mybatis简单实例 -- 初窥mybatis

系统管理员 2022-05-27 03:29 219阅读 0赞

先上项目截图:

![70][]

项目框架如图

log4j.properties:

# Global logging configuration
    log4j.rootLogger=DEBUG, stdout
    # 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

mybatis总配置文件(需先在数据库中创建对应DataBase和对应表并设置主键id自增)

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>
        <typeAliases>
            <typeAlias type="com.vina.pojo.People" alias="People"/>
        </typeAliases>
        
        <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://127.0.0.1:3306/mybatis?characterEncoding=utf-8&useSSL=false"/>
                    <property name="username" value="username" />
                    <property name="password" value="password" />
                </dataSource>
            </environment>
        </environments>
    
        
        <mappers>
            
            <mapper resource="com/vina/mapper/PeopleMapper.xml"/>
        </mappers>
    </configuration>

然后是通过单例模式获取SqlSession的SqlSessionFactoryutil.java

package com.vina.util;
    
    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;
    import java.util.logging.Level;
    import java.util.logging.Logger;
    
    //单例模式
    public class SqlSessionFactoryUtil {
        // SqlSessionFactory单例对象
        private static SqlSessionFactory sqlSessionFactory = null;
        // 类线程锁
        public static final Class CLASS_LOCK = SqlSessionFactoryUtil.class;
    
        // 私有化构造方法
        private SqlSessionFactoryUtil(){ }
    
        // 构建SqlSessionFactory
        public static SqlSessionFactory initSqlSessionFactory(){
            String resource = "com/vina/util/mybatis_config.xml";
            InputStream inputStream = null;
            try {
                inputStream = Resources.getResourceAsStream(resource);
            }catch (IOException e){
                Logger.getLogger(SqlSessionFactoryUtil.class.getName()).log(Level.SEVERE, null, e);
            }
            if(sqlSessionFactory == null)
                synchronized (CLASS_LOCK){
                    if(sqlSessionFactory == null)
                        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
                }
            return sqlSessionFactory;
    
        }
    
        // 打开SqlSession
        public static SqlSession openSqlSession(){
            if(sqlSessionFactory == null)
                initSqlSessionFactory();
            return sqlSessionFactory.openSession();
        }
    }

pojo类:

package com.vina.pojo;
    
    public class People {
        private long id;
        private String name;
        private int age;
    
        @Override
        public String toString() {
            return "id:" + id + "   name:" + name + "   age:" + age;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    
        public String getName() {
    
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public long getId() {
    
            return id;
        }
    
        public void setId(long id) {
            this.id = id;
        }
    }

People类的映射文件:

<?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="com.vina.mapper.PeopleMapper">
        
        <select id="getPeople" parameterType="long" resultType="People">
            select * from People where id = #{id}
        </select>
        <insert id="insertPeople" parameterType="People">
            insert into People(`name`, age) values (#{name}, #{age})
        </insert>
        <delete id="deletePeople" parameterType="long">
            delete from People where id = #{id}
        </delete>
        <delete id="deletePeopleFromName" parameterType="String">
            delete from People where name = #{name}
        </delete>
    </mapper>

People类接口:

package com.vina.mapper;
    import com.vina.pojo.People;
    
    public interface PeopleMapper {
        People getPeople(long id);
        int deletePeople(long id);
        int insertPeople(People people);
        int deletePeopleFromName(String name);
    }

最后是测试类:

package com.vina.main;
    
    import com.vina.util.SqlSessionFactoryUtil;
    import com.vina.mapper.PeopleMapper;
    import com.vina.pojo.People;
    import org.apache.ibatis.session.SqlSession;
    
    public class PeopleDemo1 {
        public static void main(String[] args) {
            SqlSession sqlSession = null;
            try {
                sqlSession = SqlSessionFactoryUtil.openSqlSession();
                PeopleMapper peopleMapper = sqlSession.getMapper(PeopleMapper.class);
                People people = new People();
                people.setAge(20);
                people.setName("vina");
                peopleMapper.insertPeople(people);
                System.out.println(peopleMapper.getPeople(1L));
                peopleMapper.deletePeopleFromName("vina");
                sqlSession.commit();
            } catch (Exception e){
                System.err.println(e.getMessage());
                sqlSession.rollback();
            } finally {
                if(sqlSession != null)
                    sqlSession.close();
            }
        }
    }

总结:与纯粹的JDBC编程相比,减少了传统JDBC编程中的重复代码,并增加可代码的可读性和可重用性.并且代码逻辑也较为清晰.

[70]: /images/20220527/753b673a00df495f9262fd8c0afa642f.png