开发应用程序的过程中，经常会对一些比较重要的数据修改都需要写日志。在实际工作的工程中，这些数据都是存在表中的, 一个常见的做法是用触发器，在增删改的时候，用触发器将数据写入到另一张表中去，但个人不推荐这么做，原因如下:
1. 如果有多个表，得写很多触发器。
2. 触发器与数据库特性关联太紧，不同的数据库，虽然思路一样，但语法却不太一样。
对数据库表操作的日志记录，完全可以利用Hibernate的Interceptor特性来实现，也就是拦截器。下面用一个具体的例子来说明如何使用Hibernate的Interceptor。
创建一个表，用来记录日志的表
程序代码
Create TABLE `auditlog` (
`AUDIT_LOG_ID` BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
`ACTION` VARCHAR(100) NOT NULL,
`DETAIL` text NOT NULL,
`CreateD_DATE` DATE NOT NULL,
`ENTITY_ID` BIGINT(20) UNSIGNED NOT NULL,
`ENTITY_NAME` VARCHAR(255) NOT NULL,
PRIMARY KEY (`AUDIT_LOG_ID`)
) ENGINE=InnoDB AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;
创建这个表对应的实体类:
程序代码
@Entity
@Table(name = "auditlog")
public class AuditLog implements java.io.Serializable {
private Long auditLogId;
private String action;
private String detail;
private Date createdDate;
private long entityId;
private String entityName;
public AuditLog() {
}
public AuditLog(String action, String detail, Date createdDate,
long entityId, String entityName) {
this.action = action;
this.detail = detail;
this.createdDate = createdDate;
this.entityId = entityId;
this.entityName = entityName;
}
@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "AUDIT_LOG_ID", unique = true, nullable = false)
public Long getAuditLogId() {
return this.auditLogId;
}
.... 余下部分可以参考提供下载的源代码.
创建一个接口，所有实现了这个接口的实体类，都会写日志
程序代码
package com.mkyong.interceptor;
//market interface
public interface IAuditLog {
public Long getId();
public String getLogDeatil();
}
这里有两个方法,getId,getLogDetail 需要实现类去实现具体的方法，也就是要被写入到日志表中的详细记录.
创建一个类实现了IAuditLog 接口，并给出接口方法的具体实现
程序代码
@Entity
@Table(name="stock")
public class Stock implements java.io.Serializable,IAuditLog {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="STOCK_ID")
private Integer stockId;
@Column(name="STOCK_CODE", length=10)
private String stockCode;
@Column(name="STOCK_NAME", length=20)
private String stockName;
public Stock() {
}
public Stock(String stockCode, String stockName) {
this.stockCode = stockCode;
this.stockName = stockName;
}
....省略部分getter,setter。
@Transient
public Long getId(){
return this.stockId.longValue();
}
@Transient
public String getLogDeatil(){
StringBuilder sb = new StringBuilder();
sb.append(" Stock Id : ").append(stockId)
.append(" Stock Code : ").append(stockCode)
.append(" Stock Name : ").append(stockName);
return sb.toString();
}
}
创建记录日志的工具类，所有写日志公用
程序代码
public class AuditLogUtil{
public static void LogIt(String action,
IAuditLog entity){
Session tempSession = HibernateUtil.getSessionFactory().openSession();
try {
tempSession.getTransaction().begin();
AuditLog auditRecord = new AuditLog(action,entity.getLogDeatil()
, new Date(),entity.getId(), entity.getClass().toString());
tempSession.save(auditRecord);
tempSession.getTransaction().commit();
} finally {
tempSession.close();
}
}
}
创建 Hibernate interceptor 拦截器，这是重点，这里拦截所有需要记录日志的类,并处理
程序代码
public class AuditLogInterceptor extends EmptyInterceptor{
Session session;
private Set inserts = new HashSet();
private Set updates = new HashSet();
private Set deletes = new HashSet();
public void setSession(Session session) {
this.session=session;
}
@Override
public String onPrepareStatement(String sql) {
System.out.println("execute sql: " + sql);
return super.onPrepareStatement(sql);
}
public boolean onSave(Object entity,Serializable id,
Object[] state,String[] propertyNames,Type[] types)
throws CallbackException {
System.out.println("onSave");
if (entity instanceof IAuditLog){
inserts.add(entity);
}
return false;
}
public boolean onFlushDirty(Object entity,Serializable id,
Object[] currentState,Object[] previousState,
String[] propertyNames,Type[] types)
throws CallbackException {
System.out.println("onFlushDirty");
if (entity instanceof IAuditLog){
updates.add(entity);
}
return false;
}
public void onDelete(Object entity, Serializable id,
Object[] state, String[] propertyNames,
Type[] types) {
System.out.println("onDelete");
if (entity instanceof IAuditLog){
deletes.add(entity);
}
}
//called before commit into database
public void preFlush(Iterator iterator) {
System.out.println("preFlush");
}
//called after committed into database
public void postFlush(Iterator iterator) {
System.out.println("postFlush");
try{
for (Iterator it = inserts.iterator(); it.hasNext();) {
IAuditLog entity = (IAuditLog) it.next();
System.out.println("postFlush - insert");
AuditLogUtil.LogIt("Saved",entity);
}
for (Iterator it = updates.iterator(); it.hasNext();) {
IAuditLog entity = (IAuditLog) it.next();
System.out.println("postFlush - update");
AuditLogUtil.LogIt("Updated",entity);
}
for (Iterator it = deletes.iterator(); it.hasNext();) {
IAuditLog entity = (IAuditLog) it.next();
System.out.println("postFlush - delete");
AuditLogUtil.LogIt("Deleted",entity);
}
} finally {
inserts.clear();
updates.clear();
deletes.clear();
}
}
}
这里面有几个比较常用的方法:
onSave – 保存数据的时候调用，数据还没有保存到数据库.
onFlushDirty – 更新数据时调用，但数据还没有更新到数据库
onDelete – 删除时调用.
preFlush – 保存，删除，更新 在提交之前调用 (通常在 postFlush 之前).
postFlush – 提交之后调用(commit之后)
写测试例子, 添加数据，更新数据，然后再删掉
程序代码
public class App {
public static void main(String[] args) {
Session session = null;
Transaction tx = null;
try {
AuditLogInterceptor interceptor = new AuditLogInterceptor();
session = HibernateUtil.getSessionFactory().withOptions().interceptor(interceptor).openSession();
//session = HibernateUtil.getSessionFactory().openSession();
//interceptor.setSession(session);
//test insert
tx = session.beginTransaction();
Stock stockInsert = new Stock();
stockInsert.setStockCode("1111");
stockInsert.setStockName("yihaomen");
session.saveOrUpdate(stockInsert);
tx.commit();
//test update
tx = session.beginTransaction();
Query query = session.createQuery("from Stock where stockCode = '1111'");
Stock stockUpdate = (Stock)query.list().get(0);
stockUpdate.setStockName("yihaomen-update");
session.saveOrUpdate(stockUpdate);
tx.commit();
//test delete
tx = session.beginTransaction();
session.delete(stockUpdate);
tx.commit();
} catch (RuntimeException e) {
try {
tx.rollback();
} catch (RuntimeException rbe) {
// log.error("Couldn抰 roll back transaction", rbe);
}
throw e;
} finally {
if (session != null) {
session.close();
}
}
}
}
运行结果如下:
程序代码
onSave
execute sql: insert into stock (STOCK_CODE, STOCK_NAME) values (?, ?)
Hibernate: insert into stock (STOCK_CODE, STOCK_NAME) values (?, ?)
preFlush
postFlush
postFlush - insert
Hibernate: insert into auditlog (ACTION, CreateD_DATE, DETAIL, ENTITY_ID, ENTITY_NAME) values (?, ?, ?, ?, ?)
preFlush
execute sql: select stock0_.STOCK_ID as STOCK_ID1_1_, stock0_.STOCK_CODE as STOCK_CO2_1_, stock0_.STOCK_NAME as STOCK_NA3_1_ from stock stock0_ where stock0_.STOCK_CODE='1111'
Hibernate: select stock0_.STOCK_ID as STOCK_ID1_1_, stock0_.STOCK_CODE as STOCK_CO2_1_, stock0_.STOCK_NAME as STOCK_NA3_1_ from stock stock0_ where stock0_.STOCK_CODE='1111'
preFlush
onFlushDirty
execute sql: update stock set STOCK_CODE=?, STOCK_NAME=? where STOCK_ID=?
Hibernate: update stock set STOCK_CODE=?, STOCK_NAME=? where STOCK_ID=?
postFlush
postFlush - update
Hibernate: insert into auditlog (ACTION, CreateD_DATE, DETAIL, ENTITY_ID, ENTITY_NAME) values (?, ?, ?, ?, ?)
onDelete
preFlush
execute sql: delete from stock where STOCK_ID=?
Hibernate: delete from stock where STOCK_ID=?
postFlush
postFlush - delete
Hibernate: insert into auditlog (ACTION, CreateD_DATE, DETAIL, ENTITY_ID, ENTITY_NAME) values (?, ?, ?, ?, ?)
另外查看 auditLog 这张表, 可以看到日志成功写入
另外，如果是在SPRING 容器中使用，应该将这个interceptor 注入进去
程序代码
<bean id="hibermateInterceptor" class="com.yihaomen.interceptor.AuditLogInterceptor"/>
<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource">
<ref local="dataSource_jdbc"/>
</property>
<property name="entityInterceptor" ref="hibermateInterceptor"/>
..............
</bean>
这样就能实现对整个项目中需要记录日志的实体类进行拦截，并记录增删改的日志记录. 还是很方便的，重点就是 Hibernate interceptor 的使用.
测试在是在 Hibernate 4.3 下测试的, 如果是hibernate 3 在openSession的时候是不同的，hibernate4用了session = HibernateUtil.getSessionFactory().withOptions().interceptor(interceptor).openSession(); 如果是Hibernate 3的话，应该是:session = HibernateUtil.getSessionFactory().openSession(interceptor);。
项目代码下载:
Hibernate4 interceptor audit log sample download
来源：oschina
链接：https://my.oschina.net/u/2351717/blog/674597