Android仿微信5实现滑动导航条

package com.rong;

import java.util.ArrayList;
import java.util.List;

import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;

public class ViewPagerAdapter extends PagerAdapter {

 private List<View> views;

 public ViewPagerAdapter(List<View> views) {
 this.views = views;
 }

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

 @Override
 public boolean isViewFromObject(View arg0, Object arg1) {
 return arg0 == arg1;
 }

 @Override
 public void destroyItem(View container, int position, Object object) {
 ((ViewPager) container).removeView(views.get(position));
 }

 @Override
 public Object instantiateItem(View container, int position) {
 ((ViewPager) container).addView(views.get(position));
 return views.get(position);
 }

 /**
 * 插入一个View到viewpager中
 * 
 * @param view
 * @return
 */
 public boolean insert(View view) {
 if (this.views == null) {
  this.views = new ArrayList<View>();
 }

 return this.views.add(view);
 }
}

package com.rong;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Display;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;

import com.rong.wechat5.R;

public class HomeActivity extends Activity {
 private View home_line;
 private int screenWidth1_3;
 private ViewPager home_vp;
 private ViewPagerAdapter viewPagerAdapter;
 private List<View> views = new ArrayList<View>();

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.layout_home);
 initView();
 }

 private void initView() {
 Display display = getWindow().getWindowManager().getDefaultDisplay();
 DisplayMetrics dm = new DisplayMetrics();
 display.getMetrics(dm);

 home_line = (View) findViewById(R.id.home_line);
 home_vp = (ViewPager) findViewById(R.id.home_vp);

 LayoutParams lp = home_line.getLayoutParams();
 screenWidth1_3 = dm.widthPixels / 3;
 lp.width = screenWidth1_3;
 lp.height = 5;
 home_line.setLayoutParams(lp);

 View layout1 = View.inflate(this, R.layout.layout_view1, null);
 View layout2 = View.inflate(this, R.layout.layout_view2, null);
 View layout3 = View.inflate(this, R.layout.layout_view3, null);
 views.add(layout1);
 views.add(layout2);
 views.add(layout3);
 viewPagerAdapter = new ViewPagerAdapter(views);
 home_vp.setAdapter(viewPagerAdapter);

 home_vp.setOnPageChangeListener(new OnPageChangeListener() {

  @Override
  public void onPageSelected(int arg0) {

  }

  @Override
  public void onPageScrolled(int position, float positionOffset,int positionOffsetPixels) {
  Log.i("TAG", position+"=="+positionOffset+"=="+positionOffsetPixels);
  LinearLayout.LayoutParams lp = (android.widget.LinearLayout.LayoutParams) home_line.getLayoutParams();
  lp.leftMargin = (int) (screenWidth1_3 * position + screenWidth1_3* positionOffset);
  home_line.setLayoutParams(lp);
  }

  @Override
  public void onPageScrollStateChanged(int arg0) {

  }
 });
 }

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="#ffffff"
  android:orientation="vertical" >

  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="60dp"
    android:orientation="horizontal" >

    <RelativeLayout
      android:layout_width="0dp"
      android:layout_height="match_parent"
      android:layout_weight="1" >

      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="消息"
        android:textColor="#000000"
        android:textSize="24sp" />
    </RelativeLayout>

    <RelativeLayout
      android:layout_width="0dp"
      android:layout_height="match_parent"
      android:layout_weight="1" >

      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="朋友圈"
        android:textColor="#000000"
        android:textSize="24sp" />
    </RelativeLayout>

    <RelativeLayout
      android:layout_width="0dp"
      android:layout_height="match_parent"
      android:layout_weight="1" >

      <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="我"
        android:textColor="#000000"
        android:textSize="24sp" />
    </RelativeLayout>
  </LinearLayout>

  <View
    android:id="@+id/home_line"
    android:layout_width="0dp"
    android:layout_height="0dp"
    android:background="#ff0000" />

  <android.support.v4.view.ViewPager
    android:id="@+id/home_vp"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />

</LinearLayout>