深度分析Dubbo SPI源码，扩展Dubbo Validation (groups)

本文主要是介绍深度分析Dubbo SPI源码，扩展Dubbo Validation (groups)，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

前言

架构是网关直接通过泛化调用Dubbo服务，不同于web Controller使用spring mvc模块来做到参数注解校验。不过不用担心Dubbo也考虑到了这一点，基于SPI机制提供了ValidationFilter

那我们就来看看他是如何实现的。

Dubbo源码实现

Dubbo SPI定义

你可能要问问了什么是Dubbo SPI，嗯…这个嘛，简单说是通过文件配置对应class路径后会被执行class里的invoke函数。其中的实现原理大家顺着Dubbo的ExtensionLoader去看下源码就能知道。

ValidationFilter说明

//在哪种服务类型激活
//这里的VALIDATION_KEY=“validation” 也就是我们在SPI中需要把key按这个规定定义
@Activate(group = {CONSUMER, PROVIDER}, value = VALIDATION_KEY, order = 10000)
public class ValidationFilter implements Filter {
    private Validation validation;

    public void setValidation(Validation validation) {
        this.validation = validation;
    }

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
      //如果SPI中定义了validation  那么就进行校验
        if (validation != null && !invocation.getMethodName().startsWith("$")
                && ConfigUtils.isNotEmpty(invoker.getUrl().getMethodParameter(invocation.getMethodName(), VALIDATION_KEY))) {
            try {
              	//执行参数校验
                Validator validator = validation.getValidator(invoker.getUrl());
                if (validator != null) {
                    validator.validate(invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments());
                }
            } catch (RpcException e) {
                throw e;
            } catch (ValidationException e) {
                //抛出异常 这里的ValidationException需要深挖一下，后面会说
                // only use exception's message to avoid potential serialization issue
                return AsyncRpcResult.newDefaultAsyncResult(new ValidationException(e.getMessage()), invocation);
            } catch (Throwable t) {
                return AsyncRpcResult.newDefaultAsyncResult(t, invocation);
            }
        }
        return invoker.invoke(invocation);
    }

}

基础使用

maven 依赖

springboot项目推荐使用

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-validation</artifactId>
</dependency>

手动依赖

<dependency>
  <groupId>javax.el</groupId>
  <artifactId>javax.el-api</artifactId>
  <version>3.0.0</version>
</dependency>
<dependency>
  <groupId>org.glassfish</groupId>
  <artifactId>javax.el</artifactId>
</dependency>
<dependency>
  <groupId>javax.validation</groupId>
  <artifactId>validation-api</artifactId>
</dependency>
<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-validator</artifactId>
</dependency>

DTO添加validation定义

import lombok.Data;

import javax.validation.constraints.NotBlank;
import javax.validation.constraints.NotNull;
import java.io.Serializable;

@Data
public class PracticeParam implements Serializable {
    @NotNull(message = "periodId不能为空")
    private Long periodId;
}

服务提供者interface

public interface IPracticeService {
    boolean practiceAdd(PracticeParam practiceParam);
}

Dubbo RPC单元测试

@SpringBootTest(classes = ClientApplication.class)
@RunWith(SpringRunner.class)
@Slf4j
public class PrecticeTest {
    @DubboReference(group = "user")
    private IPracticeService practiceLogicService;

    @Test
    public void add(){
        PracticeParam practiceParam=new PracticeParam();
        log.info(String.valueOf(practiceLogicService.practiceAdd(practiceParam)));
    }
}

测试结果

javax.validation.ValidationException: Failed to validate service: com.xx.contract.IPracticeService, method: practiceAdd, cause: [ConstraintViolationImpl{interpolatedMessage='periodId不能为空', propertyPath=periodId, rootBeanClass=class com.xx.request.PracticeParam, messageTemplate='periodId不能为空'}]

嗯看来是生效了，不过这和我们实际项目中还有些距离。不能把这个异常抛给网关，根据项目需要适配上我们的全局异常试试吧。

源码分析与扩展

Dubbo异常处理

再回到前面SPI文件

ExceptionFilter源码分析

//在服务提供者端生效
@Activate(group = CommonConstants.PROVIDER)
public class ExceptionFilter implements Filter, Filter.Listener {
    private Logger logger = LoggerFactory.getLogger(ExceptionFilter.class);
    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        return invoker.invoke(invocation);
    }
    @Override
    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
    		//异常处理逻辑
        if (appResponse.hasException() && GenericService.class != invoker.getInterface()) {
            try {
                Throwable exception = appResponse.getException();

                // directly throw if it's checked exception
                if (!(exception instanceof RuntimeException) && (exception instanceof Exception)) {
                    return;
                }
                // directly throw if the exception appears in the signature
                try {
                    Method method = invoker.getInterface().getMethod(invocation.getMethodName(), invocation.getParameterTypes());
                    Class<?>[] exceptionClassses = method.getExceptionTypes();
                    for (Class<?> exceptionClass : exceptionClassses) {
                        if (exception.getClass().equals(exceptionClass)) {
                            return;
                        }
                    }
                } catch (NoSuchMethodException e) {
                    return;
                }

                // for the exception not found in method's signature, print ERROR message in server's log.
                logger.error("Got unchecked and undeclared exception which called by " + RpcContext.getContext().getRemoteHost() + ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName() + ", exception: " + exception.getClass().getName() + ": " + exception.getMessage(), exception);

                // directly throw if exception class and interface class are in the same jar file.
                String serviceFile = ReflectUtils.getCodeBase(invoker.getInterface());
                String exceptionFile = ReflectUtils.getCodeBase(exception.getClass());
                if (serviceFile == null || exceptionFile == null || serviceFile.equals(exceptionFile)) {
                    return;
                }
                // directly throw if it's JDK exception
                String className = exception.getClass().getName();
                if (className.startsWith("java.") || className.startsWith("javax.")) {
                    return;
                }
                // directly throw if it's dubbo exception
                if (exception instanceof RpcException) {
                    return;
                }
                // otherwise, wrap with RuntimeException and throw back to the client
                //重点时这句，替换异常信息
                appResponse.setException(new RuntimeException(StringUtils.toString(exception)));
            } catch (Throwable e) {
                logger.warn("Fail to ExceptionFilter when called by " + RpcContext.getContext().getRemoteHost() + ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName() + ", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);
            }
        }
    }
    @Override
    public void one rror(Throwable e, Invoker<?> invoker, Invocation invocation) {
        logger.error("Got unchecked and undeclared exception which called by " + RpcContext.getContext().getRemoteHost() + ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName() + ", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);
    }
    // For test purpose
    public void setLogger(Logger logger) {
        this.logger = logger;
    }
}

项目定制化扩展

定义SPI

项目结构说明

文件定义（Dubbo SPI需要严格按如下路径和文件名）

src/main/resources/META-INF/dubbo/org.apache.dubbo.rpc.Filter

文件内容

validation=com.xx.xx.config.DubboValidationFilter
exception=com.xx.xx.config.DubboExceptionFilter

自定义DubboValidationFilter

import com.xx.exception.ParamException;
import org.apache.dubbo.common.extension.Activate;
import org.apache.dubbo.common.utils.ConfigUtils;
import org.apache.dubbo.rpc.*;
import org.apache.dubbo.validation.Validation;
import org.apache.dubbo.validation.Validator;

import javax.validation.ConstraintViolation;
import javax.validation.ConstraintViolationException;
import java.util.Set;

import static org.apache.dubbo.common.constants.CommonConstants.PROVIDER;
import static org.apache.dubbo.common.constants.FilterConstants.VALIDATION_KEY;

@Activate(group = {PROVIDER}, value = VALIDATION_KEY, order = -1)
public class DubboValidationFilter implements Filter {

    private Validation validation;

    public void setValidation(Validation validation) {
        this.validation = validation;
    }

    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        if (validation != null && !invocation.getMethodName().startsWith("$")
                && ConfigUtils.isNotEmpty(invoker.getUrl().getMethodParameter(invocation.getMethodName(), VALIDATION_KEY))) {
            try {
                Validator validator = validation.getValidator(invoker.getUrl());
                if (validator != null) {
                    //挖掘点 validate函数的源码
                    validator.validate(invocation.getMethodName(), invocation.getParameterTypes(), invocation.getArguments());
                }
            }
          //Dubbo源码里捕获的是ValidationException这个异常,原始信息变成了字符串，所以接下来
          //通过JValidator源码分析进行如下扩展
          catch (ConstraintViolationException e) {
            		//获取我们的异常，这里的异常时集合的，因为我们参数可能多个都不通过
                StringBuilder message = new StringBuilder();
                Set<ConstraintViolation<?>> violations = e.getConstraintViolations();
                for (ConstraintViolation<?> violation : violations) {
									  //这里只获取第一个不通过的原因
                    message.append(violation.getMessage().concat(";"));
                    break;
                }
                //项目自定义异常类型，网关可以捕获到该异常
                throw new ParamException(message.toString());
            } catch (RpcException e) {
                throw e;
            } catch (Throwable t) {
                return AsyncRpcResult.newDefaultAsyncResult(t, invocation);
            }
        }
        return invoker.invoke(invocation);
    }

}

JValidator源码分析

//Validated 校验过程
public void validate(String methodName, Class<?>[] parameterTypes, Object[] arguments) throws Exception {
        List<Class<?>> groups = new ArrayList<>();
        Class<?> methodClass = methodClass(methodName);
        if (methodClass != null) {
            groups.add(methodClass);
        }
				//异常返回信息 violations
        Set<ConstraintViolation<?>> violations = new HashSet<>();
        Method method = clazz.getMethod(methodName, parameterTypes);
        Class<?>[] methodClasses;
        if (method.isAnnotationPresent(MethodValidated.class)){
            methodClasses = method.getAnnotation(MethodValidated.class).value();
            groups.addAll(Arrays.asList(methodClasses));
        }
        // add into default group
        groups.add(0, Default.class);
        groups.add(1, clazz);

        // convert list to array
        Class<?>[] classgroups = groups.toArray(new Class[groups.size()]);

        Object parameterBean = getMethodParameterBean(clazz, method, arguments);
        if (parameterBean != null) {
            violations.addAll(validator.validate(parameterBean, classgroups ));
        }

        for (Object arg : arguments) {
            validate(violations, arg, classgroups);
        }

        if (!violations.isEmpty()) {
            logger.error("Failed to validate service: " + clazz.getName() + ", method: " + methodName + ", cause: " + violations);
            //这里原始异常是它，所以我们需要捕获它，得到violations
            throw new ConstraintViolationException("Failed to validate service: " + clazz.getName() + ", method: " + methodName + ", cause: " + violations, violations);
        }
    }

自定义DubboExceptionFilter

@Slf4j
@Activate(group = CommonConstants.PROVIDER)
public class DubboExceptionFilter extends ExceptionFilter {
    @Override
    public Result invoke(Invoker<?> invoker, Invocation invocation) throws RpcException {
        return invoker.invoke(invocation);
    }
    @Override
    public void onResponse(Result appResponse, Invoker<?> invoker, Invocation invocation) {
        log.error("dubbo global exception ---------->{}", appResponse.getException());
        if (appResponse.hasException() && GenericService.class != invoker.getInterface()) {
            try {
                Throwable exception = appResponse.getException();

                // 自定义异常处理
                if (exception instanceof ParamException) {
                		//按项目log收集规范输出
                    log.error("dubbo service exception ---------->{}", exception);
                    return;
                }
                ......
            } catch (Throwable e) {
                log.warn("Fail to ExceptionFilter when called by " + RpcContext.getContext().getRemoteHost() + ". service: " + invoker.getInterface().getName() + ", method: " + invocation.getMethodName() + ", exception: " + e.getClass().getName() + ": " + e.getMessage(), e);
            }
        }
    }
}

RPC单元测试

org.apache.dubbo.remoting.RemotingException: com.xx.exception.ParamException: periodId不能为空;
com.xx.exception.ParamException: periodId不能为空;

高级进阶

我们在业务里一个DTO对象会用于新增或更新，在新增时不需要主键ID，在更新时需要主键ID。

那我们就需要引入分组的概念了

定义validation groups

在API模块中定义两个分组

//用于新增
public interface InsertValidation {
}

//用于更新
public interface UpdateValidation {
}

定义DTO

@Data
public class PracticeParam implements Serializable {

		//只用于更新
    @NotNull(groups={UpdateValidation.class},message = "id不能为空")
    private Integer id;

// 如果两组校验都需要可以省去group的定义，完整的如下
//    @NotBlank(groups={InsertValidation.class, UpdateValidation.class},message = "名称不能为空")
    @NotNull(message = "periodId不能为空")
    private Long periodId;
}

服务提供者interface

public interface IPracticeService {
		//因为periodId参数是默认不区分组的，所以这里省去了Validated注解
    boolean practiceAdd(PracticeParam practiceParam);

    boolean practiceEdit(@Validated(value = {UpdateValidation.class}) PracticeParam practiceParam);
}

完工，这样我们就齐活了，截个图看看真实运行情况吧

生产环境验证

感谢您的耐心看到这里，学海无涯继续奋斗！

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Java教程

深度分析Dubbo SPI源码，扩展Dubbo Validation (groups)

前言

Dubbo源码实现

Dubbo SPI定义

ValidationFilter说明

基础使用

maven 依赖

DTO添加validation定义

服务提供者interface

Dubbo RPC单元测试

源码分析与扩展

Dubbo异常处理

项目定制化扩展

定义SPI

自定义DubboValidationFilter

JValidator源码分析

自定义DubboExceptionFilter

RPC单元测试

高级进阶

定义validation groups

定义DTO

服务提供者interface

生产环境验证

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