Spring学习-13:Spring的XML和注解的结合使用

实际开发中使用XML还是注解？

XML：

bean的管理

注解：

注入属性的时候比较方便

两种方式的结合：一般使用XML注册bean，使用注解来进行属性注入。在applicationContext.xml中配置<context:annotation-config></context:annotation-config>

举个简单的例子：

新建3个bean：

package com.js.demo4;

public class OrderDao {

}

package com.js.demo4;

public class CustomerDao {

}

package com.js.demo4;

public class CustomerService {
private CustomerDao customerDao;
private OrderDao orderDao;
@Override
public String toString() {
return "CustomerService [customerDao=" + customerDao + ", orderDao="
+ orderDao + "]";
}
public void setCustomerDao(CustomerDao customerDao) {
this.customerDao = customerDao;
}
public void setOrderDao(OrderDao orderDao) {
this.orderDao = orderDao;
}

}

配置applicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?>
<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.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 纯用注解配置bean的情况下context:annotation-config可以省略，当混合使用xml和注解配置bean的时候就不能省略了-->
<context:annotation-config></context:annotation-config>
<!-- 配置扫描注解的包 -->
<!-- <context:component-scan base-package="com.js"></context:component-scan> -->
<bean id="customerDao" class="com.js.demo4.CustomerDao"></bean>
<bean id="customerService" class="com.js.demo4.CustomerService">
<property name="customerDao" ref="customerDao"></property>
<property name="orderDao" ref="orderDao"></property>
</bean>
<bean id="orderDao" class="com.js.demo4.OrderDao"></bean>
</beans>

编写测试类：

package com.js.demo4;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test4 {
@Test
public void demo(){
ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext2.xml");
CustomerService customerService = (CustomerService)applicationContext.getBean("customerService");
System.out.println(customerService);
}
}

运行结果，注入成功：



我们能不能修改配置方式，只在xml中注册bean，而将bean的属性注入使用注解来完成呢？

修改CustomerService：使用注解传入的属性就不在需要setter方法，也不再需要Component-scan，因为我们的bean全部在xml中配置，此处修改两个属性之一的orderDao：

package com.js.demo4;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

public class CustomerService {
private CustomerDao customerDao;
@Autowired
@Qualifier("orderDao")
private OrderDao orderDao;
@Override
public String toString() {
return "CustomerService [customerDao=" + customerDao + ", orderDao="
+ orderDao + "]";
}
public void setCustomerDao(CustomerDao customerDao) {
this.customerDao = customerDao;
}

}

修改xml配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<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.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<!-- 纯用注解配置bean的情况下context:annotation-config可以省略，当混合使用xml和注解配置bean的时候就不能省略了-->
<!-- 作用是使@Resource、@PostConstruct、@PreDestroy、@AutoWired生效-->
<context:annotation-config></context:annotation-config>

<bean id="customerDao" class="com.js.demo4.CustomerDao"></bean>
<bean id="customerService" class="com.js.demo4.CustomerService">
<property name="customerDao" ref="customerDao"></property>
</bean>
<bean id="orderDao" class="com.js.demo4.OrderDao"></bean>
</beans>

运行测试，成功。