创建springboot+mybatis项目详细版全过程

其他 2019-04-17 10:21:06 阅读次数: 0
版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/skye_95/article/details/89342394

1.创建一个springboot的maven项目（完成图中勾选处后，一路next继续）

设置项目的元数据，第一个是包结构（Group），第二个是项目标识（Artifact）：

添加项目所需要的依赖，Web的依赖和数据库的依赖：

第一次建立项目，需要下载许多包，请耐心等待一下。最后pom.xml如下：

<?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>2.1.4.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.ljy.project</groupId>
    <artifactId>springdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springdemo</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>2.0.1</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>
    </dependencies>

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

</project>

手动添加的dependency需要 右键pom.xml->Maven->Reimport导入依赖。

2.在启动类同级目录下创建domain,dao,service,controller四个目录

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在domain文件夹下创建User类：

package com.ljy.project.springdemo.domain;

public class User {
    private String username;
    private String password;
    private String patternLock;

    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 String getPatternLock() {
        return patternLock;
    }

    public void setPatternLock(String patternLock) {
        this.patternLock = patternLock;
    }
}

然后在dao文件夹下创建UserDao接口：

package com.ljy.project.springdemo.dao;

import com.ljy.project.springdemo.domain.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;

import java.util.List;

@Mapper
public interface UserDao {

//    List<User> selectUsers();

    @Select("select * from user")
    public List<User> getAllUsers();
}

在service文件夹下创建UserService接口：

package com.ljy.project.springdemo.service;

import com.ljy.project.springdemo.dao.UserDao;
import com.ljy.project.springdemo.vo.ResultVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public interface UserService {

    public ResultVo getAllUsers();
    
}

该结果返回值类型为ResultVo，在启动类同级目录下创建vo视图文件夹，在vo文件夹下创建ResultVo视图：

package com.ljy.project.springdemo.vo;

/*http请求返回的最外层对象*/
public class ResultVo<T> {

    private Integer code;

    private String msg;

    private T data;

    private ResultVo(T data){
        this.code = 0;
        this.msg = "success";
        this.data = data;
    }

    private ResultVo(CodeMsg cm){
        if(cm==null){
            return;
        }else {
            this.code = cm.getCode();
            this.msg = cm.getMsg();
            this.data = null;
        }
    }

    public static <T> ResultVo<T> success(T data){
        return new ResultVo<T>(data);
    }

    public static <T> ResultVo<T> error(CodeMsg cm){
        return new ResultVo<T>(cm);
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
}

在vo文件夹下创建CodeMsg错误码视图：

package com.ljy.project.springdemo.vo;

public class CodeMsg {

    private int code;
    private String msg;

    //错误码
    public static CodeMsg SUCCESS = new CodeMsg(0,"success");
    public static CodeMsg INSERT_ERROR = new CodeMsg(100001,"插入失败");
    public static CodeMsg SELECT_ERROR = new CodeMsg(100002,"查询失败");
    public static CodeMsg UPDATE_ERROR = new CodeMsg(100003,"更新失败");

    public CodeMsg(int code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public int getCode() {
        return code;
    }

    public void setCode(int code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
}

在service文件夹下创建Impl文件夹，在Impl文件夹下创建UserServiceImpl实现类：

package com.ljy.project.springdemo.service.Impl;

import com.ljy.project.springdemo.dao.UserDao;
import com.ljy.project.springdemo.domain.User;
import com.ljy.project.springdemo.service.UserService;
import com.ljy.project.springdemo.vo.CodeMsg;
import com.ljy.project.springdemo.vo.ResultVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

    @Autowired
    UserDao userDao;

    @Override
    public ResultVo getAllUsers() {
        List<User> allUsers = userDao.getAllUsers();
        if(allUsers.size()==0){
            return ResultVo.error(CodeMsg.SELECT_ERROR);
        }else{
            return ResultVo.success(allUsers);
        }
    }
}

此处别忘了加@Service注解，我忘加了，运行时报如下错误：

Description:

Field userService in com.ljy.project.springdemo.controller.UserController required a bean of type 'com.ljy.project.springdemo.service.UserService' that could not be found.

The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)


Action:

Consider defining a bean of type 'com.ljy.project.springdemo.service.UserService' in your configuration.

Disconnected from the target VM, address: '127.0.0.1:54425', transport: 'socket'

Process finished with exit code 1

在controller文件夹下创建UserController类：

package com.ljy.project.springdemo.controller;

import com.ljy.project.springdemo.dao.UserDao;
import com.ljy.project.springdemo.domain.User;
import com.ljy.project.springdemo.service.UserService;
import com.ljy.project.springdemo.vo.ResultVo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.xml.ws.RequestWrapper;
import java.util.List;

@RestController
@RequestMapping(value = "/try")
@EnableAutoConfiguration
public class UserController {

//    @Autowired
//    private UserDao userDao;

    @Autowired
    private UserService userService;

//    @RequestMapping(value = "/user")
//    public List<User> getUsers(){
//        return userDao.selectUsers();
//    }

    @RequestMapping(value = "/getAll")
    public ResultVo getAllUsers(){
        return userService.getAllUsers();
    }
}

3.创建数据库（与domain中的实体类对应）

create table User
(
  id          int auto_increment
    primary key,
  username    varchar(20)  null,
  password    varchar(500) null,
  patternlock varchar(30)  null
);

向数据库中插入测试数据：

insert into User(username, password, patternlock) values ('zhangsan','123456','123456');
insert into User(username, password, patternlock) values ('lisi','123456','123456');
insert into User(username, password, patternlock) values ('wangwu','123456','123456');

4.在application.properties里面进行配置

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/你的数据库名?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT
spring.datasource.username=你的用户名
spring.datasource.password=你的密码
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
 
mybatis.typeAliasesPackage=你的实体类包名 （例子项目的包名是com.ljy.project.springdemo.domain）
mybatis.mapperLocations=classpath:mapper/*.xml
logging.level.com.shizhao.project.springdemo:DEBUG
server.port=你的服务端口号，要保证与其他服务不冲突，如8080

我的配置如下：

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/dbgirl?useUnicode=true&characterEncoding=UTF-8&serverTimezone=GMT
spring.datasource.username=root
spring.datasource.password=newpass
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

mybatis.typeAliasesPackage=com.ljy.project.springdemo.domain
mybatis.mapperLocations=classpath:mapper/*.xml
logging.level.com.shizhao.project.springdemo:DEBUG
server.port=8080

5.启动程序，在浏览器地址栏输入http://localhost:8080/try/getAll，得到结果：

此处能看到返回值为json格式，是因为我使用了插件：

到此，创建springboot+mybatis且返回值带错误码的项目创建成功。

补充：

sql语句除了能通过注解写在UserDao中外，还能写在mapper.xml中。在resources文件夹下创建mapper文件夹，在mapper文件夹下创建UserMapper.xml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.ljy.project.springdemo.dao.UserDao">
    <resultMap id="userMap" type="com.ljy.project.springdemo.domain.User">
        <result property="username" column="username"/>
        <result property="password" column="password"/>
        <result property="patternLock" column="patternLock"/>
    </resultMap>

    <select id="selectUsers" resultMap="userMap">
        SELECT * FROM User
    </select>

</mapper>

在UserDao中使用：

在UserController中直接调用：

在浏览器地址栏中输入http://localhost:8080/try/user,结果如下：

 完整版项目连接：https://download.csdn.net/download/skye_95/11120802

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链接：https://pan.baidu.com/s/1v5CdCY-QOet5lG6Q0cGCHA 
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