DefaultJsonWriter (gwt-jackson

java.lang.Object
- com.github.nmorel.gwtjackson.client.stream.impl.DefaultJsonWriter

All Implemented Interfaces:: JsonWriter

public class DefaultJsonWriter
extends Object
implements JsonWriter

Writes a JSON (RFC 4627) encoded value to a stream, one token at a time. The stream includes both literal values (strings, numbers, booleans and nulls) as well as the begin and end delimiters of objects and arrays.

Encoding JSON

To encode your data as JSON, create a new JsonWriter. Each JSON document must contain one top-level array or object. Call methods on the writer as you walk the structure's contents, nesting arrays and objects as necessary:

To write arrays, first call beginArray(). Write each of the array's elements with the appropriate value(java.lang.String) methods or by nesting other arrays and objects. Finally close the array using endArray().
To write objects, first call beginObject(). Write each of the object's properties by alternating calls to name(java.lang.String) with the property's value. Write property values with the appropriate value(java.lang.String) method or by nesting other objects or arrays. Finally close the object using endObject().

Example

Suppose we'd like to encode a stream of messages such as the following:

 [
   {
     "id": 912345678901,
     "text": "How do I stream JSON in Java?",
     "geo": null,
     "user": {
       "name": "json_newb",
       "followers_count": 41
      }
   },
   {
     "id": 912345678902,
     "text": "@json_newb just use JsonWriter!",
     "geo": [50.454722, -104.606667],
     "user": {
       "name": "jesse",
       "followers_count": 2
     }
   }
 ]

This code encodes the above structure:

   public void writeJsonStream(OutputStream out, List<Message> messages) {
     JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8"));
     writer.setIndentSpaces(4);
     writeMessagesArray(writer, messages);
     writer.close();
   }

   public void writeMessagesArray(JsonWriter writer, List<Message> messages) {
     writer.beginArray();
     for (Message message : messages) {
       writeMessage(writer, message);
     }
     writer.endArray();
   }

   public void writeMessage(JsonWriter writer, Message message) {
     writer.beginObject();
     writer.name("id").value(message.getId());
     writer.name("text").value(message.getText());
     if (message.getGeo() != null) {
       writer.name("geo");
       writeDoublesArray(writer, message.getGeo());
     } else {
       writer.name("geo").nullValue();
     }
     writer.name("user");
     writeUser(writer, message.getUser());
     writer.endObject();
   }

   public void writeUser(JsonWriter writer, User user) {
     writer.beginObject();
     writer.name("name").value(user.getName());
     writer.name("followers_count").value(user.getFollowersCount());
     writer.endObject();
   }

   public void writeDoublesArray(JsonWriter writer, List<Double> doubles) {
     writer.beginArray();
     for (Double value : doubles) {
       writer.value(value);
     }
     writer.endArray();
   }

Each JsonWriter may be used to write a single JSON stream. Instances of this class are not thread safe. Calls that would result in a malformed JSON string will fail with an IllegalStateException.

Since:: 1.6
Author:: Jesse Wilson

Constructor Summary

Constructors
Constructor and Description

DefaultJsonWriter(StringBuilder out)
Creates a new instance that writes a JSON-encoded stream to out.

Constructors
Constructor and Description
`DefaultJsonWriter(StringBuilder out)` Creates a new instance that writes a JSON-encoded stream to `out`.

Method Summary

Methods
Modifier and Type	Method and Description
`DefaultJsonWriter`	`beginArray()` Begins encoding a new array.
`DefaultJsonWriter`	`beginObject()` Begins encoding a new object.
`DefaultJsonWriter`	`cancelName()`
`void`	`close()` Flushes and closes this writer and the underlying `StringBuilder`.
`DefaultJsonWriter`	`endArray()` Ends encoding the current array.
`DefaultJsonWriter`	`endObject()` Ends encoding the current object.
`void`	`flush()` Ensures all buffered data is written to the underlying `StringBuilder` and flushes that writer.
`String`	`getOutput()`
`boolean`	`getSerializeNulls()` Returns true if object members are serialized when their value is null.
`boolean`	`isHtmlSafe()` Returns true if this writer writes JSON that's safe for inclusion in HTML and XML documents.
`boolean`	`isLenient()` Returns true if this writer has relaxed syntax rules.
`DefaultJsonWriter`	`name(String name)` Encodes the property name.
`DefaultJsonWriter`	`nullValue()` Encodes `null`.
`DefaultJsonWriter`	`rawValue(Object value)` Encodes `value`.toString() as is.
`void`	`setHtmlSafe(boolean htmlSafe)` Configure this writer to emit JSON that's safe for direct inclusion in HTML and XML documents.
`void`	`setIndent(String indent)` Sets the indentation string to be repeated for each level of indentation in the encoded document.
`void`	`setLenient(boolean lenient)` Configure this writer to relax its syntax rules.
`void`	`setSerializeNulls(boolean serializeNulls)` Sets whether object members are serialized when their value is null.
`DefaultJsonWriter`	`value(boolean value)` Encodes `value`.
`DefaultJsonWriter`	`value(double value)` Encodes `value`.
`DefaultJsonWriter`	`value(long value)` Encodes `value`.
`DefaultJsonWriter`	`value(Number value)` Encodes `value`.
`DefaultJsonWriter`	`value(String value)` Encodes `value`.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - DefaultJsonWriter
```
public DefaultJsonWriter(StringBuilder out)
```
    Creates a new instance that writes a JSON-encoded stream to out.
- Method Detail
  - setIndent
```
public final void setIndent(String indent)
```
    Description copied from interface: JsonWriter
    
    Sets the indentation string to be repeated for each level of indentation in the encoded document. If indent.isEmpty() the encoded document will be compact. Otherwise the encoded document will be more human-readable.
    
    Specified by:
    
    setIndent in interface JsonWriter
    
    Parameters:
    indent - a string containing only whitespace.
  - setLenient
```
public final void setLenient(boolean lenient)
```
    Description copied from interface: JsonWriter
    Configure this writer to relax its syntax rules. By default, this writer only emits well-formed JSON as specified by RFC 4627. Setting the writer to lenient permits the following:
    - Top-level values of any type. With strict writing, the top-level value must be an object or an array.
    - Numbers may be NaNs or infinities.
    Specified by:
    
    setLenient in interface JsonWriter
  - isLenient
```
public boolean isLenient()
```
    Returns true if this writer has relaxed syntax rules.
  - setHtmlSafe
```
public final void setHtmlSafe(boolean htmlSafe)
```
    Configure this writer to emit JSON that's safe for direct inclusion in HTML and XML documents. This escapes the HTML characters <, >, & and = before writing them to the stream. Without this setting, your XML/HTML encoder should replace these characters with the corresponding escape sequences.
  - isHtmlSafe
```
public final boolean isHtmlSafe()
```
    Returns true if this writer writes JSON that's safe for inclusion in HTML and XML documents.
  - setSerializeNulls
```
public final void setSerializeNulls(boolean serializeNulls)
```
    Description copied from interface: JsonWriter
    
    Sets whether object members are serialized when their value is null. This has no impact on array elements. The default is true.
    
    Specified by:
    
    setSerializeNulls in interface JsonWriter
  - getSerializeNulls
```
public final boolean getSerializeNulls()
```
    Returns true if object members are serialized when their value is null. This has no impact on array elements. The default is true.
    
    Specified by:
    
    getSerializeNulls in interface JsonWriter
  - beginArray
```
public DefaultJsonWriter beginArray()
```
    Description copied from interface: JsonWriter
    
    Begins encoding a new array. Each call to this method must be paired with a call to JsonWriter.endArray().
    
    Specified by:
    
    beginArray in interface JsonWriter
    
    Returns:
    this writer.
  - endArray
```
public DefaultJsonWriter endArray()
```
    Description copied from interface: JsonWriter
    
    Ends encoding the current array.
    
    Specified by:
    
    endArray in interface JsonWriter
    
    Returns:
    this writer.
  - beginObject
```
public DefaultJsonWriter beginObject()
```
    Description copied from interface: JsonWriter
    
    Begins encoding a new object. Each call to this method must be paired with a call to JsonWriter.endObject().
    
    Specified by:
    
    beginObject in interface JsonWriter
    
    Returns:
    this writer.
  - endObject
```
public DefaultJsonWriter endObject()
```
    Description copied from interface: JsonWriter
    
    Ends encoding the current object.
    
    Specified by:
    
    endObject in interface JsonWriter
    
    Returns:
    this writer.
  - name
```
public DefaultJsonWriter name(String name)
```
    Description copied from interface: JsonWriter
    
    Encodes the property name.
    
    Specified by:
    
    name in interface JsonWriter
    
    Parameters:
    name - the name of the forthcoming value. May not be null.
    
    Returns:
    this writer.
  - value
```
public DefaultJsonWriter value(String value)
```
    Description copied from interface: JsonWriter
    
    Encodes value.
    
    Specified by:
    
    value in interface JsonWriter
    
    Parameters:
    value - the literal string value, or null to encode a null literal.
    
    Returns:
    this writer.
  - nullValue
```
public DefaultJsonWriter nullValue()
```
    Description copied from interface: JsonWriter
    
    Encodes null.
    
    Specified by:
    
    nullValue in interface JsonWriter
    
    Returns:
    this writer.
  - cancelName
```
public DefaultJsonWriter cancelName()
```
    Specified by:
    
    cancelName in interface JsonWriter
  - value
```
public DefaultJsonWriter value(boolean value)
```
    Description copied from interface: JsonWriter
    
    Encodes value.
    
    Specified by:
    
    value in interface JsonWriter
    
    Returns:
    this writer.
  - value
```
public DefaultJsonWriter value(double value)
```
    Description copied from interface: JsonWriter
    
    Encodes value.
    
    Specified by:
    
    value in interface JsonWriter
    
    Parameters:
    value - a finite value. May not be NaNs or infinities.
    
    Returns:
    this writer.
  - value
```
public DefaultJsonWriter value(long value)
```
    Description copied from interface: JsonWriter
    
    Encodes value.
    
    Specified by:
    
    value in interface JsonWriter
    
    Returns:
    this writer.
  - value
```
public DefaultJsonWriter value(Number value)
```
    Description copied from interface: JsonWriter
    
    Encodes value.
    
    Specified by:
    
    value in interface JsonWriter
    
    Parameters:
    value - a finite value. May not be NaNs or infinities.
    
    Returns:
    this writer.
  - rawValue
```
public DefaultJsonWriter rawValue(Object value)
```
    Description copied from interface: JsonWriter
    
    Encodes value.toString() as is.
    
    Specified by:
    
    rawValue in interface JsonWriter
    
    Parameters:
    value - a value .
    
    Returns:
    this writer.
  - flush
```
public void flush()
```
    Description copied from interface: JsonWriter
    
    Ensures all buffered data is written to the underlying StringBuilder and flushes that writer.
    
    Specified by:
    
    flush in interface JsonWriter
  - close
```
public void close()
```
    Description copied from interface: JsonWriter
    
    Flushes and closes this writer and the underlying StringBuilder.
    
    Specified by:
    
    close in interface JsonWriter
  - getOutput
```
public String getOutput()
```
    Specified by:
    
    getOutput in interface JsonWriter
    
    Returns:
    the output when the serialization is over

Class DefaultJsonWriter

Encoding JSON

Example

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

DefaultJsonWriter

Method Detail

setIndent

setLenient

isLenient

setHtmlSafe

isHtmlSafe

setSerializeNulls

getSerializeNulls

beginArray

endArray

beginObject

endObject

name

value

nullValue

cancelName

value

value

value

value

rawValue

flush

close

getOutput