編輯：關於Android編程
在android使用篇（三） MVC模式中提到一個問題：
1) 視圖層（View）：一般采用XML文件進行界面的描述，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聲明並且實例化，有點麻煩，考慮能否做一個類似注解實現匹配，或者寫一個類獲取xml的各個節點然後自動進行封裝，當然，這只是個想法，以後再實現。
今天終於把這個想法實現了，使用IOC注解實現對activity中控件的實例化。
先普及一下java的反射機制和注解機制的知識：
以下引用大神的兩篇文章：
基本思路：
一，public abstract class D3Activity extends Activity 寫一個類繼承Activity。
二，重寫 setContentView 在此方法實現注解。
三，Field[] fields = activity.getClass().getDeclaredFields(); 獲取activity中的字段屬性
四， field.getAnnotation(ViewInject.class); 獲取字段的注解屬性
五， field.set(activity,sourceView.findViewById(viewId)); 實例化控件
大功告成，到此已實現了注解實現對android中activity和xml文件的實例化問題。
另外也可以實現注解對控件的事件添加，詳細
分三個類實現：
實現注解類：
注解類可注入 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，使用反射和注解實現實例化並加入事件：
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(); //獲取字段
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,注解初始化，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
}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;
}
}到此已經完成了，只需要這樣即可實例化：
public class MainActivity extends D3Activity {
//@ViewInject EditText input; //id和屬性名相同，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;
}
}
}源碼已經放在了github，有興趣的可以去看看 ：https://github.com/mozhenhau/injectAndroid.git
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