RecyclerView

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原创最新推荐文章于 2023-03-07 17:50:25 发布 · 320 阅读

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本文介绍了一个基于RecyclerView的适配器实现方法，并演示了如何通过异步任务加载网络数据，更新RecyclerView显示。文中详细解释了适配器的创建过程、点击监听器的设置方法及自定义装饰器的使用。

//适配器


import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import com.nostra13.universalimageloader.core.ImageLoader;

import java.util.List;

class Adapter extends RecyclerView.Adapter<Adapter.MyViewHolder> {
    private Context context;
    private List<Bean.NewslistBean> list;
    private OnItemClickLitener mOnItemClickLitener;

    public Adapter(Context context, List<Bean.NewslistBean> list) {
        this.context = context;
        this.list = list;
    }

    //1.创建接口
    public interface OnItemClickLitener {

        void onItemClick(View view, int position);//点击事件
        void onItemLongClick(View view , int position);
    }
    public void setOnItemClickLitener(OnItemClickLitener mOnItemClickLitener){

        this.mOnItemClickLitener=mOnItemClickLitener;

    }
    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = View.inflate(context, R.layout.one_item, null);
        MyViewHolder holder = new MyViewHolder(view);
        return holder;
    }

    @Override
    public void onBindViewHolder(final MyViewHolder holder, final int position) {

        if (list != null && list.size() > 0) {
            holder.tv1.setText(list.get(position).getTitle());
            holder.tv2.setText(list.get(position).getDescription());
            holder.tv3.setText(list.get(position).getCtime());
            ImageLoader.getInstance().displayImage(list.get(position).getPicUrl(), holder.iv1);
        }

        if (mOnItemClickLitener != null) {

            //点击事件
            holder.itemView.setOnClickListener(new View.OnClickListener() {

                public void onClick(View v) {
                    //设置点击事件 具体的调用执行，由当前的adapter实例进行操作
                    mOnItemClickLitener.onItemClick(holder.itemView, position);
                }
            });
            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View view) {
                    mOnItemClickLitener.onItemLongClick(holder.itemView, position);
                    return false;
                }
            });
        }
    }

    @Override
    public int getItemCount() {

        return list.size();
    }

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView tv1;
        TextView tv2;
        TextView tv3;
        ImageView iv1;

        public MyViewHolder(View itemView) {
            super(itemView);
            tv1 = itemView.findViewById(R.id.tv1);
            tv2= itemView.findViewById(R.id.tv2);
            tv3 = itemView.findViewById(R.id.tv3);
            iv1 = itemView.findViewById(R.id.iv1);
        }
    }


}

//Main类


import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Toast;


import com.google.gson.Gson;

import java.util.List;

public class MainActivity extends AppCompatActivity {
    RecyclerView rv;
    private List<Bean.NewslistBean> list;
    private static final String JSON_URL="http://api.tianapi.com/wxnew/?key=71e58b5b2f930eaf1f937407acde08fe&num=30";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //找控件 创建数据源
        rv = (RecyclerView) findViewById(R.id.recle);
        rv.addItemDecoration(new MyDecoration(this,MyDecoration.VERTICAL_LIST));
        initRV();
    }

    public void initRV() {
        initData();
        //布局管理器
        LinearLayoutManager manager = new LinearLayoutManager(this);
        rv.setLayoutManager(manager);

    }

    public void initData() {
        new AsyncTask<String, String, String>() {

            @Override
            protected String doInBackground(String... strings) {
                String str=new GetJson().getJson(JSON_URL);

                return str;
            }

            @Override
            protected void onPostExecute(String s) {
                Gson gson=new Gson();
                Bean bean = gson.fromJson(s, Bean.class);
                list = bean.getNewslist();
                Adapter adapter = new Adapter(MainActivity.this,list);
                rv.setAdapter(adapter);
                adapter.setOnItemClickLitener(new Adapter.OnItemClickLitener() {
                    @Override
                    public void onItemClick(View view, int position) {
                        Toast.makeText(MainActivity.this, position + "点击事件",
                                Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void onItemLongClick(View view, int position) {
                        Toast.makeText(MainActivity.this, position + "长按事件",
                                Toast.LENGTH_SHORT).show();
                    }
                });


            }
        }.execute();
    }

}

//MyDecoration添加下划线


import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;

/**
 * Created by fan on 2017/12/1.
 */

public class MyDecoration extends RecyclerView.ItemDecoration {

    private Context mContext;
    private Drawable mDivider;
    private int mOrientation;
    public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
    public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

    //我们通过获取系统属性中的listDivider来添加，在系统中的AppTheme中设置
    public static final int[] ATRRS = new int[]{
            android.R.attr.listDivider
    };

    public MyDecoration(Context context, int orientation) {
        this.mContext = context;
        final TypedArray ta = context.obtainStyledAttributes(ATRRS);
        this.mDivider = ta.getDrawable(0);
        ta.recycle();
        setOrientation(orientation);
    }

    //设置屏幕的方向
    public void setOrientation(int orientation) {
        if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
            throw new IllegalArgumentException("invalid orientation");
        }
        mOrientation = orientation;
    }

    @Override
    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == HORIZONTAL_LIST) {
            drawVerticalLine(c, parent, state);
        } else {
            drawHorizontalLine(c, parent, state);
        }


    }

    //画横线, 这里的parent其实是显示在屏幕显示的这部分
    public void drawHorizontalLine(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int left = parent.getPaddingLeft();
        int right = parent.getWidth() - parent.getPaddingRight();
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);

            //获得child的布局信息
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int top = child.getBottom() + params.bottomMargin;
            final int bottom = top + mDivider.getIntrinsicHeight();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
            //Log.d("wnw", left + " " + top + " "+right+"   "+bottom+" "+i);
        }
    }

    //画竖线
    public void drawVerticalLine(Canvas c, RecyclerView parent, RecyclerView.State state) {
        int top = parent.getPaddingTop();
        int bottom = parent.getHeight() - parent.getPaddingBottom();
        final int childCount = parent.getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = parent.getChildAt(i);

            //获得child的布局信息
            final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
            final int left = child.getRight() + params.rightMargin;
            final int right = left + mDivider.getIntrinsicWidth();
            mDivider.setBounds(left, top, right, bottom);
            mDivider.draw(c);
        }
    }

    //由于Divider也有长宽高，每一个Item需要向下或者向右偏移
    @Override
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (mOrientation == HORIZONTAL_LIST) {
            //画横线，就是往下偏移一个分割线的高度
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            //画竖线，就是往右偏移一个分割线的宽度
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    }


}
//联网工具类

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * Created by Administrator on 2017/10/11.
 */

public class GetJson {

    private String str="";

    public String getJson(String JSON_URL){
        try {
            URL url=new URL(JSON_URL);
            HttpURLConnection connection= (HttpURLConnection) url.openConnection();
            connection.setConnectTimeout(5000);
            connection.setReadTimeout(5000);
            int rescode=connection.getResponseCode();
            if(rescode==200){
                InputStream inputStream=connection.getInputStream();
                byte[] b=new byte[1024];
                int index=0;

                while((index=inputStream.read(b))!=-1){
                    str+=new String(b,0,index);
                }
            }

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


        return str;
    }

}
//Mapp

import android.app.Application;

import com.nostra13.universalimageloader.cache.disc.naming.HashCodeFileNameGenerator;
import com.nostra13.universalimageloader.cache.disc.naming.Md5FileNameGenerator;
import com.nostra13.universalimageloader.core.DisplayImageOptions;
import com.nostra13.universalimageloader.core.ImageLoader;
import com.nostra13.universalimageloader.core.ImageLoaderConfiguration;
import com.nostra13.universalimageloader.core.assist.QueueProcessingType;

import java.io.File;

public class MApp extends Application {
    @Override
    public void onCreate() {
        super.onCreate();

        File file = this.getCacheDir();

        DisplayImageOptions options = new DisplayImageOptions.Builder()
                .cacheInMemory(true)
                .cacheOnDisk(true)
                .build();

        ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(
                this)
                // max width, max height，即保存的每个缓存文件的最大长宽
                .memoryCacheExtraOptions(480, 800)
                // 线程池内加载的数量
                .threadPoolSize(3)
                // 线程优先级
                .threadPriority(Thread.NORM_PRIORITY - 2)
                .defaultDisplayImageOptions(options)
                // You can pass your own memory cache implementation你可以通过自己的内存缓存实现
                // .memoryCache(new UsingFreqLimitedMemoryCache(2 * 1024 * 1024))
                // .memoryCacheSize(2 * 1024 * 1024)
                //硬盘缓存50MB
                .diskCacheSize(50 * 1024 * 1024)
                //将保存的时候的URI名称用MD5
                .diskCacheFileNameGenerator(new Md5FileNameGenerator())
                // 加密
                .diskCacheFileNameGenerator(new HashCodeFileNameGenerator())//将保存的时候的URI名称用HASHCODE加密
                .tasksProcessingOrder(QueueProcessingType.LIFO)
                .diskCacheFileCount(100) //缓存的File数
                // .defaultDisplayImageOptions(DisplayImageOptions.createSimple())
                // .imageDownloader(new BaseImageDownloader(context, 5 * 1000,
                // 30 * 1000)) // connectTimeout (5 s), readTimeout (30 s)超时时间
                .writeDebugLogs() // Remove for release app
                .build();

        ImageLoader.getInstance().init(config);
    }
}