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
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