MyBatis3 源码解析（1）探索准备

public class JdbcTest {
    @Test    public void test() {        Connection conn = null;        Statement stmt = null;        try {            // STEP 1: 连接数据库            // JDBC driver name and database URL            String JDBC_DRIVER = "org.h2.Driver";            Class.forName(JDBC_DRIVER);
            System.out.println("Connecting to database...");            String DB_URL = "jdbc:h2:mem:test;DB_CLOSE_DELAY=-1";            //  Database credentials            String USER = "sa";            String PASS = "";            conn = DriverManager.getConnection(DB_URL, USER, PASS);
            //STEP 2: 设置参数，查询            System.out.println("Creating table in given database...");            stmt = conn.createStatement();            String sql =  "CREATE TABLE   REGISTRATION " +                    "(id INTEGER not NULL, " +                    " first VARCHAR(255), " +                    " last VARCHAR(255), " +                    " age INTEGER, " +                    " PRIMARY KEY ( id ))";            stmt.executeUpdate(sql);            System.out.println("Created table in given database...");
            //STEP 4: 处理查询结果            String insertSql = "insert into REGISTRATION (id, first, last, age) values (?, ?, ?, ?)";            PreparedStatement insertPreparedStatement = conn.prepareStatement(insertSql);            insertPreparedStatement.setInt(1, 1);            insertPreparedStatement.setString(2, "1");            insertPreparedStatement.setString(3, "1");            insertPreparedStatement.setInt(4, 1);            insertPreparedStatement.executeUpdate();
            String querySql = "select * from REGISTRATION";            ResultSet resultSet = stmt.executeQuery(querySql);            ResultSetMetaData metaData = resultSet.getMetaData();            while (resultSet.next()) {                Registration registration = new Registration();                registration.setId(resultSet.getInt(metaData.getColumnName(1)));                registration.setFirst(resultSet.getString(metaData.getColumnName(2)));                registration.setLast(resultSet.getString(metaData.getColumnName(3)));                registration.setAge(resultSet.getInt(metaData.getColumnName(4)));                System.out.println(registration);            }
            // STEP 4: 关闭连接            stmt.close();            conn.close();        } catch(Exception se) {      ......        } //end try        System.out.println("Goodbye!");    }
    @Data    static class Registration {        private int id;        private String first;        private String last;        private int age;    }}

public class MybatisTest {
    @Test    public void test() {  // 得到数据库链接        try(SqlSession session = buildSqlSessionFactory().openSession()) {            PersonMapper personMapper = session.getMapper(PersonMapper.class);      // 创建表            personMapper.createTable();      // 插入数据            personMapper.save(Person.builder().id(1L).name("1").build());      // 查询数据            Person person = personMapper.getPersonById(1);            System.out.println(person);        }    }
    // 构建数据库的连接信息和配置Mapper    public static SqlSessionFactory buildSqlSessionFactory() {        String JDBC_DRIVER = "org.h2.Driver";        String DB_URL = "jdbc:h2:mem:test;DB_CLOSE_DELAY=-1";        String USER = "sa";        String PASS = "";        DataSource dataSource = new PooledDataSource(JDBC_DRIVER, DB_URL, USER, PASS);        Environment environment = new Environment("Development", new JdbcTransactionFactory(), dataSource);        Configuration configuration = new Configuration(environment);        configuration.addMapper(PersonMapper.class);        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();        return builder.build(configuration);    }}
public interface PersonMapper {
    @Insert("create table person(id int not null, name varchar(255))")    Integer createTable();
    @Insert("Insert into person(id, name) values (#{id}, #{name})")    Integer save(Person person);
    @Select("Select id, name from Person where id=#{id}")    @Results(value = {            @Result(property = "id", column = "id"),            @Result(property="name", column = "name"),    })    Person getPersonById(Integer personId);}