android MVVM开发框架——(1)DataBinding 基础应用
附上mvvm中databinding的基本应用链接,只有找到了基本用法才能继续进阶
1,listview布局
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<!--引用自定义的适配器listviewadapter-->
<import type="com.lh.mvvm.adapter.ListViewAdapter" />
<variable
name="adapter"
type="ListViewAdapter" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<!--将适配器绑定到listview-->
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:adapter="@{adapter}" />
</LinearLayout>
</layout>
注意,这里面有个自定义的adapter,这里先把布局写出来,adapter后面再写
2,item布局
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<!--这里沿用双向绑定的userbean-->
<import type="com.lh.mvvm.observable.UserBean" />
<import
alias="mUtils"
type="com.lh.mvvm.utils.MvvmUtils" />
<variable
name="user"
type="UserBean" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:descendantFocusability="blocksDescendants"
android:orientation="horizontal">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`编号:` + user.userId }" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`姓名:` +user.userName}" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`年龄:` +user.userAge}" />
<!--两种判断性别方式-->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`性别:` +mUtils.getUserSex(user.userSex)}" />
<!--一定要使用1f而不能是使用1 ,类型必须相对应-->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`性别:` + (user.userSex == 1f ? `男` : `女`)}" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="0.1"
android:orientation="vertical">
<Button
android:id="@+id/btn_update"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="修改数据" />
<Button
android:id="@+id/btn_delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="删除数据" />
</LinearLayout>
</LinearLayout>
</layout>
3,自定义adapter
public class ListViewAdapter extends BaseAdapter {
//数据
private List<UserBean> list;
public ListViewAdapter(List<UserBean> list) {
this.list = list;
}
@Override
public int getCount() {
return 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) {
//这个databinding也是根据布局文件item_mvvm而命名的
ItemMvvmBinding itemMvvmBinding;
if (convertView == null) {
//创建一个databinding
itemMvvmBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()), R.layout.item_mvvm, parent, false);
//获取convertView
convertView = itemMvvmBinding.getRoot();
} else {
//去除convertView中bangding的dataBinding
itemMvvmBinding = DataBindingUtil.getBinding(convertView);
}
UserBean userBean = list.get(position);
//绑定数据,这里的BR.user根据item布局文件中的变量声明来决定
itemMvvmBinding.setVariable(BR.user, userBean);
itemMvvmBinding.btnUpdate.setOnClickListener(new OnBtnClickListener(1, userBean));
itemMvvmBinding.btnDelete.setOnClickListener(new OnBtnClickListener(2, position));
return convertView;
}
private class OnBtnClickListener implements View.OnClickListener {
private int stats;//1,修改;2,删除
private UserBean userBean;
private int position;
OnBtnClickListener(int stats, UserBean userBean) {
this.stats = stats;
this.userBean = userBean;
}
OnBtnClickListener(int stats, int position) {
this.stats = stats;
this.position = position;
}
@Override
public void onClick(View v) {
switch (stats) {
case 1:
userBean.userName.set("修改后的名字");
break;
case 2:
list.remove(position);
notifyDataSetChanged();
break;
}
}
}
}
可以看出,这里并没有重用view的代码了,这就是mvvm中的一大好处
4,activity运行
public class ListViewActivity extends Activity {
//相对应xml布局文件名
ActivityListViewBinding activityListViewBinding;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activityListViewBinding = DataBindingUtil.setContentView(this, R.layout.activity_list_view);
//初始化一个listview的adapter
ListViewAdapter listViewAdapter = new ListViewAdapter(initData());
//绑定adapter
activityListViewBinding.setAdapter(listViewAdapter);
//通知adapter刷新数据
listViewAdapter.notifyDataSetChanged();
}
//初始化测试数据
private List<UserBean> initData() {
List<UserBean> list = new ArrayList<>();
for (int i = 0; i < 1000; i++) {
UserBean userBean = new UserBean();
userBean.userId.set(i);
userBean.userName.set(i + "aaa");
userBean.userAge.set(18 + i);
userBean.userSex.set(i % 2 == 0 ? 1 : 0);
list.add(userBean);
}
return list;
}
}
listview与databinding的使用基本就是这样,一些更复杂的功能可以在此基础上继续深入研究