net.morimekta.util.json

Class JsonTokenizer

java.lang.Object

net.morimekta.util.json.JsonTokenizer

public class JsonTokenizer
extends Object

Class for tokenizing a JSON document and return one token at a time. It is optimized for high volume JSON parsing, and avoids things like buffer copying and utf-8 parsing. The tokens are just references back to the original input buffer, so are not safe to use as reference (except for token type) after the next token has been read.

Constructor Summary

Constructors

Constructor and Description
JsonTokenizer(InputStream in) Create a JSON tokenizer that reads from the input steam.

Method Summary

Modifier and Type	Method and Description
JsonToken	expect(String message) Expect a new JSON token on the stream.
JsonToken	expectNumber(String message) Expect a JSON number.
JsonToken	expectString(String message) Expect a string literal JSON token.
char	expectSymbol(String message, char... symbols) Expect a string literal JSON token.
String	getLine(int line) Returns the line requested.
boolean	hasNext() Whether there is another token on the stream.
JsonToken	next() Returns the next token on the stream, or null if there are no more JSON tokens on the stream.
JsonToken	peek(String message) Return the next token or throw an exception.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JsonTokenizer

public JsonTokenizer(InputStream in)

Create a JSON tokenizer that reads from the input steam. It will only read as far as requested, and no bytes further. It has no checking of whether the document follows the JSON standard, but will only accept JSON formatted tokens.

Parameters:

in - Input stream to parse.

Method Detail

expect

public JsonToken expect(String message)
                 throws JsonException,
                        IOException

Expect a new JSON token on the stream.

Parameters:

message - Message to add to exception if there are no more JSON tokens on the stream.

Returns:

The next token.

Throws:

JsonException - If no more tokens, or the token is illegally formatted.

IOException - If unable to read from stream.

expectString

public JsonToken expectString(String message)
                       throws IOException,
                              JsonException

Expect a string literal JSON token. A string literal is a double-quote delimited UTF-8 encoded, JSON-escaped string.

Parameters:

message - Message to add to exception if there are no more JSON tokens on the stream.

Returns:

The string literal token.

Throws:

JsonException - If no more tokens, or the token is illegally formatted.

IOException - If unable to read from stream.

expectNumber

public JsonToken expectNumber(String message)
                       throws IOException,
                              JsonException

Expect a JSON number. A number is a 64 bit integer (long), or a 64-bit real (double) number. The long can be decimal (base-10), octal (base-8) with '0' prefix, or hexadecimal (base-16) encoded with '0x' prefix, and the double can be a decimal point number (-0.0), or a scientific notation number (-0.0e-1).

Parameters:

message - Message to add to exception if there are no more JSON tokens on the stream.

Returns:

The number token.

Throws:

JsonException - If no more tokens, or the token is illegally formatted.

IOException - If unable to read from stream.

expectSymbol

public char expectSymbol(String message,
                         char... symbols)
                  throws IOException,
                         JsonException

Expect a string literal JSON token. A string literal is a double-quote delimited UTF-8 encoded, JSON-escaped string.

Parameters:

message - Message to add to exception if there are no more JSON tokens on the stream.

symbols - List of symbol characters to expect. If

Returns:

The symbol that was encountered.

Throws:

JsonException - If no more tokens, or the token is illegally formatted.

IOException - If unable to read from stream.

hasNext

public boolean hasNext()
                throws IOException,
                       JsonException

Whether there is another token on the stream. This will read up until it finds a JSON token, or until the stream ends.

Returns:

True if (and only if) there is at least one more token on the stream.

Throws:

JsonException - If the next token is illegally formatted.

IOException - If unable to read from stream.

peek

public JsonToken peek(String message)
               throws IOException,
                      JsonException

Return the next token or throw an exception. Though it does not consume that token.

Parameters:

message - Message to add to exception if there are no more JSON tokens on the stream.

Returns:

The next token.

Throws:

JsonException - If the next token is illegally formatted.

IOException - If unable to read from stream.

next

public JsonToken next()
               throws IOException,
                      JsonException

Returns the next token on the stream, or null if there are no more JSON tokens on the stream.

Returns:

The next token, or null.

Throws:

JsonException - If the next token is illegally formatted.

IOException - If unable to read from stream.

getLine

public String getLine(int line)
               throws IOException

Returns the line requested.

Parameters:

line - The line number (1 .. N)

Returns:

The line string, not including the line-break.

Throws:

IOException - If unable to read from the string.

IllegalArgumentException - If the line number requested is less than 1.