工具類 - MyBatisSQL會話：SqlSessionUtils

package com.itheima.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

/**
 * 會話工具類
 */
public class SqlSessionUtils {
    private static SqlSessionFactory factory;

    private static ThreadLocal<SqlSession> localSessions = new ThreadLocal<SqlSession>();

    static {
        //例項化工廠建造類
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        //讀取核心配置檔案
        try (InputStream inputStream = Resources.getResourceAsStream("sqlMapConfig.xml")) {
            //建立工廠物件
            factory = builder.build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 得到會話物件
     * @return 會話物件
     */
    public static SqlSession getSession() {
        //從容器中得到會話
        SqlSession session = localSessions.get();
        //如果會話為空，則從工廠中建立會話，並且放入容器中
        if (session == null) {
            session = factory.openSession();
            localSessions.set(session);
        }
        return session;
    }

    /**
     * 得到工廠物件
     * @return 會話工廠物件
     */
    public static SqlSessionFactory getSqlSessionFactory() {
        return factory;
    }

    /**
     * 關閉會話
     */
    public static void closeSession() {
        //從容器中得到會話
        SqlSession session = localSessions.get();
        //如果會話不會為空，則關閉會話，並且從容器中刪除會話物件
        if (session != null) {
            session.close();
            localSessions.remove();
        }
    }
}