2.4导入和混合配置

Posted 2020-10-25 Java全栈从0到1

导入和混合配置

1、拆分JavaConfig

@Configuration
public class CDConfig {
    @Bean
    public CompactDisc compactDisc() {
        return new SgtPeppers();
    }
}

使用@Import注解

@Configuration
@Import(CDConfig.class)
public class CDPlayerConfig {

    @Bean
    public CDPlayer cdPlayer(CompactDisc compactDisc) {
        return new CDPlayer(compactDisc);
    }

}

或使用一个更高级别的JavaConfig引用2个JavaConfig

@Configuration
@Import({ CDPlayerConfig.class, CDConfig.class })
public class SoundSystemConfig {
}

2、JavaConfig中引用XML配置

1中把CDPlayer和CompactDisc分开了，假设出于某些原因，需要把CompactDisc用XML来配置

<bean id="compactDisc" class="soundsystem.BlankDisc"
    c:_0="Sgt. Pepper‘s Lonely Hearts Club Band" c:_1="The Beatles">
    <constructor-arg>
        <list>
            <value>Sgt. Pepper‘s Lonely Hearts Club Band</value>
            <value>With a Little Help from My Friends</value>
            <value>Lucy in the Sky with Diamonds</value>
            <value>Getting Better</value>
            <value>Fixing a Hole</value>
            <!-- ...other tracks omitted for brevity... -->
        </list>
    </constructor-arg>
</bean>

JavaConfig引用XML配置

@Configuration
@Import(CDPlayerConfig.class)
@ImportResource("classpath:cd-config.xml")
public class SoundSystemConfig {
}

这样，CDPlayer和BlankDisc都会作为bean被加载到Spring容器中；而CDPlayer添加了@Bean注解，所需参数CompactDisc也会把BlanDisc加载进来

3、拆分XML配置

<import resource="cd-config.xml" />
<bean id="cdPlayer" class="soundsystem.CDPlayer" c:cd-ref="compactDisc" />

4、XML配置中引用JavaConfig

<bean class="soundsystem.CDConfig" />
<bean id="cdPlayer" class="soundsystem.CDPlayer" c:cd-ref="compactDisc" />

推荐无论使用JavaConfig还是XML配置，都加入一个更高层次的配置文件，负责组合这些配置文件

<bean class="soundsystem.CDConfig" />
<import resource="cdplayer-config.xml" />