文章目录
  1. 1. JAVA反射机制  
  2. 2. java 注解 

android使用篇(三)
MVC模式
中提到一个问题:

1) 视图层(View):一般采用XML文件进行界面的描述,使用的时候可以非常方便的引入,但是用xml编写了,又需要在Acitvity声明并且实例化,有点麻烦,考虑能否做一个类似注解实现匹配,或者写一个类获取xml的各个节点然后自动进行封装,当然,这只是个想法,以后再实现。


今天终于把这个想法实现了,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:

以下引用大神的两篇文章:

JAVA反射机制  



java 注解 

完成后只需要: @ViewInject(id=R.id.btn1,click="btnClick") TextView btn1;  即可完成实例化,并添加点击事件

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。

另外也可以实现注解对控件的事件添加,详细

分三个类实现:

实现注解类:

注解类可注入 id—对应xml的id,各种点击事件,可自己定义

\

@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加入事件:

\

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);   //设为可访问
     
     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 ,可以自己扩展

\

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;
}

}

到此已经完成了,只需要这样即可实例化:

\

public class MainActivity extends D3Activity {

//@ViewInject EditText input;   //id和属性名相同,自动匹配
@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;
    }

}

}

对应xml布局文件:

\

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

&lt;EditText 
    android:id=&quot;@+id/input&quot;
    android:layout_width=&quot;fill_parent&quot;
    android:layout_height=&quot;wrap_content&quot;

    /&gt;
&lt;TextView
    android:id=&quot;@+id/btn1&quot;
    android:layout_marginTop=&quot;10dp&quot;
    android:layout_width=&quot;wrap_content&quot;
    android:layout_height=&quot;wrap_content&quot;
    android:text=&quot;设置自己&quot;
     /&gt;
&lt;TextView 
    android:id=&quot;@+id/btn2&quot;
    android:layout_marginTop=&quot;10dp&quot;
    android:layout_width=&quot;wrap_content&quot;
    android:layout_height=&quot;wrap_content&quot;
    android:text=&quot;btn2&quot;
    /&gt;

&lt;TextView 
    android:id=&quot;@+id/btn3&quot;
    android:layout_marginTop=&quot;10dp&quot;
    android:layout_width=&quot;wrap_content&quot;
    android:layout_height=&quot;wrap_content&quot;
    android:text=&quot;btn3&quot;
    /&gt;

</LinearLayout>

源码已经放在了github,有兴趣的可以去看看 :https://github.com/mozhenhau/injectAndroid.git

文章目录
  1. 1. JAVA反射机制  
  2. 2. java 注解