Audit Logging using Hibernate Interceptor in JPA 2.0

If you are using JPA 2.0 with Hibernate and you want to do audit logging from middle-ware itself, I believe you landed up on the exact place where you should be. You can try audit logging in your local environment by following this post.

Required JPA/Hibernate Maven Dependencies

<dependency>          <groupId>org.hibernate.java-persistence</groupId>          <artifactId>jpa-api</artifactId>          <version>2.0-cr-1</version> </dependency> <dependency>          <groupId>org.hibernate</groupId>          <artifactId>hibernate-entitymanager</artifactId>          <version>3.6.4.Final</version>    </dependency> <dependency>          <groupId>org.springframework</groupId>          <artifactId>spring-orm</artifactId>          <version>3.0.5.RELEASE</version> </dependency>

JPA Configuration in Spring Application Context File

For JPA/Hibernate, you need to configure entity manager, transaction, data source and JPA vendor in your ‘applicationContext.xml’ file.

<bean id="dataSource"          class="org.springframework.jdbc.datasource.DriverManagerDataSource"          p:driverClassName="oracle.jdbc.driver.OracleDriver"           p:url="jdbc:oracle:thin:@127.0.0.1:1521/mydbservice "          p:username="nvuser" p:password="nvpass" /> <bean id="entityManagerFactory"          class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"          p:persistenceUnitName="MyPersistentUnit"          p:persistenceXmlLocation="classpath*:persistence.xml"          p:dataSource-ref="dataSource" p:jpaVendorAdapter-ref="jpaAdapter">          <property name="loadTimeWeaver">             <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver"/>          </property>               </bean> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"                  p:entityManagerFactory-ref="entityManagerFactory" /> <bean id="jpaAdapter"                  class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"                  p:database="ORACLE" p:showSql="true" />

Persistence.xml Configuration

To enable the hibernate audit logging you need to configure a property called ‘hibernate.ejb.interceptor’ in persistence.xml file and the value of this property should be the class that extends the Hibernate ‘EmptyInterceptor’.

<?xml version=”1.0” encoding=”UTF-8”?> <persistence version="2.0"          xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"          xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">          <persistence-unit name=" MyPersistentUnit ">                                  //JPA Entity classes are configured here                  <class>com.mycom.entities.User </class>                             <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>                  <properties>                  <property name="hibernate.ejb.interceptor"                           value=" com.xxx.entities.baseentity.AuditLogInterceptor" />                  </properties>          </persistence-unit> </persistence>

Audit Logging Interceptor Implementation

Hibernate provides an interceptor called ‘EmptyInterceptor’ with following methods.

• onSave() – This method is called when an entity is saved, but the entity is not saved into database yet.
• onFlushDirty() – This method is called when an entity is updated, the entity is not update into database yet.
• onDelete () – This method is called when an entity is deleted , the entity is not deleted into database yet.
• preFlush() – This method is called before the saved, updated or deleted entities are not committed to the database.
• postFlush() – This method is called after the saved, updated or deleted entities are committed to database. This is called after preFlush() method.

To perform audit logging follow below steps:

• Create data base table to capture audit data:

          Audit [ Row_ID, Old_Value, New_Value, Column_Changed, Table_Changed,

                    Transaction_Id, User_ID]

• Create JPA entity say ‘AuditTrail’ for above table
• Create class ‘AuditLogInterceptor’ by extending Hibernate ‘EmptyInterceptor’.
• Override interceptor methods in ‘AuditLogInterceptor’
• Capture required information into AuditTrail entity and save entity

public class AuditLogInterceptor extends EmptyInterceptor {         private List<AuditTrail> auditTrailList = new ArrayList<AuditTrail>();       . . . . . .      // First Parameter: The entity which is being updated        // Second Parameter: The primary key of updated row    // Third Parameter:  Current states of updated entity        // Fourth Parameter: Previous states of updated entity     // Fifth Parameter: The variable names of updated entity    // Sixth Parameter: The type of variables of updated entity    @Override    public boolean onFlushDirty(Object entity, Serializable id,             Object[] currentState, Object[] previousState,             String[] propertyNames, Type[] types) {                                 // Get the table name from entity            Class<?> entityClass = entity.getClass();             Table tableAnnotation = entityClass.getAnnotation(Table.class);                                   for (int i = 0; i < currentState.length; i++) {                               // Track changes only for the states which are String or Number types                             if(!(previousState[i] instanceof String                      || previousState[i] instanceof Long                      || previousState[i] instanceof BigDecimal                       || previousState[i] instanceof Integer                      || previousState[i] instanceof Timestamp))                  {                           continue;                  }                                 // Check whether column value is updated                  if(previousState[i] != null && currentState[i] != null                    &&  !(previousState[i].equals(currentState[i]))){                                             AuditTrail auditTrail = new AuditTrail();                                 // Set updated table name                  auditTrail.setTableName(tableAnnotation.name());                  // Set updated column name                  Column col = null;                  try {                                                                           String filedName = propertyNames[i];                         if(filedName.contains("serialVersionUID")){                                   continue;                         }                         Character firstChar =  filedName.charAt(0);                         firstChar = Character.toUpperCase(firstChar);                         String filedNameSubStr = filedName.substring(1);                         String methodName = "get"+ firstChar+filedNameSubStr;                                                Class[] parameterTypes = new Class[]{};                                                    Method ueMethod = entityClass.getDeclaredMethod(methodName, parameterTypes);                         col = ueMethod.getAnnotation(Column.class);                                              } catch (Exception e) {                                 e.printStackTrace();                     }                    if(col != null){                           auditTrail.setColumnIdentifier(col.name());                           }                                // Set old value                 if(previousState[i] != null){                           auditTrail.setOldValue(previousState[i] == null  ? null :                          previousState[i].toString());                     }                                // Set new value                 if(currentState[i] != null){                           auditTrail.setNewValue(currentState[i] == null ? null:                          currentState[i].toString());                 }                                // Set database operation                 auditTrail.setOperation("Update");                                // Set row primary key value                 auditTrail.setRowIdentifier(id.toString());                   auditTrailList.add(auditTrail);                                        }                        }                                 return false;     }             @Override      public void postFlush(Iterator iterator) throws CallbackException {             // Set unique transaction id in all AuditTrail Entities  String transId = UUID.randomUUID().toString();                 for (AuditTrail auditTrail: auditTrailList) {             auditTrail.setTransactionId(transId); }    // Save ‘AuditTrail’ entity list into database using AuditDAO      }   }

Audit logging Sequence Flow

Issue Faced during Audit Logging Implementation

I faced an interesting issue during audit logging implementation in my application. Let me share that issue detail.

I had ‘AbstractDAO’ and 'AuditDAO' class extends this ‘AbstractDAO’. 'AuditDAO' class is configured as ‘@Repository’. ‘AbstractDAO’ has entity manager property which is initialized by Spring Container. I wanted to auto wire ‘AuditDAO’ in ‘AuditLogInterceptor’ to save ‘AuditTrail’ entity. But, this couldn’t happen. The reason was ‘AuditLogInterceptor’ was not defined as spring resource (like @Component or @Resources or @Repository). Hence's its property can’t be auto wired. Since, this interceptor is initialized by hibernate, I couldn't configure this as spring resource. Finally, I had to take the help of StackOverflow and got the idea to solve this problem. You can refer this issue and solution from here.