ig-json-parser

General

Category
Free
Tag
JSON
License
N/A
Registered
Sep 12, 2014
Favorites
0
Link
https://github.com/Instagram/ig-json-parser
See also
GetJSON
FastJson Retrofit Converter
json-io
gson-flatten
DSL JSON

Additional

Language
Java
Version
N/A
Created
Jun 12, 2014
Updated
Mar 5, 2021
Owner
Instagram
Contributors
Tony Tung (ttung)
Ravindra Kumar (ravidsrk)
Jake Wharton (JakeWharton)
David Reiss (dreiss)
Kang Zhang (kangzhang)
Bill Phillips (jingibus)
Chris Hopman (cjhopman)
Facebook Community Bot (facebook-github-bot)
Riley Dulin (dulinriley)
knordbo
Tyler Kieft (tkieft)
Arda Cebi (ardacebi)
sashkostashuk
Maxime Goovaerts (mgoovaer)
Elisa (aimango)
Daniel Mueller (dmueller39)
Jon Janzen (bigfootjon)
17
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ig-json-parser

Fast JSON parser for java projects.

Getting started

The easiest way to get started is to look at maven-example. For more comprehensive examples, check out the unit tests or the demo.

Gradle

For Java projects, to use this library, add this to your build.gradle file:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

...

dependencies {
  implementation 'com.github.instagram.ig-json-parser:runtime:master-SNAPSHOT' // the runtime
  implementation 'com.github.instagram.ig-json-parser:processor:master-SNAPSHOT' // the annotation processor
}

For Android projects using Android Studio 3.0+ or Gradle 4.0+, you can enable the annotation processor as following:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

...

dependencies {
  annotationProcessor 'com.github.instagram.ig-json-parser:processor:master-SNAPSHOT'
  implementation 'com.github.instagram.ig-json-parser:runtime:master-SNAPSHOT'
}

If you are using older gradle versions, you can use old apt plugin to integrate the annotation processor:

allprojects {
  repositories {
    maven { url 'https://jitpack.io' }
  }
}

...

apply plugin: 'com.neenbedankt.android-apt'

dependencies {
  apt 'com.github.instagram.ig-json-parser:processor:master-SNAPSHOT'
  implementation 'com.github.instagram.ig-json-parser:runtime:master-SNAPSHOT'
}

If you are using other build systems, please find instructions here

Requirements for model classes

There should be a package-visible no-argument constructor for each of your model classes. The fields also need to be package-visible.

Each class that needs a serializer/deserializer generated should be annotated with @JsonType. Each field that needs to be mapped to/from JSON should be annotated with @JsonField. The @JsonField annotation has one mandatory argument, which is the fieldname for the field in the JSON.

The following is an example of a very simple model class:

@JsonType
class Dessert {
  @JsonField(fieldName="type")
  String type;

  @JsonField(fieldName="rating")
  float rating;
}

Serializer/deserializer

Compiling your model classes with the annotations will automatically generate the serializer and deserializer. They will be in a generated class with the same name as your class, except with the suffix __JsonHelper. For example, to deserialize the Dessert class above, simply run the code:

Dessert parsed = Dessert__JsonHelper.parseFromJson(inputJsonString);

To serialize a class, run:

String serialized = Dessert__JsonHelper.serializeToJson(dessertObject);

Supported data types

The following scalar types are supported:

  • String
  • boolean/Boolean
  • int/Integer
  • long/Long
  • float/Float
  • double/Double

The following collection types are supported:

  • List/ArrayList
  • Queue/ArrayDeque
  • Map/HashMap
  • Set/HashSet

If a json field is another dictionary, it can be represented by another model class. That model class must also have the @JsonType annotation.

Proguard

Add the following lines to your proguard-rules file:

-dontwarn sun.misc.Unsafe
-dontwarn javax.annotation.**

Advanced features

Postprocessing

If you need to process your JSON after a first pass, you can change your @JsonType annotation to be @JsonType(postprocess = true) and add a method to your code and add a method YourClass postprocess() which will be called after the JSON is processed (see: QuestionableDesignChoice in the example below)

  @JsonType
  public class Example {
    @JsonField(fieldName = "container")
    Container mContainer;

    @JsonType
    public static class Container {
        @JsonField(fieldName = "questionable_design_choice")
        List<QuestionableDesignChoice> mQuestionableDesignChoice;
    }

    @JsonType(postprocessingEnabled = true)
    public static class QuestionableDesignChoice {
        @JsonField(fieldName = "property")
        String mProperty;

        QuestionableDesignChoice postprocess() {
          // post-process things here...
          return this;
        }
    }
}

Customized parsing code

Parsing the supported data types is straightforward. For enums or built-in Java classes, you will need to add customized parsing.

Value extract formatters override how we extract the value from the JsonParser object, while serialize code formatters override how we serialize a java field back to json. We use the serde for PointF in the example below, where a point is represented as an array in json.

  @JsonField(
      fieldName = "position",
      valueExtractFormatter =
          "com.instagram.common.json.android.JsonTypeHelper.deserializePointF(${parser_object})",
      serializeCodeFormatter =
          "com.instagram.common.json.android.JsonTypeHelper.serializePointF("
              + "${generator_object}, \"${json_fieldname}\", ${object_varname}.${field_varname})")
  @Nullable
  protected PointF mPosition;

Optional serializer generation

To save generating serializer code if you only need deserialization, serializer generation can be disabled or enabled globally and per-class. The default is to generate serializers for all classes. To disable generation globally, pass

-AgenerateSerializer=false

to the command-line arguments of javac. To override the default generation option for a single class, see JsonType.generateSerializer().

Contributing

See the CONTRIBUTING file for how to help out.

License

ig-json-parser is MIT licensed, as found in the LICENSE file.

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