[Java]HttpHeadersからMultiValueMapに変換

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import org.springframework.http.HttpHeaders;
import org.springframework.util.MultiValueMap;

public class HttpHeadersToMultiValueMapConverter {

    public static MultiValueMap<String, String> convert(HttpHeaders headers) {
        MultiValueMap<String, String> multiValueMap = new LinkedMultiValueMap();
        
        headers.forEach((key, values) -> {
            multiValueMap.put(key, values);
        });
        
        return multiValueMap;
    }

    public static void main(String[] args) {
        HttpHeaders headers = new HttpHeaders();

        // java.nio.charset.StandardCharsets は、US-ASCII、ISO-8859-1、UTF-8、UTF-16BE、UTF-16LE、UTF-16のみでWindow-31jとかMS932は無い
        // 文字コードの指定はCharset.forName()
        //headers.setContentType(new MediaType(MediaType.APPLICATION_JSON, StandardCharsets.UTF_8));
        //headers.setContentType(new MediaType(MediaType.APPLICATION_JSON, Charset.forName("utf-8")));
        headers.setContentType(new MediaType(MediaType.APPLICATION_JSON, Charset.forName("MS932")));
        
        MultiValueMap<String, String> convertedHeaders = convert(headers);
        
        System.out.println("Converted MultiValueMap:");
        System.out.println(convertedHeaders);
    }
}

出力
MS932と指定。charsetはwindows-31jとなる。

Converted MultiValueMap:
[Content-Type:"application/json;charset=windows-31j"]