封装适配器

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;
}
}

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;
}
}

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);
}
}

<?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>

<?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>