Notice:本文對Validation api的使用主要是運用了Hibernate-Validator，其中Hibernate-Validator是validation-api的官方擴展，使用的pom如下：

  <dependency>
   <groupId>org.hibernate</groupId>
   <artifactId>hibernate-validator</artifactId>
   <version>5.2.4.Final</version>
  </dependency>

基于XML的校驗

validation-api支持Java Bean和校驗脫離，就是可以不在一起，這點方便Api定義者可以Java Bean，但是不添加校驗功能，而實現(xiàn)者能夠針對Java Bean的定義來決定是否需要校驗
例如，
數(shù)據(jù)模型：

public class OrderBaseModel {
    public long           id;
    public String         buyerCbAccoutId;
    public String         sellerCbAccoutId;
    public OrderSatusEnum status;
    public String         buyerCompanyName;
    public String         sellerCompanyName;
    public String         buyerBizPhone;
    public String         sellerBizPhone;
    public List           offers               = new ArrayList<>();
    public String         pickType;
    public List           receiveAddressGroups = new ArrayList<>();
    public String         message;
    public double         discountFee;
    public double         additionalFee;
    public String         payway;
    public long           payTimeout;
    public Long           autoConfirmReceipt;
    public long           appointedArrivalDate;
    ....get/set
}

校驗邏輯：

<constraint-mappings xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/mapping validation-mapping-1.1.xsd"
 xmlns="http://jboss.org/xml/ns/javax/validation/mapping" version="1.1">
  //指定校驗模型
 <default-package>com.alibaba.cb.api.order.model</default-package>
 <bean class="OrderBaseModel" ignore-annotations="true">
  //Class級別校驗，并設置忽略注解的校驗邏輯
  <class ignore-annotations="true">
    //支持jexl表達式的校驗邏輯
   <constraint annotation="org.hibernate.validator.constraints.ScriptAssert">
       <message>{com.alibaba.cb.api.order.model.ordermodel.receiveAddressGroups}</message>
    <element name="lang">jexl</element>
   // 這里如果不設置別名，_this指的是當前class的實例對象，可以取到任何一個對象中的屬性值進行聯(lián)動校驗
    <element name="script">
     if(_this.pickType=='push' and size(_this.receiveAddressGroups) > 2){ 
         return false;
      }else if(_this.pickType=='pull' and size(_this.receiveAddressGroups) > 10){
         return false; 
      }else if(size(_this.receiveAddressGroups) == 0) {
         return false;
      }
      return true;
    </element>
   </constraint>
  </class>
  <field name="buyerCbAccoutId">
   <constraint annotation="javax.validation.constraints.NotNull">
       <message>{com.alibaba.cb.api.order.model.ordermodel.buyerCbAccoutId}</message>
   </constraint>
  </field>
   <constraint annotation="javax.validation.constraints.Size">
       <message>{com.alibaba.cb.api.order.model.ordermodel.buyerCompanyNameSize}</message>
    <element name="max">20</element>
   </constraint>
  </field>
 // 支持正則校驗邏輯
  <field name="sellerBizPhone">
   <constraint annotation="javax.validation.constraints.Pattern">
       <message>{com.alibaba.cb.api.order.model.ordermodel.sellerBizPhonePattern}</message>
    <element name="regexp">^(|[0-9]{1,11})$</element>
   </constraint>
  </field>
  <field name="offers">
   <constraint annotation="javax.validation.constraints.Size">
       <message>{com.alibaba.cb.api.order.model.ordermodel.offers}</message>
    <element name="min">1</element>
   </constraint>
  </field>
  <field name="pickType">
   <constraint annotation="javax.validation.constraints.NotNull" >
      <message>{com.alibaba.cb.api.order.model.ordermodel.pickType}</message>
   </constraint>
  </field>
  <field name="discountFee">
   <constraint annotation="javax.validation.constraints.DecimalMin">
       <message>{com.alibaba.cb.api.order.model.ordermodel.discountFeeMin}</message>
    <element name="value">0</element>
   </constraint>
   <constraint annotation="javax.validation.constraints.Digits">
       <message>{com.alibaba.cb.api.order.model.ordermodel.discountFeeDigits}</message>
    <element name="integer">6</element>
    <element name="fraction">2</element>
   </constraint>
  </field>
  <field name="additionalFee">
   <constraint annotation="javax.validation.constraints.DecimalMin">
       <message>{com.alibaba.cb.api.order.model.ordermodel.additionalFeeMin}</message>
    <element name="value">0</element>
   </constraint>
   <constraint annotation="javax.validation.constraints.Digits">
       <message>{com.alibaba.cb.api.order.model.ordermodel.additionalFeeDigits}</message>
    <element name="integer">6</element>
    <element name="fraction">2</element>
   </constraint>
  </field>
  <field name="payway">
   <constraint annotation="javax.validation.constraints.NotNull">
     <message>{com.alibaba.cb.api.order.model.ordermodel.payway}</message>
   </constraint>
  </field>
  <field name="payTimeout">
   <constraint annotation="javax.validation.constraints.NotNull">
     <message>{com.alibaba.cb.api.order.model.ordermodel.payTimeoutNotNull}</message>
   </constraint>
//支持javascript表達式
   <constraint annotation="org.hibernate.validator.constraints.ScriptAssert">
       <message>{com.alibaba.cb.api.order.model.ordermodel.payTimeoutScript}</message>
    <element name="lang">javascript</element>
    <element name="script">
     _this &gt; new Date().getTime()
    </element>
   </constraint>
  </field>
  <field name="autoConfirmReceipt">
   <constraint annotation="javax.validation.constraints.Min">
       <message>{com.alibaba.cb.api.order.model.ordermodel.autoConfirmReceiptMin}</message>
    <element name="value">5</element>
   </constraint>
  </field>
 </bean>
</constraint-mappings>

從以上來看，xml其實就是annotation的另外一個翻版，但是意義卻比較大，可以實現(xiàn)定義和校驗實現(xiàn)分離
實施：

Configuration<?> config = Validation.byDefaultProvider().configure();
//對于xml文件
config.addMapping(new FileInputStream(validationFile));

基于annotation的校驗

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