java.lang.Object | |
↳ | android.util.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.
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:
beginArray()
.
Write each of the array's elements with the appropriate value(boolean)
methods or by nesting other arrays and objects. Finally close the array
using endArray()
.
beginObject()
.
Write each of the object's properties by alternating calls to
name(String)
with the property's value. Write property values with the
appropriate value(boolean)
method or by nesting other objects or arrays.
Finally close the object using endObject()
.
[
{
"id": 912345678901,
"text": "How do I write JSON on Android?",
"geo": null,
"user": {
"name": "android_newb",
"followers_count": 41
},
{
"id": 912345678902,
"text": "@android_newb just use android.util.JsonWriter!",
"geo": [50.454722, -104.606667],
"user": {
"name": "jesse",
"followers_count": 2
}
}
]}
This code encodes the above structure: public void writeJsonStream(OutputStream out, List
public void writeMessagesArray(JsonWriter writer, Listmessages) throws IOException { JsonWriter writer = new JsonWriter(new OutputStreamWriter(out, "UTF-8")); writer.setIndent(" "); writeMessagesArray(writer, messages); writer.close(); messages) throws IOException { writer.beginArray(); for (Message message : messages) { writeMessage(writer, message); } writer.endArray(); } public void writeMessage(JsonWriter writer, Message message) throws IOException { 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) throws IOException { writer.beginObject(); writer.name("name").value(user.getName()); writer.name("followers_count").value(user.getFollowersCount()); writer.endObject(); } public void writeDoublesArray(JsonWriter writer, List doubles) throws IOException { 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
.
Public Constructors | |||||||||||
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Creates a new instance that writes a JSON-encoded stream to
out . |
Public Methods | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Begins encoding a new array.
| |||||||||||
Begins encoding a new object.
| |||||||||||
Flushes and closes this writer and the underlying
Writer . | |||||||||||
Ends encoding the current array.
| |||||||||||
Ends encoding the current object.
| |||||||||||
Ensures all buffered data is written to the underlying
Writer
and flushes that writer. | |||||||||||
Returns true if this writer has relaxed syntax rules.
| |||||||||||
Encodes the property name.
| |||||||||||
Encodes
null . | |||||||||||
Sets the indentation string to be repeated for each level of indentation
in the encoded document.
| |||||||||||
Configure this writer to relax its syntax rules.
| |||||||||||
Encodes
value . | |||||||||||
Encodes
value . | |||||||||||
Encodes
value . | |||||||||||
Encodes
value . | |||||||||||
Encodes
value . |
[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
| |||||||||||
From interface
java.io.Closeable
|
Creates a new instance that writes a JSON-encoded stream to out
.
For best performance, ensure Writer
is buffered; wrapping in
BufferedWriter
if necessary.
Begins encoding a new array. Each call to this method must be paired with
a call to endArray()
.
IOException |
---|
Begins encoding a new object. Each call to this method must be paired
with a call to endObject()
.
IOException |
---|
Flushes and closes this writer and the underlying Writer
.
IOException | if the JSON document is incomplete. |
---|
Ensures all buffered data is written to the underlying Writer
and flushes that writer.
IOException |
---|
Returns true if this writer has relaxed syntax rules.
Encodes the property name.
name | the name of the forthcoming value. May not be null. |
---|
IOException |
---|
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.
indent | a string containing only whitespace. |
---|
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:
NaNs
or infinities
.
Encodes value
.
value | a finite value. May not be NaNs or
infinities unless this writer is lenient. |
---|
IOException |
---|
Encodes value
.
value | a finite value. May not be NaNs or
infinities unless this writer is lenient. |
---|
IOException |
---|
Encodes value
.
value | the literal string value, or null to encode a null literal. |
---|
IOException |
---|