在系统中使用Bean Validation验证参数

转自：http://www.importnew.com/18561.html

为什么要使用Bean Validation？

 当我们实现某个接口时，都需要对入参数进行校验。例如下面的代码

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public String queryValueByKey(String parmTemplateCode, String conditionName, String conditionKey, String resultName) {         checkNotNull(parmTemplateCode, "parmTemplateCode not null");         checkNotNull(conditionName, "conditionName not null");         checkNotNull(conditionKey, "conditionKey not null");         checkNotNull(resultName, "resultName not null");

该方法输入的四个参数都是必填项。用代码进行参数验证带来几个问题

• 需要写大量的代码来进行参数验证。
• 需要通过注释来直到每个入参的约束是什么。
• 每个程序员做参数验证的方式不一样，参数验证不通过抛出的异常也不一样。

什么是Bean Validation？

Bean Validation是一个通过配置注解来验证参数的框架，它包含两部分Bean Validation API和Hibernate Validator。

• Bean Validation API是Java定义的一个验证参数的规范。
• Hibernate Validator是Bean Validation API的一个实现。

快速开始

引入POM

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<!-- Bean Validation start --> <dependency>     <groupId>org.hibernate</groupId>     <artifactId>hibernate-validator</artifactId>     <version>5.1.1.Final</version> </dependency> <dependency>     <groupId>javax.validation</groupId>     <artifactId>validation-api</artifactId>     <version>1.1.0.Final</version> </dependency> <dependency>     <groupId>javax.el</groupId>     <artifactId>el-api</artifactId>     <version>2.2</version> </dependency> <dependency>     <groupId>org.glassfish.web</groupId>     <artifactId>javax.el</artifactId>     <version>2.2.4</version> </dependency> <dependency>     <groupId>org.jboss.logging</groupId>     <artifactId>jboss-logging</artifactId>     <version>3.1.3.GA</version> </dependency> <dependency>     <groupId>com.fasterxml</groupId>     <artifactId>classmate</artifactId>     <version>1.0.0</version> </dependency> <dependency>     <groupId>log4j</groupId>     <artifactId>log4j</artifactId>     <version>1.2.13</version> </dependency> <!-- Bean Validation end -->

实例代码如下，可以验证Bean，也可以验证方法参数

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import java.lang.reflect.Method; import java.util.Set;   import javax.validation.ConstraintViolation; import javax.validation.Validation; import javax.validation.Validator; import javax.validation.constraints.Max; import javax.validation.constraints.NotNull; import javax.validation.executable.ExecutableValidator;   public class BeanValidatorTest {       public static void main(String[] args) {         Validator validator = Validation.buildDefaultValidatorFactory().getValidator();         //验证Bean参数，并返回验证结果信息         Car car = new Car();         Set<ConstraintViolation<Car>> validators = validator.validate(car);         for (ConstraintViolation<Car> constraintViolation : validators) {             System.out.println(constraintViolation.getMessage());         }           // 验证方法参数         Method method = null;         try {             method = Car.class.getMethod("drive", int.class);         } catch (SecurityException e) {         } catch (NoSuchMethodException e) {         }         Object[] parameterValues = { 80 };         ExecutableValidator executableValidator = validator.forExecutables();         Set<ConstraintViolation<Car>> methodValidators = executableValidator.validateParameters(car,             method, parameterValues);         for (ConstraintViolation<Car> constraintViolation : methodValidators) {             System.out.println(constraintViolation.getMessage());         }     }       public static class Car {           private String name;           @NotNull(message = "车主不能为空")         public String getRentalStation() {             return name;         }           public void drive(@Max(75) int speedInMph) {           }       } }

执行代码后，输出如下：

 

1 2	车主不能为空 最大不能超过75

使用代码验证方法参数

Validation验证不成功可能返回多个验证错误信息，我们可以包装下，当有错误时直接返回第一个错误的异常。

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import static com.google.common.collect.Iterables.getFirst;   import java.util.Set;   import javax.validation.ConstraintViolation; import javax.validation.Validation; import javax.validation.Validator;   /**  * 对象验证器  *  * @author tengfei.fangtf  * @version $Id: BeanValidator.java, v 0.1 Dec 30, 2015 11:33:40 PM tengfei.fangtf Exp $  */ public class BeanValidator {       /**      * 验证某个bean的参数      *      * @param object 被校验的参数      * @throws ValidationException 如果参数校验不成功则抛出此异常      */     public static <T> void validate(T object) {         //获得验证器         Validator validator = Validation.buildDefaultValidatorFactory().getValidator();         //执行验证         Set<ConstraintViolation<T>> constraintViolations = validator.validate(object);         //如果有验证信息，则将第一个取出来包装成异常返回         ConstraintViolation<T> constraintViolation = getFirst(constraintViolations, null);         if (constraintViolation != null) {             throw new ValidationException(constraintViolation);         }     }   }

我们可以在每个方法的第一行调用BeanValidator.validate来验证参数，测试代码如下,

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import static junit.framework.Assert.assertEquals;   import javax.validation.constraints.Max; import javax.validation.constraints.NotNull;   import org.junit.Test;   /**  *  * @author tengfei.fangtf  * @version $Id: BeanValidatorTest.java, v 0.1 Dec 30, 2015 11:33:56 PM tengfei.fangtf Exp $  */ public class BeanValidatorTest {       @Test     public void test() {         try {             BeanValidator.validate(new Car());         } catch (Exception e) {             assertEquals("rentalStation 车主不能为空", e.getMessage());         }     }       public static class Car {           private String name;           @NotNull(message = "车主不能为空")         public String getRentalStation() {             return name;         }           public void drive(@Max(75) int speedInMph) {           }       }   }

使用拦截器验证方法参数

我们在对外暴露的接口的入参中使用Bean Validation API配置参数约束，如下XXXService接口

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public interface XXXService {   GetObjectResponse getObject(GetObjectRequest getObjectRequest);   }

在getObject的GetObjectRequest参数中配置注解来约束参数。

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public class GetObjectRequest {       @Valid     @NotNull     private ObjectKey      objectKey;       @Size(max = 9)     private Map<String, Object> parameters;       @AssertTrue     public boolean isEntityNameOrCodeAtLeastOneIsNotBlank() {         return isNotBlank(entityName) || isNotBlank(entityCode);     } //代码省略 }

编写参数验证拦截器，当方法被调用时，触发Validator验证器执行验证，如果不通过则抛出ParameterValidationException。

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import static com.google.common.collect.Iterables.getFirst;   import java.util.Set;   import javax.validation.ConstraintViolation; import javax.validation.Validation; import javax.validation.Validator;   import org.aopalliance.intercept.MethodInterceptor; import org.aopalliance.intercept.MethodInvocation; import org.slf4j.Logger; import org.slf4j.LoggerFactory;   import com.xx.ParameterValidationException;   /**  * 参数验证拦截器，基于JSR-303 BeanValidation  *  * @author tengfei.fangtf  *  * @version $Id: TitanValidateInterceptor.java, v 0.1 Nov 23, 2015 11:13:55 PM tengfei.fangtf Exp $  */ public class TitanValidateInterceptor implements MethodInterceptor {       private static final Logger LOGGER = LoggerFactory.getLogger(TitanValidateInterceptor.class);       private final Validator     validator;       public TitanValidateInterceptor() {         validator = Validation.buildDefaultValidatorFactory().getValidator();     }       @Override     public Object invoke(MethodInvocation invocation) throws Throwable {         if (LOGGER.isDebugEnabled()) {             LOGGER.debug("Validate arguments");         }         //获取参数，并检查是否应该验证         Object[] arguments = invocation.getArguments();         for (Object argument : arguments) {             if (LOGGER.isDebugEnabled()) {                 LOGGER.debug("Validate argument: {}", argument);             }             Set<ConstraintViolation<Object>> constraintViolations = validator.validate(argument);             ConstraintViolation<Object> constraintViolation = getFirst(constraintViolations, null);             if (constraintViolation == null) {                 continue;             }             if (LOGGER.isInfoEnabled()) {                 LOGGER.info("ConstraintViolation: {}", constraintViolation);             }             throw new ParameterValidationException(constraintViolation.getPropertyPath() + " " + constraintViolation.getMessage());         }         return invocation.proceed();     }   }

配置拦截器core-service.xml，拦截XXXService的所有方法。

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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans"     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"     xmlns:context="http://www.springframework.org/schema/context"     xmlns:webflow="http://www.springframework.org/schema/webflow-config"     xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd          http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd          http://www.springframework.org/schema/webflow-config http://www.springframework.org/schema/webflow-config/spring-webflow-config-2.0.xsd"     default-autowire="byName">       <bean id="XXXService" class="org.springframework.aop.framework.ProxyFactoryBean">         <property name="target">             <bean class="com.XXXService" />         </property>         <property name="interceptorNames">             <list>                 <value>validateInterceptor</value>             </list>         </property>     </bean>       <bean id="validateInterceptor"         class="com.mybank.bkloanapply.common.validator.ValidateInterceptor" /> </beans>

参考资料

• 注解配置参考
• http://beanvalidation.org
• http://www.ibm.com/developerworks/cn/java/j-lo-jsr303/
• http://hibernate.org/validator/