mybatis时间和timestamp对象比较

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ganmaobuhaowan 2024-10-24 21:57:41

文章标签 mybatis spring 分页数据 文章分类 架构后端开发

实现分页查询的mybatis和mybatis-plus的代码分析

mybatis-plus实现分页查询

首先，本人是在STS使用springboot脚手架建立一个maven工程，配置的依赖如下：

mybatis时间和timestamp对象比较_分页

yml的配置如下;

#server
server:
  port: 80
  servlet:
    context-path: /
  tomcat:
    max-threads: 1000
#spring
spring:
  datasource:
    url: jdbc:mysql:///jtsys?serverTimezone=GMT%2B8&characterEncoding=utf8
    username: root
    password: root
  thymeleaf:
    prefix: classpath:/templates/pages/
    suffix: .html
#mybatis
mybatis-plus:
  configuration:
    default-statement-timeout: 30
    map-underscore-to-camel-case: true
  mapper-locations:
  - classpath:/mapper/*/*.xml
#log
logging:
  level:
    com.cy: DEBUG

最后：需要安装Lombok插件，找到导入的Lombok的jar包双击就弹出安装界面，再选择自动搜索出的STS软件中就可以

1.数据库准备

建立一个数据库test，再建立一个表Sys_roles

mybatis时间和timestamp对象比较_spring_02

表Sys_roles数据代码如下：

/*
SQLyog 企业版 - MySQL GUI v8.14 
MySQL - 5.5.27 
*********************************************************************
*/
/*!40101 SET NAMES utf8 */;

create table `sys_roles` (
	`id` double ,
	`name` varchar (300),
	`note` varchar (1500),
	`createdTime` datetime ,
	`modifiedTime` datetime ,
	`createdUser` varchar (60),
	`modifiedUser` varchar (60)
); 
insert into `sys_roles` (`id`, `name`, `note`, `createdTime`, `modifiedTime`, `createdUser`, `modifiedUser`) values('47','超级管理员','负责系统所有模块的管理','2020-04-29 10:59:45','2020-05-09 16:22:24',NULL,NULL);
insert into `sys_roles` (`id`, `name`, `note`, `createdTime`, `modifiedTime`, `createdUser`, `modifiedUser`) values('48','初级软件工程师','负责代码实现','2020-04-29 11:02:01','2020-05-11 11:29:26',NULL,NULL);
insert into `sys_roles` (`id`, `name`, `note`, `createdTime`, `modifiedTime`, `createdUser`, `modifiedUser`) values('49','中级软件工程师','负责需求分析，模块设计','2020-04-29 16:05:58','2020-04-29 17:03:20',NULL,NULL);

2.pojo的准备

JsonResult 类–封装呈现到页面的数据。以及成功失败的状态信息，以及捕获的报错信息

package com.cy.pj.sys.pojo;

import java.io.Serializable;

import lombok.Data;

@Data
public class JsonResult implements Serializable {
	
	private static final long serialVersionUID = 7816949974168795608L;
	//状态码
	private int state=1;//成功表示1，执行失败表示0
	//状态信息
	private String message="ok";
	//正确数据
	private Object data;
	//写构造方法的目的吗是，在controller层直接new一个JsonRueslt来设置属性值
	public JsonResult() {}
	//如果执行失败new JsonResult对象可以获取抛出来的异常信息封装到message，并且告诉执行失败
	public JsonResult(Throwable t){
			this.state=0;
			this.message=t.getMessage();
		}
	public JsonResult(String message) {
		this.message=message;
		
	}
	public JsonResult(Object data) {
		this.data=data;
		
	}
}

SysRole–封装数据库字段的信息，传递数据库的数据

package com.cy.pj.sys.pojo;

import java.io.Serializable;
import java.util.Date;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

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

@NoArgsConstructor
@AllArgsConstructor
@TableName("sys_roles")
@Data
public class SysRole implements Serializable {
	private static final long serialVersionUID = 5013943989061127383L;
	@TableId(type = IdType.AUTO)//自增
	private Integer id;
	private String name;
	private String note;
	
	@TableField("createdTime")
	private Date createdTime;
	@TableField("modifiedTime")
	private Date modifiedTime;
	
	@TableField("createdUser")
	private String createdUser;
	
	@TableField("modifiedUser")
	private String modifiedUser;
	
}

4.定义全局异常拦截器

SystemExeAOP 类–目的是获取全局的异常传递到JsonResult类中，并且JsonResult类输出成一个JSON字符串，方便页面获取到数据信息

package com.cy.pj.sys.aop;

import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import com.cy.pj.sys.pojo.JsonResult;
import lombok.extern.slf4j.Slf4j;
@Slf4j
@RestControllerAdvice //@RestControllerAdvice=@ControllerAdvice+@ResponseBody
public class SystemExeAOP {
	@ExceptionHandler(RuntimeException.class)
	public Object systemResultExcepton(Exception exception) {
		exception.printStackTrace();
		log.error("~~~~~~~+"+exception.getMessage()+"+",exception);
		return new JsonResult(exception);
	}
}

5.控制层的实现RoleController

package com.cy.pj.sys.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.cy.pj.sys.Service.SysRoleService;
import com.cy.pj.sys.pojo.JsonResult;

@RestController
@RequestMapping("/role/")
public class RoleController {
	@Autowired
	private SysRoleService sysRoleService;

	/**
	 * 业务：查询按照用户名查询角色表的数据并按创建时间排序，同时实现分页查询
	 * equest URL: 
	 * http://localhost/role/doFindPageObjects?pageCurrent=1&name=超级管理员&pageSize=10
	 *Request Method: GET
	 * 参数：pageCurrent=1
	 *     	name=admin
	 * 		pageSize=10
	 *返回结果：new JsonResult(List...)
	 */
	@RequestMapping("doFindPageObjects")
	private JsonResult doFindPageObjects(String name,Integer pageCurrent,Integer pageSize) {
		return new JsonResult(sysRoleService.findPageObjects(name,pageCurrent,pageSize));
	}
	
}

6.服务层的实现RoleService和RoleServiceImpl

package com.cy.pj.sys.Service;

import com.baomidou.mybatisplus.core.metadata.IPage;
import com.cy.pj.sys.pojo.SysRole;
public interface SysRoleService {
	IPage<SysRole> findPageObjects(String name, Integer pageCurrent,Integer pageSize);
}

```java
package com.cy.pj.sys.Service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.cy.pj.sys.Service.SysRoleService;
import com.cy.pj.sys.dao.SysRoleDao;
import com.cy.pj.sys.pojo.SysRole;


@Service
public class SysRoleServiceImpl implements SysRoleService {
	
	@Autowired
	private SysRoleDao sysRoleDao;

	@Override
	public IPage<SysRole> findPageObjects(String name, Integer pageCurrent,Integer pageSize) {
		//PageObject<SysRole>因为我想将页面的pageCurrent(当前页码)，pageSize(分页数),rowCount(总行数),pageCount(总页数),records(查询结果的集合List<SysRole>)
		//1.定义分页对象
		Page<SysRole> mpPage=new Page<>(pageCurrent, pageSize);
		//2.定义条件构造器
		QueryWrapper<SysRole> queryWrapper2 = new QueryWrapper<>();
		//3.要求:按照更新时间,进行排序  降序排列.
		queryWrapper2.eq("name", name)
					.orderByDesc("createdTime")
					;
		IPage<SysRole> selectPage = sysRoleDao.selectPage(mpPage, queryWrapper2);
//		long current = selectPage.getCurrent();//当前页
		long total = selectPage.getTotal();//当前满足条件总行数
//		long pages = selectPage.getPages();//分页总页数
//		List<SysRole> records = selectPage.getRecords();//分页对象记录列表
		if(total<=0)
			throw new IllegalArgumentException("没有查询到对应的记录");
		return selectPage;
	}
	
}

7.持久层的实现SysRoleDao

package com.cy.pj.sys.dao;

import org.apache.ibatis.annotations.Mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;

import com.cy.pj.sys.pojo.SysRole;

@Mapper
public interface SysRoleDao extends BaseMapper<SysRole> {

}

8.mybatis-plus分页查询的分页拦截器的实现

最后一步，如果想Page<>起作用，需要创建一个mybatis-plus分页查询的分页拦截器

package com.cy.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
/*
 * 指示一个类声明一个或多个@Bean方法，并且可以由Spring容器在运行时为这些Bean生成Bean定义和服务请求
 */

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;

@Configuration
public class MybatisPlusConfig {
	@Bean//分页接受器(PaginationInterceptor)
	public PaginationInterceptor paginationInterceptor() {
		
		return new PaginationInterceptor();
	}
}