Spring 自定义接口参数解析器

场景

Spring后端某个接口的参数太多，而这些参数能够实例化一个实体类。

解决

借助WebMvcConfigurer来配置接口的参数

代码

结合容器化的思想，代码如下：
请求参数解析配置器：RequestParamResolveConfigurer.kt

import org.springframework.context.annotation.Configuration
import org.springframework.web.method.support.HandlerMethodArgumentResolver
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer

@Configuration
class RequestParamResolveConfigurer: WebMvcConfigurer {
    private val resolvers: MutableList<HandlerMethodArgumentResolver> = ArrayList()
    override fun addArgumentResolvers(resolvers: MutableList<HandlerMethodArgumentResolver>) {
        super.addArgumentResolvers(resolvers)
        super.addArgumentResolvers(this.resolvers)
    }

    fun addArgumentResolver(resolver: HandlerMethodArgumentResolver){
        resolvers.add(resolver)
    }
}

请求参数解析注册机：RequestParamResolveRegister.kt

import org.springframework.beans.factory.annotation.Autowired
import org.springframework.stereotype.Component
import org.springframework.web.method.support.HandlerMethodArgumentResolver

@Component
class RequestParamResolveRegister {
    @Autowired
    private lateinit var configurer: RequestParamResolveConfigurer

    fun registerParamHandler(handler: HandlerMethodArgumentResolver){
        configurer.addArgumentResolver(handler)
    }
}

配置具体的请求参数解析器：XXXXArgumentResolver.kt

import com.dreaming.common.kotlin.toJSONString
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.context.annotation.Bean
import org.springframework.core.MethodParameter
import org.springframework.stereotype.Component
import org.springframework.web.bind.support.WebDataBinderFactory
import org.springframework.web.context.request.NativeWebRequest
import org.springframework.web.method.support.HandlerMethodArgumentResolver
import org.springframework.web.method.support.ModelAndViewContainer

@Component
class XXXXArgumentResolver : HandlerMethodArgumentResolver {

    @Autowired
    private lateinit var register: RequestParamResolveRegister

    @Bean
    private fun initXXXXArgumentResolver(){
        register.registerParamHandler(this)
    }

    override fun supportsParameter(parameter: MethodParameter): Boolean {
        val type = parameter.parameterType
        return type.isAssignableFrom(BaseXXXXBean::class.java)
    }

    override fun resolveArgument(
        parameter: MethodParameter,
        mavContainer: ModelAndViewContainer?,
        webRequest: NativeWebRequest,
        binderFactory: WebDataBinderFactory?
    ): Any? {
        val m = HashMap<String,String>().apply {
            webRequest.parameterMap.forEach { (k, v) ->
                val v = v.mapNotNull { it }.lastOrNull { true }
                if(v != null){
                    put(k,v)
                }
            }
        }
        return XXXXParser.parse(m.toJSONString())
    }
}