1.双向数据绑定(以xml为单位)

android:text="@={testStr}"

这在官方文档中没有提到(https://developer.android.com/topic/libraries/data-binding/index.html,这个页面通常会更新,现在可能会更改).但它可以将变量绑定到xml.

2. ObservableField属性

这里的例子(https://developer.android.com/topic/libraries/data-binding/index.html#observablefields)

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.将模型类扩展为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方法必须使用“@Bindable”进行注释,并且setter方法需要使用绑定xml中的相应命名调用方法notifyPropertyChange().

我的问题是,我想知道三种绑定方法的缺点和优点.当然,我知道第一个会更容易.但是我在文档和某些网站上找到了一些时刻.它在下一刻消失了.官方文档未经任何明确公告而更改.我仍然想知道我应该使用第一种方法,所以我必须准备改变方法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;
    }
}

Student_ObserField.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;
    }
}

Student_Extend.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);
    }
}

activity_main.xml中

<?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>

活动类

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");
            }
        });
    }
}