android MVVM開發框架——(2)DataBinding 應用於ListView
阿新 • • 發佈:2019-01-05
1,listview佈局
<?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>
<!--引用自定義的介面卡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">
<!--將介面卡繫結到listview-->
<ListView
android:layout_width="match_parent"
android:layout_height="match_parent"
app:adapter="@{adapter}" />
</LinearLayout>
</layout>
注意,這裡面有個自定義的adapter,這裡先把佈局寫出來,adapter後面再寫
2,item佈局
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<!--這裡沿用雙向繫結的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="@{`編號:` + 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="@{`年齡:` +user.userAge}" />
<!--兩種判斷性別方式-->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`性別:` +mUtils.getUserSex(user.userSex)}" />
<!--一定要使用1f而不能是使用1 ,型別必須相對應-->
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@{`性別:` + (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="修改資料" />
<Button
android:id="@+id/btn_delete"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="刪除資料" />
</LinearLayout>
</LinearLayout>
</layout>
3,自定義adapter
public class ListViewAdapter extends BaseAdapter {
//資料
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) {
//這個databinding也是根據佈局檔案item_mvvm而命名的
ItemMvvmBinding itemMvvmBinding;
if (convertView == null) {
//建立一個databinding
itemMvvmBinding = DataBindingUtil.inflate(LayoutInflater.from(parent.getContext()), R.layout.item_mvvm, parent, false);
//獲取convertView
convertView = itemMvvmBinding.getRoot();
} else {
//去除convertView中bangding的dataBinding
itemMvvmBinding = DataBindingUtil.getBinding(convertView);
}
UserBean userBean = list.get(position);
//繫結資料,這裡的BR.user根據item佈局檔案中的變數宣告來決定
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,刪除
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("修改後的名字");
break;
case 2:
list.remove(position);
notifyDataSetChanged();
break;
}
}
}
}
可以看出,這裡並沒有重用view的程式碼了,這就是mvvm中的一大好處
4,activity執行
public class ListViewActivity extends Activity {
//相對應xml佈局檔名
ActivityListViewBinding activityListViewBinding;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
activityListViewBinding = DataBindingUtil.setContentView(this, R.layout.activity_list_view);
//初始化一個listview的adapter
ListViewAdapter listViewAdapter = new ListViewAdapter(initData());
//繫結adapter
activityListViewBinding.setAdapter(listViewAdapter);
//通知adapter重新整理資料
listViewAdapter.notifyDataSetChanged();
}
//初始化測試資料
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與databinding的使用基本就是這樣,一些更復雜的功能可以在此基礎上繼續深入研究