Spring 自定义对象初始化及销毁

– Start

有些对象实例化时，我们需要打开某些资源，而在销毁对象时将这些资源关闭，Spring 允许我们自定义初始化和销毁方法，下面是一个简单的例子。

package shangbo.spring.core.example9;

public class OutPutService {

// 初始化方法
public void init() {
System.out.println("Enter init");
}

// 销毁方法
public void destroy() {
System.out.println("Enter destroy");
}

public void outPut() {
System.out.println("Hello World");
}

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 
<!--
init-method 指定初始化方法
destroy-method 指定销毁方法
-->
<bean class="shangbo.spring.core.example9.OutPutService" init-method = "init" destroy-method = "destroy"/>

</beans>

package shangbo.spring.core.example9;

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

public class App {
public static void main(String[] args) {
// 实例化 Spring IoC 容器
ApplicationContext context = new ClassPathXmlApplicationContext("example.xml", OutPutService.class);

// 从容器中获得 OutPutService 对象
OutPutService printer = context.getBean(OutPutService.class);

// 使用对象
printer.outPut();
}
}

如果你有很多这样的对象且它们的初始化和销毁方法名相同，我们可以定义默认的初始化和销毁方法。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd" default-init-method = "init"
default-destroy-method = "destroy"
>
<!--
default-init-method 指定默认初始化方法
default-destroy-method 指定默认销毁方法
-->

<bean class="shangbo.spring.core.example10.OutPutService"/>

</beans>

如果使用 Java 配置文件，我们可以使用 @PostConstruct 和 @PreDestroy 注解，或@Bean(initMethod = “init”, destroyMethod = “destroy”)

package shangbo.spring.core.example11;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

public class OutPutService {

// 初始化方法
@PostConstruct
public void init() {
System.out.println("Enter init");
}

// 销毁方法
@PreDestroy
public void destroy() {
System.out.println("Enter destroy");
}

public void outPut() {
System.out.println("Hello World");
}

}

package shangbo.spring.core.example11;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class AppConfig {

//@Bean(initMethod = "init", destroyMethod = "destroy")
@Bean
public OutPutService outPutService() {
return new OutPutService();
}
}

package shangbo.spring.core.example11;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class App {
public static void main(String[] args) {
// 实例化 Spring IoC 容器，也可以一次读取多个Java配置文件
ApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);

// 从容器中获得 Service 对象
OutPutService printer = context.getBean(OutPutService.class);

// 使用对象
printer.outPut();
}
}

– 更多参见：Spring Framework 精萃

– 声 明：转载请注明出处

– Last Updated on 2017-06-17

– Written by ShangBo on 2017-05-21

– End