Java+MyBatis+MySQL开发环境搭建流程详解

主要搭建过程

1. pom.xml文件中加入mybatis和数据库依赖，这里使用mysql：

 
 3.2.3 
 5.1.26 
 1.7.5 
 6.8.7 
 
 
 
  
  org.mybatis 
  mybatis 
  ${mybatis.version} 
  
  
  
  mysql 
  mysql-connector-java 
  ${mysql.version} 
  
  
  
  org.slf4j 
  slf4j-log4j12 
  ${slf4j.api.version} 
  
  
  
  org.testng 
  testng 
  ${testng.version}

2. 在类路径下创建mybatis的配置文件Configuration.xml

3. 执行创建数据库和表的sql：

-- Create the database named 'hbatis'. 
-- It's OK to use `, not OK to use ' or " surrounding the database name to prevent it from being interpreted as a keyword if possible. 
CREATE DATAbase IF NOT EXISTS `hbatis` 
DEFAULT CHARACTER SET = `UTF8`; 
 
-- Create a table named 'User' 
CREATE TABLE `user` ( 
  `id` int(11) NOT NULL AUTO_INCREMENT, 
  `name` varchar(50) DEFAULT NULL, 
  `age` int(11) DEFAULT NULL, 
  `address` varchar(200) DEFAULT NULL, 
  PRIMARY KEY (`id`) 
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8; 
 
-- Insert a test record 
Insert INTO `user` VALUES ('1', 'john', '120', 'hangzhou,westlake');

4. com.john.hbatis.model.User类：

public class User { 
  private int id; 
  private String name; 
  private String age; 
  private String address; 
  // Getters and setters are omitted 
 
  // 如果有带参数的构造器，编译器不会自动生成无参构造器。当查询需要返回对象时，ORM框架用反射来调用对象的无参构造函数，导致异常：java.lang.NoSuchMethodException: com.john.hbatis.model.User.() 
  // 这时需要明确写出： 
  public User() { 
  } 
 
  public User(int id, String address) { 
    this.id = id; 
    this.address = address; 
  } 
 
  public User(String name, int age, String address) { 
    this.name = name; 
    this.age = age; 
    this.address = address; 
  } 
}

com/john/hbatis/model路径下的User.xml

 
 
 
   
    select * from `user` where id = #{id}

5. 测试类：

public class MyBatisBasicTest { 
  private static final Logger log = LoggerFactory.getLogger(MyBatisBasicTest.class); 
  private static SqlSessionFactory sqlSessionFactory; 
   
  private static Reader reader; 
   
  @BeforeClass 
  public static void initial() { 
    try { 
      reader = Resources.getResourceAsReader("Configuration.xml"); 
      sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader); 
    } catch (IOException e) { 
      log.error("Error thrown while reading the configuration: {}", e); 
    } finally { 
      if (reader != null) { 
 try { 
   reader.close(); 
 } catch (IOException e) { 
   log.error("Error thrown while closing the reader: {}", e); 
 } 
      } 
    } 
  } 
   
  @Test 
  public void queryTest() { 
    SqlSession session = sqlSessionFactory.openSession(); 
    User user = (User)session.selectOne("com.john.hbatis.model.UserMapper.getUserById", 1); 
    log.info("{}: {}", user.getName(), user.getAddress()); 
  } 
}

以接口方式交互数据
上面的环境搭建是采用SqlSession的通用方法并强制转换的方式，存在着转换安全的问题：

User user = (User)session.selectOne("com.john.hbatis.model.UserMapper.getUserById", 1);

可以采用接口加sql语句的方式来解决，sql语句理解为是接口的实现：

1. 新建接口类：

package com.john.hbatis.mapper; 
 
import com.john.hbatis.model.User; 
 
public interface IUserMapper { 
  User getUserById(int id); 
}

2. 修改User.xml文件，确保namespace属性值和接口的全限定名相同，且id属性值和接口方法名相同：