android使用篇（四） 注解依赖注入IOC实现绑定控件

在android使用篇（三）
MVC模式中提到一个问题：

1) 视图层（View）：一般採用XML文件进行界面的描写叙述，使用的时候能够很方便的引入，可是用xml编写了，又须要在Acitvity声明而且实例化，有点麻烦，考虑是否能做一个类似注解实现匹配，或者写一个类获取xml的各个节点然后自己主动进行封装，当然，这仅仅是个想法，以后再实现。

今天最终把这个想法实现了，使用依赖注入IOC注解实现对activity中控件的实例化。

先普及一下java的反射机制和注解机制的知识：

下面引用大神的两篇文章：

JAVA反射机制

java 注解

完毕后仅仅须要： @ViewInject(id=R.id.btn1,click="btnClick") TextView btn1;  就可以完毕实例化，并加入�点击事件

基本思路：

一，public abstract class D3Activity extends Activity    写一个类继承Activity。

二，重写  setContentView   在此方法实现注解。

三，Field[] fields = activity.getClass().getDeclaredFields();    获取activity中的字段属性

四， field.getAnnotation(ViewInject.class);         获取字段的注解属性

五， field.set(activity,sourceView.findViewById(viewId));       实例化控件

大功告成，到此已实现了注解实现对android中activity和xml文件的实例化问题。

另外也能够实现注解对控件的事件加入�，具体

分三个类实现：

实现注解类：

注解类可注入 id---相应xml的id，各种点击事件，可自定义

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface D3View {
 public int id() default 0;
 public String click() default "";
 public String longClick() default "";
 public String itemClick() default "";
 public String itemLongClick() default "";
}

重写activity类，使用反射和注解实现实例化并添�事件：

public abstract class D3Activity extends Activity {

public void setContentView(int layoutResID) {
  super.setContentView(layoutResID);
  initInjectedView(this);
 }

public void setContentView(View view, LayoutParams params) {
  super.setContentView(view, params);
  initInjectedView(this);
 }

public void setContentView(View view) {
  super.setContentView(view);
  initInjectedView(this);
 }

private void initInjectedView(Activity activity){
  initInjectedView(activity, activity.getWindow().getDecorView());
 }
 
 
 private void initInjectedView(Object activity,View sourceView){
  Field[] fields = activity.getClass().getDeclaredFields();   //获取字段
  if(fields!=null && fields.length>0){
   for(Field field : fields){
    try {
     field.setAccessible(true);   //设为可訪问
     
     if(field.get(activity)!= null )
      continue;
    
     D3View d3View = field.getAnnotation(D3View.class);
     if(d3View!=null){
      
      int viewId = d3View.id();
      if(viewId == 0)
       viewId = getResources().getIdentifier(field.getName(), "id",getPackageName());
      if(viewId == 0)
       Log.e("D3Activity", "field "+ field.getName() + "not found");
      
      //关键,注解初始化，相当于 backBtn = (TextView) findViewById(R.id.back_btn);
         field.set(activity,sourceView.findViewById(viewId)); 
         //事件
         setListener(activity,field,d3View.click(),Method.Click);
      setListener(activity,field,d3View.longClick(),Method.LongClick);
      setListener(activity,field,d3View.itemClick(),Method.ItemClick);
      setListener(activity,field,d3View.itemLongClick(),Method.itemLongClick);
     }
    } catch (Exception e) {
     e.printStackTrace();
    }
   }
  }
 }
 
 private void setListener(Object activity,Field field,String methodName,Method method)throws Exception{
  if(methodName == null || methodName.trim().length() == 0)
   return;
  
  Object obj = field.get(activity);
  
  switch (method) {
   case Click:
    if(obj instanceof View){
     ((View)obj).setOnClickListener(new EventListener(activity).click(methodName));
    }
    break;
   case ItemClick:
    if(obj instanceof AbsListView){
     ((AbsListView)obj).setOnItemClickListener(new EventListener(activity).itemClick(methodName));
    }
    break;
   case LongClick:
    if(obj instanceof View){
     ((View)obj).setOnLongClickListener(new EventListener(activity).longClick(methodName));
    }
    break;
   case itemLongClick:
    if(obj instanceof AbsListView){
     ((AbsListView)obj).setOnItemLongClickListener(new EventListener(activity).itemLongClick(methodName));
    }
    break;
   default:
    break;
  }
 }
 
 public enum Method{
  Click,LongClick,ItemClick,itemLongClick
 }
 
}

事件类： 实现了 OnClickListener, OnLongClickListener, OnItemClickListener,OnItemLongClickListener ，能够自己扩展

public class EventListener implements OnClickListener, OnLongClickListener, OnItemClickListener,OnItemLongClickListener {

	private Object handler;

	private String clickMethod;
	private String longClickMethod;
	private String itemClickMethod;
	private String itemLongClickMehtod;

	public EventListener(Object handler) {
		this.handler = handler;
	}

	public EventListener click(String method){
		this.clickMethod = method;
		return this;
	}

	public EventListener longClick(String method){
		this.longClickMethod = method;
		return this;
	}

	public EventListener itemLongClick(String method){
		this.itemLongClickMehtod = method;
		return this;
	}

	public EventListener itemClick(String method){
		this.itemClickMethod = method;
		return this;
	}

	public boolean onLongClick(View v) {
		return invokeLongClickMethod(handler,longClickMethod,v);
	}

	public boolean onItemLongClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {
		return invokeItemLongClickMethod(handler,itemLongClickMehtod,arg0,arg1,arg2,arg3);
	}

	public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {

		invokeItemClickMethod(handler,itemClickMethod,arg0,arg1,arg2,arg3);
	}

	public void onClick(View v) {

		invokeClickMethod(handler, clickMethod, v);
	}

	private static Object invokeClickMethod(Object handler, String methodName,  Object... params){
		if(handler == null) return null;
		Method method = null;
		try{
			method = handler.getClass().getDeclaredMethod(methodName,View.class);
			if(method!=null)
				return method.invoke(handler, params);
			else
				throw new RuntimeException("no such method:"+methodName);
		}catch(Exception e){
			e.printStackTrace();
		}

		return null;

	}

	private static boolean invokeLongClickMethod(Object handler, String methodName,  Object... params){
		if(handler == null) return false;
		Method method = null;
		try{
			//public boolean onLongClick(View v)
			method = handler.getClass().getDeclaredMethod(methodName,View.class);
			if(method!=null){
				Object obj = method.invoke(handler, params);
				return obj==null?false:Boolean.valueOf(obj.toString());
			}
			else
				throw new RuntimeException("no such method:"+methodName);
		}catch(Exception e){
			e.printStackTrace();
		}

		return false;

	}

	private static Object invokeItemClickMethod(Object handler, String methodName,  Object... params){
		if(handler == null) return null;
		Method method = null;
		try{
			///onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3)
			method = handler.getClass().getDeclaredMethod(methodName,AdapterView.class,View.class,int.class,long.class);
			if(method!=null)
				return method.invoke(handler, params);
			else
				throw new RuntimeException("no such method:"+methodName);
		}catch(Exception e){
			e.printStackTrace();
		}

		return null;
	}

	private static boolean invokeItemLongClickMethod(Object handler, String methodName,  Object... params){
		if(handler == null) throw new RuntimeException("invokeItemLongClickMethod: handler is null :");
		Method method = null;
		try{
			///onItemLongClick(AdapterView<?> arg0, View arg1, int arg2,long arg3)
			method = handler.getClass().getDeclaredMethod(methodName,AdapterView.class,View.class,int.class,long.class);
			if(method!=null){
				Object obj = method.invoke(handler, params);
				return Boolean.valueOf(obj==null?false:Boolean.valueOf(obj.toString()));
			}
			else
				throw new RuntimeException("no such method:"+methodName);
		}catch(Exception e){
			e.printStackTrace();
		}

		return false;
	}
}

到此已经完毕了，仅仅须要这样就可以实例化：

public class MainActivity extends D3Activity {

	//@ViewInject EditText input;   //id和属性名同样，自己主动匹配
	@ViewInject(id = R.id.input) EditText editText;
	@ViewInject(click="btnClick") TextView btn1,btn2,btn3;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }  

	public void btnClick(View v){

    	switch (v.getId()) {
		case R.id.btn1:
			btn1.setText(editText.getText().toString());
			Toast.makeText(getApplicationContext(), "111", Toast.LENGTH_SHORT).show();
			break;

		case R.id.btn2:
			Toast.makeText(getApplicationContext(), "222", Toast.LENGTH_SHORT).show();

			break;

		case R.id.btn3:
			Toast.makeText(getApplicationContext(), "333", Toast.LENGTH_SHORT).show();
			break;

		default:
			break;
		}

    }

}

相应xml布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/input"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"

        />
    <TextView
        android:id="@+id/btn1"
        android:layout_marginTop="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="设置自己"
         />
	<TextView
        android:id="@+id/btn2"
        android:layout_marginTop="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="btn2"
	    />

	<TextView
        android:id="@+id/btn3"
        android:layout_marginTop="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="btn3"
	    />
</LinearLayout>

源代码已经放在了github，有兴趣的能够去看看 ：https://github.com/mozhenhau/injectAndroid.git