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做项目，你需要。。。【持续更新】

2022-08-07 16:42:00 【胡桃姓胡，蝴蝶也姓胡】

准备工作

填写配置文件application.yml

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/reggie?characterEncoding=utf-8
    username: root
    password: Bao1417165487

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

server:
  port: 8080

目录层级

在这里插入图片描述

Common层

对象映射器

package com.example.reggie_delivery.common;

import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.module.SimpleModule;
import com.fasterxml.jackson.databind.ser.std.ToStringSerializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalDateTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.deser.LocalTimeDeserializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalDateTimeSerializer;
import com.fasterxml.jackson.datatype.jsr310.ser.LocalTimeSerializer;
import java.math.BigInteger;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.format.DateTimeFormatter;
import static com.fasterxml.jackson.databind.DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES;

/** * 对象映射器:基于jackson将Java对象转为json，或者将json转为Java对象 * 将JSON解析为Java对象的过程称为 [从JSON反序列化Java对象] * 从Java对象生成JSON的过程称为 [序列化Java对象到JSON] */
// 将 较大值的Long类型数据 传到前端，可能会造成数值的精度丢失，将Long类型数据转化为字符串再传到前端就可以解决该问题
// 同时，在WebMvcConfig中 添加消息转换方法extendMessageConverters(List<HttpMessageConverter<?>> converters)
public class JacksonObjectMapper extends ObjectMapper {
    

    public static final String DEFAULT_DATE_FORMAT = "yyyy-MM-dd";
    public static final String DEFAULT_DATE_TIME_FORMAT = "yyyy-MM-dd HH:mm:ss";
    public static final String DEFAULT_TIME_FORMAT = "HH:mm:ss";

    public JacksonObjectMapper() {
    
        super();
        //收到未知属性时不报异常
        this.configure(FAIL_ON_UNKNOWN_PROPERTIES, false);

        //反序列化时，属性不存在的兼容处理
        this.getDeserializationConfig().withoutFeatures(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);


        SimpleModule simpleModule = new SimpleModule()
                .addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)))
                .addDeserializer(LocalDate.class, new LocalDateDeserializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)))
                .addDeserializer(LocalTime.class, new LocalTimeDeserializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)))

                .addSerializer(BigInteger.class, ToStringSerializer.instance)
                .addSerializer(Long.class, ToStringSerializer.instance)
                .addSerializer(LocalDateTime.class, new LocalDateTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_TIME_FORMAT)))
                .addSerializer(LocalDate.class, new LocalDateSerializer(DateTimeFormatter.ofPattern(DEFAULT_DATE_FORMAT)))
                .addSerializer(LocalTime.class, new LocalTimeSerializer(DateTimeFormatter.ofPattern(DEFAULT_TIME_FORMAT)));

        //注册功能模块 例如，可以添加自定义序列化器和反序列化器
        this.registerModule(simpleModule);
    }
}

什么时候会用到对象映射器？

当我们做项目的时候，经常会发现，id被加密成了一个很大的数字。

但是js只能保证前16位的精确，所以这个时候我们需要将数字转换成字符串，这个时候我们用到这个通用类，以后可以随时拿过来用。

统一返回结果

@Data
public class R<T> implements Serializable {
    

    private Integer code;

    private String msg;

    private T data;

    private Map map = new HashMap();

    public static <T> R<T> success(T object) {
    
        R<T> res = new R<>();
        res.code = 1;
        res.data = object;
        return res;
    }

    public static <T> R<T> error(String msg) {
    
        R<T> res = new R<>();
        res.msg = msg;
        res.code = 0;
        return res;
    }

    public R<T> add(String key, Object value) {
    
        this.map.put(key, value);
        return this;
    }
}

全局异常处理器

@Slf4j
@ResponseBody // 将结果封装成JSON数据并且返回
@ControllerAdvice(annotations = {
    RestController.class, Controller.class})
public class GlobalExceptionHandler {
    
    @ExceptionHandler(SQLIntegrityConstraintViolationException.class)
    public R<String> exceptionHandler(SQLIntegrityConstraintViolationException e) {
    
        log.info(e.getMessage());

        if (e.getMessage().contains("Duplicate entry")) {
    
            String[] split = e.getMessage().split(" ");
            String msg = split[2] + "已存在";
            return R.error(msg);
        }
        return R.error("操作失败");
    }
}

公共字段自动填充器

@Slf4j
@Component
public class MyMetaObjectHandler implements MetaObjectHandler {
    
    @Override
    public void insertFill(MetaObject metaObject) {
    
        log.info("公共字段自动填充[insert]....");
        metaObject.setValue("createTime" , LocalDateTime.now());
        metaObject.setValue("updateTime", LocalDateTime.now());
        metaObject.setValue("createUser", BaseContext.getCurrentId());
        metaObject.setValue("updateUser", BaseContext.getCurrentId());
    }

    @Override
    public void updateFill(MetaObject metaObject) {
    
        log.info("公共字段自动填充[update]");

        metaObject.setValue("updateTime", LocalDateTime.now());
        metaObject.setValue("updateUser", BaseContext.getCurrentId());
    }
}

这里就需要使用到ThreadLocal来获取用户的id，我们再创建一个通用工具类，BaseContext

public class BaseContext {
    
    private static ThreadLocal<Long> threadLocal = new InheritableThreadLocal<>();

    public static void setCurrentId(Long id) {
    
        threadLocal.set(id);
    }

    public static Long getCurrentId() {
    
        return threadLocal.get();
    }
}

在过滤器里面获取id

Config层

静态资源映射

@Slf4j
@Configuration
public class WebMvcConfig extends WebMvcConfigurationSupport {
    
    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
    
        log.warn("开始进行静态资源映射======");
        registry.addResourceHandler("/backend/**")
                .addResourceLocations("classpath:/backend/");
        registry.addResourceHandler("/front/**")
                .addResourceLocations("classpath:/front/");
    }
}

在这里插入图片描述

如果你没有放在系统默认的static或者template里面的话，就需要进行静态资源映射。

拦截器

@Configuration
public class MybatisPlusConfig {
    
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
    
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());
        return mybatisPlusInterceptor;
    }
}

使用分页查询需要添加这个PaginationInnerInterceptor()拦截器

pom文件大全

<dependencies>
    //StringUtils.isNotEmpty()需要用到这个jar包，这个东西用来判断是否为空
    <dependency>
        <groupId>commons-lang</groupId>
        <artifactId>commons-lang</artifactId>
        <version>2.6</version>
    </dependency>
    // JSON.toJSONString()需要用到这个jar包
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>fastjson</artifactId>
        <version>1.2.28</version>
    </dependency>
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.4.1</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.2.2</version>
    </dependency>
    // 这里必须要使用1.1.21版本，不然的话LocalDataTime不支持。
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.1.21</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </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>2.2.2</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </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>
原网站

版权声明
本文为[胡桃姓胡，蝴蝶也姓胡]所创，转载请带上原文链接，感谢
https://blog.csdn.net/qq_61039408/article/details/126060965

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