(1). 概述
最近在做一些东西,想要实现对象容器之间的隔离,在看Feign时有看到这段代码,所以,特意做一个简单的实现.
(2). NamedContextFactory
package org.springframework.cloud.context.named;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.core.ResolvableType;
import org.springframework.core.env.MapPropertySource;
/**
* Creates a set of child contexts that allows a set of Specifications to define the beans
* in each child context.
*
* Ported from spring-cloud-netflix FeignClientFactory and SpringClientFactory
*
* @param <C> specification
* @author Spencer Gibb
* @author Dave Syer
*/
// TODO: add javadoc
public abstract class NamedContextFactory<C extends NamedContextFactory.Specification>
implements DisposableBean, ApplicationContextAware {
private final String propertySourceName;
private final String propertyName;
private Map<String, AnnotationConfigApplicationContext> contexts = new ConcurrentHashMap<>();
private Map<String, C> configurations = new ConcurrentHashMap<>();
private ApplicationContext parent;
private Class<?> defaultConfigType;
public NamedContextFactory(Class<?> defaultConfigType, String propertySourceName, String propertyName) {
this.defaultConfigType = defaultConfigType;
this.propertySourceName = propertySourceName;
this.propertyName = propertyName;
}
@Override
public void setApplicationContext(ApplicationContext parent) throws BeansException {
this.parent = parent;
}
public void setConfigurations(List<C> configurations) {
for (C client : configurations) {
this.configurations.put(client.getName(), client);
}
}
public Set<String> getContextNames() {
return new HashSet<>(this.contexts.keySet());
}
@Override
public void destroy() {
Collection<AnnotationConfigApplicationContext> values = this.contexts.values();
for (AnnotationConfigApplicationContext context : values) {
// This can fail, but it never throws an exception (you see stack traces
// logged as WARN).
context.close();
}
this.contexts.clear();
}
protected AnnotationConfigApplicationContext getContext(String name) {
if (!this.contexts.containsKey(name)) {
synchronized (this.contexts) {
if (!this.contexts.containsKey(name)) {
this.contexts.put(name, createContext(name));
}
}
}
return this.contexts.get(name);
}
protected AnnotationConfigApplicationContext createContext(String name) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
if (this.configurations.containsKey(name)) {
for (Class<?> configuration : this.configurations.get(name).getConfiguration()) {
context.register(configuration);
}
}
for (Map.Entry<String, C> entry : this.configurations.entrySet()) {
if (entry.getKey().startsWith("default.")) {
for (Class<?> configuration : entry.getValue().getConfiguration()) {
context.register(configuration);
}
}
}
context.register(PropertyPlaceholderAutoConfiguration.class, this.defaultConfigType);
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
context.setParent(this.parent);
// 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;
}
protected String generateDisplayName(String name) {
return this.getClass().getSimpleName() + "-" + name;
}
public <T> T getInstance(String name, Class<T> type) {
AnnotationConfigApplicationContext context = getContext(name);
try {
return context.getBean(type);
}
catch (NoSuchBeanDefinitionException e) {
// ignore
}
return null;
}
public <T> ObjectProvider<T> getLazyProvider(String name, Class<T> type) {
return new ClientFactoryObjectProvider<>(this, name, type);
}
public <T> ObjectProvider<T> getProvider(String name, Class<T> type) {
AnnotationConfigApplicationContext context = getContext(name);
return context.getBeanProvider(type);
}
public <T> T getInstance(String name, Class<?> clazz, Class<?>... generics) {
ResolvableType type = ResolvableType.forClassWithGenerics(clazz, generics);
return getInstance(name, type);
}
@SuppressWarnings("unchecked")
public <T> T getInstance(String name, ResolvableType type) {
AnnotationConfigApplicationContext context = getContext(name);
String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context, type);
if (beanNames.length > 0) {
for (String beanName : beanNames) {
if (context.isTypeMatch(beanName, type)) {
return (T) context.getBean(beanName);
}
}
}
return null;
}
public <T> Map<String, T> getInstances(String name, Class<T> type) {
AnnotationConfigApplicationContext context = getContext(name);
return BeanFactoryUtils.beansOfTypeIncludingAncestors(context, type);
}
/**
* Specification with name and configuration.
*/
public interface Specification {
String getName();
Class<?>[] getConfiguration();
}
}
(3). ClientFactoryObjectProvider
/*
* Copyright 2012-2020 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.cloud.context.named;
import java.util.Iterator;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.function.Supplier;
import java.util.stream.Stream;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.ObjectProvider;
import org.springframework.lang.Nullable;
/**
* Special ObjectProvider that allows the actual ObjectProvider to be resolved later
* because of the creation of the named child context.
*
* @param <T> - type of the provided object
*/
class ClientFactoryObjectProvider<T> implements ObjectProvider<T> {
private final NamedContextFactory<?> clientFactory;
private final String name;
private final Class<T> type;
private ObjectProvider<T> provider;
ClientFactoryObjectProvider(NamedContextFactory<?> clientFactory, String name, Class<T> type) {
this.clientFactory = clientFactory;
this.name = name;
this.type = type;
}
@Override
public T getObject(Object... args) throws BeansException {
return delegate().getObject(args);
}
@Override
@Nullable
public T getIfAvailable() throws BeansException {
return delegate().getIfAvailable();
}
@Override
public T getIfAvailable(Supplier<T> defaultSupplier) throws BeansException {
return delegate().getIfAvailable(defaultSupplier);
}
@Override
public void ifAvailable(Consumer<T> dependencyConsumer) throws BeansException {
delegate().ifAvailable(dependencyConsumer);
}
@Override
@Nullable
public T getIfUnique() throws BeansException {
return delegate().getIfUnique();
}
@Override
public T getIfUnique(Supplier<T> defaultSupplier) throws BeansException {
return delegate().getIfUnique(defaultSupplier);
}
@Override
public void ifUnique(Consumer<T> dependencyConsumer) throws BeansException {
delegate().ifUnique(dependencyConsumer);
}
@Override
public Iterator<T> iterator() {
return delegate().iterator();
}
@Override
public Stream<T> stream() {
return delegate().stream();
}
@Override
public T getObject() throws BeansException {
return delegate().getObject();
}
@Override
public void forEach(Consumer<? super T> action) {
delegate().forEach(action);
}
@Override
public Spliterator<T> spliterator() {
return delegate().spliterator();
}
private ObjectProvider<T> delegate() {
if (this.provider == null) {
this.provider = this.clientFactory.getProvider(this.name, this.type);
}
return this.provider;
}
}
(4). ActionSpecification
package help.lixin.camunda.demo.module;
import java.util.Arrays;
import java.util.Objects;
import org.springframework.cloud.context.named.NamedContextFactory;
public class ActionSpecification implements NamedContextFactory.Specification {
private String name;
private Class<?>[] configuration;
public ActionSpecification() {
}
public ActionSpecification(String name, Class<?>[] configuration) {
this.name = name;
this.configuration = configuration;
}
public String getName() {
return this.name;
}
public void setName(String name) {
this.name = name;
}
public Class<?>[] getConfiguration() {
return this.configuration;
}
public void setConfiguration(Class<?>[] configuration) {
this.configuration = configuration;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
ActionSpecification that = (ActionSpecification) o;
return Objects.equals(this.name, that.name) && Arrays.equals(this.configuration, that.configuration);
}
@Override
public int hashCode() {
return Objects.hash(this.name, this.configuration);
}
@Override
public String toString() {
return new StringBuilder("ActionSpecification{").append("name='").append(this.name).append("', ").append("configuration=").append(Arrays.toString(this.configuration)).append("}").toString();
}
}
(5). ActionContextFactory
package help.lixin.camunda.demo.module;
import lixin.help.config.ActionConfig;
import org.springframework.cloud.context.named.NamedContextFactory;
public class ActionContextFactory extends NamedContextFactory<ActionSpecification> {
public ActionContextFactory() {
// propertySourceName: 为map定义一个名称
// propertyName: map中的key
super(ActionConfig.class, "actionProperties", "tenant");
}
}
(6). ActionConfig
package lixin.help.config;
import lixin.help.service.IHelloService;
import lixin.help.service.impl.HelloService;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ActionConfig {
@Value("${tenant}")
private String tenant;
@Bean
public IHelloService helloService() {
System.out.println(tenant);
return new HelloService();
}
}
(7). ActionModuleConfig
package help.lixin.camunda.demo.module;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ActionModuleConfig {
@Bean
public ActionContextFactory actionContextFactory() {
return new ActionContextFactory();
}
}
(8). Application
package help.lixin.camunda.demo;
import help.lixin.camunda.demo.module.ActionContextFactory;
import lixin.help.service.IHelloService;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
@SpringBootApplication
public class Application {
public static void main(String... args) {
ConfigurableApplicationContext ctx = SpringApplication.run(Application.class, args);
ActionContextFactory actionContextFactory = ctx.getBean(ActionContextFactory.class);
// 此处的name可以是随意的,只是会根据这个name创建一个容器而已.
IHelloService helloService = actionContextFactory.getInstance("00007", IHelloService.class);
helloService.print();
}
}
(9). 总结
NamedContextFactory适用于根据固定的类,来生成对象,然后,这些在ApplicationContext内.
