Springboot集成mybatis通用Mapper与分页插件PageHelper详解编程语言

插件介绍

通用 Mapper 是一个可以实现任意 MyBatis 通用方法的框架，项目提供了常规的增删改查操作以及 Example 相关的单表操作。通用 Mapper 是为了解决 MyBatis 使用中 90% 的基本操作，PageHelper则提供通用的分页查询功能，使用它们可以很方便的进行开发，可以节省开发人员大量的时间。

通用Mapper的GIT地址： https://gitee.com/free/Mapper

分页插件的GIT地址： https://github.com/pagehelper/Mybatis-PageHelper

 

 !-- 通用Mapper插件 

 文档地址：https://gitee.com/free/Mapper/wikis/Home -- 

 dependency 

 groupId tk.mybatis /groupId 

 artifactId mapper-spring-boot-starter /artifactId 

 version 2.1.5 /version 

 /dependency 

 !-- 分页插件 

 文档地址：https://github.com/pagehelper/Mybatis-PageHelper/blob/master/wikis/zh/HowToUse.md -- 

 dependency 

 groupId com.github.pagehelper /groupId 

 artifactId pagehelper-spring-boot-starter /artifactId 

 version 1.2.10 /version 

 /dependency 

 !-- MYSQL包 -- 

 dependency 

 groupId mysql /groupId 

 artifactId mysql-connector-java /artifactId 

 /dependency 

 !-- 默认就内嵌了Tomcat 容器，如需要更换容器也极其简单-- 

 dependency 

 groupId org.springframework.boot /groupId 

 artifactId spring-boot-starter-web /artifactId 

 /dependency 

在 application.properties 文件中分别添加上数据库、Mybatis、通用Mapper、PageHelper的属性配置

spring.datasource.url=jdbc:mysql://localhost:3306/test?useUnicode=true characterEncoding=UTF-8 zeroDateTimeBehavior=convertToNull allowMultiQueries=true useSSL=false 

spring.datasource.username=root 

spring.datasource.password=123456 

# 如果想看到mybatis日志需要做如下配置 

logging.level.com.carry=DEBUG 

######### Mybatis 自身配置 ########## 

mybatis.mapper-locations=classpath:com/carry/mapper/*Mapper.xml 

mybatis.type-aliases-package=com.carry.entity 

# 驼峰命名规范 如：数据库字段是 order_id 那么 实体字段就要写成 orderId 

mybatis.configuration.map-underscore-to-camel-case=true
######### 通用Mapper ########## 

# 主键自增回写方法,默认值MYSQL,详细说明请看文档 

mapper.identity=MYSQL 

mapper.mappers=tk.mybatis.mapper.common.Mapper 

# 设置 insert 和 update 中，是否判断字符串类型!= 

mapper.not-empty=true 

# 枚举按简单类型处理 

mapper.enum-as-simple-type=true 

######### 分页插件 ########## 

pagehelper.helper-dialect=mysql 

pagehelper.params=count=countSql 

pagehelper.reasonable=false 

pagehelper.support-methods-arguments=true

通用Mapper： mapper.enum-as-simple-type： 枚举按简单类型处理，如果有枚举字段则需要加上该配置才会做映射 mapper.not-empty： 设置以后，会去判断 insert 和 update 中符串类型!= 分页插件： pagehelper.reasonable： 分页合理化参数，默认值为false。当该参数设置为 true 时，pageNum =0 时会查询第一页， pageNum pages（超过总数时），会查询最后一页。默认false 时，直接根据参数进行查询 support-methods-arguments： 支持通过 Mapper 接口参数来传递分页参数，默认值false，分页插件会从查询方法的参数值中，自动根据上面 params 配置的字段中取值，查找到合适的值时就会自动分页 注意事项：

由于 mybatis.mapper-locations=classpath:com/carry/mapper/*.xml配置的在java package中，而Spring Boot默认只打入java package - *.java，所以我们需要给pom.xml文件添加如下内容

 build 

 resources 

 resource 

 directory src/main/resources /directory 

 /resource 

 resource 

 directory src/main/java /directory 

 includes 

 include **/*.xml /include 

 /includes 

 filtering true /filtering 

 /resource 

 /resources 

 plugins 

 plugin 

 groupId org.springframework.boot /groupId 

 artifactId spring-boot-maven-plugin /artifactId 

 /plugin 

 /plugins 

 /build 

1、表结构

创建一张 user表

CREATE TABLE `user` ( 

 `id` int(8) NOT NULL AUTO_INCREMENT COMMENT 主键自增, 

 `username` varchar(50) NOT NULL COMMENT 用户名, 

 `password` varchar(50) NOT NULL COMMENT 密码, 

 PRIMARY KEY (`id`) 

) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT=用户表; 

2、实体类

 package com.carry.entity; 

 import java.io.Serializable; 

 import javax.persistence.GeneratedValue; 

 import javax.persistence.GenerationType; 

 import javax.persistence.Id; 

 import javax.persistence.Table; 

 @Table(name = "user") 

 public class User implements Serializable { 

 private static final long serialVersionUID = -8057591359892731452L; 

 @Id 

 @GeneratedValue(strategy = GenerationType.IDENTITY) 

 private Long id; 

 private String username; 

 private String password; 

 public Long getId() { 

 return id; 

 public void setId(Long id) { 

 this.id = id; 

 public String getUsername() { 

 return username; 

 public void setUsername(String username) { 

 this.username = username; 

 public String getPassword() { 

 return password; 

 public void setPassword(String password) { 

 this.password = password; 


import tk.mybatis.mapper.common.Mapper; 

public interface UserMapper extends Mapper User { 

 /** 
 * 根据用户名统计（假设它是一个很复杂的SQL） 
 * @param username 用户名 
 * @return 统计结果 
 */ 
 int countByUsername(String username); 
}

4、映射文件UserMapper.xml

 ?xml version="1.0" encoding="UTF-8" ? 

 !DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" 

 mapper namespace="com.carry.mapper.UserMapper" 

 select id="countByUsername" resultType="java.lang.Integer" 

 SELECT count(1) FROM user WHERE username = #{username} 

 /select 

 /mapper 

5、启动类

import org.springframework.boot.SpringApplication; 

import org.springframework.boot.autoconfigure.SpringBootApplication; 

import tk.mybatis.spring.annotation.MapperScan; 

@SpringBootApplication 

@MapperScan(basePackages = "com.carry.mapper") 

public class SpringbootMapperPagehelperApplication { 

 public static void main(String[] args) { 
 SpringApplication.run(SpringbootMapperPagehelperApplication.class, args); 

}

 

完成数据访问层接口后，编写一个junit测试类来检验代码的正确性。

 package com.carry; 

 import org.junit.Test; 

 import org.junit.runner.RunWith; 

 import org.slf4j.Logger; 

 import org.slf4j.LoggerFactory; 

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

 import org.springframework.boot.test.context.SpringBootTest; 

 import org.springframework.test.context.junit4.SpringRunner; 

 import com.carry.entity.User; 

 import com.carry.mapper.UserMapper; 

 import com.github.pagehelper.PageHelper; 

 import com.github.pagehelper.PageInfo; 

 @RunWith(SpringRunner.class) 

 @SpringBootTest 

 public class SpringbootMapperPagehelperApplicationTests { 

 private final Logger logger = LoggerFactory.getLogger(this.getClass()); 

 @Autowired 

 private UserMapper userMapper; 

 @Test 

 public void test() { 

 try { 

 final User user1 = new User("u1", "p1"); 

 final User user2 = new User("u1", "p2"); 

 final User user3 = new User("u3", "p3"); 

 userMapper.insertSelective(user1); 

 logger.info("[user1回写主键] - [{}]", user1.getId()); 

 userMapper.insertSelective(user2); 

 logger.info("[user2回写主键] - [{}]", user2.getId()); 

 userMapper.insertSelective(user3); 

 logger.info("[user3回写主键] - [{}]", user3.getId()); 

 final int count = userMapper.countByUsername("u1"); 

 logger.info("[调用自己写的SQL] - [{}]", count); 

 // TODO 模拟分页 

 for (int i = 0; i i++) { 

 userMapper.insertSelective(new User("u" + i, "p" + i)); 

 // TODO 分页 + 排序 this.userMapper.selectAll() 这一句就是我们需要写的查询，有了这两款插件无缝切换各种数据库 

 final PageInfo User pageInfo = PageHelper.startPage(1, 10).setOrderBy("id desc") 

 .doSelectPageInfo(() - this.userMapper.selectAll()); 

 logger.info("[lambda写法] - [分页信息] - [{}]", pageInfo.toString()); 

 PageHelper.startPage(1, 10).setOrderBy("id desc"); 

 final PageInfo User userPageInfo = new PageInfo (this.userMapper.selectAll()); 

 logger.info("[普通写法] - [{}]", userPageInfo); 

 } catch (Exception e) { 

 logger.error(e.getMessage()); 

 }

 

原创文章，作者：Maggie-Hunter，如若转载，请注明出处：https://blog.ytso.com/16929.html

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