java - 数据绑定(bind)不是将数据与android中的xml绑定(bind)

Question

想要实现数据绑定(bind)。我实现了代码，数据来自 API，但它没有与 xml 绑定(bind)，也没有显示任何错误。所以我很困惑问题出在哪里。请帮助我。

我的代码

content_policy_info.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <data>
        <variable
            name="policyinfo"
            type="com.exlservice.lifeprov1.service.model.GetPolicyInfoResponse" />

        <variable
            name="surrenderquote"
            type="com.exlservice.lifeprov1.service.model.SurrenderQuoteResponse" />
    </data>
<android.support.constraint.ConstraintLayout
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:id="@+id/c1"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".view.ui.PolicyInfo"
    tools:showIn="@layout/app_bar_policy_info">
    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:background="#223d50"
        android:layout_height="match_parent">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">
            <LinearLayout android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical"
                android:background="@drawable/policy_prime_info_bg"
                android:layout_marginTop="20dp"
                android:layout_marginLeft="10dp"
                android:layout_marginRight="10dp"
                >
                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginTop="8dp"
                    android:orientation="horizontal">

                    <TextView
                        android:layout_width="0dp"
                        android:layout_marginLeft="5dp"
                        android:layout_height="wrap_content"
                        android:text="@{policyInfo.ProductId}"
                        android:textColor="#76c6db"
                        android:layout_weight="1"
                        android:typeface="serif"
                        android:textStyle="bold"
                        android:id="@+id/id_fc_first_key"/>
                    <TextView
                        android:layout_width="0dp"
                        android:textColor="#76c6db"
                        android:textStyle="bold"
                        android:typeface="serif"
                        android:layout_height="wrap_content"
                        android:text="@{policyInfo.Contract}"
                        android:layout_weight="1"
                        android:id="@+id/id_fc_second_key"/>

                </LinearLayout>
           </LinearLayout>
    </android.support.v4.widget.NestedScrollView>
</android.support.constraint.ConstraintLayout>
</layout>

Policyinfo.java

public class PolicyInfo extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {
APIInterface apiInterface;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    binding= DataBindingUtil.setContentView(this,R.layout.activity_policy_info);
    Intent intent = getIntent();
    String sCompanyCode = intent.getStringExtra("CompanyCode");
    String sPolicyNumber = intent.getStringExtra("PolicyNumber");
    String sWayPoint = intent.getStringExtra("WayPoint");
    Log.e("onCreate: ",sCompanyCode+"   "+sPolicyNumber );
    SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
    String currentTime = sdf.format(new Date());
    SurrenderQuoteInput surrenderQuoteInput = new SurrenderQuoteInput();
    surrenderQuoteInput.setCoderID("TRN7");
    surrenderQuoteInput.setCompanyCode("01");   
    PolicyDetailsReq policyDetailsReq= new PolicyDetailsReq();
    policyDetailsReq.setCoderID("TRN7");

    getPolicyInfoRequest.setPolicyDetailsReq(policyDetailsReq);

    PolicyInfoViewModel.Factory factory = new PolicyInfoViewModel.Factory(
            **getApplication(),getPolicyInfoRequest,surrenderQuoteRequest);
    PolicyInfoViewModel viewModel =
            ViewModelProviders.of(this,factory).get(PolicyInfoViewModel.class);
    **observeViewModel**(viewModel);**

    // show it
    pd.show();
    DrawerLayout drawer =  findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView =  findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

}
private void **observeViewModel**(final PolicyInfoViewModel viewModel) {
    // Update the list when the data changes
    viewModel.getPolicyInfoResponsetObservable().observe(this, new Observer<GetPolicyInfoResponse>() 
{
        @Override
        public void onChanged(@Nullable GetPolicyInfoResponse getPolicyInfoResponse) {
            if(getPolicyInfoResponse!=null) {
                viewModel.setPolicyInfoResult(getPolicyInfoResponse);
                binding.setPolicyinfo(getPolicyInfoResponse);
            }

        }

    });
}

此代码用于抽屉导航 Activity ，其中我的所有组件都位于 content_policy_info.xml 中。请帮帮我。

Answer 1

数据绑定(bind)是一个非常有用的工具，如果做得正确，可以节省大量工作时间。我真的推荐阅读this guide在尝试自己实现某些事情之前。这里我只是强调数据绑定(bind)设置中的主要步骤

1. 确保在您的应用中启用数据绑定(bind):在您的应用 gradle 中添加

   dataBinding {
enabled = true
}

2. 创建特定于您的 xml 文件的绑定(bind):

   ContentPolicyInfoBinding binding = DataBindingUtil.setContentView(this,R.layout.content_policy_info);

(也许您犯了一个错误，而是夸大了activity_policy_info？

如果这些参数随时间变化，请将绑定(bind)参数设置为 ObservablFields 一次

ObservablField<GetPolicyInfoResponse> policyInfoField = new ObservablField();
...
binding.policyinfo = policyInfoField;

更改 xml 以匹配:

<import type="com.exlservice.lifeprov1.service.model.GetPolicyInfoResponse"/>
<variable name="policyinfo" type="android.databinding.ObservableField&lt;GetPolicyInfoResponse&gt;"/>

当新的policyInfo到达时更新policyInfoField

policyInfoField.set(getPolicyInfoResponse)

<小时/>

但更好的是使用 View 模型，将其字段设置为可绑定(bind)。这样就可以通过更改模型的字段来更新 View 。