Android mvvm使用實戰

本編文章簡單使用databinding，給剛入門的同學學習mvvm借鑑
進入正題

//在gradle android下加入
dataBinding {
        enabled = true
}

.xml中包含常見控件還有recycleview

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <variable
            name="userInfo"<!--activity中binding有對應setUserInfo()-->
            type="com.renli.mvvmdemo.been.UserInfo" />
        <variable
            name="click"
            type="com.renli.mvvmdemo.activity.MvvmMainActivity" />

        <!--在佈局中通過三元運算符等操作運算符來控制視圖的顯示或者隱藏，
        需要在data節點標籤中做引用View-->
        <import type="android.view.View"/>
        <variable
            name="isShow"
            type="boolean" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/tv_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{userInfo.name}"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"/>

        <TextView
            android:id="@+id/tv_age"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@{String.valueOf(userInfo.age)}"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/tv_name" />

        <Button
            android:id="@+id/bt_update"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="20dp"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/tv_age"
            android:onClick="@{click.btClick}"
            android:text="更新"/>

        <ImageView
            android:id="@+id/iv_img"
            android:layout_width="60dp"
            android:layout_height="60dp"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/bt_update"
            app:imagesUrl="@{userInfo.iconUrl}"
            app:placeUrl="@{@drawable/bm_list}"
            android:visibility="@{isShow?View.VISIBLE:View.GONE}"
            />

        <CheckBox
            android:id="@+id/cb_check"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="顯示/隱藏"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/iv_img"
            android:onCheckedChanged="@{click.onCheckedChanged}"/>

        <EditText
            android:id="@+id/et_input"
            android:layout_width="match_parent"
            android:layout_height="50dp"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toBottomOf="@id/cb_check"
            android:text="@={userInfo.name}"/>


        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/rv_user"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:layout_constraintTop_toBottomOf="@id/et_input"
            android:layout_marginTop="10dp"/>

    </androidx.constraintlayout.widget.ConstraintLayout>

</layout>

activity中

public class MvvmMainActivity extends Activity {

    private ActivityMvvmMainBinding binding;
    UserInfo userInfo = new UserInfo();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        binding = DataBindingUtil.setContentView(this, R.layout.activity_mvvm_main);

        userInfo.setName("阿萌");
        userInfo.setAge(20);
        userInfo.setSex("男");
        userInfo.setDetail("深圳");
        userInfo.setIconUrl("https://網上圖片連接.jpg");
        userInfo.setPlaceUrl(R.drawable.bm_list);

        binding.setUserInfo(userInfo);
        binding.setClick(this);

        ArrayList<UserInfo> mList = new ArrayList<>();
        mList.add(userInfo);
        mList.add(userInfo);

        UserAdapter adapter = new UserAdapter(this, mList);
        LinearLayoutManager manager = new LinearLayoutManager(this);
        manager.setOrientation(LinearLayoutManager.VERTICAL);
        binding.rvUser.setLayoutManager(manager);
        binding.rvUser.setAdapter(adapter);
    }

    /**
     * 點擊事件
     * @param view
     */
    public void btClick(View view){
        //數據源改變更新UI
        userInfo.setName("阿金金");
        userInfo.setAge(30);
    }

    @BindingAdapter({"imagesUrl", "placeUrl"})//必須靜態方法
    public static void image(ImageView view, String iconUrl, Drawable placeUrl){
        Glide.with(view.getContext()).load(iconUrl).placeholder(placeUrl).error(R.mipmap.agent_icon).into(view);
    }

    public void onCheckedChanged(View view, boolean isChecked){
        binding.setIsShow(isChecked);
    }
}

定義ViewHolder

public class BindingViewHolder<T extends ViewDataBinding> extends RecyclerView.ViewHolder {

    private T mBinding;
    public BindingViewHolder(@NonNull T binding) {
        super(binding.getRoot());
        mBinding = binding;
    }

    public T getBinding(){
        return mBinding;
    }
}

adapter中

public class UserAdapter extends RecyclerView.Adapter<BindingViewHolder> {

    private LayoutInflater inflater;
    private ArrayList<UserInfo> mList = new ArrayList<>();

    public UserAdapter(Activity activity, ArrayList<UserInfo> list){
        mList = list;
        inflater = LayoutInflater.from(activity);
    }

    @NonNull
    @Override
    public BindingViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        ViewDataBinding binding = DataBindingUtil.inflate(inflater, R.layout.activity_mvvm_main_item, parent, false);
        return new BindingViewHolder(binding);
    }

    @Override
    public void onBindViewHolder(@NonNull BindingViewHolder holder, int position) {
        ViewDataBinding binding = holder.getBinding();
        binding.setVariable(BR.userItem, mList.get(position));
        binding.executePendingBindings();//讓數據立即生效
        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

            }
        });
    }

    @Override
    public int getItemCount() {
        return mList.size();
    }
}

adapter中的xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <data>
        <variable
            name="userItem"
            type="com.renli.mvvmdemo.been.UserInfo" />
    </data>

    <androidx.constraintlayout.widget.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp">

        <TextView
            android:id="@+id/tv_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintLeft_toLeftOf="parent"
            android:text="@{userItem.name}" />

        <TextView
            android:id="@+id/tv_sex"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            app:layout_constraintLeft_toRightOf="@id/tv_name"
            app:layout_constraintRight_toRightOf="parent"
            android:layout_marginLeft="20dp"
            android:text="@{userItem.sex}" />


    </androidx.constraintlayout.widget.ConstraintLayout>
</layout>

UserInfo實體類

public class UserInfo extends BaseObservable {
    @Bindable
    private String name;
    @Bindable
    private int age;
    @Bindable
    private String sex;
    @Bindable
    private String detail;
    @Bindable
    private String iconUrl;
    @Bindable
    private int placeUrl;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
        notifyPropertyChanged(BR.name);
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
        notifyPropertyChanged(BR.age);
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
        notifyPropertyChanged(BR.sex);
    }

    public String getDetail() {
        return detail;
    }

    public void setDetail(String detail) {
        this.detail = detail;
        notifyPropertyChanged(BR.detail);
    }

    public String getIconUrl() {
        return iconUrl;
    }

    public void setIconUrl(String iconUrl) {
        this.iconUrl = iconUrl;
        notifyPropertyChanged(BR.iconUrl);
    }

    public int getPlaceUrl() {
        return placeUrl;
    }

    public void setPlaceUrl(int placeUrl) {
        this.placeUrl = placeUrl;
        notifyPropertyChanged(BR.placeUrl);
    }

}