我已经使用数据绑定一段时间了，即使现在JDK 8和API 24还不支持它。但我仍然找到了一种更容易使用数据绑定的方式。但是当我使用以下方式来进行精确的双向数据绑定（在我的想法中，双向数据绑定就像这里所说的（什么是双向绑定？）时，出现了奇怪的情况。
1. 在xml中实现双向数据绑定
android:text="@={testStr}"
private static class User {
public final ObservableField<String> firstName =
new ObservableField<>();
public final ObservableField<String> lastName =
new ObservableField<>();
public final ObservableInt age = new ObservableInt();
}
3. 将模型类扩展到 BaseObservable
private static class User extends BaseObservable {
private String firstName;
private String lastName;
@Bindable
public String getFirstName() {
return this.firstName;
}
@Bindable
public String getLastName() {
return this.lastName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
notifyPropertyChanged(BR.firstName);
}
public void setLastName(String lastName) {
this.lastName = lastName;
notifyPropertyChanged(BR.lastName);
}
}
模型类必须扩展到BaseObservable类，并且getter方法必须用"@Bindable"进行注释，setter方法需要在绑定xml中与相应的命名调用“notifyPropertyChanged()”方法。
我的问题是，我想了解三种绑定方法的优缺点。当然，我知道第一种方法更容易。但有时我在文档和一些网站上发现它，然后下一刻它就消失了。官方文档已经改变，没有任何明确的公告。我仍然不确定是否应该使用第一种方法，所以我必须准备好改变为方法2或3。
Student_XML2WAY.java
public class Student_XML2WAY {
private int age;
private String name;
public int getAge() {
return age;
}
public void setAge(int pAge) {
age = pAge;
}
public String getName() {
return name;
}
public void setName(String pName) {
name = pName;
}
}
学生观察者字段.java
public class Student_ObserField {
private ObservableInt age;
private ObservableField<String> name;
public Student_ObserField() {
age = new ObservableInt();
name = new ObservableField<>();
}
public ObservableInt getAge() {
return age;
}
public ObservableField<String> getName() {
return name;
}
}
学生扩展.java
public class Student_Extend extends BaseObservable{
private int age;
private String name;
@Bindable
public int getAge() {
return age;
}
public void setAge(int pAge) {
age = pAge;
notifyPropertyChanged(BR.student3);
}
@Bindable
public String getName() {
return name;
}
public void setName(String pName) {
name = pName;
notifyPropertyChanged(BR.student3);
}
}
主活动界面.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="student1"
type="example.com.testerapplication.sp.bean.Student_XML2WAY"/>
<variable
name="student2"
type="example.com.testerapplication.sp.bean.Student_ObserField"/>
<variable
name="student3"
type="example.com.testerapplication.sp.bean.Student_Extend"/>
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@={student1.name}"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{student2.name}"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{student3.name}"/>
<Button
android:id="@+id/btn1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="update"/>
</LinearLayout>
</layout>
public class MainActivity extends AppCompatActivity {
private Student_XML2WAY mStudent1;
private Student_ObserField mStudent2;
private Student_Extend mStudent3;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivityMainBinding binding = DataBindingUtil.inflate(LayoutInflater.from(this), R.layout.activity_main, null, false);
mStudent1 = new Student_XML2WAY();
mStudent1.setName("XML First");
mStudent2 = new Student_ObserField();
mStudent2.getName().set("ObserField Second");
mStudent3 = new Student_Extend();
mStudent3.setName("Extend Third");
binding.setStudent1(mStudent1);
binding.setStudent2(mStudent2);
binding.setStudent3(mStudent3);
setContentView(binding.getRoot());
binding.btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mStudent1.setName("Student1");
mStudent2.getName().set("Student2");
mStudent3.setName("Student3");
}
});
}
}