Java+MyBatis+MySQL开发环境搭建流程详解

<properties>  <mybatis.version>3.2.3</mybatis.version>  <mysql.version>5.1.26</mysql.version>  <slf4j.api.version>1.7.5</slf4j.api.version>  <testng.version>6.8.7</testng.version> </properties>  <dependencies>  <dependency>   <groupId>org.mybatis</groupId>   <artifactId>mybatis</artifactId>   <version>${mybatis.version}</version>  </dependency>  <!-- Database driver -->  <dependency>   <groupId>mysql</groupId>   <artifactId>mysql-connector-java</artifactId>   <version>${mysql.version}</version>  </dependency>  <!-- mybatis启动要加载log4j -->  <dependency>   <groupId>org.slf4j</groupId>   <artifactId>slf4j-log4j12</artifactId>   <version>${slf4j.api.version}</version>  </dependency>  <!-- Test -->  <dependency>   <groupId>org.testng</groupId>   <artifactId>testng</artifactId>   <version>${testng.version}</version>  </dependency> </dependencies> 

<?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><!-- 别名 -->     <typeAlias alias="User" type="com.john.hbatis.model.User" />   </typeAliases>      <environments default="development">    <environment id="development">     <transactionManager type="JDBC"/>     <dataSource type="POOLED"><!-- 数据源 -->       <property name="driver" value="com.mysql.jdbc.Driver" />       <property name="url" value="jdbc:mysql://localhost:3306/hbatis" />       <property name="username" value="root" />       <property name="password" value="123456" />     </dataSource>    </environment>   </environments>      <mappers><!-- ORM映射文件 -->     <mapper resource="com/john/hbatis/model/User.xml" />   </mappers>  </configuration> 

-- 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'); 

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.<init>()   // 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;   } } 

<?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.john.hbatis.model.UserMapper">   <select id="getUserById" parameterType="int" resultType="User">     select * from `user` where id = #{id}   </select> </mapper> 

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());   } } 

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

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

<mapper namespace="com.john.hbatis.mapper.IUserMapper">   <select id="getUserById" 

@Test public void queryInInterfaceWayTest() {   SqlSession session = sqlSessionFactory.openSession();   IUserMapper mapper = session.getMapper(IUserMapper.class); // 如果namespace和接口全限定名不一致，报org.apache.ibatis.binding.BindingException: Type interface com..IUserMapper is not known to the MapperRegistry异常。   User user = mapper.getUserById(1);   log.info("{}: {}", user.getName(), user.getAddress()); } 

package com.john.hbatis.mapper;  import org.apache.ibatis.annotations.Select;  import com.john.hbatis.model.User;  public interface IUserMapper2 {   @Select({ "select * from `user` where id = #{id}" })   User getUserById(int id); } 

<mappers>   <mapper class="com.john.hbatis.mapper.IUserMapper2" /> </mappers> 

sqlSessionFactory.getConfiguration().addMapper(IUserMapper2.class); 

IUserMapper2 mapper = session.getMapper(IUserMapper2.class);