spring boot 入门篇 – 汪明鑫的个人博客

美团前端引擎用freemarker多些

毕设打算用spring boot + freemarker + mybatis + mysql 做

因此提前做一下技术调研和整合，自己实操下

之前简单学习过一点spring boot，不够系统

也做过一些spring boot简单的增删改查

spring boot开发特别方便，很多东西不用配置（约定大于配置）

目前计划系统的学习下

先来个spring boot整合freemarker的小例子🌰

如果对spring boot已经挺熟的同学，请直接跳过本文，

这里参考了网上的一个小例子，自己做了一些改动和补充，mybatis基于注解开发：

Spring Boot 集成 FreeMarker 详解案例

准备好数据库和表已经模拟几条数据即可

SQL语句：

CREATE TABLE `city` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '城市编号',
  `province_id` int(10) unsigned  NOT NULL COMMENT '省份编号',
  `city_name` varchar(25) DEFAULT NULL COMMENT '城市名称',
  `description` varchar(25) DEFAULT NULL COMMENT '描述',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

INSERT city(province_id,city_name,description) VALUES (3,'北京','互联网公司多机会多');
INSERT city(province_id,city_name,description) VALUES (4,'信阳','环境好，宜居');
INSERT city(province_id,city_name,description) VALUES (5,'厦门','海边，风景美');

现在要实现2个功能：

1，根据id查询城市

2，查询城市列表

创建spring boot项目：

下一步

选择依赖：

下一步

项目创建成功

添加mybatis依赖

<dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
 </dependency>

整个pom文件一览：

<?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>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>pers.wmx</groupId>
    <artifactId>springboot-freemarker-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-freemarker-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-freemarker</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.2</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </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>

配置文件application.properties：

## 数据源配置
spring.datasource.url=jdbc:mysql://ip:port/数据库名?useUnicode=true&characterEncoding=utf8
spring.datasource.username=用户名
spring.datasource.password=密码
spring.datasource.driver-class-name=com.mysql.jdbc.Driver   

## Mybatis 配置
mybatis.typeAliasesPackage=pers.wmx.springbootfreemarkerdemo.domain
mybatis.configuration.mapUnderscoreToCamelCase=true

## Freemarker 配置
## 文件配置路径
spring.freemarker.template-loader-path=classpath:/templates/
spring.freemarker.cache=false
spring.freemarker.charset=UTF-8
spring.freemarker.check-template-location=true
spring.freemarker.content-type=text/html
spring.freemarker.expose-request-attributes=true
spring.freemarker.expose-session-attributes=true
spring.freemarker.request-context-attribute=request
spring.freemarker.suffix=.ftl

驼峰命名转换是什么意思？

数据库的city_name在java结果集对象中自动转换成驼峰命名参数 cityName

city表对应的实体类：

package pers.wmx.springbootfreemarkerdemo.domain;

import lombok.Data;
import lombok.Getter;
import lombok.Setter;

/**
 * @author: wangmingxin02
 * @create: 2019-03-26
 **/

@Getter
@Setter
public class City {
    Long id;
    Long provinceId;
    String cityName;
    String description;
}

@Getter、@Setter可以省略get和set方法

项目启动类（程序入口）：

@SpringBootApplication
public class SpringbootFreemarkerDemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootFreemarkerDemoApplication.class, args);
    }

}

controller层：

package pers.wmx.springbootfreemarkerdemo.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import pers.wmx.springbootfreemarkerdemo.domain.City;
import pers.wmx.springbootfreemarkerdemo.service.ICityService;

import java.util.List;

/**
 * @author: wangmingxin02
 * @create: 2019-03-26
 **/

@Controller
public class CityController {

    @Autowired
    ICityService cityService;

    @RequestMapping("/api/city/{id}")
    public String findCityById(Model model, @PathVariable("id") Long id){

        City city = cityService.findById(id);
        model.addAttribute("city",city);

        return "index";
    }

    @RequestMapping("/api/city")
    public String findCityList(Model model){

        List<City> cityList = cityService.findCityList();
        model.addAttribute("cityList",cityList);

        return "citylist";
    }

}

service层：

package pers.wmx.springbootfreemarkerdemo.service;

import pers.wmx.springbootfreemarkerdemo.domain.City;

import java.util.List;

public interface ICityService {

    public City findById(Long id);

    public List<City> findCityList();

}

package pers.wmx.springbootfreemarkerdemo.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import pers.wmx.springbootfreemarkerdemo.dao.CityMapper;
import pers.wmx.springbootfreemarkerdemo.domain.City;
import pers.wmx.springbootfreemarkerdemo.service.ICityService;

import java.util.List;

/**
 * @author: wangmingxin02
 * @create: 2019-03-26
 **/
@Service
public class CityServiceImpl implements ICityService {
    @Autowired
    CityMapper cityMapper;


    @Override
    public City findById(Long id) {
        return cityMapper.findById(id);
    }

    @Override
    public List<City> findCityList() {
        return cityMapper.findCityList();
    }
}

mapper层(mybatis基于注解开发)：

package pers.wmx.springbootfreemarkerdemo.dao;


import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import pers.wmx.springbootfreemarkerdemo.domain.City;

import java.util.List;

@Mapper
public interface CityMapper {

    @Select("select * from  city where id = #{id}")
    public City findById(Long id);

    @Select("select * from  city")
    public List<City> findCityList();

}

这样写特别方便

准备前端页面：

index.ftl

<!DOCTYPE html>

<html lang="en">

<body>
城市： ${city.cityName}! <br>
城市描述： ${city.description}!
</body>

</html>

citylist.ftl

<!DOCTYPE html>

<html lang="en">

<body>

<#list cityList as e>

    城市: ${e.cityName}! <br>

    城市描述:${e.description}!<br>

    <hr/>

</#list>

</body>

</html>

启动项目

Loading class `com.mysql.jdbc.Driver’. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver’. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.

说这个mysql驱动过时了，让用新的这个，但是感觉对这个小demo 没啥影响，我也懒得换了

访问 http://localhost:8080/api/city/3