spring boot 项目连接数据库查询数据过程

spring boot 项目搭建

pom.xml

<?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.test</groupId>
    <artifactId>springdemo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.M1</spring-cloud.version>
    </properties>

    <dependencies>
        <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>1.3.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>6.0.6</scope>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.10</version>
        </dependency>
    </dependencies>
    <!--这个插件，可以将应用进行打包成一个可执行的jar包-->
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
        <resources>
            <!-- maven项目中src源代码下的xml等资源文件编译进classes文件夹，
              注意：如果没有这个，它会自动搜索resources下是否有mapper.xml文件，
              如果没有就会报org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): com.pet.mapper.PetMapper.selectByPrimaryKey-->
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml</include>
                </includes>
            </resource>

            <!--将resources目录下的配置文件编译进classes文件  -->
            <resource>
                <directory>src/main/resources</directory>
            </resource>
        </resources>
    </build>

</project>

application.yml

server:
  port: 8088
spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=UTF-8&useSSL=false
    driverClassName: com.mysql.jdbc.Driver
    username: root
    password: 123456
    type: com.alibaba.druid.pool.DruidDataSource

  mybatis:
    #config-locations: mybatis/mybatis-config.xml
　　　　#xml文件路径
    mapper-locations: com/apple/Mapper/*.xml
    type-aliases-package: com.apple.Base

访问数据库路径：

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.apple.Mapper.UserMapper">

    <select id="selectUsers" resultType="com.apple.Base.Person">
        select p_name,p_sex from
        person
    </select>

</mapper>

namespace =UserMapper的路径

UserMapper.xml查询语句的id和UserMapper.java的方法名必须相同

UserMapper.java

package com.apple.Mapper;

import com.apple.Base.Person;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Component;

@Mapper
@Component
public interface UserMapper {

    Person selectUsers();
}

UserService.java

package com.apple.Service;

import com.apple.Base.Person;
import com.apple.Mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;

    public Person selectUsers(){
        System.out.println("222222222");
        return userMapper.selectUsers();
    }

}

UserController.java

package com.apple.Controller;

import com.apple.Base.Person;
import com.apple.Service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class UserController {
    @Autowired
    private UserService userService;

    @ResponseBody
    @RequestMapping(value ="/selectUser")
    public Person selectUser(){
        System.out.println("1111111111111111111111");
        Person pp=userService.selectUsers();
        System.out.println(pp.toString());
        return pp;
    }
}