CommonPool 配置示例

更新时间：2023-07-18 17:25:59

本文介绍 CommonPool 连接池配置依赖、配置文件和示例代码。

配置依赖

结合 hibernate 及 commonpool 对 oceanbase 数据库进行操作。

    <dependencies>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
            <version>2.7.0</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>5.0.7.Final</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-ehcache</artifactId>
            <version>4.3.11.Final</version>
        </dependency>
        <dependency>
            <groupId>com.alipay.oceanbase</groupId>
            <artifactId>oceanbase-client</artifactId>
            <version>3.2.3</version>
        </dependency>
    </dependencies>

实体类

import javax.persistence.*;

@Entity 
@Table(name = "user_test")
public class User { 

 public User() { }  
 
 @Id 
    //oracle模式不支持该主键自增
 //@GeneratedValue(strategy = GenerationType.IDENTITY)
 private Integer id; 
 
 @Column 
 private String username; 

 @Column 
 private String birthday;

 public User(Integer id, String username, String birthday) {
  this.id = id;
  this.username = username;
  this.birthday = birthday;
 }

 public Integer getId() {
  return id;
 }

 public void setId(Integer id) {
  this.id = id;
 }

 public String getUsername() {
  return username;
 }

 public void setUsername(String username) {
  this.username = username;
 }

 public String getBirthday() {
  return birthday;
 }

 public void setBirthday(String birthday) {
  this.birthday = birthday;
 }

 @Override
 public String toString() {
  return "User{" +
    "id=" + id +
    ", username='" + username + '\'' +
    ", birthday='" + birthday + '\'' +
    '}';
 }
}

hibernate

实体类映射文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        '-//Hibernate/Hibernate Mapping DTD 3.0//EN'
        'http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd'>
<hibernate-mapping>
    <!-- 类与表的映射制作在class元素上 -->
    <!-- name:全路径类名 -->
    <!-- table:表名 -->
    <class name="pojo.User" table="user_test">
        <!-- 主键的映射制作在id元素上 -->
        <!-- name:对象中用于作为主键的属性名 -->
        <!-- column:表中主键字段名 -->
        <!-- 如果name与column值相同，可以省略column -->
        <id name="id" column="id">
            <!--**要注意Hibernate主键生成策略**-->
        </id>
        <!-- 属性与字段的映射制作在property元素上 -->
        <!-- name:类中的属性名 -->
        <!-- column:表中的字段名 -->
        <!-- 如果name与column值相同，可以省略column -->
        <property name="username" />
        <property name="birthday" />
    </class>
</hibernate-mapping>

hibernate 配置文件：

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
      
        <!-- 数据库连接的配置 -->
        <!--oceanbase-->
        <property name="connection.driver_class">com.oceanbase.jdbc.Driver</property>
        <property name="connection.url">jdbc:oceanbase://10.100.xxx.xxx:18815/test</property>
        <property name="connection.username">admin@oracle</property>
        <property name="connection.password">admin</property>

        <!-- 可选配置 -->
      
        <!--是否支持方言  -->
    <!--<property name="dialect">org.hibernate.dialect.MySQLDialect</property>-->
      
        <!--在oracle模式下，必须有如下配置-->
        <property name="dialect">org.hibernate.dialect.Oracle10gDialect</property>
      
        <!--执行CURD时是否打印sql 语句  -->
        <property name="show_sql">true</property>
      
        <!--自动建表 该处注释根据需求打开或关闭-->
    <!--<property name="hbm2ddl.auto">update</property>-->
    <!--<property name="hbm2ddl.auto">create</property>-->

        <!-- 资源注册，此处即为实体类映射文件路径 -->
        <mapping resource="./UserModel.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

示例代码

实现 CommonPool 管理 Hibernate。

因 Hibernate 操作数据库的方式为 Session.xxxx();，所以此处选择实现一个 SessionPool。具体步骤如下。

首先创建几个必要的类：SessionPool(会话池)，SessionFactory(会话工厂)，SessionPoolConfig(会话池配置类)。

package sess;

import org.apache.commons.pool2.PooledObjectFactory;
import org.apache.commons.pool2.impl.GenericObjectPool;
import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
import org.hibernate.Session;

import java.io.Closeable;

public class SessionPool implements Closeable {

    //通用对象池，此处泛型决定了池中对象类型为org.hibernate.Session
    private GenericObjectPool<Session> internalPool;

    public SessionPool(GenericObjectPoolConfig poolConfig, PooledObjectFactory factory){
        if (this.internalPool != null) {
            try {
                closeInternalPool();
            } catch (Exception e) {
            }
        }
        this.internalPool = new GenericObjectPool(factory, poolConfig);
    }

    // 获取连接会话
    public Session getSession(){
        Session session = null;
        try {
            session = internalPool.borrowObject();
        } catch (Exception e) {
            throw new RuntimeException("Could not get session from the pool", e);
        }
        return session;
    }

    // 返还连接会话（将使用完毕的对象返回到池）
    public void returnSession(Session session){
        internalPool.returnObject(session);
    }

    @Override
    public void close(){
        this.closeInternalPool();
    }

    private void closeInternalPool() {
        try {
            internalPool.close();
        } catch (Exception e) {
            throw new RuntimeException("Could not destroy the pool", e);
        }
    }
}

package sess;

import org.apache.commons.pool2.BasePooledObjectFactory;
import org.apache.commons.pool2.PooledObject;
import org.apache.commons.pool2.impl.DefaultPooledObject;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;


public class SessionFactory extends BasePooledObjectFactory<Session> {

    // 创建新的数据库连接会话
    @Override
    public Session create() throws Exception {
        //加载配置信息
        Configuration conf = new Configuration().configure();
        //基于配置信息,创建SessionFactory对象
        org.hibernate.SessionFactory sessionFactory = conf.buildSessionFactory();
        //打开一个与数据库相关的session对象
        Session session = sessionFactory.openSession();
        return session;
    }

    // 使用PooledObject对数据库连接会话进行包装
    @Override
    public PooledObject<Session> wrap(Session session) {
        return new DefaultPooledObject(session);
    }

    // 由于validateObject失败或其它什么原因，对象实例从对象池中移除时调用
    // 不能保证对象实例被移除时所处的状态
    public void destroyObject(PooledObject<Session> pooledConnection) throws Exception {
        Session session = pooledConnection.getObject();
        session.close();
    }

    // 仅能被active状态的对象实例调用
    // 从对象池获取对象实例，在对象池返回该对象实例前，调用该方法校验其状态
    // 对象实例归还给对象池时，在调用passivateObject方法前，使用该方法校验其状态
    public boolean validateObject(PooledObject<Session> pooledConnection) {
        Session session = pooledConnection.getObject();
        try {
//            if (session.isValid(1))
            if (session.isOpen())
                return true;
            else
                return false;
        }catch(Exception e){
            return false;
        }
    }

    // 对象实例在归还给对象池时调用了passivateObject方法，通过对象池再次取到该对象实例
    // 在对象池返回该对象实例前，需要调用该方法
    public void activateObject(PooledObject<Session> pooledConnection) throws Exception {
  //。。。。。。。。。
    }

    // 对象实例归还给对象池时调用
    public void passivateObject(PooledObject<Session> pooledConnection) throws Exception {
  //。。。。。。。。。
    }
}

package sess;

import org.apache.commons.pool2.impl.GenericObjectPoolConfig;

public class SessionPoolConfig extends GenericObjectPoolConfig {

    public SessionPoolConfig(){
        setMaxTotal(10);
        setMaxIdle(5);
        setMinIdle(2);
    }
}

进行测试。

    @Test
    public void test() throws Exception {
        //创建公共池配置类
        SessionPoolConfig sessionPoolConfig = new SessionPoolConfig();
        //创建会话工厂
        SessionFactory sessionFactory = new SessionFactory();

        //配置会话池属性
        sessionPoolConfig.setMaxTotal(4);
        sessionPoolConfig.setMaxIdle(3);
        sessionPoolConfig.setMinIdle(2);
        sessionPoolConfig.setMaxWaitMillis(200);
        sessionPoolConfig.setTestOnBorrow(false);
        sessionPoolConfig.setTestOnReturn(false);

        //构建会话池
        SessionPool sessionPool = new SessionPool(sessionPoolConfig,sessionFactory);

        //测试
        for (int i = 1; i <= 10; i++) {
            User user = new User();
            user.setId(i);
            user.setUsername("Test");
            user.setBirthday("test");

            Session session = sessionPool.getSession();
            Transaction transaction = session.beginTransaction();
            session.save(user);

            System.out.println("第"+i+"次数据库操作，会话对象哈希值为："+session.hashCode());
            transaction.commit();
            //将该session返回到池
            sessionPool.returnSession(session);
        }
    }