Mybatis学习笔记，框架搭建 一

首先先展示一下搭建环境所需要的jar包

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.meng</groupId>
    <artifactId>TestMybatis</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.21</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/log4j/log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    </dependencies>
</project>

我们有mybatis包、mysql连接驱动包、log4j包、junit测试工具包。
下图是我工程的基本目录结构。。。。

下面是mybatis的配置文件

<?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:3306/mybatisplus"/>
                <property name="username" value="root"/>
                <property name="password" value=""/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="sql/studentMapper.xml"/>
    </mappers>
</configuration>

上面的配置文件我们设置了连接mysql数据库所需要的最基本的连接参数，然后在最下面我们还指定了mapper配置文件，这种配置文件里面存放很多的sql语句。


下面的语句我们就展示的是mybatis的mapper类

<?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.test.studentMapper">
    <select id="selectStudent" resultType="com.test.Student">
       select * from student where sid = #{id}
  </select>
</mapper>

下面是我们的pojo类

package com.test;

public class Student {
    private int sid;
    private String userName;
    private String age;
    private String userAddress;
    private String sex;
    private String version;

    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getAge() {
        return age;
    }

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

    public String getUserAddress() {
        return userAddress;
    }

    public void setUserAddress(String userAddress) {
        this.userAddress = userAddress;
    }

    public String getSex() {
        return sex;
    }

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

    public String getVersion() {
        return version;
    }

    public void setVersion(String version) {
        this.version = version;
    }

    @Override
    public String toString() {
        return "Student{" +
                "sid=" + sid +
                ", userName='" + userName + '\'' +
                ", age='" + age + '\'' +
                ", userAddress='" + userAddress + '\'' +
                ", sex='" + sex + '\'' +
                ", version='" + version + '\'' +
                '}';
    }

    public Student() {
    }

    public Student(int sid, String userName, String age, String userAddress, String sex, String version) {
        this.sid = sid;
        this.userName = userName;
        this.age = age;
        this.userAddress = userAddress;
        this.sex = sex;
        this.version = version;
    }
}

log4j日志配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<log4j:configuration  debug="true" xmlns:log4j='http://jakarta.apache.org/log4j/' >

    <!-- ========================== 自定义输出格式说明================================ -->
    <!-- %p 输出优先级，即DEBUG，INFO，WARN，ERROR，FATAL -->
    <!-- %r 输出自应用启动到输出该log信息耗费的毫秒数  -->
    <!-- %c 输出所属的类目，通常就是所在类的全名 -->
    <!-- %t 输出产生该日志事件的线程名 -->
    <!-- %n 输出一个回车换行符，Windows平台为“/r/n”，Unix平台为“/n” -->
    <!-- %d 输出日志时间点的日期或时间，默认格式为ISO8601，也可以在其后指定格式，比如：%d{yyy MMM dd HH:mm:ss,SSS}，输出类似：2002年10月18日 22：10：28，921  -->
    <!-- %l 输出日志事件的发生位置，包括类目名、发生的线程，以及在代码中的行数。举例：Testlo4.main(TestLog4.java:10)  -->
    <!-- ========================================================================== -->

    <!-- ========================== 输出方式说明================================ -->
    <!-- Log4j提供的appender有以下几种:  -->
    <!-- org.apache.log4j.ConsoleAppender(控制台),  -->
    <!-- org.apache.log4j.FileAppender(文件),  -->
    <!-- org.apache.log4j.DailyRollingFileAppender(每天产生一个日志文件), -->
    <!-- org.apache.log4j.RollingFileAppender(文件大小到达指定尺寸的时候产生一个新的文件),  -->
    <!-- org.apache.log4j.WriterAppender(将日志信息以流格式发送到任意指定的地方)   -->
    <!-- ========================================================================== -->

    <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
        <!-- <param name="Target" value="System.out"/> -->
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss a} [Thread: %t][ Class:%c  Method: %l ]%n%p:%m%n"/>
        </layout>
        <!--  <filter class="org.apache.log4j.varia.LevelRangeFilter">
            <param name="LevelMin" value="DEBUG"/>
            <param name="LevelMax" value="DEBUG"/>
        </filter> -->
    </appender>

    <root>
        <priority value="debug"/>
        <appender-ref ref="CONSOLE" />
        <appender-ref ref="log4jDebug" />
        <appender-ref ref="log4jInfo" />
        <appender-ref ref="log4jWarn" />
        <appender-ref ref="log4jError" />
        <!-- <appender-ref ref="MAIL" /> -->
    </root>
</log4j:configuration>

下面就是我们的测试类了。

@Test
    public void test01() throws Exception{
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        SqlSession sqlSession = sqlSessionFactory.openSession();
        Student student =  sqlSession.selectOne("com.test.studentMapper.selectStudent",1);
        System.out.println(student);
        sqlSession.close();
        inputStream.close();
    }

运行成功没有报错的话说明mybatis框架的最简单是使用我们已经完成了。


下面我们写一下接口式编程：

package com.test.mapper;

import com.test.Student;

public interface StudentMapper {


    public Student findStudentAll(Integer sid);
}

首先我们定义一个接口。

<?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">
<!-- 其中需要注意的是namespace一定要与mapper接口的类的全路径对应，否则是不行的 -->        
<mapper namespace="com.test.mapper.StudentMapper">
	<!-- id要与接口的方法名称一致，返回值要与接口定义的返回值一致 -->
    <select id="findStudentAll" resultType="com.test.Student">
        SELECT * from student where sid = #{sid}
    </select>
</mapper>

然后我们定义了一个mapper配置文件，其中需要注意的是一定要与mapper接口的类的全路径对应，id要与接口的方法名称一致，返回值要与接口定义的返回值一致。

	@Test
    public void test02() throws Exception{
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        SqlSession sqlSession = sqlSessionFactory.openSession();
        StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
        Student stu = studentMapper.findStudentAll(1);
        System.out.println(stu);
        sqlSession.close();
        inputStream.close();
    }

上面的代码是一个测试类，其中我们用接口的方式就是用getMapper获取接口，然后调用接口的方法，就可以实现想要的操作。这里使用了动态代理的方式。