Spring中xml配置优先于注释配置的示例

Question

但没有任何例子。

你能举个例子吗？

Answer 1

下面是一个简单的示例，展示了基于xml的Spring配置和基于Java的Spring配置的混合。示例中有5个文件：

Main.java
AppConfig.java
applicationContext.xml
HelloWorld.java
HelloUniverse.java

首先尝试在applicationContext文件中注释了HelloBeanbean的情况下运行它，您将注意到HelloBeanbean是从AppConfig配置类实例化的。然后在applicationContext.xml文件中未注释HelloBeanbean的情况下运行它，您将注意到xml定义的bean优先于AppConfig类中定义的bean。

main.java

package my.test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main {

   public static void main(String[] args) {
      ApplicationContext ctx = new AnnotationConfigApplicationContext( AppConfig.class );
      ctx.getBean("helloBean"); 
   }
}

package my.test;
import org.springframework.context.annotation.*;

@ImportResource({"my/test/applicationContext.xml"})
public class AppConfig {

   @Bean(name="helloBean")
   public Object hello() {
      return new HelloWorld();
   }
}

applicationcontext.xml

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">

    <bean id="helloBean" class="my.test.HelloUniverse"/>

</beans>

hellouniverse.java

package my.test;

public class HelloUniverse {

   public HelloUniverse() {
      System.out.println("Hello Universe!!!");
   }
}

helloworld.java

package my.test;

public class HelloWorld {

   public HelloWorld() {
      System.out.println("Hello World!!!");
   }
}