Android 反射获得控件对象

例：

@ViewInject(R.id.pull_to_refresh_listview)private PullToRefreshListView pullToRefreshListView;

不再使用一下代码初始化

pullToRefreshListView = (PullToRefreshListView) findViewById(R.id.pullToRefreshListView);

实现方式（网上有很多代码）：

一个interface和一个class

interface：

import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;/** * Created by anykaa on 2015/6/3. */@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)public @interface ViewInject {    int value();}

class

import android.app.Activity;import java.lang.reflect.Field;/** * Created by anykaa on 2015/6/3. */@SuppressWarnings("unused")public class ViewInjectClass {    public static void autoInjectAllField(Activity activity) {        //得到Activity对应的Class        Class clazz = activity.getClass();        //得到该Activity的所有字段        Field[] fields = clazz.getDeclaredFields();        try {            for (Field field : fields) {                //判断字段是否标注InjectView                if (field.isAnnotationPresent(ViewInject.class)) {                    //如果标注了，就获得它的id                    ViewInject inject = field.getAnnotation(ViewInject.class);                    int id = inject.value();                    if (id > 0) {                        //反射访问私有成员，必须加上这句                        field.setAccessible(true);                        try {                            //然后对这个属性复制                            field.set(activity, activity.findViewById(id));                        } catch (Exception ex) {                        }                    }                }            }        } catch (Exception ex) {            ex.printStackTrace();        }    }}

使用方式及建议：

统一写一个BaseActivity

import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import com.anykaalibrary.ViewInjectClass;/** * Created by anykaa on 15/12/30. */public class BaseActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);    }    @Override    public void setContentView(int layoutResID) {        super.setContentView(layoutResID);        ViewInjectClass.autoInjectAllField(this);    }}

使用

public class MainActivity extends BaseActivity {        @ViewInject(R.id.pull_to_refresh_listview)    private PullToRefreshListView pullToRefreshListView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }}

其实我并不建议这样使用，我倒是希望开发工具能够根据类似这种代码，在编译前自动将代码改成

pullToRefreshListView = (PullToRefreshListView) findViewById(R.id.pullToRefreshListView);

这种形式。

特此梳理备用。

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