Spring整理系列(16)——通过单元测试理解spring容器以及dubbo+zookeeper单元测试异常处理
一、先说一个结论：单元测试与主项目的spring容器是隔离的，也就是说，单元测试无法访问主项目spring容器，需要自己加载spring容器。
接下来是代码实例，WEB主项目出于运行状态，单元测试中可能会看到如下这样的代码：
代码一：当前类加载式
public class TestSpring {
@Test
public void testSpring(){
LoginService loginService = this.getBean("loginService");
}
//以下为容器实例声明及初始化、销毁
private ClassPathXmlApplicationContext context;
@Before
public void before(){
//加载spring容器
context = new ClassPathXmlApplicationContext("spring-context.xml");
}
@After
public void after(){
context.destroy();
}
//从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
public T getBean(String name) {
return (T) context.getBean(name);
}
//从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
public T getBean(Class requiredType) {
return context.getBean(requiredType);
}
} 代码二：继承加载式
/**
* @Description: 登录单元测试类
*/
public class LoginTest extends SpringJunitSupport{
@Autowired
private LoginService loginService;
@Test
public void testLogin(){
loginService.login();
}
}//让单元测试运行于spring环境，保证拥有spring框架相关支持
@RunWith(SpringJUnit4ClassRunner.class)
//加载spring容器
@ContextConfiguration("classpath:/spring-context.xml")
public class SpringJunitSupport {
}代码三：动态添加spring配置文件式
/**
* @Description: 登录单元测试类
*/
public class LoginTest{
//使用@Before注解方式加载spring容器配置文件，就不能通过自动装配的方式注入bean，因为自动装配注解执行要早于@Before
//@Autowired
private LoginService loginService;
private TestSpringContextSupport springContextSupport = null;
@Before
public void setUp() throws Exception {
springContextSupport = new TestSpringContextSupport();
//初始化spring容器时，再动态添加spring bean配置文件
springContextSupport.init(new String[] { "classpath:/support-quartz.xml" });
loginService = springContextSupport.getBean("loginService");
}
@Test
public void testLogin(){
loginService.login();
}
}public class TestSpringContextSupport {
//通过静态语句块初始化一个静态变量，用于存放spring容器配置文件
public static List contextList = new ArrayList();
static {
contextList.add("classpath:/spring-context.xml");
}
private ApplicationContext context;
//定义初始化方法，动态添加spring配置文件到静态配置文件集合
public void init(String[] contextFile) {
List list = new ArrayList();
list.addAll(contextList);
for (int i = 0; contextFile != null && i < contextFile.length; i++) {
list.add(contextFile[i]);
}
String[] x = new String[list.size()];
list.toArray(x);
//加载spring容器
context = new ClassPathXmlApplicationContext(x);
}
//从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
public T getBean(String name) {
return (T) context.getBean(name);
}
//从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
public T getBean(Class requiredType) {
return context.getBean(requiredType);
}
}
如上面三种方式，有一个共同点，就是在单元测试方法执行前，都大费周章的去加载了spring容器。
web主项目出于运行状态，单元测试为什么还要单独加载spring容器，因为web主项目的spring容器对单元测试是隔离的，通过如下手段验证：
验证1：
把单元测试所有加载spring容器的代码去掉，保证主项目出于运行状态，通过@Autowired注解(@Autowired注解可以装配spring内部bean)，获取spring应用上下文的bean，然后再通过其获取业务bean，代码如下：
/**
* @Description: 登录单元测试类
*/
public class LoginTest{
//自动装配spring应用上下文bean
@Autowired
private ApplicationContext context;
@Test
public void testLogin(){
//通过应用上下文bean，获取业务bean
LoginService loginService = (LoginService)context.getBean("loginService");
loginService.login();
}
}结果一定是空指针异常，context对象为null。
验证二，把web主项目停掉，单元测试使用上面第二种继承的方式加载spring容器，其它同上，代码如下：
/**
* @Description: 登录单元测试类，继承SpringJunitSupport加载spring容器
*/
public class LoginTest extends SpringJunitSupport{
//自动装配spring应用上下文bean
@Autowired
private ApplicationContext context;
@Test
public void testLogin(){
//通过应用上下文bean，获取业务bean
LoginService loginService = (LoginService)context.getBean("loginService");
loginService.login();
}
}@RunWith(SpringJUnit4ClassRunner.class)
//加载spring容器
@ContextConfiguration("classpath:/spring-context.xml")
public class SpringJunitSupport {
}
结果一切正常，如此就验证了单元测试与主项目的spring容器是隔离的，单元测试必须自己加载spring容器。
上面一直在说加载spring容器，其实就是加载配置文件，把配置文件里面的bean加载到spring容器中，上面的验证也一直通过在spring容器中搜索bean对象进行的，理解并应用这一点是非常重要的。
最后的彩蛋，理解是因为项目中有困惑，探究之后才能领悟透彻，比如一个实例：
1、主项目运行，提供服务接口，采用的方式为dubbo+zookeeper方式；
2、单元测试，调用提供者提供的服务，采用继承式加载spring配置文件；
3、抛出异常：地址已经被绑定使用(Address already in use: bind)
java.lang.IllegalStateException: Failed to load ApplicationContext
......
Caused by: com.alibaba.dubbo.rpc.RpcException: Fail to start server(url: dubbo://127.0.0.1:20880/......
......
Caused by: com.alibaba.dubbo.remoting.RemotingException: Failed to bind NettyServer on /127.0.0.1:20880, cause: Failed to bind to: /0.0.0.0:20880
......
Caused by: org.jboss.netty.channel.ChannelException: Failed to bind to: /0.0.0.0:20880
......
Caused by: java.net.BindException: Address already in use: bind
......4、异常原因：因为采用的是dubbo+zookeeper方式，主项目spring提供者注册了127.0.0.1:20880，单元测试加载spring配置文件想要注册0.0.0.0:20880地址，但是20880已经被主容器占用，所以单元测试无法正常加载。
5、解决办法：将主容器停掉，单独使用单元测试，即作为服务端又作为客户端
6、再次抛出异常：
DEBUG [2016-08-18 18:30:26,603] - ZkClient.java () - Closing ZkClient...
INFO [2016-08-18 18:30:26,603] - ZkEventThread.java () - Terminate ZkClient event thread.
DEBUG [2016-08-18 18:30:26,603] - ZkConnection.java () - Closing ZooKeeper connected to 119.254.166.167:2181
DEBUG [2016-08-18 18:30:26,603] - ZooKeeper.java () - Closing session: 0x15678a538f900ef
DEBUG [2016-08-18 18:30:26,603] - ClientCnxn.java () - Closing client for session: 0x15678a538f900ef
......
DEBUG [2016-08-18 18:30:26,808] - ZkClient.java () - Closing ZkClient...done
INFO [2016-08-18 18:30:26,810] - DubboProtocol.java () - [DUBBO] Close dubbo server: /127.0.0.1:20880, dubbo version: 2.5.4, current host: 127.0.0.1
INFO [2016-08-18 18:30:26,812] - AbstractServer.java () - [DUBBO] Close NettyServer bind /0.0.0.0:20880, export /127.0.0.1:20880, dubbo version: 2.5.4, current host: 127.0.0.1
INFO [2016-08-18 18:30:26,812] - ClientCnxn.java () - EventThread shut down for session: 0x15678a538f900ef
ERROR [2016-08-18 18:30:26,813] - FailbackRegistry.java () - [DUBBO] Failed to uregister dubbo://127.0.0.1:20880/......
com.alibaba.dubbo.rpc.RpcException: Failed to unregister dubbo://127.0.0.1:20880/业务方法......
at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry.doUnregister(ZookeeperRegistry.java:108)
at com.alibaba.dubbo.registry.support.FailbackRegistry.unregister(FailbackRegistry.java:160)
at com.alibaba.dubbo.registry.integration.RegistryProtocol$1.unexport(RegistryProtocol.java:130)
at com.alibaba.dubbo.config.ServiceConfig.unexport(ServiceConfig.java:270)
at com.alibaba.dubbo.config.spring.ServiceBean.destroy(ServiceBean.java:255)
at org.springframework.beans.factory.support.DisposableBeanAdapter.destroy(DisposableBeanAdapter.java:258)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroyBean(DefaultSingletonBeanRegistry.java:538)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingleton(DefaultSingletonBeanRegistry.java:514)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingleton(DefaultListableBeanFactory.java:831)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingletons(DefaultSingletonBeanRegistry.java:483)
at org.springframework.context.support.AbstractApplicationContext.destroyBeans(AbstractApplicationContext.java:923)
at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:897)
at org.springframework.context.support.AbstractApplicationContext$1.run(AbstractApplicationContext.java:811)
Caused by: java.lang.NullPointerException
at org.I0Itec.zkclient.ZkClient$8.call(ZkClient.java:720)
at org.I0Itec.zkclient.ZkClient.retryUntilConnected(ZkClient.java:675)
at org.I0Itec.zkclient.ZkClient.delete(ZkClient.java:716)
at com.alibaba.dubbo.remoting.zookeeper.zkclient.ZkclientZookeeperClient.delete(ZkclientZookeeperClient.java:57)
at com.alibaba.dubbo.registry.zookeeper.ZookeeperRegistry.doUnregister(ZookeeperRegistry.java:106)
... 12 more
上面需要注意的关键信息可以归结为：zookeeper客户端关闭(Closing ZkClient…)、dubbo服务关闭(Close dubbo server….)、注销dubbo的某个方法失败(Failed to uregister dubbo://127.0.0.1:20880/…)
虽然没细探究到底怎么回事，但是感觉应该是单元测试同时加载服务端和客户端(即加载spring配置文件)，当测试方法执行完毕需要关闭服务的时候，由于先后顺序问题引发的异常。
7、再次解决办法：提供者由主容器启动，至于单元测试，就到了上面最后的彩蛋那句话了，单元测试作为客户端，只需要拿到服务端提供者的bean对象，就可以完成对提供者服务端的调用。
那么这个对象从哪里来，dubbo+zookeeper方式会在客户端配置订阅服务的配置文件，这个里面有提供者对应的bean，所以单元测试只需要加载客户端订阅配置文件即可，代码如下：
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({ "classpath:/spring/test-dubbo-consumer.xml" })
public class CodeRuleRPCImplDubboTest {
@Autowired
private UserRPC UserRPC;
@Test
public void testGetUserByCode() {
bizCode = userRPC.getUserByCode("001");
}
}客户端订阅者配置文件：
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"
xmlns:task="http://www.springframework.org/schema/task" xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.0.xsd
http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.0.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd
http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.0.xsd
http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">
<dubbo:application name="SPRING_DUBBO_CONSUMER">dubbo:application>
<dubbo:registry address="zookeeper://127.0.0.1:2181"
check="true">dubbo:registry>
<dubbo:reference interface="com.test.rpc.UserRPC"
id="userRPC">dubbo:reference>
beans>至此以上问题解决，同时深入理解spring容器，单元测试，spring-bean之间的关系，同时也对dubbo和zookeeper加深了了解。