问题描述

三生大侠 猪猪侠 代码在这里

import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.View;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

public class StartMerchantActivity extends Activity {
private RecyclerView mRvDemoMain;
private Context context;
private MyRecyclerAdapter mAdapter;
protected List mList;
public static String[] URLS;
private static final String urlPath = ""http://www.imooc.com/api/teacher?type=4&num=30"";
//private static final String urlPath = ""http://14.117.17.161/json.php"";

@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.merchant);    // 1. 初始化RecyclerView中要显示的数据    initData();    // 2. 初始化本页面的控件    initView();    mRvDemoMain = (RecyclerView) findViewById(R.id.merchant_recyclerview);    new NewAsyncTask().execute(urlPath);}/** * 初始化RecyclerView中要显示的数据 */private void initData() {    mList = new ArrayList<NewsBeam>();    URLS = new String[mList.size()];    for (int i = 0; i < mList.size(); i++) {        URLS[i] = mList.get(i).newsIconUrl;    }}/** * 初始化本页面的控件 */private void initView() {    mRvDemoMain = (RecyclerView) findViewById(R.id.merchant_recyclerview);    // 设置RecyclerView的Adapter    mAdapter = new MyRecyclerAdapter(StartMerchantActivity.thismListmRvDemoMain);    mRvDemoMain.setAdapter(mAdapter);    // zz 测试    System.out.println(""==== mRvDemoMain.setAdapter(mAdapter)执行完了"");    mRvDemoMain.setLayoutManager(new StaggeredGridLayoutManager(3 StaggeredGridLayoutManager.VERTICAL));    mRvDemoMain.setItemAnimator(new DefaultItemAnimator());    // 调用Adapter中的设置监听器的方法    mAdapter.setOnItemClickListener(new MyRecyclerAdapter.OnItemClickListener() {        @Override        public void onItemClick(View view int position) {            Toast.makeText(StartMerchantActivity.thisclick : "" + position Toast.LENGTH_SHORT).show();        }    });}/** * 实现网络的异步访问 */class NewAsyncTask extends AsyncTask<String Void List<NewsBeam>>{    @Override    protected void onPostExecute(List<NewsBeam> newsBeams)    {        super.onPostExecute(newsBeams);        MyRecyclerAdapter adapter = new MyRecyclerAdapter(StartMerchantActivity.this newsBeams mRvDemoMain);        mRvDemoMain.setAdapter(adapter);    }    @Override    protected List<NewsBeam> doInBackground(String... params)    {        return getJsonData(params[0]);    }    /**     * 从 URL 中获取数据     *     * @param url     * @return     */    private List<NewsBeam> getJsonData(String url)    {        List<NewsBeam> newsBeamsList = new ArrayList<NewsBeam>();        try        {            String jsonString = readStream(new URL(urlPath).openStream());            JSONObject jsonObject;            NewsBeam newsBeam;            jsonObject = new JSONObject(jsonString);            JSONArray jsonArray = jsonObject.getJSONArray(""data"");            for(int i = 0; i < jsonArray.length(); i++)            {                jsonObject = jsonArray.getJSONObject(i);                newsBeam = new NewsBeam();                newsBeam.newsIconUrl = jsonObject.getString(""picSmall"");                newsBeam.newsTitle = jsonObject.getString(""name"");                newsBeamsList.add(newsBeam);            }        }        catch(IOException e)        {            e.printStackTrace();        }        catch(JSONException e)        {            e.printStackTrace();        }        return newsBeamsList;    }    /**     * 从 inpustStream 获取的信息     *     * @param is     * @return     */    private String readStream(InputStream is)    {        InputStreamReader isr;        String result = """";        try        {            isr = new InputStreamReader(isutf-8"");            BufferedReader br = new BufferedReader(isr);            String line = """";            while((line = br.readLine()) != null)            {                result += line;            }        }        catch(UnsupportedEncodingException e)        {            e.printStackTrace();        }        catch(IOException e)        {            e.printStackTrace();        }        return result;    }}

}

解决方案

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

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

public class MyRecyclerAdapter extends RecyclerView.Adapter {
private LayoutInflater mInflater;
protected List mList;
private List mHeights; // 随机高度的集合
private ImgLoaderRecyclerView mImgLoaderRecyclerView;
private int mStart;
private int mEnd;
public static String[] URLS;
private boolean mFirstIn;

/** * 自定义一个OnItemClickListener的回调接口 */public interface OnItemClickListener{    void onItemClick(View view int position);}/** * 创建接口的成员变量 */private OnItemClickListener mOnItemClickListener;/** * 设置监听器的方法 * @param listener listener */public void setOnItemClickListener(OnItemClickListener listener){    this.mOnItemClickListener = listener;}/** * 构造方法 * @param context context */public MyRecyclerAdapter(Context context List<NewsBeam> dataRecyclerView recyclerView) {    this.mList = data;    mImgLoaderRecyclerView = new ImgLoaderRecyclerView(recyclerView);    mInflater = LayoutInflater.from(context);    mHeights = new ArrayList<Integer>();    for (int i = 0; i < mList.size(); i++) {        mHeights.add((int) (150 + Math.random() * 150));    }    mFirstIn = true;}/** * RecyclerView中条目的数量 * * @return count */@Overridepublic int getItemCount() {    return mList.size();}/** * 创建ViewHolder * * @param parent   parent * @param viewType viewType * @return holder */@Overridepublic MyRecyclerHolder onCreateViewHolder(ViewGroup parent int viewType) {    // zz 测试    System.out.println(""====onCreateViewHolder : "" + viewType + "" == "" + parent);    View view = mInflater.inflate(R.layout.recycler_item parent false);    MyRecyclerHolder mHolder = new MyRecyclerHolder(view);    return mHolder;}/** * 绑定ViewHolder * * @param holder   holder * @param position position */@Overridepublic void onBindViewHolder(final MyRecyclerHolder holder final int position) {    System.out.println(""position""+position);    // 为ViewHolder的父控件(也即一条Item)设置高度    ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();    lp.height = mHeights.get(position);    holder.itemView.setLayoutParams(lp);    holder.mIvItem.setImageResource(R.mipmap.ic_launcher);    String url = mList.get(position).newsIconUrl;    holder.mIvItem.setTag(url);    mImgLoaderRecyclerView.showImgByAysncTask(holder.mIvItem url);    holder.mTvItem.setText(mList.get(position).newsTitle);    // 调用条目的点击事件设置方法    setUpItemEvent(holder);    // zz 测试    System.out.println(""====onBindViewHolder : "" + position + "" == "" + holder);}/** * 设置条目的点击事件(点按) * @param holder holder */protected void setUpItemEvent(final MyRecyclerHolder holder) {    if (mOnItemClickListener != null) {        holder.itemView.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                int layoutPosition = holder.getLayoutPosition();                mOnItemClickListener.onItemClick(holder.itemView layoutPosition);            }        });    }}/** * RecyclerView的ViewHolder类 */public class MyRecyclerHolder extends RecyclerView.ViewHolder {    ImageView mIvItem;    TextView mTvItem;    public MyRecyclerHolder(View itemView) {        super(itemView);        mIvItem = (ImageView) itemView.findViewById(R.id.id_image);        mTvItem = (TextView) itemView.findViewById(R.id.id_name);    }}

}

解决方案二：
public class NewsBeam {
public String newsIconUrl;
public String newsTitle;
}

解决方案三：
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Handler;
import android.os.Message;
import android.support.v7.widget.RecyclerView;
import android.util.LruCache;
import android.widget.ImageView;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashSet;
import java.util.Set;

public class ImgLoaderRecyclerView
{
private ImageView mImageView;
private String mUrl;

private LruCache<String Bitmap> mCache;private RecyclerView mRecyclerView;private Set<NewsAynsTaskImgView> mtask;public ImgLoaderRecyclerView(RecyclerView recyclerView){    int maxMemory = (int) Runtime.getRuntime().maxMemory();     //获取最大可用内存    int cacheSize = maxMemory / 4;    mRecyclerView = recyclerView;    mtask = new HashSet<NewsAynsTaskImgView>();    mCache = new LruCache<String Bitmap>(cacheSize)    {        @Override        protected int sizeOf(String key Bitmap value)        {            // 在每次存入缓存时调用            return value.getByteCount();        }    };}/** * 增加到缓存 * * @param url   图片的网站也是图片的唯一标志 * @param bitmap */public void addBitmapToCache(String url Bitmap bitmap){    if(getBitmapFromCache(url) == null)    {        mCache.put(url bitmap);    }}/** * 从缓存中获取数据 * * @param url * @return */public Bitmap getBitmapFromCache(String url){    return mCache.get(url);}private Handler mHandler = new Handler(){    @Override    public void handleMessage(Message msg)    {        super.handleMessage(msg);        if(mImageView.getTag().equals(mUrl))        {            mImageView.setImageBitmap((Bitmap) msg.obj);        }    }};/** * 线程方法加载图片 * * @param imageView * @param url */public void showImgByThread(ImageView imageView final String url){    mImageView = imageView;    this.mUrl = url;    new Thread()    {        public void run()        {            super.run();            Bitmap bitmap = getBitmapFromURL(url);            Message message = Message.obtain();            message.obj = bitmap;            mHandler.sendMessage(message);        }    }.start();}/** * 从网络中获取图片 * * @param urlString 图片网址 * @return 获取到的图片 */public Bitmap getBitmapFromURL(String urlString){    Bitmap bitmap = null;    InputStream is = null;    try    {        URL url = new URL(urlString);        HttpURLConnection conn = (HttpURLConnection) url.openConnection();        is = new BufferedInputStream(conn.getInputStream());        bitmap = BitmapFactory.decodeStream(is);        conn.disconnect();    }    catch(MalformedURLException e)    {        e.printStackTrace();    }    catch(IOException e)    {        e.printStackTrace();    }    finally    {        try        {            is.close();        }        catch(Exception e)        {            e.printStackTrace();        }    }    return bitmap;}/** * 展示图片 AysncTask() 这种方法 */public void showImgByAysncTask(ImageView imageView String url){    Bitmap bitmap = getBitmapFromCache(url);    // 从缓存中取出对应的图片    //如果没有就从网线上下载图片    if(bitmap == null)    {        imageView.setImageResource(R.mipmap.ic_launcher);    }    else        //有了直接使用缓存的图片即可    {        imageView.setImageBitmap(bitmap);    }}/** * 停止加载图片 滑动时 */public void cancelAllTasks(){    if(mtask != null)    {        for(NewsAynsTaskImgView task : mtask)        {            task.cancel(false);        }    }}private class NewsAynsTaskImgView extends AsyncTask<String Void Bitmap>{    //private ImageView mImageView;    private String mUrl;    public NewsAynsTaskImgView(String url)    {        //      mImageView = imageView;        mUrl = url;    }    @Override    protected Bitmap doInBackground(String... params)    {        String url = params[0];        Bitmap bitmap = getBitmapFromURL(url);        /**         *  从网络获取图片         */        if(bitmap != null)        {            //把图片加入缓存            addBitmapToCache(url bitmap);        }        return bitmap;    }    @Override    protected void onPostExecute(Bitmap bitmap)    {        super.onPostExecute(bitmap);        ImageView imageView = (ImageView) mRecyclerView.findViewWithTag(mUrl);        if(imageView.getTag().equals(mUrl) && bitmap != null)        {            imageView.setImageBitmap(bitmap);        }    }}/** * 加载指定的图片 * * @param start 开始图片标志 * @param end   结束图片标志 */public void loadImages(int start int end){    for(int i = start; i < end; i++)    {        String url = MyRecyclerAdapter.URLS[i];        Bitmap bitmap = getBitmapFromCache(url);        if(bitmap == null)        {            NewsAynsTaskImgView task = new NewsAynsTaskImgView(url);            task.execute(url);            mtask.add(task);        }        else        //有了直接使用缓存的图片即可        {            ImageView imageView = (ImageView) mRecyclerView.findViewWithTag(url);            imageView.setImageBitmap(bitmap);        }    }}

}