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);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"    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