3.博客项目学习技术点

1.标准返回类实现

package com.han.entity;

@JsonInclude(JsonInclude.Include.NON_NULL)
public class ResponseResult<T> implements Serializable {
    private Integer code;
    private String msg;
    private T data;

    public ResponseResult() {
        this.code = AppHttpCodeEnum.SUCCESS.getCode();
        this.msg = AppHttpCodeEnum.SUCCESS.getMsg();
    }

    public ResponseResult(Integer code, T data) {
        this.code = code;
        this.data = data;
    }

    public ResponseResult(Integer code, String msg, T data) {
        this.code = code;
        this.msg = msg;
        this.data = data;
    }

    public ResponseResult(Integer code, String msg) {
        this.code = code;
        this.msg = msg;
    }

    public static ResponseResult errorResult(int code, String msg) {
        ResponseResult result = new ResponseResult();
        return result.error(code, msg);
    }

    public static ResponseResult okResult() {
        ResponseResult result = new ResponseResult();
        return result;
    }

    public static ResponseResult okResult(int code, String msg) {
        ResponseResult result = new ResponseResult();
        return result.ok(code, null, msg);
    }

    public static ResponseResult okResult(Object data) {
        ResponseResult result = setAppHttpCodeEnum(AppHttpCodeEnum.SUCCESS, AppHttpCodeEnum.SUCCESS.getMsg());
        if (data != null) {
            result.setData(data);
        }
        return result;
    }

    public static ResponseResult errorResult(AppHttpCodeEnum enums) {
        return setAppHttpCodeEnum(enums, enums.getMsg());
    }

    public static ResponseResult errorResult(AppHttpCodeEnum enums, String msg) {
        return setAppHttpCodeEnum(enums, msg);
    }

    public static ResponseResult setAppHttpCodeEnum(AppHttpCodeEnum enums) {
        return okResult(enums.getCode(), enums.getMsg());
    }

    private static ResponseResult setAppHttpCodeEnum(AppHttpCodeEnum enums, String msg) {
        return okResult(enums.getCode(), msg);
    }

    public ResponseResult<?> error(Integer code, String msg) {
        this.code = code;
        this.msg = msg;
        return this;
    }

    public ResponseResult<?> ok(Integer code, T data) {
        this.code = code;
        this.data = data;
        return this;
    }

    public ResponseResult<?> ok(Integer code, T data, String msg) {
        this.code = code;
        this.data = data;
        this.msg = msg;
        return this;
    }

    public ResponseResult<?> ok(T data) {
        this.data = data;
        return this;
    }

    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;
    }
}

2. 通用返回的状态码code常量定义

package com.han.enums;

public enum AppHttpCodeEnum {
    // 成功
    SUCCESS(200,"操作成功"),
    // 登录
    NEED_LOGIN(401,"需要登录后操作"),
    NO_OPERATOR_AUTH(403,"无权限操作"),
    SYSTEM_ERROR(500,"出现错误"),
    USERNAME_EXIST(501,"用户名已存在"),
    PHONENUMBER_EXIST(502,"手机号已存在"), EMAIL_EXIST(503, "邮箱已存在"),
    REQUIRE_USERNAME(504, "必需填写用户名"),
    LOGIN_ERROR(505,"用户名或密码错误");
    int code;
    String msg;

    AppHttpCodeEnum(int code, String errorMessage){
        this.code = code;
        this.msg = errorMessage;
    }

    public int getCode() {
        return code;
    }

    public String getMsg() {
        return msg;
    }
}

3. 代码中魔法值的枚举类实现

package com.han.constants;

public class SystemConstants {
    /**
     * 文章是草稿
     */
    public static final int ARTICLE_STATUS_DRAFT = 1;
    /**
     * 文章是正常状态
     */
    public static final int ARTICLE_STATUS_NORMAL = 0;
    /**
     * 分类是正常状态
     */
    public static final String STATUS_NORMAL = "0";
}

4. 前后端分离跨域问题解决

package com.han.config;

@Configuration
public class WebConfig implements WebMvcConfigurer {

    /**
     * 跨域问题解决~~
     * @param registry
     */
    @Override
    public void addCorsMappings(CorsRegistry registry){
        // 允许跨域请求的路径
        registry.addMapping("/**")
                // 允许跨域请求的域名
                .allowedOriginPatterns("*")
                // 是否允许cookie
                .allowCredentials(true)
                // 允许的请求方式
                .allowedMethods("GET", "POST", "DELETE", "PUT")
                // 允许的hearder属性
                .allowedHeaders("*")
                // 跨域允许时间
                .maxAge(3600);
    }
}

5. MyBatisPlus分页插件配置类

package com.han.config;

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

6. 自定义Bean拷贝工具类

package com.han.utils;

public class BeanCopyUtils {

    private BeanCopyUtils(){}

    // 泛型方法, 前面的 <V> 说明是泛型方法, 后面的V说行返回值类型是 V
    public static <V> V copyBean(Object source, Class<V> clazz) {
        // 创建目标对象
        V result = null;
        try {
            result = clazz.newInstance();
            // 实现属性拷贝
            BeanUtils.copyProperties(source, result);
        } catch (Exception e) {
            e.printStackTrace();
        }
        // 返回结果
        return result;

    }

    public static <O, V> List<V> copyBeanList(List<O> list, Class<V> clazz){
        List<V> collect = list.stream()
                .map(o -> copyBean(o, clazz))
                .collect(Collectors.toList());
        return collect;
    }
}

7. 日期转Json使用FastJson配置类

package com.han.config;

import java.util.List;

@Configuration
public class WebConfig implements WebMvcConfigurer {
    /**
     * 解决Date转换Json出现的问题, 使用FastJson进行转换, 下边是FastJson配置类
     * @return
     */
    @Bean//使用@Bean注入fastJsonHttpMessageConvert
    public HttpMessageConverter fastJsonHttpMessageConverters() {
        //1.需要定义一个Convert转换消息的对象
        FastJsonHttpMessageConverter fastConverter = new FastJsonHttpMessageConverter();
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        fastJsonConfig.setSerializerFeatures(SerializerFeature.PrettyFormat);
        fastJsonConfig.setDateFormat("yyyy-MM-dd HH:mm:ss");

        SerializeConfig.globalInstance.put(Long.class, ToStringSerializer.instance);

        fastJsonConfig.setSerializeConfig(SerializeConfig.globalInstance);
        fastConverter.setFastJsonConfig(fastJsonConfig);
        HttpMessageConverter<?> converter = fastConverter;
        return converter;
    }

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(fastJsonHttpMessageConverters());
    }
}