这几天研究的一下java的反射与注解机制，又分析了开源的afinal框架发现里面用到了注解省去很多的findViewById和setonClick等方法，省去了很多的代码，而且代码一目了然，下面是我自己的心得自己的实现注解：
package com.example.anotationdemo;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity {
@ViewInject(id = R.id.id_button, click = "doClick")
private Button mBtn;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try {
//在这里使用注解绑定事件
injectView();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private void injectView() throws IllegalAccessException,
IllegalArgumentException {
Field[] fields = this.getClass().getDeclaredFields();
for (Field field : fields) {
field.setAccessible(true);
Annotation[] annotations = field.getAnnotations();
for (Annotation annotation : annotations) {
if (annotation instanceof ViewInject) {
int id = ((ViewInject) annotation).id();
String click = ((ViewInject) annotation).click();
field.set(this, findViewById(id));
Object object = field.get(this);
if (object instanceof View) {
//这里目前只拿setonclick为例
((View) object).setOnClickListener(new ClickImpl(click,
this));
}
}
}
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public void doClick(View view) {
Toast.makeText(this, "toast", Toast.LENGTH_SHORT).show();
}
public class ClickImpl implements OnClickListener {
private String method;
private Activity activity;
public ClickImpl(String method, Activity activity) {
this.method = method;
this.activity = activity;
}
public void setMethod(String method) {
this.method = method;
}
public String getMethod() {
return this.method;
}
@Override
public void onClick(View v) {
try {
Method click = activity.getClass()
.getMethod(method, View.class);
click.invoke(activity, v);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
这里是注解的类：
package com.example.anotationdemo;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* @author 邢安栋 E-mail:[email protected]
* @version 创建时间：2015-7-10 上午9:25:30
*/
@Retention(RetentionPolicy.RUNTIME) //表示可以通过反射获取
@Target(ElementType.FIELD)
public @interface ViewInject {
int id();
String click();
}