Mybatis初期使用比较麻烦，需要各种配置文件、实体类、dao层映射关联、还有一大推其它配置。当然Mybatis也发现了这种弊端，初期开发了generator可以根据表结构自动生成实体类、配置文件和dao层代码，可以减轻一部分开发量；后期也进行了大量的优化可以使用注解了，自动管理dao层和配置文件等，发展到最顶端就是今天要讲的这种模式，mybatis-spring-boot-starter就是springboot+mybatis完全注解不用任何配置文件，就可以简单配置轻松上手。
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。
以注解版的方式进行讲解。
users表结构
CREATE TABLE `users` ( `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT '主键id', `username` varchar(32) DEFAULT NULL COMMENT '用户名', `password` varchar(32) DEFAULT NULL COMMENT '密码', `sex` varchar(32) DEFAULT NULL, `nick_name` varchar(32) DEFAULT NULL, PRIMARY KEY (`id`), UNIQUE KEY `username` (`username`) USING HASH ) ENGINE=InnoDB AUTO_INCREMENT=39 DEFAULT CHARSET=utf8;
1、添加pom文件
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.lynch.springboot</groupId> <artifactId>spring-boot-mybatis-annotation</artifactId> <version>0.0.1-SNAPSHOT</version> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.10.RELEASE</version> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <java.version>1.8</java.version> </properties> <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.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.3.2</version> </dependency> <!-- mybatis分页插件 --> <dependency> <groupId>com.github.pagehelper</groupId> <artifactId>pagehelper-spring-boot-starter</artifactId> <version>1.1.1</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
2、application.properties 添加相关配置
#mybatis.type-aliases-package=com.lynch.entity spring.datasource.driverClassName = com.mysql.jdbc.Driver spring.datasource.url = jdbc:mysql://192.168.1.149:3306/aa?useUnicode=true&characterEncoding=utf-8&useSSL=false spring.datasource.username = root spring.datasource.password = attack
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，对于开发人员不用管，直接拿来使用即可。
在启动类中添加对mapper包扫描@MapperScan
package com.lynch; import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; @SpringBootApplication @MapperScan("com.lynch.mapper") public class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); } }
或者直接在Mapper类上面添加注解@Mapper，建议使用上面那种，不然每个mapper加个注解也挺麻烦的。
3、开发Mapper
package com.lynch.mapper; import java.util.List; import org.apache.ibatis.annotations.Delete; import org.apache.ibatis.annotations.Insert; import org.apache.ibatis.annotations.InsertProvider; import org.apache.ibatis.annotations.Param; import org.apache.ibatis.annotations.Result; import org.apache.ibatis.annotations.Results; import org.apache.ibatis.annotations.Select; import org.apache.ibatis.annotations.SelectProvider; import org.apache.ibatis.annotations.Update; import org.apache.ibatis.annotations.UpdateProvider; import com.lynch.entity.UserEntity; import com.lynch.enums.SexEnum; public interface UserMapper { @Select("SELECT * FROM users") @Results({ @Result(property = "sex", column = "sex", javaType = SexEnum.class), @Result(property = "nickName", column = "nick_name") }) List<UserEntity> getAll(); @Select("SELECT * FROM users WHERE id = #{id}") @Results({ @Result(property = "sex", column = "sex", javaType = SexEnum.class), @Result(property = "nickName", column = "nick_name") }) UserEntity getOne(Long id); @Insert("insert into users(username,password,sex) values(#{username}, #{password}, #{sex})") int 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); @InsertProvider(type=UserProvider.class, method = "batchInsert") int batchInsert(@Param("userList")List<UserEntity> userList); @SelectProvider(type = UserProvider.class, method = "queryUser") @Results({ @Result(property = "sex", column = "sex", javaType = SexEnum.class), @Result(property = "nickName", column = "nick_name") }) public List<UserEntity> queryUser(UserEntity user); @UpdateProvider(type = UserProvider.class, method = "updateUser") public int updateUser(@Param("U")UserEntity user); }
package com.lynch.mapper; import java.util.List; import java.util.Map; import org.apache.ibatis.annotations.Param; import org.apache.ibatis.jdbc.SQL; import com.github.pagehelper.util.StringUtil; import com.lynch.entity.UserEntity; /** * 利用@Provider实现动态SQL * * @author Lynch * */ public class UserProvider { public String queryUser(UserEntity user) { StringBuffer sql = new StringBuffer("select * from users where 1=1 "); if(StringUtil.isNotEmpty(user.getUsername())) { sql.append(String.format("and username like '%s'", "%"+user.getUsername()+"%")); } return sql.toString(); } public String batchInsert(Map map) { List<UserEntity> userList = (List<UserEntity>)map.get("userList"); StringBuffer sql = new StringBuffer("insert into users (username,password) values "); for(UserEntity user : userList) { sql.append(String.format("('%s', '%s'),", user.getUsername(), user.getPassword())); } sql = sql.deleteCharAt(sql.length() -1); System.out.println(sql.toString()); return sql.toString(); } public String updateUser(@Param("U")UserEntity user) { SQL sql = new SQL(){{ UPDATE("users"); if (StringUtil.isNotEmpty(user.getNickName())){ SET("nick_name = #{U.nickName}"); } WHERE("id = #{U.id}"); }}; return sql.toString(); } }
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);
4、单元测试
package com.lynch.mapper; import java.util.ArrayList; import java.util.List; import org.junit.Test; import org.junit.runner.RunWith; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.test.context.SpringBootTest; import org.springframework.test.context.junit4.SpringRunner; import com.lynch.entity.UserEntity; import com.lynch.enums.SexEnum; @RunWith(SpringRunner.class) @SpringBootTest public class UserMapperTest { @Autowired private UserMapper userMapper; @Test public void insert() throws Exception { int result = 0; try { result = userMapper.insert(new UserEntity("lisi", "123456", SexEnum.MAN)); } catch (Exception e) { System.out.println(e.getMessage().indexOf("ConstraintViolationException")); } System.out.println("result=" + result); } @Test public void batchInsert() throws Exception { List<UserEntity> userList = new ArrayList<UserEntity>(); userList.add(new UserEntity("a","a",SexEnum.MAN)); userList.add(new UserEntity("c","b",SexEnum.MAN)); userList.add(new UserEntity("b","b",SexEnum.WOMAN)); System.out.println("result=" + userMapper.batchInsert(userList)); } @Test public void getAll() throws Exception { List<UserEntity> users = userMapper.getAll(); System.out.println(users.toString()); } @Test public void testUpdate() throws Exception { UserEntity user = userMapper.getOne(45L); System.out.println(user.toString()); user.setNickName("neo"); user.setSex(SexEnum.WOMAN); userMapper.update(user); } @Test public void queryUser() throws Exception { UserEntity user = new UserEntity(); user.setUsername("l"); System.out.println(userMapper.queryUser(user)); } @Test public void updateUser() throws Exception { UserEntity user = new UserEntity(); user.setId(45L); user.setNickName("aaa"); System.out.println(userMapper.updateUser(user)); } }
