文章简介

做java开发快一年，认为学习框架还是从最基本的学习，才能融汇贯通。做个笔记，mark一下。。。

项目和数据库结构（jar包去Maven仓库下载）

Role实体类（Role.java）

package org.lbl.conn.pojo;

/**
 * @description:
 * @author: libl
 * @date: 2018年8月2日 下午5:09:33
 */
public class Role {
    private Long id;
    private String roleName;
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getRoleName() {
        return roleName;
    }
    public void setRoleName(String roleName) {
        this.roleName = roleName;
    }
    public String getNote() {
        return note;
    }
    public void setNote(String note) {
        this.note = note;
    }
    private String note;
}

1.JDBC连接

1.JDBC例子（JdbcExample .java）

package org.lbl.conn.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;

import org.lbl.conn.pojo.Role;

/**
 * @description:JDBC连接数据库实现查询一个角色编号为1的角色名称。
 * @author: libl
 * @date: 2018年8月2日 下午4:44:09
 */
public class JdbcExample {

    private Connection getConnection() {
        Connection connection = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            String url = "jdbc:mysql://localhost:3306/db_role";
            String user = "root";
            String password = "root";
            connection = DriverManager.getConnection(url, user, password);
        } catch (ClassNotFoundException | SQLException ex) {
            Logger.getLogger(JdbcExample.class.getName()).log(Level.SEVERE, null, ex);
            return null;
        }
        return connection;
    }

    public Role getRole(Long id) {
        Connection connection = getConnection();
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            ps = connection.prepareStatement("select id, role_name, note from t_role where id=?");
            ps.setLong(1, id);
            rs = ps.executeQuery();
            while (rs.next()) {
                Long roleId = rs.getLong("id");
                String userName = rs.getString("role_name");
                String note = rs.getString("note");
                Role role = new Role();
                role.setId(roleId);
                role.setRoleName(userName);
                role.setNote(note);
                return role;
            }
        } catch (SQLException ex) {
            Logger.getLogger(JdbcExample.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            this.close(rs, ps, connection);
        }
        return null;
    }

    private void close(ResultSet rs, Statement stmt, Connection connection) {
        try {
            if (rs != null && rs.isClosed()) {
                rs.close();
            }
        } catch (SQLException ex) {
            Logger.getLogger(JdbcExample.class.getName()).log(Level.SEVERE, null, ex);
        }

        try {
            if (stmt != null && !stmt.isClosed()) {
                stmt.isClosed();
            }
        } catch (SQLException ex) {
            Logger.getLogger(JdbcExample.class.getName()).log(Level.SEVERE, null, ex);
        }

        try {
            if (connection != null && connection.isClosed()) {
                connection.isClosed();
            }
        } catch (SQLException ex) {
            Logger.getLogger(JdbcExample.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    public static void main(String[] args) {
        JdbcExample example = new JdbcExample();
        Role role = example.getRole(1L);
        System.err.println("role_name => " + role.getRoleName());
    }

}

2.Hibernate连接

1. Hibernate配置文件（hibernate.cfg.xml）

<?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>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.password">root</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost/db_role</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <mapping resource="org/lbl/conn/pojo/TRole.hbm.xml" />
    </session-factory>
</hibernate-configuration>

2.Hibernate实体类映射（TRole.hbm.xml）

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2018-8-2 18:07:22 by Hibernate Tools 3.5.0.Final -->
<!-- 描述POJO和数据库表的映射关系,Hibernate通过配置文件（或注解）就可以把数据库的数据直接映射到POJO上，可以通过操作POJO去操作数据库记录 -->
<hibernate-mapping>
    <class name="org.lbl.conn.pojo.Role" table="T_ROLE">
        <id name="id" type="java.lang.Long">
            <column name="ID" />
            <generator class="assigned" />
        </id>
        <property name="roleName" type="java.lang.String">
            <column name="ROLE_NAME" />
        </property>
        <property name="note" type="java.lang.String">
            <column name="NOTE" />
        </property>
    </class>
</hibernate-mapping>

3.Hibernate工具类（HibernateUtil .java）

package org.lbl.conn.hibernate;

import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

/**
 * @description:Hibernate工厂对象，用它来做全局对象，产生Session接口，就可以操作数据库了。
 * @author: libl
 * @date: 2018年8月2日 下午6:13:22
 */
public class HibernateUtil {
    private static final SessionFactory sessionFactory;
    static {
        try {
            Configuration cfg = new Configuration().configure("/org/lbl/conn/hibernate/hibernate.cfg.xml");
            sessionFactory = cfg.buildSessionFactory();
        } catch (Throwable ex) {
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

4.Hibernate例子（HibernateExample.java ）

package org.lbl.conn.hibernate;

import org.hibernate.Session;
import org.lbl.conn.pojo.Role;

/**
 * @description:对比JDBC好处： 1.消除了代码的映射规则，它全部被分离到了XML或者注解里面去配置
 *                        2.无需再管理数据库连接，它也配置在XML里面
 *                        3.一个会话中，不要操作多个对象，只要操作Session对象即可
 *                        4.关闭资源只需要关闭一个Session便可
 * @author: libl
 * @date: 2018年8月3日 上午9:08:12
 */
public class HibernateExample {

    public static void main(String[] args) {
        Session session = null;
        try {
            session = HibernateUtil.getSessionFactory().openSession();
            Role role = (Role) session.get(Role.class, 1L);
            System.out.println("role_name => " + role.getRoleName());
        } finally {
            if (session != null) {
                session.close();
            }
        }

    }
}

3. Mybatis连接

1.Mybatis配置文件（mybatis_config.xml）

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver" />
                <property name="url" value="jdbc:mysql://localhost/db_role" />
                <property name="username" value="root" />
                <property name="password" value="root" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="RoleMapper.xml" />
    </mappers>
</configuration>

2.Mybatis工具类（MybatisUtil.java）

package org.lbl.conn.mybatis;

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

import javax.annotation.Resource;

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

/**
 * @description:
 * @author: libl
 * @date: 2018年8月3日 上午11:04:27
 */
public class MybatisUtil {
    private static SqlSessionFactory sqlSessionFactory = null;

    public static SqlSessionFactory getSqlSessionFactory() {
        if (sqlSessionFactory == null) {
            try {
                String resource = "mybatis_config.xml";
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream(resource));
                return sqlSessionFactory;
            } catch (Exception ex) {
                System.out.println(ex.getMessage());
                ex.printStackTrace();
            }
        }
        return sqlSessionFactory;
    }
}

3.Mybatis映射类（RoleMapper .java）

package org.lbl.conn.mybatis;

import org.lbl.conn.pojo.Role;

/**
 * @description:
 * @author: libl
 * @date: 2018年8月3日 上午11:03:23
 */
public interface RoleMapper {
    public Role getRole(Long id);
}

4. Mybatis映射文件（RoleMapper.xml）

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.lbl.conn.mybatis.RoleMapper">
    <select id="getRole" parameterType="long" resultType="org.lbl.conn.pojo.Role">
        select
        id,role_name as roleName, note from t_role where id=#{id}
    </select>
</mapper>

5.. Mybatis例子（MyBatisExample .java）

package org.lbl.conn.mybatis;

import org.apache.ibatis.session.SqlSession;
import org.lbl.conn.pojo.Role;

/**
 * @description:
 * @author: libl
 * @date: 2018年8月3日 上午11:11:28
 */
public class MyBatisExample {
    public static void main(String[] args) {
        SqlSession sqlSession = null;
        try {
            sqlSession = MybatisUtil.getSqlSessionFactory().openSession();
            RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
            Role role = roleMapper.getRole(1L);
            System.out.println("role_name =>" + role.getRoleName());
        } finally {
            sqlSession.close();
        }
    }
}

6. 日志文件（log4j.properties）

log4j.rootLogger=DEBUG, stdout

# SqlMap logging configuration...
log4j.logger.com.ibatis=DEBUG
log4j.logger.com.ibatis.common.jdbc.SimpleDataSource=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.cache.CacheModel=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientImpl=DEBUG
log4j.logger.com.ibatis.sqlmap.engine.builder.xml.SqlMapParser=DEBUG
log4j.logger.com.ibatis.common.util.StopWatch=DEBUG
log4j.logger.java.sql.Connection=DEBUG
log4j.logger.java.sql.Statement=DEBUG
log4j.logger.java.sql.PreparedStatement=DEBUG
log4j.logger.java.sql.ResultSet=DEBUG

# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n