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JavaWenb开发

pom.xml 文件配置

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.7.5</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.itheima</groupId><artifactId>tlias-web-management</artifactId><version>0.0.1-SNAPSHOT</version><name>tlias-web-management</name><description>Demo project for Spring Boot</description><properties><java.version>1.8</java.version></properties><dependencies><!--web起步依赖--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency>
<!--mybatis起步依赖--><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>2.2.2</version></dependency>
<!--mysql驱动--><dependency><groupId>com.mysql</groupId><artifactId>mysql-connector-j</artifactId><scope>runtime</scope></dependency>
<!--lombok--><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency>

<!--        <dependency>-->
<!--            <groupId>org.slf4j</groupId>-->
<!--            <artifactId>slf4j-log4j12</artifactId>-->
<!--            <version>1.6.4</version>-->
<!--        </dependency>-->
<!--springboot单元测试--><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency></dependencies>
<build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><excludes><exclude><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></exclude></excludes></configuration></plugin></plugins></build>

</project>

链接数据库和驼峰命名

application.propertoen 文件配置

#驱动类名称
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
#数据库连接的url
spring.datasource.url=jdbc:mysql://localhost:3306/mybatis
#连接数据库的用户名
spring.datasource.username=root
#连接数据库的密码
spring.datasource.password=123456


#配置mybatis的日志, 指定输出到控制台
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl

#开启mybatis的驼峰命名自动映射开关 a_column ------> aCloumn
mybatis.configuration.map-underscore-to-camel-case=true

Controller 层

处理前端请求的数据

package com.itheima.controller;

import com.itheima.pojo.Dept;
import com.itheima.pojo.Result;
import com.itheima.service.DeptService;
import lombok.extern.slf4j.Slf4j;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

/*** 部门管理Controller*/
@Slf4j
@RestController
public class DeptController {

//固定代码  也可也用注解 @Slf4j  private static Logger log=LoggerFactory.getLogger(DeptController.class);//  private static Logger log=LoggerFactory.getLogger(DeptController.class);// @RequestMapping(value = "/depts",method = RequestMethod.GET)  //指定请求方式get@Autowiredprivate DeptService deptService;
@GetMapping("/depts")public Result list(){log.info("查询全部部门数据");//调用ServiceList<Dept> deptList= deptService.list();return Result.success(deptList);}
}

service 层

服务处理逻辑调用操作

服务层接口

package com.itheima.service;

import com.itheima.pojo.Dept;

import java.util.List;

/*** 部门管理*/
public interface DeptService {/**查询全部员工数据*  @return* */
List<Dept> list();
}

服务层实类

package com.itheima.service.impl;

import com.itheima.mapper.DeptMapper;
import com.itheima.pojo.Dept;
import com.itheima.service.DeptService;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class DeptServiceImpl implements DeptService {
@Autowiredprivate DeptMapper deptMapper;
@Overridepublic List<Dept> list() {return deptMapper.lidt();}
//部门管理
}

数据库调用（mybatis）跟数据库链接层

package com.itheima.mapper;

import com.itheima.pojo.Dept;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

/*** 部门管理*/
@Mapper
public interface DeptMapper {

//查询前部部门数据
@Select("select * from tlias.dept")List<Dept> lidt();
}

实体类

package com.itheima.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import java.time.LocalDateTime;

/*** 部门实体类*/
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Dept {private Integer id; //IDprivate String name; //部门名称private LocalDateTime createTime; //创建时间private LocalDateTime updateTime; //修改时间
}

返回状态码

package com.itheima.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class Result {private Integer code;//响应码，1 代表成功; 0 代表失败private String msg;  //响应信息 描述字符串private Object data; //返回的数据

//增删改 成功响应public static Result success(){return new Result(1,"success",null);}//查询 成功响应public static Result success(Object data){return new Result(1,"success",data);}//失败响应public static Result error(String msg){return new Result(0,msg,null);}
}

报错

报错代码
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.binding.BindingException: Parameter 'start' not found. Available parameters are [arg0, pageSize, param1, param2]] with root cause

@Select("select  * from emp limit #{start},#{pageSize}")public List <Emp> page(@Param("start") Integer start,@Param("pageSize")Integer pageSize );

   <!-- 分页查询  --><dependency><groupId>com.github.pagehelper</groupId><artifactId>pagehelper-spring-boot-starter</artifactId><version>1.4.6</version></dependency>

    @Overridepublic PageBean page(Integer page, Integer pageSize) {// 1 分页查询PageHelper.startPage(page, pageSize);// 2 执行查询List<Emp> empList = empMaqqer.list();Page<Emp> p=  (Page<Emp>)empList;// 3 封装pageBean 对象PageBean pageBean=new PageBean(p.getTotal(),p.getResult());return pageBean;}