DUBBO项目构建问题记录

　　目前公司需要对当前的业务进行微服务化改造，经过讨论选择使用用dubbo进行服务治理，并在我的业务功能模块中进行试点，由于之前写过dubbo相关的demo，基础知识就不再重复了，demo地址：

https://github.com/liujifei/dubbo.git

 工程的基本搭建参照了另一篇博客，写的十分详尽，推荐一下：

Maven多模块，Dubbo分布式服务框架，SpringMVC，前后端分离项目，基础搭建，搭建过程出现的问题

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基本配置完成之后，当使用组播的方式时没有发现问题，服务提供方和调用方都正常，当使用zk集群作为注册中心时，项目启动报错：

java.lang.NoClassDefFoundError: org/apache/curator/shaded/com/google/common/cache/CacheBuilder

处理方法：

在parent的pom.xml中dependencyManagement加入

<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-framework</artifactId>
<version>2.11.0</version>
</dependency>

子module的pom.xml中加入

<dependency>
<groupId>org.apache.curator</groupId>
<artifactId>curator-framework</artifactId>
</dependency>

问题解决。

另附zk集群配置方法：

<dubbo:registry address="zookeeper://10.20.153.10:2181?backup=10.20.153.11:2181,10.20.153.12:2181" />

或

<dubbo:registry protocol="zookeeper" address="10.20.153.10:2181,10.20.153.11:2181,10.20.153.12:2181" />

同中心多组的配置方法：

<dubbo:registry id="chinaRegistry" protocol="zookeeper" address="10.20.153.10:2181" group="china" />

<dubbo:registry id="intlRegistry" protocol="zookeeper" address="10.20.153.10:2181" group="intl" />

若遇到其他问题再记录

2018-04-12 11:05:16

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上面的provider搞定了，之后就是consumer。之前的调用方式是简单的sdk调用，服务化之后，需要将原web工程改造为dubbo调用方。

具体改造内容很简单主要包括两个文件：

1、pom.xml

<properties>

<!-- dubbo -->
<dubbo.version>2.6.1</dubbo.version>

</properties>

<!-- dubbo相关依赖 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo</artifactId>
<version>${dubbo.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo-rpc-dubbo</artifactId>
<version>${dubbo.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo-registry-api</artifactId>
<version>${dubbo.version}</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>dubbo-registry-zookeeper</artifactId>
<version>${dubbo.version}</version>
</dependency>

另外添加服务提供方api的依赖

2、spring-context.xml

• beans的namespace添加    xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"；xsi:schemaLocation中添加

  http://code.alibabatech.com/schema/dubbo
  http://code.alibabatech.com/schema/dubbo/dubbo.xsd

• 文件内容中添加

  <dubbo:application name="***" />
  <dubbo:registry address="***" />
  <dubbo:reference id="***" check="false" interface="***"/>

 回调：

当provider需要调用consumer中的回调方法时，首先需要在provider的配置文件中修改如下：

<dubbo:service interface="com.***.quality.api.QualityService" ref="qualityService" protocol="dubbo">
<dubbo:method name="excuteJob" >
<dubbo:argument index="1" callback="true" type="com.inspur.quality.api.CallBack"/>
</dubbo:method>
</dubbo:service>

另外需要注意的是，callback作为调用方实现的回调方法，其中不要包含需要dubbo来序列化的对象以及调用其方法，否则会报如下错误：

com.alibaba.dubbo.remoting.RemotingException: Fail to decode request due to: RpcInvocation

如：

        qualityService.excuteJob(job);
        // 生产报告
        qualityService.productReport(new CallBack() {

            @Override
            public void productReport(String dataBaseName, RuleResult[] result, String jobId, String instanceId) {
                Long time = System.currentTimeMillis();
                for(RuleResult single : result){
                    StringBuilder sqlB = new StringBuilder();
                    sqlB.append("insert into ");
                    sqlB.append(RESULT_TABLE);
                    sqlB.append(" (RESULTID,JOBID,INSTANCEID,CHECKID,RESULT) VALUES ( '");
                    sqlB.append(UUID.randomUUID().toString());
                    sqlB.append("','");
                    sqlB.append(jobId);
                    sqlB.append("','");
                    sqlB.append(instanceId);
                    sqlB.append("','");
                    sqlB.append(single.getRule().getRuleName());
                    sqlB.append("','");
                    sqlB.append(single.getResultNumber());
                    sqlB.append("')");
                    
                    JdbcUtil.exeSql(dataBaseName, sqlB.toString());
                }
            }
        }, dataSources[2]);

需要改成

        qualityService.excuteJob(job, new CallBack() {

            /**
             * @Field @serialVersionUID : TODO
             */
            private static final long serialVersionUID = -5914504806295102148L;

            @Override
            public String productReport(String dataBaseName, RuleResult[] result, String jobId, String instanceId) {
                Long time = System.currentTimeMillis();
                StringBuilder sqlB = new StringBuilder();
                for(RuleResult single : result){
                    sqlB.append("insert into ");
                    sqlB.append("QUALITY_RESULT");
                    sqlB.append(" (RESULTID,JOBID,INSTANCEID,CHECKID,RESULT) VALUES ( '");
                    sqlB.append(UUID.randomUUID().toString());
                    sqlB.append("','");
                    sqlB.append(jobId);
                    sqlB.append("','");
                    sqlB.append(instanceId);
                    sqlB.append("','");
                    sqlB.append(single.getRule().getRuleName());
                    sqlB.append("','");
                    sqlB.append(single.getResultNumber());
                    sqlB.append("')");
                    
                }
                return sqlB.toString();
            }
        }, dataSources[2]);

2018-04-18 15:14:13

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java.lang.NoSuchMethodError: org.apache.curator.utils.ZKPaths.fixForNamespace

问题原因：curator-framework版本为2.11.0与原项目中的包有冲突，改为原项目中的版本2.6.0后，问题解决。

2018-04-23 15:46:31

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代码的改造进行完之后，调用时发现报错如下：

服务提供方报错：

Caused by: com.alibaba.dubbo.remoting.RemotingException: com.alibaba.com.caucho.hessian.io.HessianProtocolException: 'com.***.quality.rule.MultiCountRule' could not be instantiated
com.alibaba.com.caucho.hessian.io.HessianProtocolException: 'com.***.quality.rule.MultiCountRule' could not be instantiated

Caused by: java.lang.reflect.InvocationTargetException

Caused by: java.lang.NullPointerException
at com.***.quality.rule.MultiCountRule.<init>(MultiCountRule.java:27)

服务调用方报错：

com.alibaba.dubbo.rpc.RpcException: Failed to invoke the method excuteJob in the service com.***.quality.api.QualityService. Tried 3 times of the providers [192.168.138.1:20880] (1/1) from the registry 172.22.5.2:2181 on the consumer 192.168.138.1 using the dubbo version 2.6.1. Last error is: Failed to invoke remote method: excuteJob, provider: dubbo://192.168.138.1:20880/com.***.quality.api.QualityService?anyhost=true&application=crawlManage&check=false&dubbo=2.6.1&excuteJob.1.callback=true&generic=false&interface=com.***.quality.api.QualityService&methods=newExpectCountRule,registDataSource,newNotNullRule,newMultiCountRule,newPatternRule,newUniqueRule,excuteJob,newIntegrityRule,newDataCountRule&pid=115308&register.ip=192.168.138.1&remote.timestamp=1524468008733&revision=0.0.1-SNAPSHOT&side=consumer&timestamp=1524468416127, cause: Fail to decode request due to: RpcInvocation [methodName=excuteJob, parameterTypes=[class com.***.quality.common.QualityCheckJob, interface com.***.quality.api.CallBack, class java.lang.String], arguments=null, attachments={path=com.***.quality.api.QualityService, input=3355, dubbo=2.6.1, version=0.0.0}]

com.alibaba.dubbo.rpc.RpcException: Failed to invoke the method newMultiCountRule in the service com.***.quality.api.QualityService. Tried 3 times of the providers ......

Caused by: com.alibaba.dubbo.remoting.RemotingException: Fail to decode request due to: RpcInvocation [methodName=excuteJob, parameterTypes=[class com.***.quality.common.QualityCheckJob, interface com.***.quality.api.CallBack, class java.lang.String], arguments=null, attachments={path=com.***.quality.api.QualityService, input=3355, dubbo=2.6.1, version=0.0.0}]

问题是由于参数excuteJob中的属性MultiCountRule的类中没有默认构造方法，导致hessian不能正确序列化。

        qualityService.productReport(new CallBack() {
            /**             * @Field @serialVersionUID : TODO             */            private static final long serialVersionUID = -5914504806295102148L;
            @Override            public void productReport(String dataBaseName, RuleResult[] result, String jobId, String instanceId) {                Long time = System.currentTimeMillis();                for(RuleResult single : result){                    StringBuilder sqlB = new StringBuilder();                    sqlB.append("insert into ");                    sqlB.append("QUALITY_RESULT");                    sqlB.append(" (RESULTID,JOBID,INSTANCEID,CHECKID,RESULT) VALUES ( '");                    sqlB.append(UUID.randomUUID().toString());                    sqlB.append("','");                    sqlB.append(jobId);                    sqlB.append("','");                    sqlB.append(instanceId);                    sqlB.append("','");                    sqlB.append(single.getRule().getRuleName());                    sqlB.append("','");                    sqlB.append(single.getResultNumber());                    sqlB.append("')");                                        JdbcUtil.exeSql(dataBaseName, sqlB.toString());                }            }        }, dataSources[2]);