在上一篇中，我们说过，在setData中如果有很多控件的话，我们还是要在该方法中写入很多代码，为了降低开发的方便性，本次就在此基础上再一次优化。实现原理是这样的，每次在setData中都要查找控件，然后setXXX()什么的，我们可以把这写实现放如到ViewHolder中去，在ViewHolder中写入一个链式的方法，来帮助我们来实现功能(关于ViewHodler类的代码我就不再重复写了，代码在此：Android之自定义实现BaseAdapter(通用适配器一) )，链式方法如下：

public ViewHolder setText(int viewId, String data){

TextView tv = getView(viewId);

tv.setText(data);

return this;

}

通过这个方法，我们可以很好的去设置对应的内容，只需要传一个需要设置控件的id，然后传对应的数据，就可以达到设置文字的效果了，下面再看看我们的MyAdapter.java中的代码

MyAdapter.java

/**

* 上一篇中的MyAdapter

*/

public class MyAdapter extends MyBaseAdapter {

public MyAdapter(List data) {

super(data);

}

@Override

public void setData(ViewHolder holder, Student t) {

TextView tvName = holder.getView(R.id.mTv1);

tvName.setText(t.getName());

TextView tvSex = holder.getView(R.id.mTv2);

tvSex.setText(t.getSex());

}

}

/**

* 优化后的MyAdapter

*/

public class MyAdapter extends MyBaseAdapter {

public MyAdapter(List data) {

super(data);

}

@Override

public void setData(ViewHolder holder, Student t) {

holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());

}

}

ok，对比一下setData中的实现，我们这里只用一条代码就可以代替上面的实现了，这样是不是更方便呢，这样的话，我们的扩展就更加方便了，如果说，我们不仅仅只是设置文本内容，而是通过图片控件设置图片呢？很简单，我们只需要在ViewHolder中再添加我们要实现的方法即可，比如设置图片，我们可以添加如下代码：

public ViewHolder setImageResource(int viewId,int resId){

ImageView img = getView(viewId);

img.setImageResource(resId);

return this;

}

public ViewHolder setImageBitmap(int viewId, Bitmap bm){

ImageView img = getView(viewId);

img.setImageBitmap(bm);

return this;

}

添加这两个方法后，需要设置图片就很轻松了，只需在setData中传递对应的参数即可

@Override

public void setData(ViewHolder holder, Student t) {

holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());

holder.setImageResource(R.id.img1,资源id).setImageBitmap(R.id.img2,bm);

}

好了，一个通用的适配器就已经完成了，整体框架和代码都已经实现了，我将所有的代码都综合一下，写在下面，方便大家使用，分别是MainActivity.java(主界面类，负责传参设置ListView的数据)、MyAdapter.java(自定义的适配器)、MyBaseAdapter.java(通用的适配器类)、ViewHolder.java(通用的持有类对象)、以及实体类Student.java

MainActivity.java

public class MainActivity extends AppCompatActivity{

private List data;

private ListView mList;

MyAdapter adapter;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

getData();

mList = (ListView) findViewById(R.id.mList);

adapter = new MyAdapter(data);

mList.setAdapter(adapter);

}

private void getData() {

data = new ArrayList<>();

Student stu = null;

for (int i = 0; i < 20; i++) {

stu = new Student();

stu.setName("姓名" + i);

stu.setSex(i % 2 == 0 ? "男" : "女");

data.add(stu);

}

}

}

MyAdapter.java

public class MyAdapter extends MyBaseAdapter {

public MyAdapter(List data) {

super(data);

}

@Override

public void setData(ViewHolder holder, Student t) {

holder.setText(R.id.mTv1, t.getName()).setText(R.id.mTv2, t.getSex());

}

}

MyBaseAdapter.java

public abstract class MyBaseAdapter extends BaseAdapter {

protected List data;

public MyBaseAdapter(List data){

this.data = data;

}

@Override

public int getCount() {

return data == null ? 0 : data.size();

}

@Override

public Object getItem(int position) {

return data.get(position);

}

@Override

public long getItemId(int position) {

return position;

}

@Override

public View getView(int position, View convertView, ViewGroup parent) {

ViewHolder holder = ViewHolder.getHolder(convertView,parent,position, R.layout.list_item);

setData(holder,data.get(position));

return holder.getConvertView();

}

public abstract void setData(ViewHolder holder,T t);

}

ViewHolder.java

public class ViewHolder {

private int position;

private SparseArray array;

private View convertView;

private Context context;

private ViewHolder(ViewGroup parent, int position, int layout) {

this.position = position;

this.context = parent.getContext();

convertView = LayoutInflater.from(parent.getContext()).inflate(layout, null);

convertView.setTag(this);

array = new SparseArray<>();

}

public static ViewHolder getHolder(View convertView, ViewGroup parent, int position, int layout) {

if (convertView == null) {

return new ViewHolder(parent, position, layout);

} else {

ViewHolder holder = (ViewHolder) convertView.getTag();

holder.position = position;

return holder;

}

}

public T getView(int viewId) {

View view = array.get(viewId);

if (view == null) {

view = convertView.findViewById(viewId);

array.put(viewId, view);

}

return (T) view;

}

public View getConvertView() {

return convertView;

}

public ViewHolder setText(int viewId, String data) {

TextView tv = getView(viewId);

tv.setText(data);

return this;

}

public ViewHolder setImageResource(int viewId, int resId) {

ImageView img = getView(viewId);

img.setImageResource(resId);

return this;

}

public ViewHolder setImageBitmap(int viewId, Bitmap bm) {

ImageView img = getView(viewId);

img.setImageBitmap(bm);

return this;

}

}

Student.java

public class Student {

private String name;

private String sex;

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getSex() {

return sex;

}

public void setSex(String sex) {

this.sex = sex;

}

}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。