Remove leading and trailing spaces on Strings across your spring application with Jackson

If you are using Jackson to convert http messages, you can add a custom String Deserializer to removes heading and trailing spaces across you application in a few lines.

import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
import org.apache.commons.lang3.StringUtils;

import java.io.IOException;

public class StringDeserializer extends StdDeserializer<string> {

  private static final long serialVersionUID = 1623333240815834335L;

  public StringDeserializer() {
    this(null);
  }

  private StringDeserializer(Class vc) {
    super(vc);
  }

  @Override
  public String deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
    String valueAsString = jp.getValueAsString();
    if (StringUtils.isEmpty(valueAsString)) {
      return null;
    }

    return valueAsString.trim();
  }
}

To activate it, add this bean to your WebConfig file.

@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {

  @Bean
  public MappingJackson2HttpMessageConverter mappingJackson2HttpMessageConverter() {
    MappingJackson2HttpMessageConverter jsonConverter = new MappingJackson2HttpMessageConverter();
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
    objectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);
    jsonConverter.setObjectMapper(objectMapper);

    SimpleModule module = new SimpleModule();

    module.addDeserializer(String.class, new StringDeserializer());
    objectMapper.registerModule(module);

    return jsonConverter;
  }
}