DataBinding的基本使用(五)

ゝ一纸荒年。 2022-09-25 05:29 198阅读 0赞

## DataBinding的基本使用(五) ##

DataBinding基本使用包括以下内容：  
\- 单纯的摆脱findviewbyid  
\- 绑定基本数据类型及String  
\- 绑定Model数据  
\- 绑定事件  
\- 通过静态方法转换数据类型  
\- 通过运算符操作数据  
\- 自定义Binding的类名  
\- 绑定相同Model的操作  
\- model变量改变自动更新数据  
\- 绑定List/Map等集合数据  
\- Observable自动更新  
\- Databinding与include标签的结合  
\- DataBinding与RecyclerView的结合

##### 3.12 Databinding与include标签的结合 #####

布局文件

activity\_five.xml

<?xml version="1.0" encoding="utf-8"?>
    <layout>
    
        <data >
            <import type="www.zhang.com.databinding.model.Content"/>
            <variable name="con" type="Content"/>
        </data>
        
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:bind="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical">
            <include android:id="@+id/toolbar" layout="@layout/toolbar" android:layout_height="56dp" android:layout_width="match_parent" bind:content="@{con}" />
     
                <TextView android:text="@string/app_name" android:layout_width="match_parent" android:layout_height="wrap_content" />
        </LinearLayout>
    </layout>

toolbar.xml

<?xml version="1.0" encoding="utf-8"?>
    <layout >
        <data>
            <import type="www.zhang.com.databinding.model.Content"/>
          <variable name="content" type="Content"/>
        </data>
    
    <android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/toolbar" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_height="56dp" android:layout_width="match_parent" app:title="@{content.title}" app:subtitle="@{content.subTitle}" android:background="@color/colorPrimary" app:titleTextColor="@android:color/white" app:subtitleTextColor="@android:color/white" />
    </layout>

*在activity\_five.xml中的include属性中定义了一个id,同时又在toolbar.xml中的Toolbar标签中又定义了一个id,其作用是通过binding.toolbar.toolbar等同于Toolbar控件，可以方便做一些操作等*

FiveActivity中

public class FiveActivity extends AppCompatActivity { 
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
    
            ActivityFiveBinding binding =DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
    
            Content con = new Content("Title","SubTitle");
            binding.setCon(con);
    
    // binding.toolbar.setContent(con); //这个测试没有效果，不会显示toolbar的title/subTitle
    // binding.toolbar.toolbar.setTitle(""); 
    // binding.toolbar.toolbar.setSubtitle("");
    
            //下面的代码也可以通过DataBinding绑定数据
            binding.toolbar.toolbar.setNavigationIcon(R.mipmap.ic_launcher);
            setSupportActionBar(binding.toolbar.toolbar);
            binding.toolbar.toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    finish();
                }
            });
        }
    }

Content

public class Content extends BaseObservable { 
        private String title;
        private String subTitle;
    
        public Content(String title, String subTitle) {
            this.title = title;
            this.subTitle = subTitle;
        }
    
        @Bindable public String getSubTitle() {
            return subTitle;
        }
    
        public void setSubTitle(String subTitle) {
            this.subTitle = subTitle;
            notifyPropertyChanged(BR.subTitle);
        }
    
        @Bindable public String getTitle() {
            return title;
        }
    
        public void setTitle(String title) {
            this.title = title;
            notifyPropertyChanged(BR.title);
        }
    }

##### 3.13 DataBinding与RecyclerView的结合 #####

布局文件

activity\_five.xml

<?xml version="1.0" encoding="utf-8"?>
    <layout>
    
        <data >
            <import type="www.zhang.com.databinding.model.Content"/>
            <variable name="con" type="Content"/>
        </data>
        
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:bind="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical">
            <include android:id="@+id/toolbar" layout="@layout/toolbar" android:layout_height="56dp" android:layout_width="match_parent" bind:content="@{con}" />
            
                <android.support.v7.widget.RecyclerView android:id="@+id/recycler" android:layout_width="match_parent" android:layout_height="wrap_content" />
        </LinearLayout>
    </layout>

recycler\_item.xml

<?xml version="1.0" encoding="utf-8"?>
    <layout>
        <data>
            <variable name="str" type="String"/>
        </data>
        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:orientation="vertical">
    
            <TextView android:text="@{str}" android:gravity="center_vertical" android:textColor="@android:color/black" android:textSize="16sp" android:layout_width="match_parent" android:layout_height="48dp" />
        </LinearLayout>
    </layout>

--------------------

FiveActivity

public class FiveActivity extends AppCompatActivity { 
    
        private ActivityFiveBinding binding;
    
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            supportRequestWindowFeature(Window.FEATURE_NO_TITLE);
    
            binding = DataBindingUtil.setContentView(FiveActivity.this, R.layout.activity_five);
    
            initToolbar();
            initRecyclerView();
        }
    
        private void initRecyclerView() {
            LinearLayoutManager manager = new LinearLayoutManager(FiveActivity.this);
            binding.recycler.setLayoutManager(manager);
            binding.recycler.setHasFixedSize(true);
            MyAdapter adapter = new MyAdapter(getApplicationContext());
            binding.recycler.setAdapter(adapter);
        }
    
        private void initToolbar() {
            Content con = new Content("Title","SubTitle");
            binding.setCon(con);
    
    // binding.toolbar.setContent(con); //这个测试没有效果，不会显示toolbar的title/subTitle
    // binding.toolbar.toolbar.setTitle("");
    // binding.toolbar.toolbar.setSubtitle("");
    
            //下面的代码也可以通过DataBinding绑定数据
            binding.toolbar.toolbar.setNavigationIcon(R.mipmap.ic_launcher);
            setSupportActionBar(binding.toolbar.toolbar);
            binding.toolbar.toolbar.setNavigationOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    finish();
                }
            });
        }
    }

MyAdapter

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> { 
    
        private Context mContext;
        String[] datas;
    
        public MyAdapter(Context context) {
            mContext = context;
            datas = context.getResources().getStringArray(R.array.item_list);
        }
    
        @Override
        public MyAdapter.MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            RecyclerItemBinding binding = DataBindingUtil.inflate(LayoutInflater.from(mContext), R.layout.recycler_item, parent, false);
            return new MyViewHolder(binding);
        }
    
        @Override
        public void onBindViewHolder(MyAdapter.MyViewHolder holder, int position) {
            String name = datas[position];
            holder.getBinding().setVariable(www.zhang.com.databinding.BR.str,name);
            //holder.getBinding().setStr(name); //两者都可以
    
            //executePendingBindings()方法说明
            // When a variable or observable changes, the binding will be scheduled to change before the next frame. 
            // There are times, however, when binding must be executed immediately. 
            // To force execution, use the executePendingBindings() method.
            holder.getBinding().executePendingBindings();//此方法必须执行在UI线程，当绑定的数据修改时更新视图（不知道翻译的准不准）
        }
    
        @Override
        public int getItemCount() {
            return datas.length;
        }
    
        public class MyViewHolder extends RecyclerView.ViewHolder { 
            private RecyclerItemBinding binding;
    
            public MyViewHolder(ViewDataBinding binding) {
                super(binding.getRoot());
                this.binding = (RecyclerItemBinding) binding;
            }
    
            public RecyclerItemBinding getBinding() {
                return binding;
            }
    
            public void setBinding(RecyclerItemBinding binding) {
                this.binding = binding;
            }
        }
    }

--------------------

参考文章

[Google官方文档][Google]

[Android数据绑定框架DataBinding][Android_DataBinding]

[ Android-MVVM架构-Data Binding的使用][Android-MVVM_-Data Binding]

[Google]: https://developer.android.com/topic/libraries/data-binding/index.html#attribute_setters
[Android_DataBinding]: http://www.jianshu.com/p/2d3227d9707d
[Android-MVVM_-Data Binding]: http://blog.csdn.net/johnny901114/article/details/50706329