Android [文字] 中的静态 data-binding

Question

我创建了自定义布局，其中包含图像和标题。为了重用这个布局，我使用了 <include> 标签。问题是我什至无法 将字符串文字 绑定到所包含的布局中。我尝试遵循这些 instructions，但没有成功。

layout/titlebar.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable name="title" type="String"/>
        <!-- <variable name="imgSrc" type="android.graphics.drawable.Drawable" /> -->
    </data>
    <LinearLayout ... >
        <!-- <ImageView ... android:src="{imgSrc}" /> -->
        <TextView ... android:text="@{title, default=DefaultTitle}" />
    </LinearLayout>
</layout>

layout/otherlayout.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:bind="http://schemas.android.com/apk/res-auto"
              ... 
              >
    <!-- bind:imgSrc="@{@drawable/some_image}" -->
    <include layout="@layout/titlebar"
             bind:title="@{Example}"  <---------- does not work 
             />
    ...
</LinearLayout>

在 gradle 中，我为模块启用了 data-binding：

android {
    ...
    dataBinding {
        enabled = true
    }
    ...
}

Answer 1

来自文档：

Variables may be passed into an included layout's binding from the containing layout by using the application namespace and the variable name in an attribute

这意味着，您的 titlebar 和 otherlayout XML 文件中必须包含以下数据变量：

<data>
    <variable name="title" type="java.lang.String"/>
</data>

并且 <include> 应该看起来像这样：

<include layout="@layout/titlebar"
       bind:title="@{title}"/>

有关详细信息，请参阅数据绑定文档：

https://developer.android.com/topic/libraries/data-binding/index.html#includes

Answer 2

已修复 layout/otherlayout.xml 基于@CzarMatt 的回答

<?xml version="1.0" encoding="utf-8"?>
<!-- 
layout with bindings has to be wrapped in <layout> tag so {LayoutName}Bindings 
class can be auto-generated for binding purposes 

xmlns:alias="http://schemas.android.com/apk/res-auto" 
creates an "app namespace" for custom attributes
-->
<layout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:bind="http://schemas.android.com/apk/res-auto">
    <LinearLayout  ... >
        <!-- 
        // if this layout is also using title "data variable" 
        // and we want to use default value if title is null
        bind:title='@{title ?? "Settings"} 

        // passing literal reference into the binding
        bind:title="@{@string/settings_constant}"
        -->
        <include layout="@layout/titlebar"
                 bind:title='@{"Settings"}'
                 />
        ...
    </LinearLayout>
</layout>

数据绑定需要按照@RaviRupareliya 的建议通过DataBindingUtil 设置布局，否则数据绑定将不起作用：

public class OtherActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); 
        // setContentView(R.layout.otherlayout);
        DataBindingUtil.setContentView(this, R.layout.otherlayout);
    }
    ...
}

Android [文字] 中的静态 data-binding

Static data-binding in Android [literals]

android

android-databinding