概述
当下作为Java开发人员，运行一个服务基本上都会直接基于springboot，因此启动N个服务是需要启动N个springboot程序的。特别在本地环境通过intellij运行多个服务的时候，会需要占用较大的资源，电脑往往会出现卡顿现象。
本文主要介绍如何通过启动一个（入口） main 方法来运行多个服务，从而提高本地的开发爽度。
如何运行
本文例子参考于github的地址，文末有提供
创建项目
基本结构
通过 intellij 创建一个项目，并创建如下module
- launcher
- common-service
- first-service
- second-service
导入必要的依赖
<dependencyManagement>
<dependencies>
<!-- springboot -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<version>${spring.boot.version}</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>${spring.boot.version}</version>
</dependency>
<!-- 会引起一个JMX的问题，下文会说明如何解决 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
<version>${spring.boot.version}</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
</dependencyManagement>
单个服务说明
sbojvm-3-wm-1571537594.jpg
在 first-service 和 second-service 编写最基本的 web 所需要的类 Application 和 Controller
代码如下:
@SpringBootApplication
public class FirstApplication {
public static void main(String[] args) {
SpringApplication.run(FirstApplication.class, args);
}
}
@RestController
public class FirstController {
@GetMapping(value = "/index")
public String index() throws Exception {
return "Hello from first microservice!";
}
}
public class FirstServiceBackendRunner extends BackendRunner {
public FirstServiceBackendRunner() {
super("first", FirstApplication.class, CustomizationBean.class);
}
}
// 如果是springboot1.x
public class CustomizationBean implements EmbeddedServletContainerCustomizer {
@Value( "${backend.apps.first.contextPath}" )
private String contextPath;
@Value( "${backend.apps.first.port}" )
private Integer port;
@Override
public void customize(ConfigurableEmbeddedServletContainer container) {
container.setContextPath(contextPath);
container.setPort(port);
}
}
// 如果是springboot2.x
public class CustomizationBean implements WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> {
@Value( "${backend.apps.first.contextPath}" )
private String contextPath;
@Value( "${backend.apps.first.port}" )
private Integer port;
@Override
public void customize(ConfigurableServletWebServerFactory factory) {
factory.setContextPath(contextPath);
factory.setPort(port);
}
}
图片中的两个 yml 写下面一个内容即可
spring:
application:
name: FirstService
server:
port: 8110
servlet:
contextPath: /first
运行核心类
在common模块的核心类
public abstract class BackendRunner {
// 区分不通服务的配置
private String profile;
private ConfigurableApplicationContext appContext;
private final Class<?>[] backendClasses;
private Object monitor = new Object();
private boolean shouldWait;
protected BackendRunner(String profile, final Class<?>... backendClasses) {
this.backendClasses = backendClasses;
this.profile = profile;
}
public void run() {
if (appContext != null) {
throw new IllegalStateException("AppContext must be null to run this backend");
}
runBackendInThread();
waitUntilBackendIsStarted();
}
private void waitUntilBackendIsStarted() {
try {
synchronized (monitor) {
if (shouldWait) {
monitor.wait();
}
}
} catch (InterruptedException e) {
throw new IllegalStateException(e);
}
}
private void runBackendInThread() {
final Thread runnerThread = new BackendRunnerThread();
shouldWait = true;
runnerThread.setContextClassLoader(backendClasses[0].getClassLoader());
runnerThread.start();
}
public void stop() {
SpringApplication.exit(appContext);
appContext = null;
}
private class BackendRunnerThread extends Thread {
@Override
public void run() {
// 真正启动
// 设置环境，加载不同配置
System.setProperty("spring.profiles.active", profile);
appContext = SpringApplication.run(backendClasses, new String[] {});
synchronized (monitor) {
shouldWait = false;
monitor.notify();
}
}
}
}
启动核心类
public class MicroservicesStarter {
private static final List<Backend> activeBackends = new ArrayList<>();
public MicroservicesStarter() {
}
public static void startBackends() throws Exception {
startBackend("first-software", "com.gongdao.middleware.first.backendRunner.FirstServiceBackendRunner");
startBackend("second-software", "com.gongdao.middleware.second.backendRunner.SecondServiceBackendRunner");
}
/**
* 启动入口
*
* @param backendProjectName 项目名称，对应文件路径
* @param backendClassName 每个服务的启动类
* @throws Exception
*/
private static void startBackend(final String backendProjectName, final String backendClassName) throws Exception {
URL runnerUrl = new File(
System.getProperty("user.dir") + "/" + backendProjectName + "/target/classes/").toURI()
.toURL();
URL[] urls = new URL[] {runnerUrl};
URLClassLoader cl = new URLClassLoader(urls, MicroservicesStarter.class.getClassLoader());
Class<?> runnerClass = cl.loadClass(backendClassName);
Object runnerInstance = runnerClass.newInstance();
final Backend backend = new Backend(runnerClass, runnerInstance);
activeBackends.add(backend);
runnerClass.getMethod("run").invoke(runnerInstance);
}
public static void stopAllBackends()
throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
for (Backend b : activeBackends) {
b.runnerClass.getMethod("stop").invoke(b.runnerInstance);
}
}
private static class Backend {
private Class<?> runnerClass;
private Object runnerInstance;
public Backend(final Class<?> runnerClass, final Object runnerInstance) {
this.runnerClass = runnerClass;
this.runnerInstance = runnerInstance;
}
}
}
启动
点击 com.gongdao.middleware.LauncherApplication#main 启动
public class LauncherApplication {
public static void main(String[] args) {
try {
MicroservicesStarter.startBackends();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
sbojvm-1-wm-1571537591.jpg
sbojvm-2-wm-1571537593.jpg
补充说明
原理
利用了不同的classloader（默认类+指定的路径的class文件）去加载不同的服务
actuate包的JMX注册异常
在 springboot1.x 的时候出现
2019-09-27 15:13:11.343 ERROR 51322 --- [ Thread-5] o.s.b.a.e.jmx.EndpointMBeanExporter : Could not register JmxEndpoint [auditEventsEndpoint]
org.springframework.jmx.export.UnableToRegisterMBeanException: Unable to register MBean [org.springframework.boot.actuate.endpoint.jmx.AuditEventsJmxEndpoint@65a39e41] with key 'auditEventsEndpoint'; nested exception is javax.management.InstanceAlreadyExistsException: org.springframework.boot:type=Endpoint,name=auditEventsEndpoint
at org.springframework.jmx.export.MBeanExporter.registerBeanNameOrInstance(MBeanExporter.java:628) ~[spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBeanExporter.registerJmxEndpoints(EndpointMBeanExporter.java:174) [spring-boot-actuator-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBeanExporter.locateAndRegisterEndpoints(EndpointMBeanExporter.java:162) [spring-boot-actuator-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBeanExporter.doStart(EndpointMBeanExporter.java:158) [spring-boot-actuator-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.actuate.endpoint.jmx.EndpointMBeanExporter.start(EndpointMBeanExporter.java:337) [spring-boot-actuator-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:173) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:50) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:350) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:149) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:112) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:880) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:146) [spring-boot-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:545) [spring-context-4.3.23.RELEASE.jar:4.3.23.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:124) [spring-boot-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.20.RELEASE.jar:1.5.20.RELEASE]
at com.gongdao.middleware.common.BackendRunner$BackendRunnerThread.run(BackendRunner.java:58) [classes/:na]
......
通过引入 profile 让每个服务调用自己的配置文件，通过配置如下内容解决：
需要在 launcher 的resource下添加对应的 yml 文件
spring:
jmx:
default-domain: FirstService
endpoints:
jmx:
unique-names: true
domain: FirstService
参考资料
https://github.com/rameez4ever/springboot-demo/tree/master/springboot-multi-service-launcher
https://www.davidtanzer.net/david's%20blog/2015/04/01/running-multiple-spring-boot-apps-in-the-same-jvm.html
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