Package org.opencms.json

Class JSONWriter

java.lang.Object
org.opencms.json.JSONWriter
Direct Known Subclasses:
JSONStringer
public class JSONWriter extends 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 Details

    • m_mode

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

    • m_writer

      protected Writer m_writer
      The m_writer that will receive the output.

  • Constructor Details

    • JSONWriter

      public JSONWriter(Writer w)
      Make a fresh JSONWriter.

      It can be used to build one JSON text.

      Parameters:
      w - the writer to use

  • Method Details

    • 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(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(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