java将json数据解析为sql语句？

import java.util.Iterator;
import java.util.Set;
import java.util.Map.Entry;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

public class Sql
{
	public static String parseSQL(String json)
	{
		JsonParser parser = new JsonParser();
		JsonObject obj = (JsonObject) parser.parse(json);;
		String table = obj.get("table").getAsString();
		String op_type = obj.get("op_type").getAsString();
		String sql = "";
		if("I".equals(op_type))
		{
			sql += "INSERT INTO " + table + " (";
			JsonObject after = (JsonObject) obj.get("after");
			Set<Entry<String, JsonElement>> entry = after.entrySet();
			Iterator<Entry<String, JsonElement>> it = entry.iterator();
			String vs = " values (";
			while(it.hasNext())
			{
				Entry<String, JsonElement> elem = it.next();
				String key = elem.getKey();
				String val = elem.getValue().toString();
				sql += key + ", ";
				vs += val + ", ";
			}
			sql = sql.replaceAll(",\\s*$", "");
			vs = vs.replaceAll(",\\s*$", "");
			sql += ") " + vs + ")";
		}
		else if("U".equals(op_type))
		{
			sql += "UPDATE " + table + " SET ";
			JsonObject after = (JsonObject) obj.get("after");
			Set<Entry<String, JsonElement>> entry = after.entrySet();
			Iterator<Entry<String, JsonElement>> it = entry.iterator();
			while(it.hasNext())
			{
				Entry<String, JsonElement> elem = it.next();
				String key = elem.getKey();
				String val = elem.getValue().toString();
				sql += key + "=" + val + ", ";
			}
			sql = sql.replaceAll(",\\s*$", "");
			sql += " WHERE ";
			after = (JsonObject) obj.get("before");
			entry = after.entrySet();
			it = entry.iterator();
			while(it.hasNext())
			{
				Entry<String, JsonElement> elem = it.next();
				String key = elem.getKey();
				String val = elem.getValue().toString();
				sql += key + "=" + val + " AND ";
			}
			sql = sql.replaceAll("\\s*AND\\s*$", "");
		}
		else if("D".equals(op_type))
		{
			sql += "DELETE FROM " + table + " WHERE ";
			JsonObject after = (JsonObject) obj.get("before");
			Set<Entry<String, JsonElement>> entry = after.entrySet();
			Iterator<Entry<String, JsonElement>> it = entry.iterator();
			while(it.hasNext())
			{
				Entry<String, JsonElement> elem = it.next();
				String key = elem.getKey();
				String val = elem.getValue().toString();
				sql += key + "=" + val + " AND ";
			}
			sql = sql.replaceAll("\\s*AND\\s*$", "");
		}
		return sql;
	}

	public static void main(String[] args)
	{
		String insert =
		        "{\"table\":\"GG.TCUSTORD\",\"op_type\":\"I\",\"op_ts\":\"2013-06-02 22:14:36.000000\",\"current_ts\":\"2015-09-18T13:39:35.447000\",\"pos\":\"00000000000000001444\",\"tokens\":{\"R\":\"AADPkvAAEAAEqL2AAA\"},\"after\":{\"CUST_CODE\":\"WILL\",\"ORDER_DATE\":\"1994-09-30:15:33:00\",\"PRODUCT_CODE\":\"CAR\",\"ORDER_ID\":\"144\",\"PRODUCT_PRICE\":17520.00,\"PRODUCT_AMOUNT\":3,\"TRANSACTION_ID\":\"100\"}}";
		String update =
		        "{\"table\":\"GG.TCUSTORD\",\"op_type\":\"U\",\"op_ts\":\"2013-06-02 22:14:41.000000\",\"current_ts\":\"2015-09-18T13:39:35.748000\",\"pos\":\"00000000000000002891\",\"tokens\":{\"L\":\"206080450\",\"6\":\"9.0.80330\",\"R\":\"AADPkvAAEAAEqLzAAC\"},\"before\":{\"CUST_CODE\":\"BILL\",\"ORDER_DATE\":\"1995-12-31:15:00:00\",\"PRODUCT_CODE\":\"CAR\",\"ORDER_ID\":\"765\",\"PRODUCT_PRICE\":15000.00,\"PRODUCT_AMOUNT\":3,\"TRANSACTION_ID\":\"100\"},\"after\":{\"CUST_CODE\":\"BILL\",\"ORDER_DATE\":\"1995-12-31:15:00:00\",\"PRODUCT_CODE\":\"CAR\",\"ORDER_ID\":\"765\",\"PRODUCT_PRICE\":14000.00,\"PRODUCT_AMOUNT\":3,\"TRANSCATION_ID\":\"100\"}}";
		String delete =
		        "{\"table\":\"GG.TCUSTORD\",\"op_type\":\"D\",\"op_ts\":\"2013-06-02 22:14:41.000000\",\"current_ts\":\"2015-09-18T13:39:35.766000\",\"pos\":\"00000000000000004338\",\"tokens\":{\"L\":\"206080450\",\"6\":\"9.0.80330\",\"R\":\"AADPkvAAEAAEqLzAAC\"},\"before\":{\"CUST_CODE\":\"DAVE\",\"ORDER_DATE\":\"1993-11-03:07:51:35\",\"PRODUCT_CODE\":\"PLANE\",\"ORDER_ID\":\"600\"}}";
		System.out.println(parseSQL(insert));
		System.out.println(parseSQL(update));
		System.out.println(parseSQL(delete));
	}
}