【Android自定义注解】BindView

注意：定义的控件变量必须是public，否则报错

1、添加类

package com.example.zhujie;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
@Retention(RetentionPolicy.RUNTIME)
public @interface BindView {
    int value();
}

2、添加类

package com.example.zhujie;
import android.app.Activity;
import android.view.View;
import java.lang.reflect.Field;
//创建注解处理器
public class InjectUtils {
    public static void inject(Activity activity) throws IllegalAccessException {
        Field[] fields = activity.getClass().getDeclaredFields();
        for (Field field : fields) {
            BindView bindView = field.getAnnotation(BindView.class);
            if (bindView != null) {
                int value = bindView.value();
                View view = activity.findViewById(value);
                try {
                    field.set(activity, view);
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

3、在activity中调用

package com.example.zhujie;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {

    @BindView(R.id.tv)
    public TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        try {
            InjectUtils.inject(this);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
        textView.setText("测hi注解");
    }
}