lookup-method
示例：
步骤一：定义一个Car类
package org.hope.spring.bean.lookup; public class Car { private String brand; private String corp; private double price; getter()&setter().... }
步骤二：定义一个Boss接口
package org.hope.spring.bean.lookup; public interface Boss { Car haveCar(); }
步骤三：在spring的配置文件bean.xml中定义三个bean
<bean id="honeqi" class="org.hope.spring.bean.lookup.Car" p:brand="红旗" p:price="400000" scope="prototype" /> <bean id="bmw" class="org.hope.spring.bean.lookup.Car" p:brand="奔驰GLC260" p:price="500000" scope="prototype" /> <bean id="boss" class="org.hope.spring.bean.lookup.Boss"> <lookup-method name="haveCar" bean="bmw"/> </bean>
步骤四：写单元测试测试
package org.hope.spring.bean.lookup; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.test.context.ContextConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = {"classpath:bean.xml"}) public class LookUpTest { @Autowired private Boss boss; @Test public void testBoss() { Car car = boss.haveCar(); System.out.println(car.getBrand()); } }
输出：
奔驰GLC260
结论：
1、通过lookup-method元素标签可以为Boss的haveCar()提供动态实现，返回prototype类型的car Bean。
2、lookup方法注入是有一定使用范围的，一般在希望通过一个singleton Bean获取一个prototypeBean时使用
3、lookup方法注入需要用到CGLib类包
replaced-method(方法替换)
可以再运行时用新的方法替换久的方法
步骤一：新建一个Player.java
package org.hope.spring.bean.model; public class Player { private int id; private String name; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return "Player{" + "id=" + id + ", name=‘" + name + ‘\‘‘ + ‘}‘; } }
步骤二：新建一个将要被替换的类
package org.hope.spring.bean.replacedmethod; import org.hope.spring.bean.model.Car; import org.hope.spring.bean.model.Player; public class YiJianLian { public Player onPlace() { Player player = new Player(); player.setName("易建联"); return player; } }
步骤三：新建一个替换类，实现 MethodReplacer
package org.hope.spring.bean.replacedmethod; import org.hope.spring.bean.model.Player; import org.springframework.beans.factory.support.MethodReplacer; import java.lang.reflect.Method; /** * @Description: 用于替换他人的bean，必须实现MethodReplacer */ public class Yao implements MethodReplacer { public Object reimplement(Object obj, Method method, Object[] args) throws Throwable { Player player = new Player(); player.setName("姚明"); return player; } }
步骤四：在bean2.xml中配置bean关系
<bean id="yao" class="org.hope.spring.bean.replacedmethod.Yao"> </bean> <bean id="yiJianLian" class="org.hope.spring.bean.replacedmethod.YiJianLian"> <replaced-method name="onPlace" replacer="yao"/> </bean>
步骤五：测试
package org.hope.spring.bean.replacedmethod; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.test.context.ContextConfiguration; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations = {"classpath:bean2.xml"}) public class ReplacedTest { @Autowired private YiJianLian yiJianLian; @Test public void test() { System.out.println(yiJianLian.onPlace()); } }
输出：
Player{id=0, name=‘姚明‘}
结论：
1、可以在运行时用新的方法替换旧的方法。
2、用于替换他人的Bean必须实现MethodReplacer接口。
参考:
[1] 《精通Spring4.x企业应用开发实战》，电子工业出版社，陈雄华
