美文网首页
Android组件RecyclerView的使用方法

Android组件RecyclerView的使用方法

作者: i宁静的鱼 | 来源:发表于2019-08-10 11:18 被阅读0次
    1. 创建RecyclerView的布局文件activity_recycler.xml
    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent" android:layout_height="match_parent">
    
        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    
    </RelativeLayout>
    
    1. 创建单条item的布局文件activity_recycler_item.xml
    <?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent" android:layout_height="match_parent"
        android:paddingTop="5dp">
    
        <TextView
            android:id="@+id/coursename"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="16sp"
            android:textStyle="bold"
            android:layout_marginStart="110dp"
            android:ellipsize="end"
            android:singleLine="true" />
        <TextView
            android:id="@+id/teachername"
            android:layout_below="@id/coursename"
            android:textSize="16sp"
            android:layout_marginStart="110dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ellipsize="end"
            android:singleLine="true" />
        <TextView
            android:id="@+id/studentnum"
            android:textSize="16sp"
            android:layout_below="@id/teachername"
            android:layout_marginStart="110dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ellipsize="end"
            android:singleLine="true" />
    
        <ImageView
            android:id="@+id/courselogo"
            android:layout_width="100dp"
            android:layout_height="65dp"
            android:layout_marginStart="5dp"
            android:scaleType="centerCrop"
            android:contentDescription="@string/app_name" />
    
        <View
            android:layout_below="@id/courselogo"
            android:layout_width="match_parent"
            android:layout_height="1dp"
            android:layout_marginTop="5dp"
            android:layout_marginBottom="5dp"
            android:background="@color/colorPrimary"/>
    
    </RelativeLayout>
    
    1. 创建RecyclerView的activity类
    package com.iefeel.yudemo;
    
    import android.content.DialogInterface;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Toast;
    
    import androidx.recyclerview.widget.LinearLayoutManager;
    import androidx.recyclerview.widget.RecyclerView;
    
    import com.iefeel.tools.YuRecyclerAdapter;
    import com.mumu.dialog.MMAlertDialog;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    
    public class RecyclerActivity extends BaseActivity {
    
        //定义数组以填充数据
        private String[][] coursedata = {
                {"722", "物联网硬件基础1", "教师三", "1111", "http://xuexi.iefeel.com/userfiles/logo/201903/30/7e723fc7a3aa607502c502b6f9fc2ea7_s.jpg"},
                {"720", "基于LabVIEW的物联网程序设计", "教师二", "2222", "http://xuexi.iefeel.com/userfiles/logo/201903/30/7710e65597136cdd3465e2211edeb90f_s.jpg"},
                {"658", "建筑装饰表现技法", "教师一", "3333", "http://xuexi.iefeel.com/public/images/course.png"}
        };
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_recycler);
    
            //定义一个HashMap构成的列表以键值对的方式存放数据
            ArrayList<HashMap<String, Object>> listItem = new ArrayList<>();
            //循环填充数据
            for(int i=0;i<coursedata.length;i++){
                HashMap<String,Object> map = new HashMap<>();
                map.put("courseid", coursedata[i][0]);
                map.put("coursename", coursedata[i][1]);
                map.put("teachername", "主讲:" + coursedata[i][2]);
                map.put("studentnum", "学员:" + coursedata[i][3]);
                map.put("courselogo", coursedata[i][4]);
                listItem.add(map);
            }
    
            RecyclerView recyclerv = findViewById(R.id.recycler_view);
            LinearLayoutManager layomanager = new LinearLayoutManager(this);
            recyclerv.setLayoutManager(layomanager);
            YuRecyclerAdapter madapter = new YuRecyclerAdapter(RecyclerActivity.this, listItem);
            recyclerv.setAdapter(madapter);
            madapter.setOnItemClickListener(new YuRecyclerAdapter.OnItemClickListener() {
                @Override
                public void onItemClick(View view, int Position) {
                    String s = listItem.get(Position).toString();
                    MMAlertDialog.showDialog(RecyclerActivity.this,
                            "这是第"+ (Position+1) +"个item",
                            s,
                            null,
                            "确定",
                            false,
                            null,
                            new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    Toast.makeText(RecyclerActivity.this, "确定", Toast.LENGTH_SHORT).show();
                                    dialog.dismiss();
                                }
                            });
                }
            });
        }
    
    }
    
    1. 自定义RecyclerView的adapter
    package com.iefeel.tools;
    
    import android.content.Context;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.AdapterView;
    import android.widget.ImageView;
    import android.widget.TextView;
    
    import androidx.annotation.NonNull;
    import androidx.recyclerview.widget.RecyclerView;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    
    import com.iefeel.yudemo.R;
    
    public class YuRecyclerAdapter extends RecyclerView.Adapter<YuRecyclerAdapter.YuViewHolder> {
    
        //当前上下文对象
        Context context;
        //RecyclerView填充Item数据的List对象
        ArrayList<HashMap<String, Object>> datas;
        private YuViewHolder holder;
    
        RemoteImageHelper imghelper = new RemoteImageHelper();
    
        public YuRecyclerAdapter(Context context, ArrayList<HashMap<String, Object>> datas){
            this.context = context;
            this.datas = datas;
        }
    
        //创建ViewHolder
        @NonNull
        @Override
        public YuViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            //实例化得到Item布局文件的View对象
            View v = View.inflate(context, R.layout.activity_recycler_item,null);
            //返回YuViewHolder的对象
            return new YuViewHolder(v);
        }
    
        private OnItemClickListener mItemClickListener;
        //item的回调接口
        public interface OnItemClickListener {
            void onItemClick(View view, int Position);
        }
        //定义一个设置点击监听器的方法
        public void setOnItemClickListener(OnItemClickListener itemClickListener) {
            this.mItemClickListener = itemClickListener;
        }
    
        //绑定数据
        @Override
        public void onBindViewHolder(@NonNull YuViewHolder holder, int position) {
            holder.coursename.setText(datas.get(position).get("coursename").toString());
            holder.teachername.setText(datas.get(position).get("teachername").toString());
            holder.studentnum.setText(datas.get(position).get("studentnum").toString());
            imghelper.loadImage(holder.courselogo, datas.get(position).get("courselogo").toString());
            //如果设置了回调,则设置点击事件
            if (mItemClickListener != null) {
                holder.itemView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        mItemClickListener.onItemClick(holder.itemView, position);
                    }
                });
            }
        }
    
        //返回Item的数量
        @Override
        public int getItemCount() {
            return datas.size();
        }
    
        //继承RecyclerView.ViewHolder抽象类的自定义ViewHolder
        class YuViewHolder extends RecyclerView.ViewHolder{
            TextView coursename;
            TextView teachername;
            TextView studentnum;
            ImageView courselogo;
    
            public YuViewHolder(View itemView) {
                super(itemView);
                coursename = itemView.findViewById(R.id.coursename);
                teachername = itemView.findViewById(R.id.teachername);
                studentnum = itemView.findViewById(R.id.studentnum);
                courselogo = itemView.findViewById(R.id.courselogo);
            }
        }
        
    }
    
    1. 获取网络图片辅助类
    package com.iefeel.tools;
    
    import android.graphics.drawable.Drawable;
    import android.os.Handler;
    import android.os.Message;
    import android.util.Log;
    import android.widget.ImageView;
    
    import java.io.IOException;
    import java.io.InputStream;
    import java.net.MalformedURLException;
    import java.net.URL;
    import java.util.HashMap;
    import java.util.Map;
    
    import com.iefeel.yudemo.R;
    
    public class RemoteImageHelper {
    
        private final Map<String, Drawable> cache = new HashMap<String, Drawable>();
    
        public void loadImage(final ImageView imageView, final String urlString) {
            loadImage(imageView, urlString, true);
        }
    
        public void loadImage(final ImageView imageView, final String urlString, boolean useCache) {
            if (useCache && cache.containsKey(urlString)) {
                imageView.setImageDrawable(cache.get(urlString));
            }
    
            //You may want to show a "Loading" image here
            imageView.setImageResource(R.drawable.ic_launcher);
    
            //Log.d(this.getClass().getSimpleName(), "Image url:" + urlString);
    
            final Handler handler = new Handler() {
                @Override
                public void handleMessage(Message message) {
                    imageView.setImageDrawable((Drawable) message.obj);
                }
            };
    
            Runnable runnable = new Runnable() {
                public void run() {
                    Drawable drawable = null;
                    try {
                        InputStream is = download(urlString);
                        drawable = Drawable.createFromStream(is, "src");
    
                        if (drawable != null) {
                            cache.put(urlString, drawable);
                        }
                    } catch (Exception e) {
                        Log.e(this.getClass().getSimpleName(), "Image download failed", e);
                        //Show "download fail" image
                        drawable = imageView.getResources().getDrawable(R.drawable.ic_launcher);
                    }
    
                    //Notify UI thread to show this image using Handler
                    Message msg = handler.obtainMessage(1, drawable);
                    handler.sendMessage(msg);
                }
            };
            new Thread(runnable).start();
    
        }
    
        /**
         * Download image from given url.
         * Make sure you have "android.permission.INTERNET" permission set in AndroidManifest.xml.
         *
         * @param urlString
         * @return
         * @throws MalformedURLException
         * @throws IOException
         */
        private InputStream download(String urlString) throws MalformedURLException, IOException {
            InputStream inputStream = (InputStream) new URL(urlString).getContent();
            return inputStream;
        }
    }
    
    1. 运行结果


      RecyclerView效果图.jpg
    2. item点击事件
      RecyclerView点击事件.jpg
      更多内容点此查看。

    相关文章

      网友评论

          本文标题:Android组件RecyclerView的使用方法

          本文链接:https://www.haomeiwen.com/subject/osoljctx.html