在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 ViewInject { 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; ViewInject viewInject = field.getAnnotation(ViewInject.class); if(viewInject!=null){ int viewId = viewInject.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,viewInject.click(),Method.Click); setListener(activity,field,viewInject.longClick(),Method.LongClick); setListener(activity,field,viewInject.itemClick(),Method.ItemClick); setListener(activity,field,viewInject.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 { [email protected] 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" 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>
源码已经放在了github，有兴趣的可以去看看 ：https://github.com/mozhenhau/injectAndroid.git
- 2楼what7abc7小时前
- 写得不错，很有用，学习了
- 1楼what7abc7小时前
- 是只有继承了activity的才能用注解绑定吗？ adapter这些好像不能使用，如果能会用就更好了，但已经极大地方便了