感謝 鴻洋 :http://blog.csdn.net/lmj623565791/article/details/39269193
http://blog.csdn.net/lmj623565791/article/details/39275847
如果大家用過xUtils,就一定見過這種寫法,使用@ViewInject 省去之前大量使用的findviewById,其實雖然使用了注釋方法,但這隻是減去了碼農們寫重複代碼的工作量,提高碼字速度,真正的實作的原理還是通過findViewById,隻是把他寫在了一個配置檔案中,不同類可以共用。說白了就是減少重複代碼的另外一種方式(通過注釋),這裡面用到了一點點的反射的知識。話不多說,直接上代碼:
一共分為三部分:
1,注釋類 ViewInject
2,通過反射,查找注釋的變量、類、方法等等,注入控件。(相當一個連接配接器,連接配接注釋和activity。相當于一個公用的方法)
3,activity中使用
package com.tjove.ipcdemo;
/**
* 通過注釋減少重複代碼 Annotation
*/
import java.io.File;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import com.tjove.ipcdemo.R.id;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
@ContextViewInject(R.layout.activity_main)//通過注釋的方式引入布局
public class Demo3 extends Activity implements OnClickListener{
@ViewInject(R.id.button01)
private Button button;
@ViewInject(R.id.text)
private TextView textView;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
// setContentView(R.layout.activity_main);
ViewInjectUtils.inject(this);
textView.setText("Annotation");
button.setOnClickListener(this);
}
@Override
public void onClick(View v) {
Toast.makeText(Demo3.this, textView.getText(), Toast.LENGTH_SHORT).show();
}
}
@Target(ElementType.FIELD)//注釋變量
@Retention(RetentionPolicy.RUNTIME)
@interface ViewInject{
int value();
}
@Target(ElementType.TYPE)//注釋 類
@Retention(RetentionPolicy.RUNTIME)
@interface ContextViewInject{
int value();
}
class ViewInjectUtils{
private static final String METHOD_FIND_VIEW_BY_ID="findViewById";
private static final String METHOD_SET_CONTENTVIEW = "setContentView";
static void inject(Activity activity){
Class<?> class1=activity.getClass();
injectContextView(activity,class1);
injectView(activity,class1);
}
private static void injectContextView(Activity activity, Class<?> class1) {
ContextViewInject contextViewInject=class1.getAnnotation(ContextViewInject.class);
if (contextViewInject==null) {
return;
}
int viewId=contextViewInject.value();//找 布局id
if (viewId<0) {
continue;
}
try {
Method method=class1.getMethod(METHOD_SET_CONTENTVIEW, int.class);//找 設定布局的方法
method.setAccessible(true);
method.invoke(activity, viewId);//實作setContentView()方法
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/**
* 注入所有控件
* @param activity
* @param class1
*/
private static void injectView(Activity activity,Class class1) {
Field[] fields=class1.getDeclaredFields();
for (Field field : fields) {
ViewInject viewInject=field.getAnnotation(ViewInject.class);
if (viewInject!=null) {
int id=viewInject.value();
if (id<0) {
return;
}
try {
Method method=class1.getMethod(METHOD_FIND_VIEW_BY_ID, int.class);
Object object=method.invoke(activity, id);
field.setAccessible(true);
field.set(activity, object);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}
xml:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.tjove.ipcdemo.MainActivity" >
<Button
android:id="@+id/button01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button01"
/>
<TextView
android:id="@+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/button01"
android:text="aa"/
代碼下載下傳,其中包括對點選事件的監聽