android使用篇（四） 註解實現繫結控制項執行個體化

在android使用篇（三） MVC模式中提到一個問題：

1) 視圖層（View）：一般採用XML檔案進行介面的描述，使用的時候可以非常方便的引入，但是用xml編寫了，又需要在Acitvity聲明並且執行個體化，有點麻煩，考慮能否做一個類似註解實現匹配，或者寫一個類擷取xml的各個節點然後自動進行封裝，當然，這隻是個想法，以後再實現。

今天終於把這個想法實現了，使用IOC註解實現對activity中控制項的執行個體化。

先普及一下java的反射機制和註解機制的知識：

以下引用大神的兩篇文章：

JAVA反射機制  java 註解 完成後只需要： @ViewInject(id=R.id.btn1,click="btnClick") TextView btn1;  即可完成執行個體化，並添加點擊事件

基本思路： 

一，public abstract class D3Activity extends Activity    寫一個類繼承Activity。

二，重寫  setContentView   在此方法實現註解。

三，Field[] fields = activity.getClass().getDeclaredFields();    擷取activity中的欄位屬性

四， field.getAnnotation(ViewInject.class);         擷取欄位的註解屬性

五， field.set(activity,sourceView.findViewById(viewId));       執行個體化控制項

大功告成，到此已實現了註解實現對android中activity和xml檔案的執行個體化問題。

另外也可以實現註解對控制項的事件添加，詳細

分三個類實現：

實現註解類：

註解類可注入 id---對應xml的id，各種點擊事件，可自己定義

@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 "";}

重寫activity類，使用反射和註解實現執行個體化並加入事件：

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();   //擷取欄位if(fields!=null && fields.length>0){for(Field field : fields){try {field.setAccessible(true);   //設為可訪問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");//關鍵,註解初始化，相當於 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}

事件類別： 實現了 OnClickListener, OnLongClickListener, OnItemClickListener,OnItemLongClickListener ，可以自己擴充

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);elsethrow 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());}elsethrow 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);elsethrow 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()));}elsethrow new RuntimeException("no such method:"+methodName);}catch(Exception e){e.printStackTrace();}return false;}}

到此已經完成了，只需要這樣即可執行個體化：

public class MainActivity extends D3Activity {    //@ViewInject EditText input;   //id和屬性名稱相同，自動匹配@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;}        }    }

對應xml布局檔案：

<?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="設定自己"         /><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>

源碼已經放在了github，有興趣的可以去看看 ：https://github.com/mozhenhau/injectAndroid.git