课时1 Mybatis配置以及入门示例

1.）导入所需的jar包 mvn

 <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
 </dependency>

.2)Mapper SQL映射的头部

<?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.hbz.dao.IPersonDao">

.3)mapper SQL映射配置----编写实体对应数据库

<mapper namespace="org.hbz.dao.IPersonDao">
        <select id="selectPersonById" parameterType="Integer" resultType="org.hbz.entity.Person">
            select * from person where id=#{id}
        </select>
</mapper>

package org.hbz.entity;

public class Person {
    private Integer id;
    private String name;
    private Integer age;
    private String sex;

    public Person() {

    }

    public Person(Integer id, String name, Integer age, String sex) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.sex = sex;
    }

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                '}';
    }
}

.4) mybatis的主配置文件头

<?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">

.5)mybatis的主配置文件体

<configuration>
    <environments default="mysql">
        <environment id="mysql">
<!--                配置事务-->
            <transactionManager type="JDBC">
            </transactionManager>
<!--            配置数据库连接信息-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/ssm"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
<!--加载sql映射文件-->
    <mappers>
<!--        注意如果是xml文件 格式是../../..-->
        <mapper resource="org/hbz/dao/personMapper.xml"></mapper>
    </mappers>
</configuration>

.6)log4j配置文件如下

### 设置###
log4j.rootLogger = debug,stdout,D,E

### 输出信息到控制抬 ###
log4j.appender.stdout = org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target = System.out
log4j.appender.stdout.layout = org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern = [%-5p] %d{yyyy-MM-dd HH:mm:ss,SSS} method:%l%n%m%n

### 输出DEBUG 级别以上的日志到=E://logs/error.log ###
log4j.appender.D = org.apache.log4j.DailyRollingFileAppender
log4j.appender.D.File = E://logs/log.log
log4j.appender.D.Append = true
log4j.appender.D.Threshold = DEBUG 
log4j.appender.D.layout = org.apache.log4j.PatternLayout
log4j.appender.D.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

### 输出ERROR 级别以上的日志到=E://logs/error.log ###
log4j.appender.E = org.apache.log4j.DailyRollingFileAppender
log4j.appender.E.File =E://logs/error.log 
log4j.appender.E.Append = true
log4j.appender.E.Threshold = ERROR 
log4j.appender.E.layout = org.apache.log4j.PatternLayout
log4j.appender.E.layout.ConversionPattern = %-d{yyyy-MM-dd HH:mm:ss}  [ %t:%r ] - [ %p ]  %m%n

.7)dao层

/**
     * 按照id查询一个学生
     * @param id
     * @return
     */
    Student selectStudentById(Integer id);

.8)测试类

package org.hbz.test;

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 org.hbz.dao.IPersonDao;
import org.hbz.entity.Person;

import java.io.IOException;
import java.io.Reader;

/**
 * 测试类
 */
public class MybatisTest {
    public static void main(String [] args) throws IOException {
        //加载mybatis配置文件(为了访问数据库)
       Reader reader= Resources.getResourceAsReader("config.xml");
       //创建工厂
        SqlSessionFactory sessionFactory=new SqlSessionFactoryBuilder().build(reader);
        //打开一次会话
        SqlSession session=sessionFactory.openSession();
        //获取代理对象
        IPersonDao iPersonDao = (IPersonDao)session.getMapper(IPersonDao.class);
        //执行方法
        Person person = iPersonDao.selectPersonById(1);
        System.out.println(person.getName());

        //关闭流
        reader.close();
        //关闭会话
        session.close();
    }

}

.8)mybatis通过namespace加id定位出唯一的sql