org.apache.wicket.ajax.json
Class JSONTokener

java.lang.Object
  org.apache.wicket.ajax.json.JSONTokener

Direct Known Subclasses:

HTTPTokener, XMLTokener

public class JSONTokener
extends Object

Parses a JSON (RFC 4627) encoded string into the corresponding object. Most clients of this class will use only need the constructor and nextValue() method. Example usage:

 String json = "{" + "  \"query\": \"Pizza\", " + "  \"locations\": [ 94043, 90210 ] " + "}";

 JSONObject object = (JSONObject)new JSONTokener(json).nextValue();
 String query = object.getString("query");
 JSONArray locations = object.getJSONArray("locations");
 

For best interoperability and performance use JSON that complies with RFC 4627, such as that generated by JSONStringer. For legacy reasons this parser is lenient, so a successful parse does not indicate that the input string was valid JSON. All of the following syntax errors will be ignored:

• End of line comments starting with // or # and ending with a newline character.
• C-style comments starting with /* and ending with */. Such comments may not be nested.
• Strings that are unquoted or 'single quoted'.
• Hexadecimal integers prefixed with 0x or 0X.
• Octal integers prefixed with 0.
• Array elements separated by ;.
• Unnecessary array separators. These are interpreted as if null was the omitted value.
• Key-value pairs separated by = or =>.
• Key-value pairs separated by ;.

Each tokener may be used to parse a single JSON string. Instances of this class are not thread safe. Although this class is nonfinal, it was not designed for inheritance and should not be subclassed. In particular, self-use by overrideable methods is not specified. See Effective Java Item 17, "Design and Document or inheritance or else prohibit it" for further information.

Constructor Summary

JSONTokener(InputStream inputStream)
Deprecated. since 6.27.0/7.7.0 for legal reasons.

JSONTokener(Reader input)

JSONTokener(String in)

Method Summary

void	back() Unreads the most recent character of input.
static int	dehexchar(char hex) Returns the integer [0..15] value for the given hex character, or -1 for non-hex input.
boolean	end() Deprecated. since 6.27.0/7.7.0 for legal reasons.
boolean	more() Returns true until the input has been exhausted.
char	next() Returns the next available character, or the null character '\0' if all input has been exhausted.
char	next(char c) Returns the next available character if it equals c.
String	next(int length) Returns the next length characters of the input.
char	nextClean() Returns the next character that is not whitespace and does not belong to a comment.
String	nextString(char quote) Returns the string up to but not including quote, unescaping any character escape sequences encountered along the way.
String	nextTo(char excluded) Equivalent to nextTo(String.valueOf(excluded)).
String	nextTo(String excluded) Returns the trimmed string holding the characters up to but not including the first of: any character in excluded a newline character '\n' a carriage return '\r'
Object	nextValue() Returns the next value from the input.
boolean	skipPast(String thru) Advances past all input up to and including the next occurrence of thru.
char	skipTo(char to) Advances past all input up to but not including the next occurrence of to.
JSONException	syntaxError(String message) Returns an exception containing the given message plus the current position and the entire input string.
String	toString() Returns the current position and the entire input string.

Methods inherited from class java.lang.Object

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

Constructor Detail

JSONTokener

public JSONTokener(String in)

Parameters:

in - JSON encoded string. Null is not permitted and will yield a tokener that throws NullPointerExceptions when methods are called.

JSONTokener

public JSONTokener(Reader input)
            throws IOException

Throws:

IOException

JSONTokener

@Deprecated
public JSONTokener(InputStream inputStream)

Deprecated. since 6.27.0/7.7.0 for legal reasons.

Method Detail

nextValue

public Object nextValue()
                 throws JSONException

Returns the next value from the input.

Returns:

a JSONObject, JSONArray, String, Boolean, Integer, Long, Double or JSONObject.NULL.

Throws:

JSONException - if the input is malformed.

nextString

public String nextString(char quote)
                  throws JSONException

Returns the string up to but not including quote, unescaping any character escape sequences encountered along the way. The opening quote should have already been read. This consumes the closing quote, but does not include it in the returned string.

Parameters:

quote - either ' or ".

Returns:

The unescaped string.

Throws:

JSONException - if the string isn't terminated by a closing quote correctly.

syntaxError

public JSONException syntaxError(String message)

Returns an exception containing the given message plus the current position and the entire input string.

Parameters:

message - The message we want to include.

Returns:

An exception that we can throw.

toString

public String toString()

Returns the current position and the entire input string.

Overrides:

toString in class Object

more

public boolean more()

Returns true until the input has been exhausted.

Returns:

true if more input exists.

next

public char next()

Returns the next available character, or the null character '\0' if all input has been exhausted. The return value of this method is ambiguous for JSON strings that contain the character '\0'.

Returns:

the next character.

next

public char next(char c)
          throws JSONException

Returns the next available character if it equals c. Otherwise an exception is thrown.

Parameters:

c - The character we are looking for.

Returns:

the next character.

Throws:

JSONException - If the next character isn't c

nextClean

public char nextClean()
               throws JSONException

Returns the next character that is not whitespace and does not belong to a comment. If the input is exhausted before such a character can be found, the null character '\0' is returned. The return value of this method is ambiguous for JSON strings that contain the character '\0'.

Returns:

The next non-whitespace character.

Throws:

JSONException - Should not be possible.

next

public String next(int length)
            throws JSONException

Returns the next length characters of the input.

The returned string shares its backing character array with this tokener's input string. If a reference to the returned string may be held indefinitely, you should use new String(result) to copy it first to avoid memory leaks.

Parameters:

length - The desired number of characters to return.

Returns:

The next few characters.

Throws:

JSONException - if the remaining input is not long enough to satisfy this request.

nextTo

public String nextTo(String excluded)

Returns the trimmed string holding the characters up to but not including the first of:

• any character in excluded
• a newline character '\n'
• a carriage return '\r'

The returned string shares its backing character array with this tokener's input string. If a reference to the returned string may be held indefinitely, you should use new String(result) to copy it first to avoid memory leaks.

Parameters:

excluded - The limiting string where the search should stop.

Returns:

a possibly-empty string

nextTo

public String nextTo(char excluded)

Equivalent to nextTo(String.valueOf(excluded)).

Parameters:

excluded - The limiting character.

Returns:

a possibly-empty string

skipPast

public boolean skipPast(String thru)

Advances past all input up to and including the next occurrence of thru. If the remaining input doesn't contain thru, the input is exhausted.

Parameters:

thru - The string to skip over.

Returns:

skipTo

public char skipTo(char to)

Advances past all input up to but not including the next occurrence of to. If the remaining input doesn't contain to, the input is unchanged.

Parameters:

to - The character we want to skip to.

Returns:

The value of to or null.

back

public void back()

Unreads the most recent character of input. If no input characters have been read, the input is unchanged.

dehexchar

public static int dehexchar(char hex)

Returns the integer [0..15] value for the given hex character, or -1 for non-hex input.

Parameters:

hex - a character in the ranges [0-9], [A-F] or [a-f]. Any other character will yield a -1 result.

Returns:

The decoded integer.

end

@Deprecated
public boolean end()

Deprecated. since 6.27.0/7.7.0 for legal reasons.