Integrated spring boot mybatis (2) - used to implement paging pagehelper

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Spring Boot Integration Tutorial

• Spring Boot Introduction
• Spring Boot development environment to build (Eclipse)
• Spring Boot Hello World (restful Interface) Examples
• spring boot connect Mysql
• spring boot configuration druid connection pool mysql
• Integrated spring boot mybatis (1)
• Integrated spring boot mybatis (2) - used to implement paging pagehelper
• Integrated spring boot mybatis (3) - mybatis generator arranged
• Interface package return spring boot value
• input data check spring boot (Validation)
• spring boot rest interface Integrated spring security (1) - the most simple configuration
• Interface integrated spring boot rest spring security (2) - JWT Configuration
• spring boot exception (Exception) Processing
• spring boot environment configuration (Profile) switch
• spring boot redis cache (cache) Integration

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Outline

In this paper the basis of the previous tutorial, using a common pagehelper plug-ins, add paging functionality. This article will implement a list of all user interface, paged return results

Prepare data

Database data tables and use the previous section [spring boot integrated mybatis (1)] is used, due to the tab, insertion need more data table.

mysql command-line client database connection

mysql -h localhost -u root -p

Insert data sql statement:

INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc3', '13512345603', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc4', '13512345604', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc5', '13512345605', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc6', '13512345606', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc7', '13512345607', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc8', '13512345608', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc9', '13512345609', '123');
INSERT INTO `qikegu_demo`.`user` (`nickname`, `mobile`, `password`) VALUES ('abc10', '13512345610', '123');

Project Dependencies

Do not create a new project, reuse sections [spring boot integrated mybatis (1)] in the project, the project does not create according to the paper.
Eclipse open the item, in pom.xml file, adding a dependency: pagehelper-spring-boot-starter , the introduction of dependent packages pagehelper

Add Dependency: pagehelper-spring-boot-starter

Add depend in pom.xml

        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.10</version>
        </dependency>

Complete pom.xml file

<?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 http://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>2.1.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.qikegu</groupId>
    <artifactId>springboot-mybatis-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-mybatis-demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        
        <!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper-spring-boot-starter -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.10</version>
        </dependency>
        
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Project Configuration

Add pagehelper Configuration

Add pagehelper configuration in application.properties

pagehelper.helperDialect=mysql
pagehelper.reasonable=true
pagehelper.supportMethodsArguments=true
pagehelper.params=count=countSql

Description:

• helperDialect: Pagination plug-in will automatically detect the current database link, automatically selects the appropriate way paging. You can also configure helperDialect attribute to specify which dialect to use plug-ins page.
• reasonable: Page rationalizing parameter, the default value is false. When this parameter is set to true, pageNum <= 0, the first page queries, pageNum> pages (more than the total number), the last page queries. Default false, according to a direct query parameters.
• params: A property name from the subject according to the value, may be configured pageNum, pageSize, count, pageSizeZero, reasonable, not configured with a default value map, the default value pageNum = pageNum; pageSize = pageSize; count = countSql; reasonable = reasonable ; pageSizeZero = pageSizeZero
• supportMethodsArgumentsDefault: false, pagination plug-in will automatically based on field values ​​in the above params configuration parameters from the query method, the page will automatically find the time to the appropriate value.

More information pagehelper official website

Full content application.properties

## 服务器端口，如果不配置默认是8080端口
server.port=8096 

## 数据库设置
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://192.168.0.99:3306/qikegu_demo?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8
spring.datasource.username=root
spring.datasource.password=qazwsx

## mybatis配置
#  指向映射类目录
mybatis.type-aliases-package=com.qikegu.demo.model
# 指向映射xml文件目录
mybatis.mapper-locations=classpath:mapper/*.xml

## pagehelper
pagehelper.helperDialect=mysql
pagehelper.reasonable=true
pagehelper.supportMethodsArguments=true
pagehelper.params=count=countSql

Add code

pagehelper use

There are several methods pagehelper use, here we introduce the most commonly used two kinds:

//方法1，Mapper接口方式的调用，推荐这种使用方式。
PageHelper.startPage(1, 10); // pageNum=1, pageSize=10
List<Country> list = countryMapper.selectIf(1);

//方法2，参数方法调用
//存在以下 Mapper 接口方法，你不需要在 xml 处理后两个参数
public interface CountryMapper {
    List<Country> selectByPageNumSize(
            @Param("user") User user,
            @Param("pageNum") int pageNum,
            @Param("pageSize") int pageSize);
}
//配置supportMethodsArguments=true
//在代码中直接调用：
List<Country> list = countryMapper.selectByPageNumSize(user, 1, 10);

This article take the example of Method 1, more Reference pagehelper official website

Code

Add features we want to achieve: list all users, paging returns the result. The following documents need to modify a few:

• UserController.java - control layer
• UserService.java & UserServiceImpl.java - service layer
• UserMapper.java & UserMapper.xml - Data Access Layer

Figure:

UserController.java

Add a function

   @RequestMapping(value="", method = RequestMethod.GET, produces="application/json")
    public PageInfo<User> listUser(
            @RequestParam(value="page", required=false, defaultValue="1") int page,
            @RequestParam(value="page-size", required=false, defaultValue="5") int pageSize){
        

        List<User> result = userService.listUser(page, pageSize);
        // PageInfo包装结果，返回更多分页相关信息
        PageInfo<User> pi = new PageInfo<User>(result);
        
        return pi;
    }

Description :

This function is a control layer interface, wherein

• @RequestParamNotes get the url ?page=1&page-size=5parameter value="page"is the parameter name in the url, requiredrefers to whether the parameters must, if it is necessary but not this URL parameter error, defaultValue="1"the default value
• PageInfo PageInfo packaging results, returns more information about pagination

Complete code:

package com.qikegu.demo.controller;

import java.util.List;

import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;

import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import com.qikegu.demo.model.User;
import com.qikegu.demo.service.UserService;

@RestController
@EnableAutoConfiguration
@RequestMapping("/user")
public class UserController {
    
    // 注入mapper类
    @Resource
    private UserService userService;
    
    @RequestMapping(value="{id}", method=RequestMethod.GET, produces="application/json")
    public User getUser(@PathVariable long id) throws Exception {
        
        User user = this.userService.getUserById(id);
        
        return user;
    }
    
    @RequestMapping(value="", method = RequestMethod.GET, produces="application/json")
    public PageInfo<User> listUser(
            @RequestParam(value="page", required=false, defaultValue="1") int page,
            @RequestParam(value="page-size", required=false, defaultValue="5") int pageSize){
        

        List<User> result = userService.listUser(page, pageSize);
        // PageInfo包装结果，返回更多分页相关信息
        PageInfo<User> pi = new PageInfo<User>(result);
        
        return pi;
    }

}

UserService.java & UserServiceImpl.java

UserService.java add an interface

public List<User> listUser(int page, int pageSize);

UserServiceImpl.java new implementation of the interface above

    @Override
    public List<User> listUser(int page, int pageSize) {
        List<User> result = null;
        try {
            // 调用pagehelper分页，采用starPage方式。starPage应放在Mapper查询函数之前
            PageHelper.startPage(page, pageSize); //每页的大小为pageSize，查询第page页的结果
            PageHelper.orderBy("id ASC "); //进行分页结果的排序
            result = userMapper.selectUser();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return result;
    }

Description:

See the code comments

Complete code:

UserService.java

package com.qikegu.demo.service;

import java.util.List;

import com.qikegu.demo.model.User;

public interface UserService {
    
    public User getUserById(long userId);
    
    public List<User> listUser(int page, int pageSize);
}

UserServiceImpl.java

package com.qikegu.demo.service.impl;

import java.util.List;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import com.github.pagehelper.PageHelper;
import com.qikegu.demo.model.User;
import com.qikegu.demo.repository.UserMapper;
import com.qikegu.demo.service.UserService;

@Service("userService")
public class UserServiceImpl implements UserService {

    //注入mybatis数据库查询类
    @Resource
    private UserMapper userMapper;
    
    @Override
    public User getUserById(long userId) {
        return userMapper.selectByPrimaryKey(userId);
    }
    
    @Override
    public List<User> listUser(int page, int pageSize) {
        List<User> result = null;
        try {
            // 调用pagehelper分页，采用starPage方式。starPage应放在Mapper查询函数之前
            PageHelper.startPage(page, pageSize); //每页的大小为pageSize，查询第page页的结果
            PageHelper.orderBy("id ASC "); //进行分页结果的排序
            result = userMapper.selectUser();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return result;
    }
}

UserMapper.java & UserMapper.xml

UserMapper.java New Interface

    // 列出用户，对应xml映射文件元素的ID
    List<User> selectUser();

The interface UserMapper.xml achieve new mybatis xml

  <select id="selectUser" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from user
  </select>

Explanation

See the code comments

The complete code

UserMapper.java

package com.qikegu.demo.repository;

import java.util.List;

import com.qikegu.demo.model.User;

public interface UserMapper {

    // 查询某个用户，对应xml映射文件元素的ID
    User selectByPrimaryKey(long id);
    
    // 列出用户，对应xml映射文件元素的ID
    List<User> selectUser();
}

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.qikegu.demo.repository.UserMapper">
  <resultMap id="BaseResultMap" type="com.qikegu.demo.model.User">
    <constructor>
      <idArg column="id" javaType="_long" jdbcType="BIGINT" />
      <arg column="nickname" javaType="java.lang.String" jdbcType="VARCHAR" />
      <arg column="mobile" javaType="java.lang.String" jdbcType="VARCHAR" />
      <arg column="password" javaType="java.lang.String" jdbcType="CHAR" />
      <arg column="role" javaType="java.lang.String" jdbcType="VARCHAR" />
    </constructor>
  </resultMap>
  
  <sql id="Base_Column_List">
    id, nickname, mobile, password, role
  </sql>
  <select id="selectByPrimaryKey" parameterType="_long" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from user
    where id = #{id,jdbcType=BIGINT}
  </select>
  
  <select id="selectUser" resultMap="BaseResultMap">
    select 
    <include refid="Base_Column_List" />
    from user
  </select>
  
</mapper>

run

Eclipse on the left, right click on the project root directory pop-up menu, choose: run as -> spring boot apprun the program.
We use Postman access interface, Postman is a very powerful interface testing tool, it is commonly regarded as "essential travel home," it recommended. Installation is very simple, go to the official website to download it and follow the steps to install it. Results are as follows:

to sum up

Paging function can be said to be an essential feature of web development, this basic tutorial on the front, introduces the integration process mybatis pagehelper plug, pagehelper is a common pagination plug-ins, and have completely decoupled Mapper.xml advantages, recommended for use in the project.

The complete code