dubbo客户端初始化问题

背景：工作中遇到了调用dubbo服务的场景，项目不是spring项目，我只想简单的调用服务端的接口，不想加入那么多配置。

在服务对接中，遇到调用dubbo服务的场景。按照公司的框架给的开发文档，要加配置！要写注解！不符合我的期望。我只是想用一下Dubbo！

于是把目光转向了dubbo官网的示例。

1、添加依赖

首先是添加pom依赖，我是一步步添加这么多的

<spring.version>4.2.5.RELEASE</spring.version>
 
<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>dubbo</artifactId>
   <version>2.6.2</version>
   <exclusions>
    <exclusion>
     <groupId>com.101tec</groupId>
     <artifactId>zkclient</artifactId>
    </exclusion>
   </exclusions>
  </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>
  <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>
        <dependency>
     <groupId>org.springframework</groupId>
     <artifactId>spring-tx</artifactId>
     <version>${spring.version}</version>
  </dependency>

2、写代码

a、有错误的代码示例（Dubbo的示例，这也是坑的开始。）

 ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"META-INF/spring/dubbo-demo-consumer.xml"});
        context.start();
        DemoService demoService = (DemoService) context.getBean("demoService"); // get remote service proxy
        while (true) {
            try {
                Thread.sleep(1000);
                String hello = demoService.sayHello("world"); // call remote method
                System.out.println(hello); // get result
            } catch (Throwable throwable) {
                throwable.printStackTrace();
            }
        }

 我这样用了，项目启动的时候一直报错，如下：

2018-10-15 16:30:30 [org.springframework.beans.factory.xml.XmlBeanDefinitionReader]-[INFO] Loading XML bean definitions from class path resource [E:/opt/dwf/dwf-dispatch-center/conf/dubbo_consumer.xml]
java.lang.reflect.InvocationTargetException
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
 at java.lang.reflect.Method.invoke(Method.java:498)
 at com.daojia.dwf.mvc.initial.app.AppInitial.initial(AppInitial.java:30)
 at com.daojia.dwf.mvc.DWFBootstrap.init(DWFBootstrap.java:71)
 at org.apache.catalina.core.ApplicationFilterConfig.initFilter(ApplicationFilterConfig.java:279)
 at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:260)
 at org.apache.catalina.core.ApplicationFilterConfig.<init>(ApplicationFilterConfig.java:105)
 at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:4950)
 at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5652)
 at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
 at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1694)
 at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1684)
 at java.util.concurrent.FutureTask.run(FutureTask.java:266)
 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
 at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ExceptionInInitializerError
 at com.daojia.dispatchcenter.inits.ServerInit.initial(ServerInit.java:38)
 ... 18 more
Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from class path resource [E:/opt/dwf/dwf-dispatch-center/conf/dubbo_consumer.xml]; nested exception is java.io.FileNotFoundException: class path resource [E:/opt/dwf/dwf-dispatch-center/conf/dubbo_consumer.xml] cannot be opened because it does not exist
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:344)
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:304)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:181)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:217)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
 at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:252)
 at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:127)
 at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:93)
 at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:129)
 at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:614)
 at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:515)
 at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
 at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
 at com.daojia.dispatchcenter.inits.DubboInit.<clinit>(DubboInit.java:33)
 ... 19 more
Caused by: java.io.FileNotFoundException: class path resource [E:/opt/dwf/dwf-dispatch-center/conf/dubbo_consumer.xml] cannot be opened because it does not exist
 at org.springframework.core.io.ClassPathResource.getInputStream(ClassPathResource.java:172)
 at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:330)
 ... 32 more

一直报找不到配置，这就奇怪了。尝试了许多次，依然这样。

我在代码里尝试把配置文件打印出来，内容是可以打印出来的。这说明路径是没有错的。

搜索了一番，

https://blog.csdn.net/tiananma0607/article/details/76595187

看了这篇文章之后，才了解到，

ClassPathXmlApplicationContext 对于文件的路径是有要求的。类似于类需要先被加载一样。我这配置文件很明显是没有被提前加载的。

因为使用框架的原因，我又不想把配置放到那个目录下，于是查看该继承的父类，找到了“FileSystemXmlApplicationContext”这个方法，改了之后，不再提示那个错误了。

  b、正常的代码

String configFolder = Config.getConfigFolder();
if(configFolder.startsWith("/")) {
    configFolder = "/" + configFolder;
}
String dubboConfig = configFolder + ServerInit.getConfigPath(SystemConstant.DUBBO_CONFIG_NAME);
log.warn("DubboInit,dubboConfig:" + dubboConfig);
FileSystemXmlApplicationContext context = new FileSystemXmlApplicationContext(new String[] {dubboConfig});
context.start();