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>