mybatis

docs

• http://www.mybatis.org/mybatis-3/getting-started.html

glossary

关系路线： SqlSessionFactoryBuilder --> SqlSessionFactory --> SqlSession -query-> Mapper Instances

SqlSessionFactoryBuilder

• 功能：获取SqlSessionFactory
• recommend scope: method scope(i.e. a local method variable)
• 一般只要用一次，通过SqlSessionFactoryBuilder获得SqlSessionFactory

SqlSessionFactory

• 功能：创建SqlSession
• recommend scope: application scope， 应用程序存在就不该销毁或丢弃引用，
• 最好是单例实现

SqlSession

• 功能：会话连接用来查询
• recommend scope: thread scope，request scope， method scope，不要保存引用在类成员变量或者静态变量中
• 使用姿势：

SqlSession session = sqlSessionFactory.openSession();
try {
  // do work
} finally {
  session.close();
}

Mapper Instances

• SqlSession通过mapped statement查询到的实例，
• recommend scope: thread scope，request scope， method scope

mapped statements

查询语句

使用过程

• http://www.mybatis.org/mybatis-3/getting-started.html

1. Building SqlSessionFactory from XML

• 加载配置代码

String resource = "org/mybatis/example/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

• xml配置

<?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="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="org/mybatis/example/BlogMapper.xml"/>
  </mappers>
</configuration>

• JavaConfig

DataSource dataSource = BlogDataSourceFactory.getBlogDataSource();
TransactionFactory transactionFactory = new JdbcTransactionFactory();
Environment environment = new Environment("development", transactionFactory, dataSource);
Configuration configuration = new Configuration(environment);
configuration.addMapper(BlogMapper.class);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);

2. Acquiring a SqlSession from SqlSessionFactory

SqlSession session = sqlSessionFactory.openSession();
try {
  Blog blog = session.selectOne("org.mybatis.example.BlogMapper.selectBlog", 101);
} finally {
  session.close();
}

3. query

SqlSession session = sqlSessionFactory.openSession();
try {
  BlogMapper mapper = session.getMapper(BlogMapper.class);
  Blog blog = mapper.selectBlog(101);
} finally {
  session.close();
}

4. 配置mapped statements

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.mybatis.example.BlogMapper">
  <select id="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select>
</mapper>

• Namespaces: 尽量用包名路径
• Name Resolve： 如果不存在歧义的Mapper statement id，可以直接使用“selectBlog”，建议还是用全名
• 查询：Blog blog = session.selectOne("org.mybatis.example.BlogMapper.selectBlog", 101);

annotation

package org.mybatis.example;
public interface BlogMapper {
  @Select("SELECT * FROM blog WHERE id = #{id}")
  Blog selectBlog(int id);
}

• 查询：

BlogMapper mapper = session.getMapper(BlogMapper.class);
Blog blog = mapper.selectBlog(101);