Java使用反射、自定义注解注入对象

package com.lxq.annotationAndreflection;

public class Person
{
String name="default";
Integer age=0;

public Person()
{
super();
}
public Person(String name, Integer age)
{
super();
this.name = name;
this.age = age;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public Integer getAge()
{
return age;
}
public void setAge(Integer age)
{
this.age = age;
}

}

package com.lxq.annotationAndreflection;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

@Retention(RetentionPolicy.RUNTIME)
public @interface SelfAnnotation
{
String name();
}

package com.lxq.annotationAndreflection;

public class Injection
{
@SelfAnnotation(name = "Person")
static Person person;
public void show()
{
System.out.println(person.getName()+","+person.getAge());
}

}

package com.lxq.annotationAndreflection;

import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;

public class Test
{
public static void main(String[] args) throws Exception
{
//取得Injection的类描述类
Class<Injection> clazz=Injection.class;
//取得所有的字段描述对象
Field[] fields=clazz.getDeclaredFields();
System.out.println(fields.length);
for(Field field:fields){
//取得每个字段上面的注解对象
Annotation[] annotations=field.getDeclaredAnnotations();
System.out.println(annotations.length);
for(Annotation annotation:annotations){
//判断注解对象是不是SelfAnnotation类型的
if(annotation.annotationType()==SelfAnnotation.class){
System.out.println("yes");
//通过SelfAnnotation的name获取要使用的beanName
String beanName=((SelfAnnotation) annotation).name();
//生成一个Peron的类描述类
Class<?> cc=Class.forName("com.lxq.annotation."+beanName);
//生成一个Person对象
Object ob=cc.newInstance();
System.out.println(field.getName());
//通过此方法将新建的实例对象赋值给 static Peron person
//如果是非static，那么set的第一个参数必须指定实例对象，也就是哪个Injection对象
field.set(null, ob);
//获取名字为show的方法
Method method=clazz.getDeclaredMethod("show");
//调用该方法
method.invoke(clazz.newInstance());

//基本和上面的一样，只是生成Person对象时，反射调用了带参数的构造
Class<?> c2=Class.forName("com.lxq.annotation."+beanName);
Class<?>[] ptype=new Class[]{String.class,Integer.class};
Constructor<?> ctor=c2.getConstructor(ptype);
Object[] obj=new Object[]{new String("lxq"),new Integer(25)};
Object object=ctor.newInstance(obj);
field.set(null, object);
Method method2=clazz.getDeclaredMethod("show");
method2.invoke(clazz.newInstance());

}
}
}
//因为 static Peron person，所以新建的Injectin对象的Peron对象都是通过反射最后赋值过得
Injection injection=new Injection();
System.out.println(injection.person.getName()+","+injection.person.getAge());

}
}