在这漫长的岁月里，一个人敲敲代码也是一件不容易的事情啊
入门
maven构建classpath:
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>x.x.x</version>
</dependency>
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>
<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>
构建SqlSessionFactory:
方法一：
String resource = "org/mybatis/example/mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
方法二：
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);
从SqlSessionFactory中构建SqlSession:
方法一：
SqlSession session = sqlSessionFactory.openSession();
try {
Blog blog = (Blog) session.selectOne("org.mybatis.example.BlogMapper.selectBlog", 101);
} finally {
session.close();
}
方法二：
SqlSession session = sqlSessionFactory.openSession();
try {
BlogMapper mapper = session.getMapper(BlogMapper.class);
Blog blog = mapper.selectBlog(101);
} finally {
session.close();
}
xml Sql语句编写
<?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>
然后使用Sqlsession进行调用：
方法一：
Blog blog = (Blog) session.selectOne("org.mybatis.example.BlogMapper.selectBlog", 101);这个命名可以直接映射到在命名空间中同名的 Mapper 类，并将已映射的 select 语句中的名字、参数和返回类型匹配成方法。
方法二：
BlogMapper mapper = session.getMapper(BlogMapper.class);
Blog blog = mapper.selectBlog(101);
可以将xml sql语句改为：
public interface BlogMapper {
@Select("SELECT * FROM blog WHERE id = #{id}")
Blog selectBlog(int id);
}技术实战
//使用@Configuration实现配置
@Configuration
@MapperScan(basePackages = {"xxxx.mapper"}, sqlSessionFactoryRef = "sqlSessionFactory1")
public class MybatisCsmerConfig {
@Autowired
@Qualifier("dataSourceCsmer")
private DataSource dataSource;
@Bean
public SqlSessionFactory sqlSessionFactory1() throws Exception {
SqlSessionFactoryBean factoryBean = new SqlSessionFactoryBean();
factoryBean.setDataSource(dataSource);
factoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
.getResources("classpath*:mybatis/mapper/*.xml"));
factoryBean.setConfigLocation(new PathMatchingResourcePatternResolver()
.getResource("classpath:mybatis/mybatis-config.xml"));
return factoryBean.getObject();
}
@Bean
public SqlSessionTemplate sqlSessionTemplate1() throws Exception {
SqlSessionTemplate template = new SqlSessionTemplate(sqlSessionFactory1()); // 使用上面配置的Factory
return template;
}
}
spring boot集成mybatis
pom.xml中引入依赖：
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.3.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.21</version>
</dependency>
</dependencies>
在application.properties中配置mysql的连接配置
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
然后写一个例子：
//使用@Mapper注解，告诉spring boot自动扫描这个类为mapper
import org.apache.ibatis.annotations.*;
@Mapper
public interface UserMapper {
@Select("SELECT * FROM USER WHERE NAME = #{name}")
User findByName(@Param("name") String name);
@Insert("INSERT INTO USER(NAME, AGE) VALUES(#{name}, #{age})")
int insert(@Param("name") String name, @Param("age") Integer age);
}
相应的实体：
public class User {
private Long id;
private String name;
private Integer age;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}springboot整合mybatis会自动配置完所有信息，用户只需要在写的时候加入@Mapper注解，会自动进行扫描。
原理：
mybatis-spring-boot-starter就是springboot+mybatis可以完全注解不用配置文件，mybatis-spring-boot-starter主要有两种解决方案，一种是使用注解解决一切问题，一种是简化后的老传统。springboot会自动加载spring.datasource.*相关配置，数据源就会自动注入到sqlSessionFactory中，sqlSessionFactory会自动注入到Mapper中，对了你一切都不用管了，直接拿起来使用就行了。
首先，在启动类中添加对mapper包扫描@MapperScan
@SpringBootApplication
@MapperScan("com.neo.mapper")
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
方式一：
直接在Mapper类上面添加注解@Mapper。
####Mapper的写法
public interface UserMapper {
@Select("SELECT * FROM users")
@Results({
@Result(property = "userSex", column = "user_sex", javaType = UserSexEnum.class),
@Result(property = "nickName", column = "nick_name")
})
List<UserEntity> getAll();
@Select("SELECT * FROM users WHERE id = #{id}")
@Results({
@Result(property = "userSex", column = "user_sex", javaType = UserSexEnum.class),
@Result(property = "nickName", column = "nick_name")
})
UserEntity getOne(Long id);
@Insert("INSERT INTO users(userName,passWord,user_sex) VALUES(#{userName}, #{passWord}, #{userSex})")
void insert(UserEntity user);
@Update("UPDATE users SET userName=#{userName},nick_name=#{nickName} WHERE id =#{id}")
void update(UserEntity user);
@Delete("DELETE FROM users WHERE id =#{id}")
void delete(Long id);
}注解解释
@Select 是查询类的注解，所有的查询均使用这个
@Result 修饰返回的结果集，关联实体类属性和数据库字段一一对应，如果实体类属性和数据库属性名保持一致，就不需要这个属性来修饰。
@Insert 插入数据库使用，直接传入实体类会自动解析属性到对应的值
@Update 负责修改，也可以直接传入对象
@delete 负责删除
注意，使用#符号和$符号的不同：
// This example creates a prepared statement, something like select * from teacher where name = ?;
@Select("Select * from teacher where name = #{name}")
Teacher selectTeachForGivenName(@Param("name") String name);
// This example creates n inlined statement, something like select * from teacher where name = 'someName';
@Select("Select * from teacher where name = '${name}'")
Teacher selectTeachForGivenName(@Param("name") String name);
方式二：极简xml
application.properties新增以下配置
mybatis.config-locations=classpath:mybatis/mybatis-config.xml
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml
mybatis-config.xml 配置:
<configuration>
<typeAliases>
<typeAlias alias="Integer" type="java.lang.Integer" />
<typeAlias alias="Long" type="java.lang.Long" />
<typeAlias alias="HashMap" type="java.util.HashMap" />
<typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap" />
<typeAlias alias="ArrayList" type="java.util.ArrayList" />
<typeAlias alias="LinkedList" type="java.util.LinkedList" />
</typeAliases>
</configuration>
添加映射文件：
<mapper namespace="com.neo.mapper.UserMapper" >
<resultMap id="BaseResultMap" type="com.neo.entity.UserEntity" >
<id column="id" property="id" jdbcType="BIGINT" />
<result column="user_name" property="userName" jdbcType="VARCHAR" />
<result column="pass_word" property="passWord" jdbcType="VARCHAR" />
<result column="user_sex" property="userSex" javaType="com.neo.enums.UserSexEnum"/>
<result column="nick_name" property="nickName" jdbcType="VARCHAR" />
</resultMap>
<sql id="Base_Column_List" >
id, userName, passWord, user_sex, nick_name
</sql>
<select id="getAll" resultMap="BaseResultMap" >
SELECT
<include refid="Base_Column_List" />
FROM users
</select>
<select id="getOne" parameterType="java.lang.Long" resultMap="BaseResultMap" >
SELECT
<include refid="Base_Column_List" />
FROM users
WHERE id = #{id}
</select>
<insert id="insert" parameterType="com.neo.entity.UserEntity" >
INSERT INTO
users
(userName,passWord,user_sex)
VALUES
(#{userName}, #{passWord}, #{userSex})
</insert>
<update id="update" parameterType="com.neo.entity.UserEntity" >
UPDATE
users
SET
<if test="userName != null">userName = #{userName},</if>
<if test="passWord != null">passWord = #{passWord},</if>
nick_name = #{nickName}
WHERE
id = #{id}
</update>
<delete id="delete" parameterType="java.lang.Long" >
DELETE FROM
users
WHERE
id =#{id}
</delete>
</mapper>
其实就是把上个版本中mapper的sql搬到了这里的xml中了。
我们的结构原本是按照第二种模式动态生成sqlnode，为了增强代码的可维护性，我们使用了mybatis的拦截器方法将动态生成改为更加简单的通过java语言来控制，而不需要去修改xml语句。见下文