public static void main(String... strings) throws TrendrrException {
String json = "blah blah{ \"key\" : \"value\"}{ \"key1\" : \"valu\\\"e1}\"}";
try {
json = FileHelper.loadString("tweetparse.json");
} catch (Exception e) {
log.error("Caught", e);
}
JSONStreamReader reader = new JSONStreamReader(new StringReader(json));
DynMap mp;
while ((mp = reader.readNext()) != null) {
System.out.println(mp.toJSONString());
}
}
/**
* Provides a way to read streams of json dictionaries.
*
* <p>will start a dictionary on the first '{' and finish the dict on the corresponding '}'
*
* <p>It will ignore any characters between dicts, so any dilimiter can be used. each dict must be
* valid, an exception will be thrown on the first parse error.
*
* @author Dustin Norlander
* @created Nov 2, 2011
*/
public class JSONStreamReader {
protected static Log log = LogFactory.getLog(JSONStreamReader.class);
Reader reader;
long maxBufferedChars =
FileHelper.megsToBytes(4); // max size to write before we assume this is an invalid stream.
public JSONStreamReader(InputStream stream) {
this(new InputStreamReader(stream));
}
public JSONStreamReader(Reader reader) {
this.reader = new BufferedReader(reader);
}
public static void main(String... strings) throws TrendrrException {
String json = "blah blah{ \"key\" : \"value\"}{ \"key1\" : \"valu\\\"e1}\"}";
try {
json = FileHelper.loadString("tweetparse.json");
} catch (Exception e) {
log.error("Caught", e);
}
JSONStreamReader reader = new JSONStreamReader(new StringReader(json));
DynMap mp;
while ((mp = reader.readNext()) != null) {
System.out.println(mp.toJSONString());
}
}
/**
* returns null on eof. throws exception or returns parsed object.
*
* @return
* @throws java.io.IOException
*/
public DynMap readNext() throws TrendrrException {
StringBuilder json = new StringBuilder("{");
try {
long numRead = 0;
int openBrackets = 1;
boolean isQuote = false;
boolean isEscape = false;
// read until the first open bracket
int current = this.reader.read();
while (current != '{' && current != -1) {
numRead++;
if (numRead > this.maxBufferedChars) {
throw new TrendrrParseException(
"Read "
+ this.maxBufferedChars
+ " chars without a valid json dict. Beginning with: "
+ json.substring(0, 256));
}
current = this.reader.read();
}
do {
current = this.reader.read();
if (current == -1) {
return null;
}
char c = (char) current;
json.append(c);
if (!isQuote) {
if (c == '{') {
openBrackets++;
} else if (c == '}') {
openBrackets--;
}
}
if (c == '"' && !isEscape) {
isQuote = !isQuote;
}
if (isQuote && !isEscape && c == '\\') {
isEscape = true;
} else {
isEscape = false;
}
numRead++;
if (numRead > this.maxBufferedChars) {
throw new TrendrrParseException(
"Read "
+ this.maxBufferedChars
+ " chars without a valid json dict. Beginning with: "
+ json.substring(0, 256));
}
} while (openBrackets != 0);
DynMap dm = DynMapFactory.instanceFromJSON(json.toString());
if (dm == null) {
throw new TrendrrParseException("unable to parse json string");
}
return dm;
} catch (IOException x) {
throw new TrendrrIOException(x);
}
}
}