org.opencms.json

Class JSONWriter

java.lang.Object

org.opencms.json.JSONWriter

Direct Known Subclasses:

JSONStringer

public class JSONWriter
extends java.lang.Object

JSONWriter provides a quick and convenient way of producing JSON text. The texts produced strictly conform to JSON syntax rules. No whitespace is added, so the results are ready for transmission or storage. Each instance of JSONWriter can produce one JSON text.

A JSONWriter instance provides a value method for appending values to the text, and a key method for adding keys before values in objects. There are array and endArray methods that make and bound array values, and object and endObject methods which make and bound object values. All of these methods return the JSONWriter instance, permitting a cascade style. For example,

 new JSONWriter(myWriter)
     .object()
         .key("JSON")
         .value("Hello, World!")
     .endObject();

which writes

 {"JSON":"Hello, World!"}

The first method called must be array or object. There are no methods for adding commas or colons. JSONWriter adds them for you. Objects and arrays can be nested up to 20 levels deep.

This can sometimes be easier than using a JSONObject to build a string.

Field Summary

Fields

Modifier and Type	Field and Description
protected char	m_mode The current m_mode.
protected java.io.Writer	m_writer The m_writer that will receive the output.

Constructor Summary

Constructors

Constructor and Description
JSONWriter(java.io.Writer w) Make a fresh JSONWriter.

Method Summary

Methods

Modifier and Type	Method and Description
JSONWriter	array() Begin appending a new array.
JSONWriter	endArray() End an array.
JSONWriter	endObject() End an object.
JSONWriter	key(java.lang.String s) Append a key.
JSONWriter	object() Begin appending a new object.
JSONWriter	value(boolean b) Append either the value true or the value false.
JSONWriter	value(double d) Append a double value.
JSONWriter	value(long l) Append a long value.
JSONWriter	value(java.lang.Object o) Append an object value.

Methods inherited from class java.lang.Object

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

Field Detail

m_mode

protected char m_mode

The current m_mode. Values: 'a' (array), 'd' (done), 'i' (initial), 'k' (key), 'o' (object).

m_writer

protected java.io.Writer m_writer

The m_writer that will receive the output.

Constructor Detail

JSONWriter

public JSONWriter(java.io.Writer w)

Make a fresh JSONWriter.

It can be used to build one JSON text.

Parameters:

w - the writer to use

Method Detail

array

public JSONWriter array()
                 throws JSONException

Begin appending a new array.

All values until the balancing endArray will be appended to this array. The endArray method must be called to mark the array's end.

Returns:

this

Throws:

JSONException - if the nesting is too deep, or if the object is started in the wrong place (for example as a key or after the end of the outermost array or object)

endArray

public JSONWriter endArray()
                    throws JSONException

End an array. This method most be called to balance calls to array.

Returns:

this

Throws:

JSONException - if incorrectly nested

endObject

public JSONWriter endObject()
                     throws JSONException

End an object. This method most be called to balance calls to object.

Returns:

this

Throws:

JSONException - if incorrectly nested

key

public JSONWriter key(java.lang.String s)
               throws JSONException

Append a key. The key will be associated with the next value. In an object, every value must be preceded by a key.

Parameters:

s - a key string

Returns:

this

Throws:

JSONException - if the key is out of place. For example, keys do not belong in arrays or if the key is null

object

public JSONWriter object()
                  throws JSONException

Begin appending a new object.

All keys and values until the balancing endObject will be appended to this object. The endObject method must be called to mark the object's end.

Returns:

this

Throws:

JSONException - if the nesting is too deep, or if the object is started in the wrong place (for example as a key or after the end of the outermost array or object)

value

public JSONWriter value(boolean b)
                 throws JSONException

Append either the value true or the value false.

Parameters:

b - a boolean

Returns:

this

Throws:

JSONException - if something goes wrong

value

public JSONWriter value(double d)
                 throws JSONException

Append a double value.

Parameters:

d - a double

Returns:

this

Throws:

JSONException - if the number is not finite

value

public JSONWriter value(long l)
                 throws JSONException

Append a long value.

Parameters:

l - a long

Returns:

this

Throws:

JSONException - if something goes wrong

value

public JSONWriter value(java.lang.Object o)
                 throws JSONException

Append an object value.

Parameters:

o - the object to append. It can be null, or a Boolean, Number, String, JSONObject, or JSONArray, or an object with a toJSONString() method

Returns:

this

Throws:

JSONException - if the value is out of sequence