SpringBoot入门

1. 什么是SpringBoot

学习完SSM框架后，我们会发现java代码量急剧减少，基本上用注解实现了大部分功能。但是相对的，我们需要写很多的spring的配置文件，SpringBoot就是用来简化配置文件的同时与各种功能整合，让代码可以拓展的更宽。

我们SpringBoot版本基于2.5.0来开发

2. 创建流程

创建项目：

所有SpringBoot的父类

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.0</version>
</parent>

基础需要的依赖：

<dependencies>
        <!--springboot web开发依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.30</version>
        </dependency>
        <!--mybatis-spring依赖-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.1</version>
        </dependency>
        <!-- mysql 数据库驱动 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
        <!--redis-spring依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <!--JSON依赖-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.33</version>
        </dependency>
        <!--JWT-->
        <dependency>
            <groupId>io.jsonwebtoken</groupId>
            <artifactId>jjwt</artifactId>
            <version>0.9.0</version>
        </dependency>
    </dependencies>

resources下的配置文件：

application.yml模板

#有代码提醒的，是系统自带的配置信息
spring:
  profiles:
    active: xxx《多环境配置文件后缀application-xxx.yml》不加为默认8080
  application:
    name: 《项目起名》
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/《数据库名称》?useUnicode=true&autoReconnect=true&autoReconnectForPools=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
    username: root
    password: ok
  redis:
    host: 127.0.0.1
    port: 6379
#输出mybatis执行sql的日志
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*.xml #加载映射文件
#用自定义的配置
#img:
#  path:
#    header: C:\Users\Administrator\Desktop\page\myboot_01\src\main\resources\headImg
#    other: C:\Users\Administrator\Desktop\page\myboot_01\src\main\resources\others

3. SpringBoot整合MyBatis

上面模板已经有了，mapper就是把之前的xxxMapper文件放在resources/mapper下即可

数据库连接：

加载映射文件并添加日志文件：

驼峰映射等价于在resultMap里做映射

第一种实现方式，在mapper接口下直接@Mapper：

第二种实现方式，在MyBootApplication中添加@MapperScan

喜欢哪个用哪个就好了

3. Spring Boot 整合Redis

添加两个配置类：

RedisConfig配置类：

package com.zb.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.StringRedisSerializer;

@Configuration
public class RedisConfig {

    @Bean
    public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory connectionFactory) {
        RedisTemplate<Object, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(connectionFactory);

        FastJsonRedisSerializer serializer = new FastJsonRedisSerializer(Object.class);

        // 使用StringRedisSerializer来序列化和反序列化redis的key值
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(serializer);

        // Hash的key也采用StringRedisSerializer的序列化方式
        template.setHashKeySerializer(new StringRedisSerializer());
        template.setHashValueSerializer(serializer);

        template.afterPropertiesSet();
        return template;
    }
}

FastJsonRedisSerializer配置类：

package com.zb.config;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.parser.ParserConfig;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.type.TypeFactory;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.SerializationException;

import java.nio.charset.Charset;

/**
 * Redis使用FastJson序列化
 *
 * @author sg
 */
public class FastJsonRedisSerializer<T> implements RedisSerializer<T> {

    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

    private Class<T> clazz;

    static {
        ParserConfig.getGlobalInstance().setAutoTypeSupport(true);
    }

    public FastJsonRedisSerializer(Class<T> clazz) {
        super();
        this.clazz = clazz;
    }

    @Override
    public byte[] serialize(T t) throws SerializationException {
        if (t == null) {
            return new byte[0];
        }
        return JSON.toJSONString(t, SerializerFeature.WriteClassName).getBytes(DEFAULT_CHARSET);
    }

    @Override
    public T deserialize(byte[] bytes) throws SerializationException {
        if (bytes == null || bytes.length <= 0) {
            return null;
        }
        String str = new String(bytes, DEFAULT_CHARSET);

        return JSON.parseObject(str, clazz);
    }


    protected JavaType getJavaType(Class<?> clazz) {
        return TypeFactory.defaultInstance().constructType(clazz);
    }
}

4. 解决跨域问题

CorsConfig配置类：

package com.zb.config;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.parser.ParserConfig;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.type.TypeFactory;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.SerializationException;

import java.nio.charset.Charset;

/**
 * Redis使用FastJson序列化
 *
 * @author sg
 */
public class FastJsonRedisSerializer<T> implements RedisSerializer<T> {

    public static final Charset DEFAULT_CHARSET = Charset.forName("UTF-8");

    private Class<T> clazz;

    static {
        ParserConfig.getGlobalInstance().setAutoTypeSupport(true);
    }

    public FastJsonRedisSerializer(Class<T> clazz) {
        super();
        this.clazz = clazz;
    }

    @Override
    public byte[] serialize(T t) throws SerializationException {
        if (t == null) {
            return new byte[0];
        }
        return JSON.toJSONString(t, SerializerFeature.WriteClassName).getBytes(DEFAULT_CHARSET);
    }

    @Override
    public T deserialize(byte[] bytes) throws SerializationException {
        if (bytes == null || bytes.length <= 0) {
            return null;
        }
        String str = new String(bytes, DEFAULT_CHARSET);

        return JSON.parseObject(str, clazz);
    }


    protected JavaType getJavaType(Class<?> clazz) {
        return TypeFactory.defaultInstance().constructType(clazz);
    }
}

下一章节将会讲解Swagger2和拦截器（servlet里的过滤器）与请求头Token的处理