springBoot集成Mybatis

1.添加依赖

<?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>

    <groupId>com.huawei.springboot</groupId>
    <artifactId>springBoot-mybatis</artifactId>
    <version>1.0-SNAPSHOT</version>


    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.6.RELEASE</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>

        <dependency><!--MVC,AOP的依赖包-->
            <!--在parent中已经设置了version，这里就不需要设置，spring会自动设置合适的version-->
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
            <scope>true</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>jstl</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-jasper</artifactId>
            <scope>provided</scope>
        </dependency>
        <!--添加mysql数据库驱动依赖包-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>
        <!--
                MyBatis提供了拦截器接口，我们可以实现自己的拦截器，
                将其作为一个plugin装入到SqlSessionFactory中。
                Github上有位开发者写了一个分页插件，我觉得使用起来还可以，挺方便的。
                Github项目地址： https://github.com/pagehelper/Mybatis-PageHelper
             -->
        <!-- https://mvnrepository.com/artifact/com.github.pagehelper/pagehelper -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper</artifactId>
            <version>4.2.1</version>
        </dependency>

    </dependencies>

    <build>
        <finalName>spring-web</finalName>
        <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
            <plugins>
                <plugin>
                    <artifactId>maven-clean-plugin</artifactId>
                    <version>3.1.0</version>
                </plugin>
                <plugin>
                    <groupId>org.springframework.boot</groupId>
                    <artifactId>spring-boot-maven-plugin</artifactId>
                    <configuration>
                        <!--fork :  如果没有该项配置，devtools不会起作用，即应用不会restart -->
                        <fork>true</fork>
                    </configuration>
                </plugin>
            </plugins>
        </pluginManagement>
    </build>
</project>

2.添加配置文件

########################################################
###datasource
########################################################
#后面加的一长串是为了解决乱码
spring.datasource.url = jdbc:mysql://localhost:3306/springboot?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
spring.datasource.username = root
spring.datasource.password = Root@123
spring.datasource.driverClassName = com.mysql.jdbc.Driver
spring.datasource.max-active=20
spring.datasource.max-idle=8
spring.datasource.min-idle=8
spring.datasource.initial-size=10

3.创建持久化bean

package com.huawei.beans;

public class Student {
    private Integer id;
    private String name;

    public Student() {
    }

    public Student(String name) {
        this.name = name;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Student{" + "id=" + id + ", name='" + name + '\'' + '}';
    }
}

4.创建dao

package com.huawei.mapper;

import com.huawei.beans.Student;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface StudentMapper {

    @Select("select * from student where name = #{name}")
    public List<Student> likeName(String name);

    @Select("select *from student where id = #{id}")
    public Student getById(long id);

    @Select("select name from student where id = #{id}")
    public String getNameById(long id);
}

5.创建service

package com.huawei.service;

import com.huawei.beans.Student;
import com.huawei.mapper.StudentMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class StudentService {

    @Autowired
    private StudentMapper studentMapper;

    public List<Student> likeName(String name) {
        return studentMapper.likeName(name);
    }


}

6.创建controller

package com.huawei.controller;

import com.github.pagehelper.PageHelper;
import com.huawei.beans.Student;
import com.huawei.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
public class StudentController {
    @Autowired
    StudentService studentService;

    @RequestMapping("/likeName")
    public List<Student> likeName(String name){
        PageHelper.startPage(1,2);
        return studentService.likeName(name);
    }
}

7.创建分页配置bean

package com.huawei.config;

import com.github.pagehelper.PageHelper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import java.util.Properties;

@Configuration
public class MyBatisConfiguration {

    @Bean
    public PageHelper pageHelper() {
        System.out.println("MyBatisConfiguration.pageHelper()");

        PageHelper pageHelper = new PageHelper();
        Properties p = new Properties();
        p.setProperty("offsetAsPageNum", "true");
        p.setProperty("rowBoundsWithCount", "true");
        p.setProperty("reasonable", "true");
        pageHelper.setProperties(p);
        return pageHelper;
    }


}

8.创建启动类

package com.huawei;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.huawei.*")
public class App
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, args);
    }
}

运行：

问题：

分页版本是4.2.0时，会导致第一次分页成功，第二层抛出异常的问题，使用4.2.1就可以解决问题

9.使用insert获取自增长ID

在mapper中添加insert方法

 @Insert("insert into student(name) values(#{name})")
 @Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
 public void save(Student student);

添加service

 public void addStudent(Student student) {
     studentMapper.save(student);
 }

添加controller

    @RequestMapping("/save")
    public Student save(){
        Student student = new Student("mn");
        studentService.addStudent(student);
        return student;
    }