封装适配器

先看效果：

具体实现：

1.CommonAdapter：import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import java.util.List;public abstract class CommonAdapter<T> extends BaseAdapter {    private Context context;    private List<T> list;    private LayoutInflater inflater;    private int itemLayoutId;    public CommonAdapter(Context context, List<T> list, int itemLayoutId) {        this.context = context;        this.list = list;        this.itemLayoutId = itemLayoutId;        inflater = LayoutInflater.from(context);    }    @Override    public int getCount() {        return list == null ? 0 : list.size();    }    @Override    public Object getItem(int position) {        return list.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {        CommonViewHolder holder = getViewHolder(position, convertView, parent);        convert(holder, (T) getItem(position));        return holder.getConvertView();    }    public abstract void convert(CommonViewHolder holder, T item);    private CommonViewHolder getViewHolder(int position, View convertView, ViewGroup parent) {        return CommonViewHolder.get(context, convertView, parent, itemLayoutId, position);    }}2.commonViewHolder: 
import android.content.Context;import android.graphics.Bitmap;import android.util.SparseArray;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ImageView;import android.widget.TextView;import com.bumptech.glide.Glide;public class CommonViewHolder {    //现在对于int作为键的官方推荐用SparseArray替代HashMap    private final SparseArray<View> views;    private View convertView;    private Context context;    private CommonViewHolder(Context context, ViewGroup parent, int layoutId, int position) {        this.context = context;        this.views = new SparseArray<>();        this.convertView = LayoutInflater.from(parent.getContext()).inflate(layoutId, parent, false);        convertView.setTag(this);    }    /**     * 拿到一个ViewHolder对象     */    public static CommonViewHolder get(Context context, View convertView, ViewGroup parent, int layoutId, int position) {        if (convertView == null) {            return new CommonViewHolder(parent.getContext(), parent, layoutId, position);        }        return (CommonViewHolder) convertView.getTag();    }    /**     * 通过控件的Id获取对于的控件，如果没有则加入views     */    public <T extends View> T getView(int viewId) {        View view = views.get(viewId);        if (view == null) {            view = convertView.findViewById(viewId);            views.put(viewId, view);        }        return (T) view;    }    public View getConvertView() {        return convertView;    }    //设置字符串    public CommonViewHolder setText(int viewId, String text) {        TextView tv = getView(viewId);        tv.setText(text);        return this;    }    //设置图片    public CommonViewHolder setImageByUrl(int viewId, String url) {        Glide.with(context).load(url).into((ImageView) getView(viewId));        return this;    }    public CommonViewHolder setImageResource(int viewId, int drawableId) {        ImageView iv = getView(viewId);        iv.setImageResource(drawableId);        return this;    }    public CommonViewHolder setImageBitmap(int viewId, Bitmap bitmap) {        ImageView iv = getView(viewId);        iv.setImageBitmap(bitmap);        return this;    }}

3.MyData:

public class MyData {    private String name;    public MyData(String name) {        this.name = name;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

4.MainActivity:

import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.widget.ListView;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity {    private ListView mListView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();        initData();    }    private void initData() {        final List<MyData> list = new ArrayList<>();        for (int i = 0; i < 50; i++) {            list.add(new MyData("刘婕" + i + ""));        }        mListView.setAdapter(new CommonAdapter<MyData>(this, list, R.layout.item) {            @Override            public void convert(CommonViewHolder holder, MyData item) {                holder.setText(R.id.text, item.getName());                holder.setImageResource(R.id.image,R.mipmap.ic_launcher);            }        });    }    private void initView() {        mListView = (ListView) findViewById(R.id.listView);    }}

5.activity_main:

<?xml version="1.0" encoding="utf-8"?><android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    tools:context="com.example.administrator.commonadapter.MainActivity">   <ListView       android:id="@+id/listView"       android:layout_width="match_parent"       android:layout_height="wrap_content"></ListView></android.support.constraint.ConstraintLayout>

6.item:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="horizontal">    <TextView        android:id="@+id/text"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:textSize="20sp" />    <ImageView        android:id="@+id/image"        android:layout_width="30dp"        android:layout_height="20dp" /></LinearLayout>

这就封装好了。