Spring Boot - readMessageInternal of AbstractHttpMessageConverter implementation not getting invoked - spring-boot

Question

Trying to write very simple http message converter to add encryption around request & respose.
Implemented rest controller and messageConverter. writeInternal does get invoked during response. However readInternal does not get invoked when request is sent to the rest end point.
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;
import org.json.JSONException;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.stereotype.Component;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.techm.bm.util.EncryptDecryptUtil;
#Component
public class MessageEncryptionConverter extends AbstractHttpMessageConverter<Object> {
#Autowired
private ObjectMapper objectMapper;
public MessageEncryptionConverter() {
super(MediaType.ALL);
}
#Override
protected boolean supports(Class<?> clazz) {
return true;
}
#Override
protected Object readInternal(Class<? extends Object> clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
return objectMapper.readValue(decrypt(inputMessage.getBody()), clazz);
}
#Override
protected void writeInternal(Object o, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
outputMessage.getBody().write(encrypt(objectMapper.writeValueAsBytes(o)));
}

Answer 1

The below code is for encryption and decryption of request and response body For overall Project to modify response body and request parameters. Please check this code is works for me
For Request Encryption refer readInternal
below is the front-end or postman request sending, you have to add encrypted request in Json formate
Ex.{data : "+++++++++++++YOUR_ENCRYPTED_STRING++++++++++"}
For Response Descryption refer writeInternal
sending back to your front-end or postman request response with encrypted string
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;
import org.json.JSONException;
import org.json.JSONObject;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpInputMessage;
import org.springframework.http.HttpOutputMessage;
import org.springframework.http.MediaType;
import org.springframework.http.converter.AbstractHttpMessageConverter;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.converter.HttpMessageNotWritableException;
import org.springframework.stereotype.Component;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.techm.bm.util.EncryptDecryptUtil;
#Component
public class MessageEncryptionConverter extends AbstractHttpMessageConverter<Object> {
#Autowired
private ObjectMapper objectMapper;
public MessageEncryptionConverter() {
super(MediaType.ALL);
}
#Override
protected boolean supports(Class<?> clazz) {
return true;
}
#Override
protected Object readInternal(Class<? extends Object> clazz, HttpInputMessage inputMessage)
throws IOException, HttpMessageNotReadableException {
return objectMapper.readValue(decrypt(inputMessage.getBody()), clazz);
}
#Override
protected void writeInternal(Object o, HttpOutputMessage outputMessage)
throws IOException, HttpMessageNotWritableException {
outputMessage.getBody().write(encrypt(objectMapper.writeValueAsBytes(o)));
}
// Convert request to input stream for sending to the controller
private InputStream decrypt(InputStream inputStream) throws IOException {
//this is API request params
Writer writer = new StringWriter();
char[] buffer = new char[1024];
try {
Reader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
int n;
while ((n = reader.read(buffer)) != -1) {
writer.write(buffer, 0, n);
}
} catch (UnsupportedEncodingException e) {
logger.error("UnsupportedEncodingException" + e.getMessage());
} catch (IOException e) {
logger.error("IOException" + e.getMessage());
} finally {
inputStream.close();
}
try {
JSONObject requestJsonObject = new JSONObject(writer.toString().replace("\n", ""));
// Add your decryption method the object data will get your encrypted string data and return with string of your JSON object
String decryptRequestString = EncryptionUtils.decryptText(requestJsonObject.getString("data"));
if (decryptRequestString != null) {
return new ByteArrayInputStream(decryptRequestString.getBytes(StandardCharsets.UTF_8));
} else {
return inputStream;
}
} catch (JSONException err) {
logger.error("Error" + err.toString());
} catch (NoSuchAlgorithmException | BadPaddingException | DigestException | InvalidKeyException
| InvalidAlgorithmParameterException | NoSuchPaddingException | IllegalBlockSizeException e) {
logger.info("NoSuchAlgorithmException | BadPaddingException | DigestException | InvalidKeyException | " +
"InvalidAlgorithmParameterException | NoSuchPaddingException | IllegalBlockSizeException:: " + e.getMessage());
}
return inputStream;
}
private byte[] encrypt(Object obj) throws JsonProcessingException {
// do your encryption here
try {
String stringFromObject = objectMapper.writeValueAsString(obj);
// Add your encryption method
String encrypt = EncryptionUtils.encryptText(stringFromObject);
return objectMapper.writeValueAsBytes(encrypt);
} catch (Exception e) {
logger.info("Error While Encrypt data :: " + e.getMessage());
return objectMapper.writeValueAsBytes(obj);
}
}
}
Reference code Spring Boot - Encrypt JSON data
Hope this code is working for you

Answer 2

It is invoking if the request has body and "supports" method return ture