Ribbon principle analysis namedcontextfactory

Tracking Ribbon In the process of source code, I saw  NamedContextFactory, Do not understand the essence of its existence , It is hereby recorded that .

  stay SpringCloud in , Due to the different systems between microservices , Different configurations may be required for remote calls , For example, order system A And inventory system B,ribbon request A,B The connection timeout that may be required and the number of retries are inconsistent , How to do it at this time ribbon request A,B System

When using different configurations . So this is introduced NamedContextFactory.

From the perspective of notes ：

It can create a series of sub containers , Allow a series of Specification Define your own... In each sub container bean. You can see FeignClientFactory,SpringClientFactory. It's from netflix Draw lessons from .

 Ribbon It uses SpringClientFactory.

In this NamedContextFactory There is also an internal interface ：Specification

The annotation means ： Use name,configuration Differentiated specifications .

in general ：NamedContextFactory  Maintain a collection of sub containers used by a client , To configure , Get... In the container bean etc. .

In fact, this content is a little similar nacos Of group,Specification Used to configure grouping , One Specification The instance is a configuration group , Press name distinguish .NamedContextFactory It maintains a series of Specification In the instance configuration.

NamedContextFactory According to these Specification Configuration creation in creates sub containers for some columns , For this sub container, also press this name grouping . This call NamedContextFactory#getInstance It's time to take name To get , It's about getting

In that container bean.

Let's take a look first NamedContextFactory  Some of the attributes inside .

1：propertySourceName,propertyName Constructor passed in assignment , A configuration will be generated in each sub container propertySourceName=propertyName

2: Map<String, AnnotationConfigApplicationContext> contexts Sub containers created by each group , It's all in this map in ,key It's grouped name. Namely Specification The one in the example name.

3：Map<String, C> configurations  Store a series of Specification example ,key Namely Specification Medium name.

4：ApplicationContext parent  The parent container of each child container , Generally, it is currently started spring Project context .

4：defaultConfigType A configuration class used by each sub container . Default configuration class .

1： Constructors .

The first parameter ： Is the default configuration class , This configuration class , It's a public , All sub containers will load it , Hereunder createContext Method .

The second parameter , The third parameter ： It's also public , Add a configuration attribute in each sub container ：propertySourceName=propertyName   Hereunder createContext Method .

 2： Set the parent container of all child containers , When creating sub containers , If it is not empty, it will put this parent Set as your own parent container . General parent It's all current spring project .

 3： This is used to create a series Specification The instance is passed in , Use the inside configuration Used to create sub containers .

 4:  Get the grouping of all sub containers name.

 5： Get a sub container , Can be rewritten .

 6： Create sub containers

protected AnnotationConfigApplicationContext createContext(String name) {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
        if (this.configurations.containsKey(name)) {
            //this.configurations.get(name)  What you get is the corresponding Specification example 
         for (Class<?> configuration : this.configurations.get(name) .getConfiguration()) {
                //  Enter a name of name Configuration class of the sub container of 
                context.register(configuration);
            }
        }
        for (Map.Entry<String, C> entry : this.configurations.entrySet()) {
            //  Self defined Specification The instance can also be named default. start , In this way, each sub container will also use injection .
            if (entry.getKey().startsWith("default.")) {
                for (Class<?> configuration : entry.getValue().getConfiguration()) {
                    context.register(configuration);
                }
            }
        }
        //  The default configuration class used by the sub container .
        context.register(PropertyPlaceholderAutoConfiguration.class,
                this.defaultConfigType);
       //  Add a configuration .
        context.getEnvironment().getPropertySources().addFirst(new MapPropertySource(
                this.propertySourceName,
                Collections.<String, Object>singletonMap(this.propertyName, name)));
        if (this.parent != null) {
            // Uses Environment from parent as well as beans
            //  The child container can get the name of the parent container bean

            context.setParent(this.parent);
              //  solve java 11 The problem of 
            // jdk11 issue
            // https://github.com/spring-cloud/spring-cloud-netflix/issues/3101
            context.setClassLoader(this.parent.getClassLoader());
        }
        context.setDisplayName(generateDisplayName(name));
        context.refresh();
        return context;
    }

7： according to name Get an instance , First, according to name Get a sub container and then get bean.

	public <T> T getInstance(String name, Class<T> type) {
		AnnotationConfigApplicationContext context = getContext(name);
		if (BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context,
				type).length > 0) {
			return context.getBean(type);
		}
		return null;
	}

---

practice

We customize a set Client, and Specification Feel this mechanism .

 As a client 

public class MytestClientNamedContextFactory  extends NamedContextFactory<MytestClientSpecification> {
    public MytestClientNamedContextFactory() {
        super(BeanBaseConfig.class, "test", "myTest");
    }
}

Specification example 

public class MytestClientSpecification implements NamedContextFactory.Specification {
    private String name;

    private Class<?>[] configuration;

    public MytestClientSpecification(){

    }

    public MytestClientSpecification(String name, Class<?>[] configuration){
        this.name=name;
        this.configuration=configuration;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public Class<?>[] getConfiguration() {
        return configuration;
    }
}

 Default configuration class 
@Configuration
public class BeanBaseConfig {
    @Bean
    public TestBean testBeanCommon(){
        TestBean testBean = new TestBean();
        testBean.setBeanName("byBeanBaseConfig1");
        return testBean;
    }
}

@Configuration
public class BeanBaseConfig1 {
    @Bean
    public TestBean testBean(){
        TestBean testBean = new TestBean();
        testBean.setBeanName("byBeanBaseConfig1");
        return testBean;
    }
}

@Configuration
public class BeanBaseConfig2 {
    @Bean
    public TestBean testBean1(){
        TestBean testBean = new TestBean();
        testBean.setBeanName("byBeanBaseConfig1");
        return testBean;
    }
}

public class TestBean {
    private String beanName="testBean";

    public String getBeanName() {
        return beanName;
    }

    public void setBeanName(String beanName) {
        this.beanName = beanName;
    }
}

test ：

@SpringBootTest
public class SpringRunTest {
    
    @Test
    public void test(){
        AnnotationConfigApplicationContext parent = new AnnotationConfigApplicationContext();
        parent.register(BeanBaseConfig.class);

        parent.refresh();

        //  Declare a client     Use the default configuration   BeanBaseConfig
        MytestClientNamedContextFactory testClient=new MytestClientNamedContextFactory();

        //  Declare the  specification  Actually this specification  Equivalent to one nacos group  Group the configurations 
        //  For example ribbon client in   It may be necessary to request that the configuration of the order microservice and the inventory microservice are different    You need it 
        MytestClientSpecification mytestClientSpecification1 = new MytestClientSpecification("specification1",new Class[]{BeanBaseConfig1.class});

        MytestClientSpecification mytestClientSpecification2 = new MytestClientSpecification("specification2",new Class[]{BeanBaseConfig1.class, BeanBaseConfig2.class});

        testClient.setConfigurations(Arrays.asList(mytestClientSpecification1,mytestClientSpecification2));
        testClient.setApplicationContext(parent);

        System.out.println(testClient.getInstances("specification1", TestBean.class));
        System.out.println("=====================================");
        System.out.println(testClient.getInstances("specification2", TestBean.class));
    }

}

give the result as follows ：

{[email protected], [email protected]}
=====================================
{[email protected], [email protected], [email protected]}

You can see through Specification Instances can separate sub containers .

Ribbon Also use this mechanism . Back analysis Ribbon I'll mention it when I get the source code .