Android 中的 IOC 框架 【ViewInject】

要实现的目标结果如下 ：

@ContentView(R.layout.activity_main)public class MainActivity extends Activity implements View.OnClickListener {    @ViewInject(R.id.id_btn)    private Button mBtn1;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        ViewUtil.inject(this);

1、定义注解

首先我们需要两个注解文件：

1.1

package com.zhy.ioc.view.annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)public @interface ContentView{int value();}

ContentView用于在类上使用，主要用于标明该Activity需要使用的布局文件

@ContentView(value = R.layout.activity_main)public class MainActivity

1.2

package com.zhy.ioc.view.annotation;import java.lang.annotation.ElementType;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;import java.lang.annotation.Target;@Target(ElementType.FIELD)@Retention(RetentionPolicy.RUNTIME)public @interface ViewInject{int value();}

在成员变量上使用，用于指定View的Id

@ViewInject(R.id.id_btn)private Button mBtn1;

此两个注解定义，需分别写在两个类文件上

ContentView.java
ViewInject.java

2、MainActivity

package com.example.administrator.camera;import android.app.Activity;import android.jni.ContentView;import android.jni.ViewInject;import android.jni.ViewUtil;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.Toast;@ContentView(R.layout.activity_main)public class MainActivity extends Activity implements View.OnClickListener {    @ViewInject(R.id.id_btn)    private Button mBtn1;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        ViewUtil.inject(this);        //        mBtn1.setOnClickListener(new View.OnClickListener() {//            @Override//            public void onClick(View view) {//                Toast.makeText(MainActivity.this, "how old are you ?", Toast.LENGTH_SHORT).show();//            }//        });        mBtn1.setOnClickListener(this);    }    public void onClick(View v)    {        switch (v.getId())        {            case R.id.id_btn:                Toast.makeText(MainActivity.this, "Why do you click me ?",                        Toast.LENGTH_SHORT).show();                break;        }    }}

注解都写好了，核心的代码就是 

ViewUtil.inject(this);

 

ViewUtil.inject(this);

ViewUtil.java

如下：

package android.jni;import android.app.Activity;import android.util.Log;import java.lang.reflect.Field;import java.lang.reflect.Method;/** * Created by Administrator on 2017-11-20. *//** * 核心控制类 * * @author leilu * */public class ViewUtil {    public static void inject(Activity activity)    {        injectContentView(activity);        injectViews(activity);    }    private static final String METHOD_SET_CONTENTVIEW = "setContentView";    /**     * 注入主布局文件     *     * @param activity     */    private static void injectContentView(Activity activity)    {        Class<? extends Activity> clazz = activity.getClass();        // 查询类上是否存在ContentView注解        ContentView contentView = clazz.getAnnotation(ContentView.class);        if (contentView != null)// 存在        {            int contentViewLayoutId = contentView.value();            try            {                Method method = clazz.getMethod(METHOD_SET_CONTENTVIEW,                        int.class);                method.setAccessible(true);                method.invoke(activity, contentViewLayoutId);            } catch (Exception e)            {                e.printStackTrace();            }        }    }    private static final String METHOD_FIND_VIEW_BY_ID = "findViewById";    /**     * 注入所有的控件     *     * @param activity     */    private static void injectViews(Activity activity)    {        Class<? extends Activity> clazz = activity.getClass();        Field[] fields = clazz.getDeclaredFields();        // 遍历所有成员变量        for (Field field : fields)        {            ViewInject viewInjectAnnotation = field                    .getAnnotation(ViewInject.class);            if (viewInjectAnnotation != null)            {                int viewId = viewInjectAnnotation.value();                if (viewId != -1)                {                    Log.e("TAG", viewId+"");                    // 初始化View                    try                    {                        Method method = clazz.getMethod(METHOD_FIND_VIEW_BY_ID,                                int.class);                        Object resView = method.invoke(activity, viewId);                        field.setAccessible(true);                        field.set(activity, resView);                    } catch (Exception e)                    {                        e.printStackTrace();                    }                }            }        }    }}

参考文献：http://android.jobbole.com/81051/

                  http://android.jobbole.com/81053/