com.google.gson.stream.JsonWriter类 参考

类 com.google.gson.stream.JsonWriter 继承关系图:

Public 成员函数
	JsonWriter (Writer out)
final void	setIndent (String indent)
final void	setLenient (boolean lenient)
boolean	isLenient ()
final void	setHtmlSafe (boolean htmlSafe)
final boolean	isHtmlSafe ()
final void	setSerializeNulls (boolean serializeNulls)
final boolean	getSerializeNulls ()
JsonWriter	beginArray () throws IOException
JsonWriter	endArray () throws IOException
JsonWriter	beginObject () throws IOException
JsonWriter	endObject () throws IOException
JsonWriter	name (String name) throws IOException
JsonWriter	value (String value) throws IOException
JsonWriter	nullValue () throws IOException
JsonWriter	value (boolean value) throws IOException
JsonWriter	value (double value) throws IOException
JsonWriter	value (long value) throws IOException
JsonWriter	value (Number value) throws IOException
void	flush () throws IOException
void	close () throws IOException

包函数
	[instance initializer]

Private 成员函数
JsonWriter	open (JsonScope empty, String openBracket) throws IOException
JsonWriter	close (JsonScope empty, JsonScope nonempty, String closeBracket) throws IOException
JsonScope	peek ()
void	replaceTop (JsonScope topOfStack)
void	writeDeferredName () throws IOException
void	string (String value) throws IOException
void	newline () throws IOException
void	beforeName () throws IOException
void	beforeValue (boolean root) throws IOException

Private 属性
final Writer	out
final List< JsonScope >	stack = new ArrayList<JsonScope>()
String	indent
String	separator = ":"
boolean	lenient
boolean	htmlSafe
String	deferredName
boolean	serializeNulls = true

详细描述

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 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 with the property's value. Write property values with the appropriate value 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) throws IOException {
  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) 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<Double> 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.

作者

Jesse Wilson

自从

1.6

构造及析构函数说明

com.google.gson.stream.JsonWriter.JsonWriter ( Writer  out )

inline

Creates a new instance that writes a JSON-encoded stream to

out 

. For best performance, ensure Writer is buffered; wrapping in BufferedWriter if necessary.

成员函数说明

com.google.gson.stream.JsonWriter.[instance initializer] ( )

inlinepackage

void com.google.gson.stream.JsonWriter.beforeName ( ) throws IOException

inlineprivate

Inserts any necessary separators and whitespace before a name. Also adjusts the stack to expect the name's value.

void com.google.gson.stream.JsonWriter.beforeValue ( boolean  root ) throws IOException

inlineprivate

Inserts any necessary separators and whitespace before a literal value, inline array, or inline object. Also adjusts the stack to expect either a closing bracket or another element.

参数

root	true if the value is a new array or object, the two values permitted as top-level elements.

JsonWriter com.google.gson.stream.JsonWriter.beginArray ( ) throws IOException

inline

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

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.beginObject ( ) throws IOException

inline

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

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.close ( JsonScope  empty, JsonScope  nonempty, String  closeBracket  ) throws IOException

inlineprivate

Closes the current scope by appending any necessary whitespace and the given bracket.

void com.google.gson.stream.JsonWriter.close ( ) throws IOException

inline

Flushes and closes this writer and the underlying Writer.

异常

IOException

if the JSON document is incomplete.

JsonWriter com.google.gson.stream.JsonWriter.endArray ( ) throws IOException

inline

Ends encoding the current array.

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.endObject ( ) throws IOException

inline

Ends encoding the current object.

返回

this writer.

void com.google.gson.stream.JsonWriter.flush ( ) throws IOException

inline

Ensures all buffered data is written to the underlying Writer and flushes that writer.

final boolean com.google.gson.stream.JsonWriter.getSerializeNulls ( )

inline

Returns true if object members are serialized when their value is null. This has no impact on array elements. The default is true.

final boolean com.google.gson.stream.JsonWriter.isHtmlSafe ( )

inline

Returns true if this writer writes JSON that's safe for inclusion in HTML and XML documents.

boolean com.google.gson.stream.JsonWriter.isLenient ( )

inline

Returns true if this writer has relaxed syntax rules.

JsonWriter com.google.gson.stream.JsonWriter.name ( String  name ) throws IOException

inline

Encodes the property name.

参数

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

返回

this writer.

void com.google.gson.stream.JsonWriter.newline ( ) throws IOException

inlineprivate

JsonWriter com.google.gson.stream.JsonWriter.nullValue ( ) throws IOException

inline

Encodes

null 

.

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.open ( JsonScope  empty, String  openBracket  ) throws IOException

inlineprivate

Enters a new scope by appending any necessary whitespace and the given bracket.

JsonScope com.google.gson.stream.JsonWriter.peek ( )

inlineprivate

Returns the value on the top of the stack.

void com.google.gson.stream.JsonWriter.replaceTop ( JsonScope  topOfStack )

inlineprivate

Replace the value on the top of the stack with the given value.

final void com.google.gson.stream.JsonWriter.setHtmlSafe ( boolean  htmlSafe )

inline

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.

final void com.google.gson.stream.JsonWriter.setIndent ( String  indent )

inline

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.

参数

indent

a string containing only whitespace.

final void com.google.gson.stream.JsonWriter.setLenient ( boolean  lenient )

inline

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.

final void com.google.gson.stream.JsonWriter.setSerializeNulls ( boolean  serializeNulls )

inline

Sets whether object members are serialized when their value is null. This has no impact on array elements. The default is true.

void com.google.gson.stream.JsonWriter.string ( String  value ) throws IOException

inlineprivate

JsonWriter com.google.gson.stream.JsonWriter.value ( String  value ) throws IOException

inline

Encodes

value 

.

参数

value

the literal string value, or null to encode a null literal.

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.value ( boolean  value ) throws IOException

inline

Encodes

value 

.

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.value ( double  value ) throws IOException

inline

Encodes

value 

.

参数

value

a finite value. May not be NaNs or infinities.

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.value ( long  value ) throws IOException

inline

Encodes

value 

.

返回

this writer.

JsonWriter com.google.gson.stream.JsonWriter.value ( Number  value ) throws IOException

inline

Encodes

value 

.

参数

value

a finite value. May not be NaNs or infinities.

返回

this writer.

void com.google.gson.stream.JsonWriter.writeDeferredName ( ) throws IOException

inlineprivate

类成员变量说明

String com.google.gson.stream.JsonWriter.deferredName

private

boolean com.google.gson.stream.JsonWriter.htmlSafe

private

String com.google.gson.stream.JsonWriter.indent

private

A string containing a full set of spaces for a single level of indentation, or null for no pretty printing.

boolean com.google.gson.stream.JsonWriter.lenient

private

final Writer com.google.gson.stream.JsonWriter.out

private

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

String com.google.gson.stream.JsonWriter.separator = ":"

private

The name/value separator; either ":" or ": ".

boolean com.google.gson.stream.JsonWriter.serializeNulls = true

private

final List<JsonScope> com.google.gson.stream.JsonWriter.stack = new ArrayList<JsonScope>()

private

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该类的文档由以下文件生成:

• src/com/google/gson/stream/JsonWriter.java