org.apache.wicket.ajax.json
Class JSONStringer

java.lang.Object
  org.apache.wicket.ajax.json.JSONWriter
      org.apache.wicket.ajax.json.JSONStringer

public class JSONStringer
extends JSONWriter

Implements JSONObject.toString() and JSONArray.toString(). Most application developers should use those methods directly and disregard this API. For example:

 JSONObject object = ...
 String json = object.toString();

Stringers only encode well-formed JSON strings. In particular:

• The stringer must have exactly one top-level array or object.
• Lexical scopes must be balanced: every call to array() must have a matching call to endArray() and every call to object() must have a matching call to endObject().
• Arrays may not contain keys (property names).
• Objects must alternate keys (property names) and values.
• Values are inserted with either literal value calls, or by nesting arrays or objects.

Calls that would result in a malformed JSON string will fail with a JSONException.

This class provides no facility for pretty-printing (ie. indenting) output. To encode indented output, use JSONObject.toString(int) or JSONArray.toString(int).

Some implementations of the API support at most 20 levels of nesting. Attempts to create more than 20 levels of nesting may fail with a JSONException.

Each stringer may be used to encode a single top level value. 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.

Field Summary

protected StringBuilder

out The output data, containing at most one top-level array or object.

Fields inherited from class org.apache.wicket.ajax.json.JSONWriter

mode, writer

Constructor Summary

JSONStringer()

Method Summary

JSONStringer	array() Begins encoding a new array.
protected JSONStringer	createKey(String name) Creates String representation of the key (property name) to this stringer Override this method to provide your own representation of the name.
JSONStringer	endArray() Ends encoding the current array.
JSONStringer	endObject() Ends encoding the current object.
JSONStringer	entry(Map.Entry<String,Object> entry) Encodes key/value pair to this stringer.
JSONStringer	key(String name) Encodes the key (property name) to this stringer.
JSONStringer	object() Begins encoding a new object.
String	toString() Returns the encoded JSON string.
JSONStringer	value(boolean value) Encodes value to this stringer.
JSONStringer	value(double value) Encodes value to this stringer.
JSONStringer	value(long value) Encodes value to this stringer.
JSONStringer	value(Object value) Encodes value.

Methods inherited from class java.lang.Object

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

Field Detail

out

protected final StringBuilder out

The output data, containing at most one top-level array or object.

Constructor Detail

JSONStringer

public JSONStringer()

Method Detail

array

public JSONStringer array()
                   throws JSONException

Begins encoding a new array. Each call to this method must be paired with a call to endArray().

Overrides:

array in class JSONWriter

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

endArray

public JSONStringer endArray()
                      throws JSONException

Ends encoding the current array.

Overrides:

endArray in class JSONWriter

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

object

public JSONStringer object()
                    throws JSONException

Begins encoding a new object. Each call to this method must be paired with a call to endObject().

Overrides:

object in class JSONWriter

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

endObject

public JSONStringer endObject()
                       throws JSONException

Ends encoding the current object.

Overrides:

endObject in class JSONWriter

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(Object value)
                   throws JSONException

Encodes value.

Overrides:

value in class JSONWriter

Parameters:

value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double or null. May not be NaNs or infinities.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(boolean value)
                   throws JSONException

Encodes value to this stringer.

Overrides:

value in class JSONWriter

Parameters:

value - The value to encode.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(double value)
                   throws JSONException

Encodes value to this stringer.

Overrides:

value in class JSONWriter

Parameters:

value - a finite value. May not be NaNs or infinities.

Returns:

this stringer.

Throws:

JSONException - On internal errors. Shouldn't happen.

value

public JSONStringer value(long value)
                   throws JSONException

Encodes value to this stringer.

Overrides:

value in class JSONWriter

Parameters:

value - The value to encode.

Returns:

this stringer.

Throws:

JSONException - If we have an internal error. Shouldn't happen.

entry

public JSONStringer entry(Map.Entry<String,Object> entry)

Encodes key/value pair to this stringer.

Parameters:

entry - The entry to encode.

Returns:

this stringer.

Throws:

JSONException - If we have an internal error. Shouldn't happen.

createKey

protected JSONStringer createKey(String name)

Creates String representation of the key (property name) to this stringer Override this method to provide your own representation of the name.

Parameters:

name - the name of the forthcoming value.

Returns:

this stringer.

key

public JSONStringer key(String name)
                 throws JSONException

Encodes the key (property name) to this stringer.

Overrides:

key in class JSONWriter

Parameters:

name - the name of the forthcoming value. May not be null.

Returns:

this stringer.

Throws:

JSONException - on internal errors, shouldn't happen.

toString

public String toString()

Returns the encoded JSON string.

If invoked with unterminated arrays or unclosed objects, this method's return value is undefined.

Warning: although it contradicts the general contract of Object.toString(), this method returns null if the stringer contains no data.

Overrides:

toString in class Object