毕业设计之外卖管理系统(1)-分页查询

1.配置mybatisPlus 的分页查询配置项

// 配置mp的分页插件
@Configuration
public class MybatisPlusConfig {


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


}

2. 分页接口

 @RequestMapping("/page")
    public Result<Page> page(int page,int pageSize,String name){
        log.info("page={},pageSize={},name={}",page,pageSize,name);
        // 构造分页构造器
        Page pageInfo = new Page(page,pageSize);
        // 构造条件构造器
        LambdaQueryWrapper<Employee> queryWrapper = new LambdaQueryWrapper();
        if(name!=null) {
            queryWrapper.like(Employee::getName,name);
        }
        queryWrapper.orderByDesc(Employee::getUpdateTime);
        employeeService.page(pageInfo,queryWrapper);
        // 执行查询
        return Result.success(pageInfo);
    }

3.修改员工信息

/**
     * 根据id修改员工信息
     * @param employee
     * @return
     */
    @PutMapping
    public Result<String> update(HttpServletRequest request,@RequestBody Employee employee){
        employee.setUpdateTime(LocalDateTime.now());
        employee.setUpdateUser((Long)request.getSession().getAttribute("employee"));
        employeeService.updateById(employee);
        return Result.success("员工信息修改成功");
    }

4. 根据前端传的id来获取数据库中对应的数据，JS由于精度问题会导致雪花算法生成的id最后3位被四舍五入

# 解决方法 将id转化为json的时候 Long类型转化为 string 类型
/**
 * 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]
 */
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);
    }
}

5. 配置上述jsonMapper

@Configuration
@Slf4j
public class WebMvcConfig extends WebMvcConfigurationSupport {

    @Override
    protected void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/backend/**").addResourceLocations("classpath:/backend/");
        registry.addResourceHandler("/front/**").addResourceLocations("classpath:/front/");
        log.info("静态资源映射成功");
    }

    @Override
    protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        MappingJackson2HttpMessageConverter messageConverter = new MappingJackson2HttpMessageConverter();
        messageConverter.setObjectMapper(new JacksonObjectMapper());

        converters.add(0,messageConverter);
    }
}