MyBatis之SqlSessionFactory-白红宇

MyBatis之SqlSessionFactory

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发布时间：2019-05-26

本文共 3950 字，大约阅读时间需要 13 分钟。

MyBatis官方文档

ORM框架

范围和生命周期

SqlSessionFactory 一旦被创建就应该在应用的运行期间一直存在，没有任何理由对它进行清除或重建。使用 SqlSessionFactory 的最佳实践是在应用运行期间不要重复创建多次，多次重建 SqlSessionFactory 被视为一种代码“坏味道（bad smell）”。因此 SqlSessionFactory 的最佳范围是应用范围。有很多方法可以做到，最简单的就是使用单例模式或者静态单例模式。【】

源码

package org.apache.ibatis.session;import java.sql.Connection;/** * Creates an {@link SqlSession} out of a connection or a DataSource * @author Clinton Begin */public interface SqlSessionFactory {
     // 自动提交属性默认为false  SqlSession openSession(); // 自定义自动提交属性  SqlSession openSession(boolean autoCommit);  SqlSession openSession(Connection connection);  SqlSession openSession(TransactionIsolationLevel level);  SqlSession openSession(ExecutorType execType);  SqlSession openSession(ExecutorType execType, boolean autoCommit);  SqlSession openSession(ExecutorType execType, TransactionIsolationLevel level);  SqlSession openSession(ExecutorType execType, Connection connection);  Configuration getConfiguration();}

实战

package com.sankuai.inf.leaf.segment.dao.impl;import com.sankuai.inf.leaf.segment.dao.IDAllocDao;import com.sankuai.inf.leaf.segment.dao.IDAllocMapper;import com.sankuai.inf.leaf.segment.model.LeafAlloc;import org.apache.ibatis.mapping.Environment;import org.apache.ibatis.session.Configuration;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.apache.ibatis.transaction.TransactionFactory;import org.apache.ibatis.transaction.jdbc.JdbcTransactionFactory;import javax.sql.DataSource;import java.util.List;public class IDAllocDaoImpl implements IDAllocDao {
       SqlSessionFactory sqlSessionFactory;    public IDAllocDaoImpl(DataSource dataSource) {
           TransactionFactory transactionFactory = new JdbcTransactionFactory();        Environment environment = new Environment("development", transactionFactory, dataSource);        Configuration configuration = new Configuration(environment);        configuration.addMapper(IDAllocMapper.class);        sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);    }    @Override    public List
   
     getAllLeafAllocs() {
           // 设置自动提交属性为false        SqlSession sqlSession = sqlSessionFactory.openSession(false);        try {
               // 查询不需要提交事务            return sqlSession.selectList("com.sankuai.inf.leaf.segment.dao.IDAllocMapper.getAllLeafAllocs");        } finally {
               // 关闭sqlSession            sqlSession.close();        }    }    @Override    public LeafAlloc updateMaxIdAndGetLeafAlloc(String tag) {
           // 自动提交属性默认为false        SqlSession sqlSession = sqlSessionFactory.openSession();        try {
               sqlSession.update("com.sankuai.inf.leaf.segment.dao.IDAllocMapper.updateMaxId", tag);            LeafAlloc result = sqlSession.selectOne("com.sankuai.inf.leaf.segment.dao.IDAllocMapper.getLeafAlloc", tag);            // 手动提交事务            sqlSession.commit();            return result;        } finally {
               // 关闭sqlSession            sqlSession.close();        }    }    @Override    public LeafAlloc updateMaxIdByCustomStepAndGetLeafAlloc(LeafAlloc leafAlloc) {
           SqlSession sqlSession = sqlSessionFactory.openSession();        try {
               sqlSession.update("com.sankuai.inf.leaf.segment.dao.IDAllocMapper.updateMaxIdByCustomStep", leafAlloc);            LeafAlloc result = sqlSession.selectOne("com.sankuai.inf.leaf.segment.dao.IDAllocMapper.getLeafAlloc", leafAlloc.getKey());            sqlSession.commit();            return result;        } finally {
               sqlSession.close();        }    }    @Override    public List
    
      getAllTags() {
           SqlSession sqlSession = sqlSessionFactory.openSession(false);        try {
               return sqlSession.selectList("com.sankuai.inf.leaf.segment.dao.IDAllocMapper.getAllTags");        } finally {
               sqlSession.close();        }    }}