MultipartParseTest.java

import com.google.common.io.CharStreams;

import javax.activation.DataSource;
import javax.mail.BodyPart;
import javax.mail.Header;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMultipart;
import java.io.*;
import java.util.Enumeration;
import java.util.HashMap;


public class MultipartParseTest {
  public static void main(String...args) throws MessagingException, IOException {
    MemDataSource memDataSource = new MemDataSource();
    MimeMultipart multipart = new MimeMultipart(memDataSource);

    for( int i = 0; i < multipart.getCount(); i++ ) {
      BodyPart bodyPart = multipart.getBodyPart(i);
      System.out.println("==========================");
      System.out.println(bodyPart.getContentType());
      System.out.println(getHeaders(bodyPart));
      System.out.println(bodyPart.getContent());
      System.out.println(CharStreams.toString(new InputStreamReader(bodyPart.getInputStream())));
    }

  }

  private static HashMap<String, String> getHeaders(BodyPart bodyPart) throws MessagingException {
    Enumeration allHeaders = bodyPart.getAllHeaders();
    HashMap<String, String> r = new HashMap<>();
    while(allHeaders.hasMoreElements()) {
      Header header = (Header)allHeaders.nextElement();
      r.put(header.getName(), header.getValue());
    }
    return r;
  }

  private static class MemDataSource implements DataSource {

    private String content = """
      ------=_Part_0_1119962679.1679025450048
      Content-Type: application/json
      Content-ID: jsonData

      {"n1MessageContainer":{"n1MessageClass":"LPP","n1MessageContent":{"contentId":"binaryDataN1Message"},"nfId":"250787ff-edac-4779-a5a2-542ea214b250"},"lcsCorrelationId":"be6e5ae8-4d00-4ece-b412-b72f83aba8d2"}
      ------=_Part_0_1119962679.1679025450048
      Content-Type: application/vnd.3gpp.5gnas
      Content-ID: binaryDataN1Message

      this is the content
      ------=_Part_0_1119962679.1679025450048--
      """;

    private String content_1 = """
      GET /namf-comm/v1/ue-contexts/imsi-1480136000106/n1-n2-messages HTTP/1.1
      user-agent: LMF
      accept: application/json
      content-type: multipart/related;         boundary="----=_Part_0_1119962679.1679025450048"
      3gpp-sbi-discovery-requester-nf-type: LMF
      3gpp-sbi-discovery-target-nf-type: AMF
      3gpp-sbi-discovery-target-nf-instance-id: 250787ff-edac-4779-a5a2-542ea214b250
      3gpp-sbi-discovery-service-names: ["namf-comm"]

      ------=_Part_0_1119962679.1679025450048
      Content-Type: application/json
      Content-ID: jsonData

      {"n1MessageContainer":{"n1MessageClass":"LPP","n1MessageContent":{"contentId":"binaryDataN1Message"},"nfId":"250787ff-edac-4779-a5a2-542ea214b250"},"lcsCorrelationId":"be6e5ae8-4d00-4ece-b412-b72f83aba8d2"}
      ------=_Part_0_1119962679.1679025450048
      Content-Type: application/vnd.3gpp.5gnas
      Content-ID: binaryDataN1Message

      this is the content
      ------=_Part_0_1119962679.1679025450048--
      """;

    @Override
    public InputStream getInputStream() throws IOException {
      return new ByteArrayInputStream(content.getBytes());
    }

    @Override
    public OutputStream getOutputStream() throws IOException {
      return new ByteArrayOutputStream();
    }

    @Override
    public String getContentType() {
      return "multipart/related;         boundary=\"----=_Part_0_1119962679.1679025450048\"";
    }

    @Override
    public String getName() {
      return null;
    }
  }
}