com.cedarsoftware.util.io

Class JsonWriter

java.lang.Object

com.cedarsoftware.util.io.JsonWriter

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

public class JsonWriter
extends Object
implements Closeable, Flushable

Output a Java object graph in JSON format. This code handles cyclic references and can serialize any Object graph without requiring a class to be 'Serializeable' or have any specific methods on it.

• Call the static method: JsonWriter.toJson(employee). This will convert the passed in 'employee' instance into a JSON String.
• Using streams:

       JsonWriter writer = new JsonWriter(stream);
       writer.write(employee);
       writer.close();

  This will write the 'employee' object to the passed in OutputStream.

That's it. This can be used as a debugging tool. Output an object graph using the above code. You can copy that JSON output into this site which formats it with a lot of whitespace to make it human readable: http://jsonformatter.curiousconcept.com



This will output any object graph deeply (or null). Object references are properly handled. For example, if you had A->B, B->C, and C->A, then A will be serialized with a B object in it, B will be serialized with a C object in it, and then C will be serialized with a reference to A (ref), not a redefinition of A.

Author:

John DeRegnaucourt ([email protected])
Copyright (c) John DeRegnaucourt

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	JsonWriter.BigDecimalWriter
static class	JsonWriter.BigIntegerWriter
static class	JsonWriter.CalendarWriter
static class	JsonWriter.ClassWriter
static class	JsonWriter.DateWriter
static interface	JsonWriter.JsonClassWriter
static class	JsonWriter.JsonStringWriter
static class	JsonWriter.LocaleWriter
static class	JsonWriter.SqlDateWriter
static class	JsonWriter.StringBufferWriter
static class	JsonWriter.StringBuilderWriter
static class	JsonWriter.TimestampWriter
static class	JsonWriter.TimeZoneWriter

Constructor Summary

Constructors

Constructor and Description
JsonWriter(OutputStream out)

Method Summary

Methods

Modifier and Type	Method and Description
static void	addNotCustomWriter(Class c)
static void	addWriter(Class c, JsonWriter.JsonClassWriter writer)
void	close()
void	flush()
static int	getDistance(Class a, Class b)
static String	objectToJson(Object item) Convert a Java Object to a JSON String.
static String	toJson(Object item) Convert a Java Object to a JSON String.
void	write(Object obj)
boolean	writeArrayElementIfMatching(Class arrayComponentClass, Object o, boolean showType, Writer out)
boolean	writeIfMatching(Object o, boolean showType, Writer out)
static void	writeJsonUtf8String(String s, Writer out) Write out special characters "\b, \f, \t, \n, \r", as such, backslash as \\ quote as \" and values less than an ASCII space (20hex) as "\\u00xx" format, characters in the range of ASCII space to a '~' as ASCII, and anything higher in UTF-8.

Methods inherited from class java.lang.Object

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

Constructor Detail

JsonWriter

public JsonWriter(OutputStream out)
           throws IOException

Throws:

IOException

Method Detail

getDistance

public static int getDistance(Class a,
              Class b)

writeIfMatching

public boolean writeIfMatching(Object o,
                      boolean showType,
                      Writer out)
                        throws IOException

Throws:

IOException

writeArrayElementIfMatching

public boolean writeArrayElementIfMatching(Class arrayComponentClass,
                                  Object o,
                                  boolean showType,
                                  Writer out)
                                    throws IOException

Throws:

IOException

addWriter

public static void addWriter(Class c,
             JsonWriter.JsonClassWriter writer)

addNotCustomWriter

public static void addNotCustomWriter(Class c)

toJson

public static String toJson(Object item)

Convert a Java Object to a JSON String. This is the easy-to-use API - it returns null if there was an error.

Parameters:

item - Object to convert to a JSON String.

Returns:

String containing JSON representation of passed in object, or null if an error occurred.

objectToJson

public static String objectToJson(Object item)
                           throws IOException

Convert a Java Object to a JSON String.

Parameters:

item - Object to convert to a JSON String.

Returns:

String containing JSON representation of passed in object.

Throws:

IOException - If an I/O error occurs

write

public void write(Object obj)
           throws IOException

Throws:

IOException

writeJsonUtf8String

public static void writeJsonUtf8String(String s,
                       Writer out)
                                throws IOException

Write out special characters "\b, \f, \t, \n, \r", as such, backslash as \\ quote as \" and values less than an ASCII space (20hex) as "\\u00xx" format, characters in the range of ASCII space to a '~' as ASCII, and anything higher in UTF-8.

Parameters:

s - String to be written in utf8 format on the output stream.

Throws:

IOException - if an error occurs writing to the output stream.

flush

public void flush()

Specified by:

flush in interface Flushable

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable