test

Main.java

package test;

import java.io.IOException;
import java.util.Objects;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonToken;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;

public class Main {

	public static void main(String[] args) throws IOException {
		String content = "{\"a\": {\"test\":\"1\"}}";
		Test test = new ObjectMapper().readValue(content, Test.class);
		System.out.println(test.getA());

		String prop = "a";
		String substring = extract(content, prop);
		System.out.println(substring);

	}

	private static String extract(String content, String prop) throws IOException {
		String substring = null;
		JsonParser parser = new JsonFactory().createParser(content);
		while (parser.nextToken() != JsonToken.END_OBJECT) {
			if (parser.getCurrentToken() != JsonToken.FIELD_NAME) {
				continue;
			}
			if (!Objects.equals(parser.getText(), prop)) {
				parser.skipChildren();
				continue;
			}
			parser.nextToken();
			long begin = parser.getCurrentLocation().getCharOffset();
			parser.skipChildren();
			long end = parser.getCurrentLocation().getCharOffset();
			String json = parser.getCurrentLocation().getSourceRef().toString();
			substring = json.substring((int) begin - 1, (int) end);
			break;
		}
		return substring;
	}

	public static class Test {
		@JsonDeserialize(using = RawJsonDeserializer.class)
		private String a;

		public String getA() {
			return a;
		}

		public void setA(String a) {
			this.a = a;
		}
	}

	public static class RawJsonDeserializer extends JsonDeserializer<String> {
		@Override
		public String deserialize(JsonParser jp, DeserializationContext ctxt)
				throws IOException {

			long begin = jp.getCurrentLocation().getCharOffset();
			jp.skipChildren();
			long end = jp.getCurrentLocation().getCharOffset();

			String json = jp.getCurrentLocation().getSourceRef().toString();
			return json.substring((int) begin - 1, (int) end);
		}
	}

}