How to read multiple JSON syntax blocks in a single input #269
Description
See also Read Multiple Objects JSON with Java.
If a JSON object is parsed, it is expected to be able to get the current position like
- ftell(3p) - Linux manual page (The
ftell()function shall obtain the current value of the file- position indicator for the stream pointed to by stream.) or - tell - cppreference.com (Returns the file position indicator for the file stream stream.)
Error example,
package ss;
import net.minidev.json.JSONArray;
import net.minidev.json.JSONObject;
import net.minidev.json.JSONValue;
import net.minidev.json.parser.JSONParser;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.nio.charset.StandardCharsets;
import static net.minidev.json.parser.JSONParser.DEFAULT_PERMISSIVE_MODE;
public class JsonSmartExample {
public static void main(String[] args) throws Exception {
testMultipleJsons2();
String json = "[{\"friends\":[{\"id\":0,\"name\":\"test1\"},{\"id\":1,\"name\":\"test2\"}]}] other data";
JSONArray root = (JSONArray) JSONValue.parseWithException(json);
JSONObject rootObj = (JSONObject) root.get(0);
JSONArray array = (JSONArray) rootObj.get("friends");
for (int idx = 0; idx < array.size(); idx++) {
JSONObject cap = (JSONObject) array.get(idx);
String first = (String) cap.get("name");
System.out.println(first);
}
}
private static void testMultipleJsons() throws Exception {
String json = "{tranid:\"1212\", \"user\":{\"name\":\"123\",\"addr\":\"786 rt\"}}"
+ "\n{tranid:\"1213\", \"user\":{\"name\":\"345\",\"addr\":\"4234 iu\"}}";
ByteArrayInputStream stream = new ByteArrayInputStream(json.getBytes(StandardCharsets.UTF_8));
JSONObject root1 = (JSONObject) JSONValue.parseWithException(stream);
System.out.println(root1.get("tranid"));
System.out.println(stream.available());
JSONObject root2 = (JSONObject) JSONValue.parseWithException(stream);
System.out.println(root2.get("tranid"));
}
private static void testMultipleJsons2() throws Exception {
String json = "{tranid:\"1212\", \"user\":{\"name\":\"123\",\"addr\":\"786 rt\"}}"
+ "\n{tranid:\"1213\", \"user\":{\"name\":\"345\",\"addr\":\"4234 iu\"}}";
JSONParser parser = new JSONParser(DEFAULT_PERMISSIVE_MODE);
JSONObject root1 = (JSONObject) parser.parse(json, JSONValue.defaultReader.DEFAULT);
System.out.println(root1.get("tranid"));
// for (Class<?> c = parser.getClass(); c != null; c = c.getSuperclass()) Field f = c.getDeclaredField("pos");
Field field = Class.forName("net.minidev.json.parser.JSONParserBase").getDeclaredField("pos");
field.setAccessible(true);
Field pStringField = JSONParser.class.getDeclaredField("pString");
pStringField.setAccessible(true);
Object parser2 = pStringField.get(parser);
Integer ipos = (Integer) field.get(parser2);
System.out.println("pos=" + ipos);
JSONObject root2 = (JSONObject) parser.parse(json.substring(ipos), JSONValue.defaultReader.DEFAULT);
System.out.println(root2.get("tranid"));
ipos = (Integer) field.get(parser2);
System.out.println("pos=" + ipos);
}
}