整合Mybtis對于Spring Boot來說,是非常簡單的, 通過這一篇文章, 你可以無壓力快速入門,不過開始之前我要說一下我的版本信息:
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maven 3.2.5
jdk 1.8
Spring Boot 2.1.6
創(chuàng)建項目
依然是使用idea的自動化配置, 不過這里,我們需要勾選以下依賴:
如果你勾選了 MyBatis , 你會發(fā)現(xiàn)你的pom文件里有 :
? org.mybatis.spring.boot ?mybatis-spring-boot-starter ?2.1.0 ?
這條依賴
只要是帶 *-spring-boot-starter的,都是Spring Boot官方推薦的, 這里的mybatis就是, 讓我們來看一下mybatis包下的所有包:
我們發(fā)現(xiàn)它引入了, mybatis-spring 的包等等,以及還有mybatis-spring-boot-autoconfigure, 這個是自動配置的意思, 對于Spring Boot來說,自動配置是一大特點
配置Druid數(shù)據(jù)源
Spring Boot2.x的數(shù)據(jù)源 hikari 的, 而1.x則是 Tomcat的, 所以我們要配置以下自己的數(shù)據(jù)源
?? com.alibaba ?druid ?1.1.16 ?
引入這個依賴就好了
然后在 application.yml 配置文件下:
spring: ?datasource: ?password:?root ?username:?root ?url:?jdbc:MySQL://localhost:3306/mybatis?serverTimezone=UTC ?driver-class-name:?com.mysql.cj.jdbc.Driver ?type:?com.alibaba.druid.pool.DruidDataSource ?initialSize:?5 ?minIdle:?5 ?maxActive:?20 ?maxWait:?60000 ?timeBetweenEvictionRunsMillis:?60000 ?minEvictableIdleTimeMillis:?300000 ?validationQuery:?SELECT?1?FROM?DUAL ?testWhileIdle:?true ?testOnBorrow:?false ?testOnReturn:?false ?poolPreparedStatements:?true ?#?配置監(jiān)控統(tǒng)計攔截的filters，去掉后監(jiān)控界面sql無法統(tǒng)計，'wall'用于防火墻 ?filters:?stat,wall,log4j ?maxPoolPreparedStatementPerConnectionSize:?20 ?useGlobalDataSourceStat:?true ?connectionProperties:?druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500
下面這一堆的屬性是不生效的, 如果想要生效, 需要特殊配置一下, Druid監(jiān)控也配置了:
重慶分公司
重慶分公司
package?com.carson.config;
import?com.alibaba.druid.pool.DruidDataSource;
import?com.alibaba.druid.support.http.StatViewServlet;
import?com.alibaba.druid.support.http.WebStatFilter;
import?org.springframework.boot.context.properties.ConfigurationProperties;
import?org.springframework.boot.web.servlet.FilterRegistrationBean;
import?org.springframework.boot.web.servlet.ServletRegistrationBean;
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;
import?javax.sql.DataSource;
import?java.util.Arrays;
import?java.util.HashMap;
import?java.util.Map;
@Configuration
public?class?DruidConfig?{
?@ConfigurationProperties(prefix?=?"spring.datasource")
?@Bean
?public?DataSource?druid()?{
?return?new?DruidDataSource();
?}
?//?配置?Druid?監(jiān)控
?//1)?配置一個管理后臺的Servlet
?@Bean
?public?ServletRegistrationBean?statViewServlet()?{
?ServletRegistrationBean?bean?=?new?ServletRegistrationBean(new?StatViewServlet(),?"/druid/*");
?Map?initParams?=?new?HashMap<>();
?//?這里是?druid?monitor(監(jiān)視器)的?賬號密碼,?可以任意設(shè)置
?initParams.put("loginUsername",?"admin");
?initParams.put("loginPassword",?"123456");
?initParams.put("allow",?"");
?initParams.put("deny",?"192.123.11.11");
?//?設(shè)置初始化參數(shù)
?bean.setInitParameters(initParams);
?return?bean;
?}
?//?2)配置一個監(jiān)控的?filter
?@Bean
?public?FilterRegistrationBean?webStatFilter()?{
?FilterRegistrationBean?bean?=?new?FilterRegistrationBean();
?bean.setFilter(new?WebStatFilter());
?Map?initParams?=?new?HashMap<>();
?initParams.put("exclusions","*.js,*.css,/druid/*");
?bean.setInitParameters(initParams);
?bean.setUrlPatterns(Arrays.asList("/*"));
?return?bean;
?}
} 啟動主類, 查看是否可以進(jìn)入到?德魯伊監(jiān)視器, 如果你報錯了請?zhí)砑?log4j 依賴:
?? log4j ?log4j ?1.2.17 ?
查看效果:
利用SpringBoot建表
然后在 resources/sql 下引入兩個建表的sql文件:
department.sql:
SET?FOREIGN_KEY_CHECKS?=?0; --?---------------------------- --?Table?structure?for?department --?---------------------------- DROP?TABLE?IF?EXISTS?`department`; CREATE?TABLE?`department`?( ?`id`?INT(11)?NOT?NULL?AUTO_INCREMENT, ?`departmentName`?VARCHAR(255)?DEFAULT?NULL, ?PRIMARY?KEY?(`id`) ) ?ENGINE?=?InnoDB ?AUTO_INCREMENT?=?1 ?DEFAULT?CHARSET?=?utf8;
employee.sql:
SET?FOREIGN_KEY_CHECKS?=?0; --?---------------------------- --?Table?structure?for?employee --?---------------------------- DROP?TABLE?IF?EXISTS?`employee`; CREATE?TABLE?`employee`?( ?`id`?INT(11)?NOT?NULL?AUTO_INCREMENT, ?`lastName`?VARCHAR(255)?DEFAULT?NULL, ?`email`?VARCHAR(255)?DEFAULT?NULL, ?`gender`?INT(2)?DEFAULT?NULL, ?`d_id`?INT(11)?DEFAULT?NULL, ?PRIMARY?KEY?(`id`) ) ?ENGINE?=?InnoDB ?AUTO_INCREMENT?=?1 ?DEFAULT?CHARSET?=?utf8;
并且在 application.yml 文件下寫入:
?schema: ?-?classpath:sql/department.sql ?-?classpath:sql/employee.sql ?initialization-mode:?always
schema`是與 password/username 等等同級的,哦對了, 如果你是 springboot 2.x版本以上的, 你可能需要加上initialization-mode這個屬性。
運行主類, 查看是否建表成功,
如果你的程序在設(shè)置sql文件后 啟動報錯了:
重啟 idea (重啟大法好啊!)
查看 schema是否配置對了 sql文件的名字
schema:
-(空格)classpath:sql/xxx.sql
注意格式
對應(yīng)數(shù)據(jù)庫實體類
Employee.java
package?com.carson.domain;
public?class?Employee?{
?private?Integer?id;
?private?String?lastName;
?private?Integer?gender;
?private?String?email;
?private?Integer?dId;
?public?Integer?getId()?{
?return?id;
?}
?public?void?setId(Integer?id)?{
?this.id?=?id;
?}
?public?String?getLastName()?{
?return?lastName;
?}
?public?void?setLastName(String?lastName)?{
?this.lastName?=?lastName;
?}
?public?Integer?getGender()?{
?return?gender;
?}
?public?void?setGender(Integer?gender)?{
?this.gender?=?gender;
?}
?public?String?getEmail()?{
?return?email;
?}
?public?void?setEmail(String?email)?{
?this.email?=?email;
?}
?public?Integer?getdId()?{
?return?dId;
?}
?public?void?setdId(Integer?dId)?{
?this.dId?=?dId;
?}
}Department.java
package?com.carson.domain;
public?class?Department?{
?private?Integer?id;
?private?String?departmentName;
?public?Integer?getId()?{
?return?id;
?}
?public?void?setId(Integer?id)?{
?this.id?=?id;
?}
?public?String?getDepartmentName()?{
?return?departmentName;
?}
?public?void?setDepartmentName(String?departmentName)?{
?this.departmentName?=?departmentName;
?}
}記得把剛才我配置文件的 schema屬性全部注釋掉, 我們不希望下次運行的時候會再次創(chuàng)建表
數(shù)據(jù)庫交互
- 注解版
建立一個 Mapper, 把sql語句直接寫在上面
package?com.carson.mapper;
import?com.carson.domain.Department;
import?org.apache.ibatis.annotations.*;
//?指定這是一個?mapper
@Mapper
public?interface?DepartmentMapper?{
?@Select("select?*?from?department?where?id=#{id}")
?public?Department?getDepById(Integer?id);
?@Delete("delete?from?department?where?id=#{id}")
?public?int?deleteDepById(Integer?id);
?@Insert("insert?into?department(departmentName)?values(#{departmentName})")
?public?int?insertDept(Department?department);
?@Update("update?department?set?departmentName=#{departmentName}?where?id=#{id}")
?public?int?updateDept(Department?department);
}然后寫一個Controller :
package?com.carson.controller;
import?com.carson.domain.Department;
import?com.carson.mapper.DepartmentMapper;
import?org.springframework.beans.factory.annotation.Autowired;
import?org.springframework.web.bind.annotation.GetMapping;
import?org.springframework.web.bind.annotation.PathVariable;
import?org.springframework.web.bind.annotation.RestController;
@RestController?//?代表返回?json?數(shù)據(jù)的?controller
public?class?DeptController?{
?@Autowired
?DepartmentMapper?departmentMapper;
?@GetMapping("/dept/{id}")
?public?Department?getDept(@PathVariable("id")?Integer?id)?{
?return?departmentMapper.getDepById(id);
?}
?@GetMapping
?public?Department?inserDept(Department?department)?{
?departmentMapper.insertDept(department);
?return?department;
?}
}通過?@PathVariable?可以將?URL?中占位符參數(shù)綁定到控制器處理方法的入?yún)⒅校篣RL 中的 {xxx} 占位符可以通過@PathVariable(“xxx“) 綁定到操作方法的入?yún)⒅小?/p>
啟動主類, 輸入這個: localhost:8080/dept?departmentName=AA , 這是往數(shù)據(jù)庫增加一條數(shù)據(jù):
然后查詢: localhost:8080/dept/3 , 我數(shù)據(jù)庫id是3, 所以我要查詢3:
不過發(fā)現(xiàn)一個問題, 在插入數(shù)據(jù)的時候獲取不到 id:
所以我們要使用一個@Options注解:
?@Options(useGeneratedKeys?=?true,keyProperty?=?"id")
?@Insert("insert?into?department(departmentName)?values(#{departmentName})")
?public?int?insertDept(Department?department);添加到剛才 mapper中insert 的 @value注解上面
useGeneratedKeys : 使用生成的主鍵
keyProperty: 意思是 Department 里面的哪個屬性是主鍵, 就是我們的 id
試著插入一條數(shù)據(jù):
但是實際忘記注釋掉 schema , 導(dǎo)致每次運行都會重新創(chuàng)建數(shù)據(jù)庫, 各位要注意
還有一個問題
我們把數(shù)據(jù)庫的字段名改成 department_name 而實體類是departmentName;
并且把sql語句也改正
?@Options(useGeneratedKeys?=?true,keyProperty?=?"id")
?@Insert("insert?into?department(department_name)?values(#{departmentName})")
?public?int?insertDept(Department?department);
?@Update("update?department?set?department_name=#{departmentName}?where?id=#{id}")
?public?int?updateDept(Department?department);然后在進(jìn)行查詢操作的話:
我們發(fā)現(xiàn)獲取不到 departmentName 了, 以前Spring 我們是使用配置文件來應(yīng)對這種情況的, 但是我們現(xiàn)在沒有了xml文件,我們該怎么辦呢?
世上無難事
創(chuàng)建自定義配置類:
package?com.carson.config;
import?org.mybatis.spring.boot.autoconfigure.ConfigurationCustomizer;
import?org.springframework.context.annotation.Bean;
import?org.springframework.context.annotation.Configuration;
@Configuration
public?class?MyBatisConfig?{
?@Bean
?public?ConfigurationCustomizer?configurationCustomizer()?{
?return?new?ConfigurationCustomizer()?{
?@Override
?public?void?customize(org.apache.ibatis.session.Configuration?configuration)? ?{
?configuration.setMapUnderscoreToCamelCase(true);
?}
?};
?}
}注意這里面的 setMapUnderscoreToCamelCase,意思是:
翻譯大法好啊, 我的英文太差了, 再次訪問 http://localhost:8080/dept/1 查詢操作, 我發(fā)現(xiàn)已經(jīng)不是 null了:
{"id":1,"departmentName":"jackMa"}馬總正確的展現(xiàn)出來了!
MapperScan注解
掃描器, 用來掃描mapper接口的
我把它標(biāo)記到 啟動類 上(你可以標(biāo)記在任何地方):
指定一個包,它會掃描這個包下所有的 mapper 接口, 防止你的mapper文件太多, 并且忘記加 @mapper 注解, 這樣可以提高正確性
- 配置文件版
注解版貌似很方便, 但是如果遇到復(fù)雜的sql , 比如動態(tài)sql等等, 還是需要用 xml 配置文件的;
創(chuàng)建一個 Employee 的Mapper接口:
package?com.carson.mapper;
import?com.carson.domain.Employee;
public?interface?EmployeeMapper?{
?public?Employee?getEmpById(Integer?id);
?public?void?insertEmp(Employee?employee);
}在 resources/mybatis 下創(chuàng)建一個 mybatis-config.xml 全局配置文件:
?
在 resources/mybatis/mapper 包下創(chuàng)建 EmployeeMapper.xml 映射文件:
