springboot整合mybatis

最新推荐文章于 2022-03-12 19:41:12 发布

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最新推荐文章于 2022-03-12 19:41:12 发布

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分类专栏： springboot 文章标签： springboot mybatis springboot整合mybatis springboot示例 springboot入门

本文链接：https://blog.youkuaiyun.com/m0_37981235/article/details/84284985

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本文分享了一个SpringBoot结合MyBatis的实战案例，详细介绍了项目结构、代码实现及常见问题解决，适合初学者快速上手。

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刚写个springboot的demo就遇到这么个大坑，在此记录一下，顺便贴一下代码，方便新手入门，springboot简单整合mybati详细代码及目录结构如下：

cintroller代码：

package com.yango.controller;

import com.yango.entity.User;
import com.yango.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import javax.servlet.http.HttpServletRequest;

@Controller
@RequestMapping(value = "/user")
public class UserController {
    @Autowired
    private UserService userService;
    @RequestMapping("/showUser")
    @ResponseBody
    public User toIndex(HttpServletRequest request, Model model){
        int userId = Integer.parseInt(request.getParameter("id"));
        User user = this.userService.getUserById(userId);
        return user;
    }
}

dao层：

package com.yango.dao;

import com.yango.entity.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserDao {
    int insertSelective(User record);
    User selectByPrimaryKey(Integer id);
}

entity层：

package com.yango.entity;

public class User {
    private Integer id;
    private String userName;
    private String password;
    private Integer age;
    public Integer getId() {
        return id;
    }
    public void setId(Integer 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;
    }
    public Integer getAge() {
        return age;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
}

service接口：

package com.yango.service;

import com.yango.entity.User;

public interface UserService {

    public User getUserById(int userId);

    boolean addUser(User record);
}

service层：

package com.yango.service.impl;

import com.yango.dao.UserDao;
import com.yango.entity.User;
import com.yango.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserServiceImp implements UserService {

    @Autowired
    private UserDao userDao;


    public User getUserById(int userId) {
        return userDao.selectByPrimaryKey(userId);
    }

    public boolean addUser(User record){
        boolean result = false;
        try {
            userDao.insertSelective(record);
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
        }

        return result;
    }
}

启动类：

package com.yango;

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

@SpringBootApplication
@MapperScan(basePackages = "com.yango.dao")
//@ComponentScan({"com.yango"})
public class Entry {
    public static void main(String[] args) throws Exception {
        SpringApplication.run(Entry.class, args);
    }
}

mapper文件：

<?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.yango.dao.UserDao" >
    <resultMap id="BaseResultMap" type="com.yango.entity.User" >
        <id column="id" property="id" jdbcType="INTEGER" />
        <result column="user_name" property="userName" jdbcType="VARCHAR" />
        <result column="password" property="password" jdbcType="VARCHAR" />
        <result column="age" property="age" jdbcType="INTEGER" />
    </resultMap>
    <sql id="Base_Column_List" >
        id
    </sql>
    <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
        select
        <include refid="Base_Column_List" />
        from tbl_user
        where id = #{id,jdbcType=INTEGER}
    </select>

    <insert id="insert" parameterType="com.yango.entity.User" >
        insert into user_t (id, user_name, password,
        age)
        values (#{id,jdbcType=INTEGER}, #{userName,jdbcType=VARCHAR}, #{password,jdbcType=VARCHAR},
        #{age,jdbcType=INTEGER})
    </insert>
    <insert id="insertSelective" parameterType="com.yango.entity.User" >
        insert into user_t
        <trim prefix="(" suffix=")" suffixOverrides="," >
            <if test="id != null" >
                id,
            </if>
            <if test="userName != null" >
                user_name,
            </if>
            <if test="password != null" >
                password,
            </if>
            <if test="age != null" >
                age,
            </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides="," >
            <if test="id != null" >
                #{id,jdbcType=INTEGER},
            </if>
            <if test="userName != null" >
                #{userName,jdbcType=VARCHAR},
            </if>
            <if test="password != null" >
                #{password,jdbcType=VARCHAR},
            </if>
            <if test="age != null" >
                #{age,jdbcType=INTEGER},
            </if>
        </trim>
    </insert>
</mapper>

application.yml文件：

#默认使用配置
spring:
  profiles:
    active: dev
---
#公共配置与profiles选择无关
mybatis:
  type-aliases-package: com.yango.entity
  mapper-locations: classpath:com/yango/dao/*.xml
server:
  tomcat:
    uri-encoding: utf-8
#pagehelper分页插件
pagehelper:
  helperDialect: mysql
  reasonable: true
  supportMethodsArguments: true
  params: count=countSql

这里需要注意，使用了springboot中提供的环境切换的功能，上面配置的dev，程序会默认加载application-dev.yml，也就是说，程序会加载application-${var}的文件。

application-dev.yml文件：

spring:
#  profiles: test
  datasource:
    url: jdbc:mysql://localhost:3306/demo
    username: root
    password: admin
    driver-class-name: com.mysql.jdbc.Driver
server:
  port: 8081

pom文件：

<?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.yango</groupId>
    <artifactId>boot-project</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.1.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.39</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-thymeleaf -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
            <version>1.4.0.RELEASE</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.data/spring-data-jpa -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
            <version>1.5.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.0</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>
        <!-- 热部署 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
            <scope>true</scope>
        </dependency>
    </dependencies>
    <build>
        <resources>
            <resource>
                <directory>src/main/resources</directory>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>
        </resources>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <!-- 没有该配置，devtools 不生效 -->
                    <fork>true</fork>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

常见问题：

问题1

注意在application.yml文件中标注蓝色的部分，如果配置这样扫描mybatis的mapper文件程序会报错，如下：

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.yango.dao.UserDao.selectByPrimaryKey
   at org.apache.ibatis.binding.MapperMethod$SqlCommand.<init>(MapperMethod.java:225) ~[mybatis-3.4.4.jar:3.4.4]
   at org.apache.ibatis.binding.MapperMethod.<init>(MapperMethod.java:48) ~[mybatis-3.4.4.jar:3.4.4]
   at org.apache.ibatis.binding.MapperProxy.cachedMapperMethod(MapperProxy.java:65) ~[mybatis-3.4.4.jar:3.4.4]
   at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:58) ~[mybatis-3.4.4.jar:3.4.4]
   at com.sun.proxy.$Proxy74.selectByPrimaryKey(Unknown Source) ~[na:na]
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
   at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
   at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333) ~[spring-aop-4.3.6.RELEASE.jar:4.3.6.RELEASE]

找不到对应的mapper，这时需要将mapper-locations: classpath:com/yango/dao/*.xml改为mapper-locations: classpath:com.yango.dao/*.xml即可，

问题2

application.yml从别处复制过来之后启动报错，前言中不允许有内容。则可能是编码的问题，这时候可以将复制的文本放到txt中设置为UTF-8再复制进项目即可。