OkHttp3网络加载Bitmap到DataBinding中BindingAdapter自定义属性

定义User：

import android.databinding.BaseObservable;
import android.databinding.ObservableField;
import android.graphics.Bitmap;

public class User extends BaseObservable {
    public ObservableField<Bitmap> bitmap = new ObservableField<>();
}

在XML布局中写入User：

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

    <data>

        <variable
            name="user"
            type="com.example.fly.myapplication.User" />
    </data>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerInParent="true"
            app:userImage="@{user.bitmap}" />
    </RelativeLayout>
</layout>

其中的app:userImage为自己专门为ImageView自定义的属性。

下面单独为userImage属性增加绑定。Utils.java：

import android.databinding.BindingAdapter;
import android.graphics.Bitmap;
import android.widget.ImageView;

public class Utils {
    @BindingAdapter({"userImage"})
    public static void setImageError(ImageView imageView, Bitmap bitmap) {
        imageView.setImageBitmap(bitmap);
    }
}

接着在上层Java代码使用Okhttp3加载一个网络图片到ImageView的userImage中去：

import android.databinding.DataBindingUtil;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import java.io.IOException;

import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

        final User user = new User();
        binding.setUser(user);

        String url = "http://avatar.csdn.net/9/7/A/1_zhangphil.jpg";

        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url(url)
                .build();

        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {

            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                byte[] bytes = response.body().bytes();
                Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0, bytes.length);
                user.bitmap.set(bitmap);
            }
        });
    }
}

.gradle添加的okhttp3引用：

implementation 'com.squareup.okhttp3:okhttp:3.9.1'