Spring Mvc那點事---(40)SSM服務框架使用aop進行數據驗證

引子

  數據驗證是每個系統都經常要做的，大多數情況下，我們是直接在方法裏面使用if語句判斷是否爲空，判斷是否是數字類型，判斷是否滿足條件，如果不滿足，就返回客戶端錯誤信息，這樣的話，就會顯得麻煩，可能同樣的判斷，在每個方法裏面都有寫一遍，代碼顯得臃腫，而且冗餘。其實我們有另一種方法進行判斷，使用AOP進行攔截，在方法執行前，先把不滿足條件的字段進行驗證。

準備

    我們使用AOP進行判斷，主要的實現思路是結合註解實現，使用註解判斷標註要驗證的方法，然後使用AOP進行方法參數攔截，在dto對象上標註每個字段需要滿足的條件。需要使用如下JAR包validation-api.jar, spring-aop.jar

示例

我們創建一個項目， 首先創建攔截器，攔截器的作用是對方法進行攔截，對方法參數進行校驗，這裏使用MethodInterceptor環繞通知

package org.supersoft.erp.validation;

import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;

import javax.validation.ConstraintViolation;
import javax.validation.Validation;
import javax.validation.Validator;
import javax.validation.ValidatorFactory;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;


public class ValidationMethodInterceptor implements MethodInterceptor {

    /**
     * 環繞通知
     */
    public Object invoke(MethodInvocation invocation) throws Throwable {
        Method method = invocation.getMethod();

        Object[] arguments = invocation.getArguments();
        //判斷是否開啓校驗,凡是標註有@Validatable纔開啓校驗
        boolean validation = method.isAnnotationPresent(Validatable.class);
        if(!validation) {
            //沒有開啓校驗的直接執行
            return invocation.proceed();
        }
        try {

            //開啓校驗後，並且有參數的進行判斷
            if(arguments != null && arguments.length > 0){
                ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
                Validator validator = factory.getValidator();
                Validatable validatable = method.getAnnotation(Validatable.class);
                Class<?>[] groups = validatable.groups();
                for(Object argument : arguments){
                    Set<ConstraintViolation<Object>> constraintViolations = new HashSet<ConstraintViolation<Object>>();
                    System.out.println(argument+"-------");
                    if(groups != null && groups.length > 0)
                    {
                        constraintViolations = validator.validate(argument, groups);
                    } else 
                    {
                        constraintViolations = validator.validate(argument);
                    }

                    if(constraintViolations != null && !constraintViolations.isEmpty())
                    {
                        for(Iterator<ConstraintViolation<Object>> iterator = constraintViolations.iterator(); iterator.hasNext();)
                        {
                            String msgKey = iterator.next().getMessage();
                            Class<?> clazz = method.getReturnType();
                            return clazz.getConstructor(String.class).newInstance(msgKey);
                        }
                    }
                }
            }
        } catch(NoSuchMethodException e){
            System.out.println(method.getReturnType()+ "缺少僅包含一個String變量的構建方法");
        } catch (Exception e) {
              System.out.println(method.getName()+ "方法參數校驗失敗！");
        }

        return invocation.proceed();
    }

}

添加一個註解，用於標註攔截哪些方法

package org.supersoft.erp.validation;

import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@Target({ METHOD})
@Retention(RUNTIME)
public @interface Validatable {
    Class<?>[] groups() default {};
}

接下來建立幾個接口，用於操作分組，標註某個字段在執行什麼操作的時候進行判斷，比如同一個字段，有的時候需要在創建的時候進行判斷，有點需要在更新的時候進行判斷，

package org.supersoft.erp.validation;

public interface Create {

}
package org.supersoft.erp.validation;

public interface Retrieve {

}

package org.supersoft.erp.validation;

public interface Delete {

}

package org.supersoft.erp.validation;

public interface Update {

}

驗證規則

org.hibernate.validator.constraints包下面有許多定義好的驗證註解規則，可以直接標註在字段上，@NotBlank判斷是否爲空，@NotNull判斷是否爲null,引入hibernate-validator-5.3.0.Final.jar

<dependency>
                <groupId>org.hibernate</groupId>
                <artifactId>hibernate-validator</artifactId>
                <version>5.3.0.Final</version>
            </dependency>

創建一個dto對象

package org.supersoft.erp.rest.dto;

import javax.validation.constraints.NotNull;

import org.hibernate.validator.constraints.Length;
import org.hibernate.validator.constraints.NotBlank;
import org.supersoft.erp.validation.Create;
import org.supersoft.erp.validation.Delete;
import org.supersoft.erp.validation.Retrieve;
import org.supersoft.erp.validation.Update;

public class ProductDto {

    public final static String CODE_REQUIRED = "code-required";
    public final static String SCOPE_REQUIRED = "scope-required";
    public final static String SCOPE_LENGTH = "scope-length-30";
    public final static String CODE_LENGTH = "code-length-30";
    public final static String NAME_REQUIRED = "name-required";
    public final static String NAME_LENGTH = "name-length-30";


    //編碼不能爲空,並且長度最大30
    @NotBlank(message = CODE_REQUIRED, groups = { Update.class, Retrieve.class, Delete.class })
    @Length(message = SCOPE_LENGTH, max = 30)
  private String code;

    //名稱不能爲空
     @NotNull(message = NAME_REQUIRED, groups = { Create.class, Update.class })
      private String name;

      private String color;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getColor() {
        return color;
    }

    public void setColor(String color) {
        this.color = color;
    }
}

使用驗證註解，將驗證註解標註在方法上，並配置spring.aop

<?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:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="
     http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd
     http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
     http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <bean id="validationMethodInterceptor" class="org.supersoft.erp.validation.ValidationMethodInterceptor">
    </bean>

    <aop:config proxy-target-class="true">
        <aop:pointcut id="restMethodPointcut" expression="execution(* org.supersoft.erp.rest..*.*(..))" />
        <aop:advisor pointcut-ref="restMethodPointcut" advice-ref="validationMethodInterceptor" />
    </aop:config> 

</beans>

標註方法

   * 修改
     */
    @RequestMapping(value = "update", method = RequestMethod.POST)
    @ResponseBody
    @Validatable(groups = { Update.class })
    public CommonResponse<?> updateProduct(@RequestBody ProductDto product) {
        try
        {
            Product p=new Product();
            BeanUtils.copyProperties(product, p);
            productService.updateProduct(p);
            return CommonResponse.result();
        }
        catch(Throwable t)
        {
            return CommonResponse.error();
        }
    }

然後，我們啓動程序，就可以進行驗證了

demo下載 http://download.csdn.net/detail/zx13525079024/9677511