仿美团首页功能选择的实现

一、效果

二、在MainActivity中

package com.shangyu.meituanviewpager;

import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.GridView;
import android.widget.LinearLayout;

import java.util.ArrayList;

import butterknife.ButterKnife;
import butterknife.InjectView;
    /**
 * Created by 黄家三少 on 2016/10/15.
 */
    public class MainActivity extends AppCompatActivity {

    @InjectView(R.id.viewpager)
    ViewPager viewpager;
    @InjectView(R.id.ll_dot)
    LinearLayout llDot;
    private String[] titles = {"美食", "电影", "酒店住宿", "休闲娱乐", "外卖", "自助餐", "KTV", "机票/火车票", "周边游", "美甲美睫",
            "火锅", "生日蛋糕", "甜品饮品", "水上乐园", "汽车服务", "美发", "丽人", "景点", "足疗按摩", "运动健身", "健身", "超市", "买菜",
            "今日新单", "小吃快餐", "面膜", "洗浴/汗蒸", "母婴亲子", "生活服务", "婚纱摄影", "学习培训", "家装", "结婚", "全部分配"};
    private ArrayList mDatas;
    /**
     * 总的页数
     */
    private int pageCount;
    /**
     * 每一页显示的个数
     */
    private int pageSize = 10;
    /**
     * 当前显示的是第几页
     */
    private int curIndex = 0;
    private LayoutInflater inflater;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.inject(this);
        initData();
        inflater = LayoutInflater.from(this);
        //总的页数=总数/每页数量，并取整
        pageCount = (int) Math.ceil(mDatas.size() * 1.0 / pageSize);
        ArrayList mPagerList = new ArrayList<>();
        for (int i = 0; i < pageCount; i++) {
            //每个页面都是inflate出一个新实例
            GridView gridView = (GridView) inflater.inflate(R.layout.gridview, viewpager, false);
            gridView.setAdapter(new GridViewAdapter(this, mDatas, i, pageSize));
            mPagerList.add(gridView);

            gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView parent, View view, int position, long id) {
                    int pos = position + curIndex * pageSize;
                    UIUtils.showToast(mDatas.get(pos).getName());
                }
            });
        }
        //设置适配器
        viewpager.setAdapter(new ViewPagerAdapter(mPagerList));
        //设置圆点
        setOvalLayout();
    }

    /**
     * 初始化
     */
    private void initData() {
        mDatas = new ArrayList<>();
        for (int i = 0; i < titles.length; i++) {
            //动态获取资源ID，第一个参数是资源名，第二个参数是资源类型例如drawable，string等，第三个参数包名
            int imageId = getResources().getIdentifier("ic_category_" + i, "mipmap", getPackageName());
            mDatas.add(new Bean(titles[i], imageId));
        }
    }

    /**
     * 设置圆点
     */
    public void setOvalLayout() {
        for (int i = 0; i < pageCount; i++) {
            llDot.addView(inflater.inflate(R.layout.dot, null));
        }
        // 默认显示第一页
        llDot.getChildAt(0).findViewById(R.id.v_dot)
                .setBackgroundResource(R.drawable.dot_selected);
        viewpager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            public void onPageSelected(int position) {
                // 取消圆点选中
                llDot.getChildAt(curIndex)
                        .findViewById(R.id.v_dot)
                        .setBackgroundResource(R.drawable.dot_normal);
                // 圆点选中
                llDot.getChildAt(position)
                        .findViewById(R.id.v_dot)
                        .setBackgroundResource(R.drawable.dot_selected);
                curIndex = position;
            }

            public void onPageScrolled(int arg0, float arg1, int arg2) {
            }

            public void onPageScrollStateChanged(int arg0) {
            }
        });
    }
}

二、Bean

package com.shangyu.meituanviewpager;

/**
 * Created by 黄家三少 on 2016/10/15.
 */
public class Bean {
    public String name;
    public int iconRes;

    public Bean(String name, int iconRes) {
        this.name = name;
        this.iconRes = iconRes;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getIconRes() {
        return iconRes;
    }

    public void setIconRes(int iconRes) {
        this.iconRes = iconRes;
    }
}

三、在GridViewAdapter中

package com.shangyu.meituanviewpager;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

/**
 * Created by 黄家三少 on 2016/10/15.
 */
public class GridViewAdapter extends BaseAdapter {
    private List mDatas;
    private LayoutInflater inflater;
    /**
     * 页数下标,从0开始(当前是第几页)
     */
    private int curIndex;
    /**
     * 每一页显示的个数
     */
    private int pageSize;

    public GridViewAdapter(Context context, List mDatas, int curIndex, int pageSize) {
        inflater = LayoutInflater.from(context);
        this.mDatas = mDatas;
        this.curIndex = curIndex;
        this.pageSize = pageSize;
    }

    /**
     * 先判断数据集的大小是否足够显示满本页？mDatas.size() > (curIndex+1)*pageSize,
     * 如果够，则直接返回每一页显示的最大条目个数pageSize,
     * 如果不够，则有几项返回几,(mDatas.size() - curIndex * pageSize);(也就是最后一页的时候就显示剩余item)
     */
    @Override
    public int getCount() {
        return mDatas.size() > (curIndex + 1) * pageSize ? pageSize : (mDatas.size() - curIndex * pageSize);

    }

    @Override
    public Object getItem(int position) {
        return mDatas.get(position + curIndex * pageSize);
    }

    @Override
    public long getItemId(int position) {
        return position + curIndex * pageSize;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.item_gridview, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.tv = (TextView) convertView.findViewById(R.id.textView);
            viewHolder.iv = (ImageView) convertView.findViewById(R.id.imageView);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        /**
         * 在给View绑定显示的数据时，计算正确的position = position + curIndex * pageSize，
         */
        int pos = position + curIndex * pageSize;
        viewHolder.tv.setText(mDatas.get(pos).name);
        viewHolder.iv.setImageResource(mDatas.get(pos).iconRes);
        return convertView;
    }


    class ViewHolder {
        public TextView tv;
        public ImageView iv;
    }
}

四、在ViewPagerAdapter中

package com.shangyu.meituanviewpager;

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

import java.util.List;

/**
 * Created by 黄家三少 on 2016/10/15.
 */
public class ViewPagerAdapter extends PagerAdapter {
    private List mViewList;

    public ViewPagerAdapter(List mViewList) {
        this.mViewList = mViewList;
    }

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

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        container.addView(mViewList.get(position));
        return (mViewList.get(position));
    }

    @Override
    public int getCount() {
        if (mViewList == null)
            return 0;
        return mViewList.size();
    }

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

感谢Adan0520提供的思路。