mybatis

[uniquejava]

网站

http://www.mybatis.org/mybatis-3/

https://blog.lanyonm.org/articles/2013/01/19/mybatis-spring-java-config-contribution.html

书

Java Persistence with MyBatis 3.pdf

示例

spring4+SpringMVC4+Mybatis+Gradle j2ee快速开发脚手架ssm-easy-template

Hello

pom.xml

<dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.8</version>
            <scope>compile</scope>
            <optional>true</optional>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.22</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.7.10</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

src/main/resources/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 alias="Student" type="com.mybatis3.domain.Student"/>
    </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://localhost:3306/cms"/>
                <property name="username" value="root"/>
                <property name="password" value="xxxxx"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/mybatis3/mappers/StudentMapper.xml"/>
    </mappers>
</configuration>

src/main/resources/com/mybatis3/mappers/StudentMapper.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="com.mybatis3.mappers.StudentMapper">
    <resultMap type="Student" id="StudentResult">
        <id property="studId" column="stud_id"/>
        <result property="name" column="name"/>
        <result property="email" column="email"/>
        <result property="dob" column="dob"/>
    </resultMap>
    <select id="findAllStudents" resultMap="StudentResult">
        SELECT * FROM STUDENTS
    </select>
    <select id="findStudentById" parameterType="int"
            resultType="Student">
        SELECT STUD_ID AS STUDID, NAME, EMAIL, DOB
        FROM STUDENTS WHERE STUD_ID=#{Id}
    </select>
    <insert id="insertStudent" parameterType="Student">
        INSERT INTO STUDENTS(STUD_ID,NAME,EMAIL,DOB)
        VALUES(#{studId },#{name},#{email},#{dob})
    </insert>
</mapper>

模型Student.java

public class Student {
    private Integer studId;
    private String name;
    private String email;
    private Date dob;

Mapper类: StudentMapper.java

public interface StudentMapper {
    List<Student> findAllStudents();

    Student findStudentById(Integer id);

    void insertStudent(Student student);
}

服务: StudentService.java

public class StudentService {
    private Logger logger = LoggerFactory.getLogger(getClass());

    public List<Student> findAllStudents() {
        SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
        try {
            StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
            return studentMapper.findAllStudents();
        } finally {
            // if sqlSession is not closed
            // then database connection associated this sqlSession will not be returned to pool
            sqlSession.close();
        }
    }

    public Student findStudentById(Integer studId) {
        logger.debug("Select Student By ID: {}", studId);
        SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
        try {
            StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
            return studentMapper.findStudentById(studId);
        } finally {
            sqlSession.close();
        }
    }

    public void createStudent(Student student) {
        SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
        try {
            StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
            studentMapper.insertStudent(student);
            sqlSession.commit();
        } finally {
            sqlSession.close();
        }
    }
}

工具类: MyBatisSqlSessionFactory.java

public class MyBatisSqlSessionFactory {
    private static SqlSessionFactory sqlSessionFactory;

    public static SqlSessionFactory getSqlSessionFactory() {
        if (sqlSessionFactory == null) {
            InputStream inputStream;
            try {
                inputStream = Resources.getResourceAsStream("mybatis-config.xml");
                sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            } catch (IOException e) {
                throw new RuntimeException(e.getCause());
            }
        }

        return sqlSessionFactory;
    }

    public static SqlSession openSession() {
        return getSqlSessionFactory().openSession();
    }
}

测试类: StudentServiceTest.java <== IDEA插件生成. src/test/java/com/mybatis3/services/

public class StudentServiceTest {
    private StudentService studentService;

    @Before
    public void before() throws Exception {
        studentService = new StudentService();
    }

    @After
    public void after() throws Exception {
        studentService = null;
    }

    @Test
    public void testFindAllStudents() throws Exception {
        List<Student> students = studentService.findAllStudents();
        Assert.assertNotNull(students);
        for (Student student : students) {
            System.out.println(student);
        }
    }

    @Test
    public void testFindStudentById() throws Exception {
        Student student = studentService.findStudentById(1);
        Assert.assertNotNull(student);
        System.out.println(student);
    }

    @Test
    public void testCreateStudent() throws Exception {
        Student student = new Student();
        int id = 3;
        student.setStudId(id);
        student.setName("student_" + id);
        student.setEmail("student_" + id + "@gmail.com");
        student.setDob(new Date());
        studentService.createStudent(student);
        Student newStudent = studentService.findStudentById(id);
        Assert.assertNotNull(newStudent);
    }

} 

[uniquejava]

什么时候需要@Param

You do not need to use @Param with only a single parameter. In your example, you could have used any string you want between the delimiters: #{foo} would produce the same result as #{customerId}.

You only need to use @Param when you have more than one parameter. You can't use the Java parameter name because unfortunately Java introspection doesn't provide parameter names, only types. That's why the @Param annotation was added in the first place.

这里有详解！

https://stackoverflow.com/a/59811574/2497876