打开IDEA 初始化Spring Boot 项目,记得钩上 lombok
在pom.xml 下添加
<dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.21</version> </dependency> <dependency> <groupId>org.postgresql</groupId> <artifactId>postgresql</artifactId> <scope>runtime</scope> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>2.1.1</version> </dependency>
在application.properties 下添加,注意数据库名
# 日志的打印级别 logging.level.org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping=trace # 大象数据库 spring.datasource.druid.url=jdbc:postgresql://localhost:5432/你的数据库名 spring.datasource.druid.username=你的用户名 spring.datasource.druid.password=你的密码 spring.datasource.druid.driver-class-name=org.postgresql.Driver # 配置Druid的连接池 spring.datasource.druid.initialSize=10 spring.datasource.druid.maxActive=20 spring.datasource.druid.maxWait=60000 spring.datasource.druid.minIdle=1 spring.datasource.druid.timeBetweenEvictionRunsMillis=60000 spring.datasource.druid.minEvictableIdleTimeMillis=300000 spring.datasource.druid.testWhileIdle=true spring.datasource.druid.testOnBorrow=true spring.datasource.druid.testOnReturn=false spring.datasource.druid.poolPreparedStatements=true spring.datasource.druid.maxOpenPreparedStatements=20 spring.datasource.druid.validationQuery=SELECT 1 spring.datasource.druid.validation-query-timeout=500 spring.datasource.druid.filters=stat
创建大象数据库表
CREATE TABLE HEXINFO( -- SERIAL 自增主键 ID SERIAL PRIMARY KEY NOT NULL, -- 摘要 HEX TEXT NOT NULL, SPAWNTIME TIMESTAMP NOT NULL, INFO TEXT NOT NULL, NODEID TEXT NOT NULL, CHUNKID INT NOT NULL, ); -- 查询最大值语句,等下用的到 select * from hexinfo where id in(select max(id) from hexinfo); -- 插入一条信息 INSERT INTO HEXINFO (HEX,SPAWNTIME,INFO,NODEID) VALUES(‘000000000001‘,current_timestamp,‘oxoxoxox‘,‘123456‘);
在项目路径下创建 3 个 文件
第一个 Hexinfo.java
package cn.edu.zzuli.fabriciec; import lombok.Data; import lombok.NoArgsConstructor; import java.util.Date; @Data @NoArgsConstructor public class Hexinfo { private Integer id; private String hex; private Date spawntime; private String info; private String nodeid; private Integer chunkid; }
第二个 HexinfoMapper.java
package cn.edu.zzuli.fabriciec; import org.apache.ibatis.annotations.Mapper; import org.apache.ibatis.annotations.Select; import java.util.List; @Mapper public interface HexinfoMapper { @Select("select * from hexinfo where id in(select max(id) from hexinfo);") // 这里是使用Mapper List<Hexinfo> getMax(); }
第三个 HexinfoController.java
package cn.edu.zzuli.fabriciec; import lombok.AllArgsConstructor; import lombok.Data; import org.springframework.web.bind.annotation.CrossOrigin; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RestController; import java.util.List; @CrossOrigin // 跨域请求 @Data @AllArgsConstructor @RestController public class HexinfoController { private HexinfoMapper hexinfoMapper; @GetMapping("/max") public List<Hexinfo> getByMax() { //return hexinfoService.getByMax(); return hexinfoMapper.getMax(); } }
启动项目
访问端口 localhost:8080/max
返回和这段类似就是成功
0 id 22 hex "fec6d532f885902bf5136588f0ebd52e0b8f13fc365ec65d763c150000000000" spawntime "2020-04-28T04:02:12.420+0000" info "I-Love-Java" nodeid "java-point" chunkid 666
可能不理解为什么这么写 安利一个教程,我是在这里学的不过自己用的数据库还是比较喜欢大象。为啥用大象?emmm....
http://blog.didispace.com/spring-boot-learning-2x/