使用ViewPager+Fragment实现选项卡切换效果

实现效果

本实例主要实现用ViewPage和Fragment实现选项卡切换效果，选项卡个数为3个，点击选项卡或滑动屏幕会切换Fragment并实现选项卡下方下边框条跟随移动效果。

本程序用android4.2.2真机调试，为方便部署，我使用adbWireless做为部署工具，电脑和手机接入同一局域网，在PC端输入名称adb connect 手机端ip 默认连接5555端口。之后再Eclipse的Devices中即可看到介入设备。前提是android系统需要Root。如下图：

2015-06-21_090912.png

设计实现

• 创建项目（此过程不做赘述）
• 在activity_main.xml中设置布局。xml内容如下：

上面布局页实现的效果如下：

2015-06-21_112628.png

• 接下来，增加3个Fragment布局页 ，分别在里面填充简单的内容
  第一个：

第二个：

第三个:

以上3个Fragment的布局文件已创建完毕，每个文件中只显示简单的文本内容，用做演示。

• 加载3个Fragment到Activity中。

首先实现3个Fragment对应的后台类

热点布局页对应的类：

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class FragmentHot extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragmenthot, container, false);
        return view;
    }
}

news布局页对应的类：

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class FragmentNews extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragmentnews, container, false);
        return view;
    }
}

收藏布局页对应的类：

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class FragmentFavorite extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragmentfav, container, false);
        return view;
    }
}

• 之后再activity中初始化这3个Fragment

注意要点：
Activity继承自FragmentActivity
要实现一个FragmentPagerAdapter，内容如下：

import java.util.ArrayList;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
public class MyFragmentAdapter extends FragmentPagerAdapter {
    ArrayList list;
    public MyFragmentAdapter(FragmentManager fm,ArrayList list){
        super(fm);
        this.list = list;
    }
    @Override
    public Fragment getItem(int arg0) {
        // TODO Auto-generated method stub
        return list.get(arg0);
    }
    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return list.size();
    }
}

然后在Activity中实现切换和动画效果，代码如下：

import java.util.ArrayList;
import android.app.Activity;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.support.v4.app.FragmentActivity;
import android.view.MenuItem;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends FragmentActivity {
    private ViewPager mViewPager;
    private ArrayList fragments;
    private TextView view1, view2, view3;  
    private int currIndex;
    private ImageView image;
    private static int bmpW;//横线图片宽度  
    private static int offset;//图片移动的偏移量  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initViewPager();
        InitTextView();
        InitImage();
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
    private void InitTextView(){
        view1 = (TextView) findViewById(R.id.tv_hot);
        view2 = (TextView) findViewById(R.id.tv_news);
        view3 = (TextView) findViewById(R.id.tv_fav);
        view1.setOnClickListener(new txtListener(0));
        view2.setOnClickListener(new txtListener(1));
        view3.setOnClickListener(new txtListener(2));
    }
    //内部类 重写TextView点击事件
    public class txtListener implements View.OnClickListener{
        private int index = 0;
        public txtListener(int i){
            index = i;
        }
        @Override
        public void onClick(View v){
            mViewPager.setCurrentItem(index);
        }
    }
    /* 
     * 初始化图片的位移像素 
     */  
    public void InitImage(){  
        image = (ImageView)findViewById(R.id.cursor);  
        bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.bgborder).getWidth();  
        DisplayMetrics dm = new DisplayMetrics();  
        getWindowManager().getDefaultDisplay().getMetrics(dm);  
        int screenW = dm.widthPixels;  
        offset = (screenW/3 - bmpW)/2;  
        Log.i("screenW",String.valueOf(screenW));
        Log.i("bmpW",String.valueOf(bmpW));
        Log.i("offset",String.valueOf(offset));
        //imgageview设置平移，使下划线平移到初始位置（平移一个offset）  
        Matrix matrix = new Matrix();  
        matrix.postTranslate(offset, 0);  
        image.setImageMatrix(matrix);  
    }  
    private void initViewPager(){
        mViewPager = (ViewPager)findViewById(R.id.myViewPager);
        fragments = new ArrayList();
        Fragment fragmentHot = new FragmentHot();
        Fragment fragmentNews = new FragmentNews();
        Fragment fragmentFav = new FragmentFavorite();
        fragments.add(fragmentHot);
        fragments.add(fragmentNews);
        fragments.add(fragmentFav);
        mViewPager.setAdapter(new MyFragmentAdapter(getSupportFragmentManager(), fragments));
        mViewPager.setCurrentItem(0);
        mViewPager.setOnPageChangeListener(new myOnPageChangeListener());
    }
    public class myOnPageChangeListener implements OnPageChangeListener {
        private int one = offset*2 +bmpW;//两个相邻页面的偏移量   
        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }
        @Override
        public void onPageScrollStateChanged(int arg0) {
            // TODO Auto-generated method stub
        }
        @Override  
        public void onPageSelected(int arg0) {  
            // TODO Auto-generated method stub  
            Log.i("aaaaaaaaaaaaa",String.valueOf(arg0));
            Log.i("one",String.valueOf(one));
            Animation animation = new TranslateAnimation(currIndex*one,arg0*one,0,0);//平移动画  
            currIndex = arg0; 
            animation.setFillAfter(true);//动画终止时停留在最后一帧，不然会回到没有执行前的状态  
            animation.setDuration(200);//动画持续时间0.2秒  
            image.startAnimation(animation);//是用ImageView来显示动画的  
            //int i = currIndex + 1;  
           // Toast.makeText(MainActivity.this, "您选择了第"+i+"个页卡", Toast.LENGTH_SHORT).show();  
        }  
    }  
}