【金蝶天燕鲲鹏云最佳实践 三】springboot源码浅析（二）spring的模块装配

一、springboot的模块装配

什么是模块？  

       模块定义：Spring Framework 3.1 开始支持”@Enable 模块驱动“。所谓“模块”是指具备相同领域的功能组件集合， 组合所形成一个独立
的单元。比如 Web MVC 模块、AspectJ代理模块、Caching（缓存）模块、JMX（Java 管 理扩展）模块、Async（异步处
理）模块等。

创建自己的模块注解：

我们通过自己实现一个自定义的模块注解，来加深对模块注解的理解。

实现模块注解有2中方式：

1、import具体实现类——ApusicConfiguration.class。

2、import ImportSelector接口的具体实现类——ApusicConfigImportSelector

第二种方式可以在ImportSelector接口的具体实现类中添加判断逻辑

第一种方式代码：EnableApusicConfig.java

package com.apusic.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.Import;
import com.apusic.config.ApusicConfiguration;
 
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
//通过ImportSelector的实现类,进行自己的逻辑判断
//@Import(ApusicConfigImportSelector.class)
//指向具体的实现类
@Import(ApusicConfiguration.class)//
public @interface EnableApusicConfig {
}

第一种方式代码：ApusicConfiguration.java

package com.apusic.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
 
//EnableApusicConfig注解具体实现类
@Configuration
public class ApusicConfiguration {
@Bean
public String helloApusicString()
{
return "hello,ApusicConfig";
}
}

第一种方式代码：ConfigurationApusicTest.java

package com.apusic.test;
 
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
import com.apusic.annotation.EnableApusicConfig;
 
@EnableApusicConfig
public class ConfigurationApusicTest {
public static void main(String[] args) {
ConfigurableApplicationContext context = new SpringApplicationBuilder(ConfigurationApusicTest.class)
.web(WebApplicationType.NONE)
.run(args);
 
String bean = context.getBean("helloApusicString",String.class);

System.out.println(bean);
context.close();
}
}

第二种方式代码：EnableApusicConfig.java

package com.apusic.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.Import;
import com.apusic.config.ApusicConfiguration;
 
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
//通过ImportSelector的实现类,进行自己的逻辑判断
//@Import(ApusicConfigImportSelector.class)
//指向具体的实现类
@Import(ApusicConfiguration.class)//
public @interface EnableApusicConfig {
}

第二种方式代码：ApusicConfigImportSelector.java

package com.apusic.annotation;
import org.springframework.context.annotation.ImportSelector;
import org.springframework.core.type.AnnotationMetadata;
import com.apusic.config.ApusicConfiguration;
import com.apusic.config.WbmConfiguration;
public class ApusicConfigImportSelector implements ImportSelector{
 
@Override
public String[] selectImports(AnnotationMetadata importingClassMetadata) {
System.out.println("111111111111111111111"+importingClassMetadata.getClassName());
if(importingClassMetadata.getClassName().equals("com.apusic.test.ConfigurationApusicTest"))
{
return new String[] {ApusicConfiguration.class.getName()};
}
else if(importingClassMetadata.getClassName().equals("com.apusic.test.ConfigurationWbmTest")){

return new String[] {WbmConfiguration.class.getName()};
}
return null;
}
}

第二种方式代码：WbmConfiguration.java

package com.apusic.config;
 
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
 
//EnableApusicConfig注解具体实现类
@Configuration
public class ApusicConfiguration {
@Bean
public String helloApusicString()
{
return "hello,ApusicConfig";
}
}

第二种方式代码：WbmConfiguration.java

package com.apusic.config;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class WbmConfiguration {
@Bean
public String helloWBMApusicString()
{
return "hello,WbmConfig";
}
}

第二种方式代码：ConfigurationApusicTest.java

package com.apusic.test;
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
import com.apusic.annotation.EnableApusicConfig;
@EnableApusicConfig
public class ConfigurationApusicTest {
public static void main(String[] args) {
ConfigurableApplicationContext context = new SpringApplicationBuilder(ConfigurationApusicTest.class)
.web(WebApplicationType.NONE)
.run(args);
String bean = context.getBean("helloApusicString",String.class);
System.out.println(bean);
context.close();
}
}

第二种方式代码：ConfigurationWbmTest.java

package com.apusic.test;
 
import org.springframework.boot.WebApplicationType;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.context.ConfigurableApplicationContext;
 
import com.apusic.annotation.EnableApusicConfig;
 
@EnableApusicConfig
public class ConfigurationWbmTest {
public static void main(String[] args) {

ConfigurableApplicationContext context = new SpringApplicationBuilder(ConfigurationWbmTest.class)
.web(WebApplicationType.NONE)
.run(args);
String bean = context.getBean("helloWBMApusicString",String.class);
System.out.println(bean);
context.close();
}
}

总结：

1、import具体实现类——ApusicConfiguration.class。

我们通过Import指向具体的注解实现类，进行bean的装载

2、import ImportSelector接口的具体实现类——ApusicConfigImportSelector

我们通过Import指向一个ImportSelector接口的实现类，在里面进行判断处理，判断什么情况下装载哪些bean。

@EnableXXX注解能够简化配置，但是还是需要我们写@EnableXXX注解，并且需要通过import来指向具体的实现类。后面介绍的springboot自动装配，会告诉大家springboot是如何完成自动装配的。