果

使用SlidingTabLayout需要准备2个类，分别是 SlidingTabLayout，与SlidingTabStrip，，放进项目中时只用修改下包名即可。

效果制作的不是很好。
这篇文章，也是在网上搜了很多资源参考，对 SlidingTabLayout.java和SlidingTabStrip.java进行了修改。大家可以更改他的格式字体大小、选中状态，分割线调整等等。先上传这两个文件，改动支出都做了注释。
SlidingTabLayout.java

/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*  http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.example.my.slidingtablayout;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.graphics.Typeface;
import android.os.Build;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TextView;

/**
* To be used with ViewPager to provide a tab indicator component which give constant feedback as to
* the user's scroll progress.
* <p>
* To use the component, simply add it to your view hierarchy. Then in your
* {@link android.app.Activity} or {@link android.support.v4.app.Fragment} call
* {@link #setViewPager(ViewPager)} providing it the ViewPager this layout is being used for.
* <p>
* The colors can be customized in two ways. The first and simplest is to provide an array of colors
* via {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)}. The
* alternative is via the {@link TabColorizer} interface which provides you complete control over
* which color is used for any individual position.
* <p>
* The views used as tabs can be customized by calling {@link #setCustomTabView(int, int)},
* providing the layout ID of your custom layout.
*/
public class SlidingTabLayout extends HorizontalScrollView {

/**
 * Allows complete control over the colors drawn in the tab layout. Set with
 * {@link #setCustomTabColorizer(TabColorizer)}.
 */
public interface TabColorizer {

/**
  * @return return the color of the indicator used when {@code position} is selected.
  */
 int getIndicatorColor(int position);

/**
  * @return return the color of the divider drawn to the right of {@code position}.
  */
 int getDividerColor(int position);

}

private static final int TITLE_OFFSET_DIPS = 24;
private static final int TAB_VIEW_PADDING_DIPS = 16; //内边距
private static int TAB_VIEW_TEXT_SIZE_SP = 16; //字体大小

private int mTitleOffset;

private int mTabViewLayoutId;
private int mTabViewTextViewId;

// 定义两种需要添加的选项卡颜色
private int mDefaultTextColor;
private int mSelectedTextColor;

private ViewPager mViewPager;
private ViewPager.OnPageChangeListener mViewPagerPageChangeListener;

private final SlidingTabStrip mTabStrip;

public SlidingTabLayout(Context context) {
 this(context, null);
}

public SlidingTabLayout(Context context, AttributeSet attrs) {
 this(context, attrs, 0);
}

public SlidingTabLayout(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);

// 获取选项卡颜色，如果未定义的话，则使用主题默认的颜色
 TypedArray a = context.obtainStyledAttributes(attrs,
   R.styleable.SlidingTabLayout);
 int defaultTextColor = a.getColor(
   R.styleable.SlidingTabLayout_android_textColorPrimary, 0);
 mDefaultTextColor = a.getColor(
   R.styleable.SlidingTabLayout_textColorTabDefault, defaultTextColor);
 mSelectedTextColor = a.getColor(
   R.styleable.SlidingTabLayout_textColorTabSelected ,defaultTextColor);
 a.recycle();

// Disable the Scroll Bar
 setHorizontalScrollBarEnabled(false);
 // Make sure that the Tab Strips fills this View
 setFillViewport(true);

mTitleOffset = (int) (TITLE_OFFSET_DIPS * getResources().getDisplayMetrics().density);

mTabStrip = new SlidingTabStrip(context);
 addView(mTabStrip, LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
}

// 在每次选项改变时更新选项卡文本颜色的新方法
private void updateSelectedTitle(int position) {
 final PagerAdapter adapter = mViewPager.getAdapter();
 for (int i = 0; i < adapter.getCount(); i++) {
  final View tabView = mTabStrip.getChildAt(i);
  if (TextView.class.isInstance(tabView)) {
   TextView titleView = (TextView)tabView;
   boolean isSelected = i == position;
   titleView.setTextColor(isSelected ? mSelectedTextColor : mDefaultTextColor);
  }
 }
}
/**
 * Set the custom {@link TabColorizer} to be used.
 * <p>
 * If you only require simple custmisation then you can use
 * {@link #setSelectedIndicatorColors(int...)} and {@link #setDividerColors(int...)} to achieve
 * similar effects.
 */
public void setCustomTabColorizer(TabColorizer tabColorizer) {
 mTabStrip.setCustomTabColorizer(tabColorizer);
}

/**
 * Sets the colors to be used for indicating the selected tab. These colors are treated as a
 * circular array. Providing one color will mean that all tabs are indicated with the same color.
 */
public void setSelectedIndicatorColors(int... colors) {
 mTabStrip.setSelectedIndicatorColors(colors);
}

/**
 * Sets the colors to be used for tab dividers. These colors are treated as a circular array.
 * Providing one color will mean that all tabs are indicated with the same color.
 */
public void setDividerColors(int... colors) {
 mTabStrip.setDividerColors(colors);
}

//...设置字体大小
public void setTitleSize(int size) {
 this.TAB_VIEW_TEXT_SIZE_SP = size;
}

/**
 * Set the {@link ViewPager.OnPageChangeListener}. When using {@link SlidingTabLayout} you are
 * required to set any {@link ViewPager.OnPageChangeListener} through this method. This is so
 * that the layout can update it's scroll position correctly.
 *
 * @see ViewPager#setOnPageChangeListener(ViewPager.OnPageChangeListener)
 */
public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
 mViewPagerPageChangeListener = listener;
}

/**
 * Set the custom layout to be inflated for the tab views.
 *
 * @param layoutResId Layout id to be inflated
 * @param textViewId id of the {@link TextView} in the inflated view
 */
public void setCustomTabView(int layoutResId, int textViewId) {
 mTabViewLayoutId = layoutResId;
 mTabViewTextViewId = textViewId;
}

/**
 * Sets the associated view pager. Note that the assumption here is that the pager content
 * (number of tabs and tab titles) does not change after this call has been made.
 */
public void setViewPager(ViewPager viewPager) {
 mTabStrip.removeAllViews();

mViewPager = viewPager;
 if (viewPager != null) {
  viewPager.setOnPageChangeListener(new InternalViewPagerListener());
  populateTabStrip();
 }
}

/**
 * Create a default view to be used for tabs. This is called if a custom tab view is not set via
 * {@link #setCustomTabView(int, int)}.
 */
protected TextView createDefaultTabView(Context context) {
 TextView textView = new TextView(context);
 textView.setGravity(Gravity.CENTER);
 textView.setTextSize(TypedValue.COMPLEX_UNIT_SP, TAB_VIEW_TEXT_SIZE_SP);
 textView.setTypeface(Typeface.DEFAULT_BOLD);

//...这会移除 Holo 的默认背景强调以及选项卡的粗体文本
 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
  // If we're running on Honeycomb or newer, then we can use the Theme's
  // selectableItemBackground to ensure that the View has a pressed state
  TypedValue outValue = new TypedValue();
  getContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground,
    outValue, true);
  textView.setBackgroundResource(outValue.resourceId);
 }

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
  // If we're running on ICS or newer, enable all-caps to match the Action Bar tab style
  textView.setAllCaps(true);
 }

int padding = (int) (TAB_VIEW_PADDING_DIPS * getResources().getDisplayMetrics().density);
 textView.setPadding(padding, padding, padding, padding);

return textView;
}

private void populateTabStrip() {
 final PagerAdapter adapter = mViewPager.getAdapter();
 final OnClickListener tabClickListener = new TabClickListener();

for (int i = 0; i < adapter.getCount(); i++) {
  View tabView = null;
  TextView tabTitleView = null;

if (mTabViewLayoutId != 0) {
   // If there is a custom tab view layout id set, try and inflate it
   tabView = LayoutInflater.from(getContext()).inflate(mTabViewLayoutId, mTabStrip,
     false);
   tabTitleView = (TextView) tabView.findViewById(mTabViewTextViewId);
  }

if (tabView == null) {
   tabView = createDefaultTabView(getContext());
  }

if (tabTitleView == null && TextView.class.isInstance(tabView)) {
   tabTitleView = (TextView) tabView;
  }

tabTitleView.setText(adapter.getPageTitle(i));
  //... 设置头部均分
  LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(0, LayoutParams.WRAP_CONTENT, 1.0f);
  tabView.setLayoutParams(layoutParams);
  tabView.setOnClickListener(tabClickListener);

mTabStrip.addView(tabView);
 }
}

@Override
protected void onAttachedToWindow() {
 super.onAttachedToWindow();

if (mViewPager != null) {
  scrollToTab(mViewPager.getCurrentItem(), 0);
 }
}

private void scrollToTab(int tabIndex, int positionOffset) {
 final int tabStripChildCount = mTabStrip.getChildCount();
 if (tabStripChildCount == 0 || tabIndex < 0 || tabIndex >= tabStripChildCount) {
  return;
 }

View selectedChild = mTabStrip.getChildAt(tabIndex);
 if (selectedChild != null) {

// 调用在每次选项改变时更新文本颜色的新方案
  updateSelectedTitle(tabIndex);

int targetScrollX = selectedChild.getLeft() + positionOffset;

if (tabIndex > 0 || positionOffset > 0) {
   // If we're not at the first child and are mid-scroll, make sure we obey the offset
   targetScrollX -= mTitleOffset;
  }

scrollTo(targetScrollX, 0);
 }
}

private class InternalViewPagerListener implements ViewPager.OnPageChangeListener {
 private int mScrollState;

@Override
 public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
  int tabStripChildCount = mTabStrip.getChildCount();
  if ((tabStripChildCount == 0) || (position < 0) || (position >= tabStripChildCount)) {
   return;
  }

mTabStrip.onViewPagerPageChanged(position, positionOffset);

View selectedTitle = mTabStrip.getChildAt(position);
  int extraOffset = (selectedTitle != null)
    ? (int) (positionOffset * selectedTitle.getWidth())
    : 0;
  scrollToTab(position, extraOffset);

if (mViewPagerPageChangeListener != null) {
   mViewPagerPageChangeListener.onPageScrolled(position, positionOffset,
     positionOffsetPixels);
  }
 }

@Override
 public void onPageScrollStateChanged(int state) {
  mScrollState = state;

if (mViewPagerPageChangeListener != null) {
   mViewPagerPageChangeListener.onPageScrollStateChanged(state);
  }
 }

@Override
 public void onPageSelected(int position) {
  if (mScrollState == ViewPager.SCROLL_STATE_IDLE) {
   mTabStrip.onViewPagerPageChanged(position, 0f);
   scrollToTab(position, 0);
  }

if (mViewPagerPageChangeListener != null) {
   mViewPagerPageChangeListener.onPageSelected(position);
  }
 }

}

private class TabClickListener implements OnClickListener {
 @Override
 public void onClick(View v) {
  for (int i = 0; i < mTabStrip.getChildCount(); i++) {
   if (v == mTabStrip.getChildAt(i)) {
    mViewPager.setCurrentItem(i);
    return;
   }
  }
 }
}

}

SlidingTabStrip.java

/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*  http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.example.my.slidingtablayout;

import android.R;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.View;
import android.widget.LinearLayout;

class SlidingTabStrip extends LinearLayout {

private static final int DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS = 0; //去除阴影
private static final byte DEFAULT_BOTTOM_BORDER_COLOR_ALPHA = 0x26;
private static final int SELECTED_INDICATOR_THICKNESS_DIPS = 4;  //设置滚动条的高度
private static final int DEFAULT_SELECTED_INDICATOR_COLOR = 0xFF33B5E5;

private static final int DEFAULT_DIVIDER_THICKNESS_DIPS = 1;
private static final byte DEFAULT_DIVIDER_COLOR_ALPHA = 0x20;
private static final float DEFAULT_DIVIDER_HEIGHT = 0.5f;

private final int mBottomBorderThickness;
private final Paint mBottomBorderPaint;

private final int mSelectedIndicatorThickness;
private final Paint mSelectedIndicatorPaint;

private final int mDefaultBottomBorderColor;

private final Paint mDividerPaint;
private final float mDividerHeight;

private int mSelectedPosition;
private float mSelectionOffset;

private SlidingTabLayout.TabColorizer mCustomTabColorizer;
private final SimpleTabColorizer mDefaultTabColorizer;

SlidingTabStrip(Context context) {
 this(context, null);
}

SlidingTabStrip(Context context, AttributeSet attrs) {
 super(context, attrs);
 setWillNotDraw(false);

final float density = getResources().getDisplayMetrics().density;

TypedValue outValue = new TypedValue();
 context.getTheme().resolveAttribute(R.attr.colorForeground, outValue, true);
 final int themeForegroundColor = outValue.data;

mDefaultBottomBorderColor = setColorAlpha(themeForegroundColor,
   DEFAULT_BOTTOM_BORDER_COLOR_ALPHA);

mDefaultTabColorizer = new SimpleTabColorizer();
 mDefaultTabColorizer.setIndicatorColors(DEFAULT_SELECTED_INDICATOR_COLOR);
 mDefaultTabColorizer.setDividerColors(setColorAlpha(themeForegroundColor,
   DEFAULT_DIVIDER_COLOR_ALPHA));

mBottomBorderThickness = (int) (DEFAULT_BOTTOM_BORDER_THICKNESS_DIPS * density);
 mBottomBorderPaint = new Paint();
 mBottomBorderPaint.setColor(mDefaultBottomBorderColor);

mSelectedIndicatorThickness = (int) (SELECTED_INDICATOR_THICKNESS_DIPS * density);
 mSelectedIndicatorPaint = new Paint();

mDividerHeight = DEFAULT_DIVIDER_HEIGHT;
 mDividerPaint = new Paint();
 mDividerPaint.setStrokeWidth((int) (DEFAULT_DIVIDER_THICKNESS_DIPS * density));
}

void setCustomTabColorizer(SlidingTabLayout.TabColorizer customTabColorizer) {
 mCustomTabColorizer = customTabColorizer;
 invalidate();
}

void setSelectedIndicatorColors(int... colors) {
 // Make sure that the custom colorizer is removed
 mCustomTabColorizer = null;
 mDefaultTabColorizer.setIndicatorColors(colors);
 invalidate();
}

void setDividerColors(int... colors) {
 // Make sure that the custom colorizer is removed
 mCustomTabColorizer = null;
 mDefaultTabColorizer.setDividerColors(colors);
 invalidate();
}

void onViewPagerPageChanged(int position, float positionOffset) {
 mSelectedPosition = position;
 mSelectionOffset = positionOffset;
 invalidate();
}

@Override
protected void onDraw(Canvas canvas) {
 final int height = getHeight();
 final int childCount = getChildCount();
 final int dividerHeightPx = (int) (Math.min(Math.max(0f, mDividerHeight), 1f) * height);
 final SlidingTabLayout.TabColorizer tabColorizer = mCustomTabColorizer != null
   ? mCustomTabColorizer
   : mDefaultTabColorizer;

// Thick colored underline below the current selection
 if (childCount > 0) {
  View selectedTitle = getChildAt(mSelectedPosition);
  int left = selectedTitle.getLeft();
  int right = selectedTitle.getRight();
  int color = tabColorizer.getIndicatorColor(mSelectedPosition);

if (mSelectionOffset > 0f && mSelectedPosition < (getChildCount() - 1)) {
   int nextColor = tabColorizer.getIndicatorColor(mSelectedPosition + 1);
   if (color != nextColor) {
    color = blendColors(nextColor, color, mSelectionOffset);
   }

// Draw the selection partway between the tabs
   View nextTitle = getChildAt(mSelectedPosition + 1);
   left = (int) (mSelectionOffset * nextTitle.getLeft() +
     (1.0f - mSelectionOffset) * left);
   right = (int) (mSelectionOffset * nextTitle.getRight() +
     (1.0f - mSelectionOffset) * right);
  }

mSelectedIndicatorPaint.setColor(color);

canvas.drawRect(left, height - mSelectedIndicatorThickness, right,
    height, mSelectedIndicatorPaint);
 }

// Thin underline along the entire bottom edge
 canvas.drawRect(0, height - mBottomBorderThickness, getWidth(), height, mBottomBorderPaint);

// Vertical separators between the titles
 int separatorTop = (height - dividerHeightPx) / 2;
 for (int i = 0; i < childCount - 1; i++) {
  View child = getChildAt(i);
  mDividerPaint.setColor(tabColorizer.getDividerColor(i));
  canvas.drawLine(child.getRight(), separatorTop, child.getRight(),
    separatorTop + dividerHeightPx, mDividerPaint);
 }
}

/**
 * Set the alpha value of the {@code color} to be the given {@code alpha} value.
 */
private static int setColorAlpha(int color, byte alpha) {
 return Color.argb(alpha, Color.red(color), Color.green(color), Color.blue(color));
}

/**
 * Blend {@code color1} and {@code color2} using the given ratio.
 *
 * @param ratio of which to blend. 1.0 will return {@code color1}, 0.5 will give an even blend,
 *    0.0 will return {@code color2}.
 */
private static int blendColors(int color1, int color2, float ratio) {
 final float inverseRation = 1f - ratio;
 float r = (Color.red(color1) * ratio) + (Color.red(color2) * inverseRation);
 float g = (Color.green(color1) * ratio) + (Color.green(color2) * inverseRation);
 float b = (Color.blue(color1) * ratio) + (Color.blue(color2) * inverseRation);
 return Color.rgb((int) r, (int) g, (int) b);
}

private static class SimpleTabColorizer implements SlidingTabLayout.TabColorizer {
 private int[] mIndicatorColors; //
 private int[] mDividerColors;  //

@Override
 public final int getIndicatorColor(int position) {
  return mIndicatorColors[position ％ mIndicatorColors.length];
 }

@Override
 public final int getDividerColor(int position) {
  return mDividerColors[position ％ mDividerColors.length];
 }

void setIndicatorColors(int... colors) {
  mIndicatorColors = colors;
 }

void setDividerColors(int... colors) {
  mDividerColors = colors;
 }
}
}

上边因为使用了自定义的颜色，所以这里要在attrs.xml声明一下，不然找不到：

<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="SlidingTabLayout">
 <attr name="android:textColorPrimary" />
 <attr name="textColorTabDefault" format="color" />
 <attr name="textColorTabSelected" format="color" />
</declare-styleable>
</resources>

布局文件也要用到自定义：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.my.slidingtablayout.MainActivity">
<!-- 在上方就在上面，在下方就在下面（tab栏） -->
<com.example.my.slidingtablayout.SlidingTabLayout
 android:id="@+id/sliding"
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 app:textColorTabDefault="#000000"
 app:textColorTabSelected="@color/colorAccent"
 />

<android.support.v4.view.ViewPager
 android:id="@+id/view_pager"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 />
</LinearLayout>

最后一道就是在你的Activity运用这种开源：可以调整之处也做了说明

package com.example.my.slidingtablayout;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
//创建 颜色数组 用来做viewpager的背景
@Override
protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 ViewPager pager = (ViewPager) findViewById(R.id.view_pager);
 SlidingTabLayout tab = (SlidingTabLayout) findViewById(R.id.sliding);
 tab.setDividerColors(Color.TRANSPARENT); //设置标题的分割线
 tab.setSelectedIndicatorColors(Color.rgb(51, 181, 229)); //设置滚动条的颜色
 tab.setTitleSize(18); //...设置字体的颜色，默认16

MyAdapte adapter = new MyAdapte();
 pager.setAdapter(adapter);
 tab.setViewPager(pager);
}

int[] colors = {0xFF123456, 0xFF654321, 0xFF336699};

class MyAdapte extends PagerAdapter {
 //可以考虑把这个数组添加到集合里面
 String[] titles = {"AA", "BB", "CC"};

ArrayList<LinearLayout> layouts = new ArrayList<LinearLayout>();

MyAdapte() {

for (int i = 0; i < 3; i++) {
   LinearLayout l = new LinearLayout(MainActivity.this);
   l.setBackgroundColor(colors[i]);
   l.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
   layouts.add(l);
  }

}

@Override
 public int getCount() {
  return layouts.size();
 }

@Override
 public boolean isViewFromObject(View view, Object o) {
  return view == o;
 }

@Override
 public Object instantiateItem(ViewGroup container, int position) {
  LinearLayout l = layouts.get(position);
  container.addView(l);
  return l;
 }

@Override
 public void destroyItem(ViewGroup container, int position, Object object) {
  container.removeView(layouts.get(position));
 }

@Override
 public CharSequence getPageTitle(int position) {
  //...可以返回集合list.get(position);
  return titles[position];
 }
}
}