spring boot +Mybatis -plus 入门学习 搭建我的第一个项目

总结：

1、开始搭建mybatis-plus 时，报org.h2.jdbc.JdbcSQLSyntaxErrorException: Table "USER" not found; 

2、报"unexpected status 1308622848" [90067-180]

以上的异常，我被spring boot 和h2的版本不匹配所引导在里面出不来了。

其实我们在配置这个spring.datasource数据库连接时，采用了h2的org.h2.Driver,因为没有弄清楚其原理，所以被带到里面好长时间没出来，搞得心情很不舒服。个人觉得用h2的org.h2Driver，不清楚其原理的话，还是先不要急着学习，很容易被带到里面一时半会儿出不来的。

 

我们采用com.mysql.cj.jdbc.Driver其实也是可以使用mybatis-plus的。

 

 

 

 

以下是我经过测试运行正常且能返回数据的代码，供大家学习。

一、pom.xml

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter</artifactId>
    <version>2.3.4.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <version>2.3.4.RELEASE</version>
    <scope>test</scope>
</dependency> 


<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.1</version>

</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
     <optional>true</optional>
</dependency>
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <scope>runtime</scope>
</dependency>

<!--添加Servlet依赖，只在编译时有效 -->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>javax.servlet-api</artifactId>
    <version>3.0.1</version>
    <scope>provided</scope>
</dependency>

<!--JavaServer Pages Standard Tag Library，JSP标准标签库-->
<dependency>
    <groupId>javax.servlet</groupId>
    <artifactId>jstl</artifactId>
</dependency>

二、application.xml

server.port=8080

spring.datasource.url=jdbc:mysql://127.0.0.1/pxks?serverTimezone=UTC&useUnicode=true&charaterEncoding=utf-8&useSSL=false
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=helloliuting001
spring.datasource.druid.url=rewriteBatchedStatements=true

spring.h2.console.enabled=false
spring.h2.console.settings.web-admin-password=123456

mybatis-plus.config-location=classpath:/mybatis-config.xml

#延时加载   忽略无法转换的对象
spring.jackson.serialization.fail-on-empty-beans=false

spring.mvc.view.prefix=/
spring.mvc.view.suffix=.jsp
server.servlet.context-path=/pxks

 

三、DemoApplication.java

@MapperScan("com.example.demo.mapper")
@SpringBootApplication
@Controller
public class DemoApplication {
    @Autowired
    private UserMapper userMapper;
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
    @RequestMapping("/")
    public @ResponseBody
    List<User> index(HttpSession session )throws Exception{
        List<User> list=userMapper.selectList(null);
        return list;
    }
}

四、UserMapper.java

public interface UserMapper  extends BaseMapper<User> {
}

五、User.java

import lombok.Data;

@Data
@TableName(value = "tb_User")
public class User {
    private long id;
@TableField(exist = true,value = "name")//与数据对应列名
    private String name;
    private String age;
    private String email;
    @TableField(exist = false) //exist默认为true(对应数据库字段) false为数据库中未有与之对应的字段，仅是后端操作便利
    private String cz;
}