前后端联调_代码007

Jav aWenb 开发

&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;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"&gt;
    &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
    <parent&gt;
        <groupId&gt;org.springframework.boot</groupId&gt;
        <artifactId&gt;spring-boot-starter-parent</artifactId&gt;
        <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
    @Autowired
    private DeptService deptService;

    @GetMapping("/depts")
    public Result list(){
      log.info("查询全部部门数据");
      //调用Service
     List<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 {

    @Autowired
    private DeptMapper deptMapper;

    @Override
    public 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; //ID
    private 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>

    @Override
    public 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;
    }