java.io

java.io

A node implement of "java.io.InputObjectStream.readObject()" and "java.io.OutputObjectStream.writeObject()".

Protocol

• Object Serialization Stream Protocol (A protocal is not all, still need to refer to the implementation.)
• Object Serialization Stream Protocol Mind Node

Install

$ npm install java.io --save

Usage

1. readObject()

var fs = require('fs');
var io = require('java.io');
var InputObjectStream = io.InputObjectStream;
var OutputObjectStream = io.OutputObjectStream;

// Read object and return whole info
var buf = fs.readFileSync('./test/fixtures/out/int/1024.bin');
var in = new InputObjectStream(buf, true);
var obj = in.readObject();

// Read object but return value only
var buf2 = fs.readFileSync('./test/fixtures/out/int/1024.bin');
var in2 = new InputObjectStream(buf);
var obj2 = in.readObject();

obj should be:

{
  '$' : {
    value : 1024
  },
  '$class' : {
    name : 'java.lang.Integer',
    serialVersionUID : '1360826667806852920',
    flags : 2,
    fields : [{
      type : 'I',
      name : 'value'
    }],
    superClass : {
      name : 'java.lang.Number',
      serialVersionUID : '-8742448824652078965',
      flags : 2,
      fields : [],
      superClass : null
    }
  }
}

obj2 should be:

1024

if you only care about the first object from input stream, you could write the code briefly:

var buf3 = fs.readFileSync('./test/fixtures/out/map/boolean.bin');
var obj3 = InputObjectStream.readObject(buf);

then obj3 should be:

{ 'true': true, 'false': false }

2. writeObject(obj)

var outputObjectStream = new OutputObjectStream();

// 1. Passed in argument must contains the whole info
// 2. Every time calling the writeObject function
//    will return the buf had written in
var buf = outputObjectStream.writeObject(obj);

A brief style is also OK:

OutputObjectStream.writeObject(obj);

3. OutputObjectStream.normalize(obj, type)

A convenient way to convert ordinary JavaScript object to object of standard format with whole info.

• params
  • obj: accept all primitive value or primitive array and map
  • type: string | boolean | int | short | long | char | byte | float | double |
• return: normalized object

var outputObjectStream = new OutputObjectStream();
var normalizedObj = OutputObjectStream.normalize(true);
var buf = outputObjectStream.writeObject(normalizedObj);

normalize(null)

normalize('string')

normalize(true)

normalize(1) // quals to normalize(1, 'int')

normalize(-123456, long)

normalize([ true, false, false, false ], 'boolean')

normalize( {'true': true, 'false': false}, 'boolean')

4. addObject()

If a class has writeObject/readObject methods, you need to implement the corresponding methods, and add them via addObject() before read or write the object.

var io = require('java.io');
io.addObject({{className}}, {{class}});

Builtin classes:

• java.util.ArrayList
• java.util.LinkedList
• java.util.HashMap
• java.util.HashSet
• java.util.TreeMap
• java.util.TreeSet
• java.util.Date

Data structure

{
  // if a object has it's own readObject/writeObject method
  // save it's special value here
  '_$': ...,

  // value of object
  '$': ...,

  // class description
  '$class': {
    name: 'className',
    serialVersionUID: 'SVUID',
    flags: flags,
    fields:
     [ { type: 'F', name: 'primitiveProperty' },
       { type: 'L', name: 'objProperty', classname: 'Ljava/lang/String;' }],
    superClass: parentClassDescriptionOrNull
  }
}

Some more examples

Incompatible between 1.x and 2.x

• decode java [B to new Buffer([1, 2, 3]) not [1, 2, 3] #10

License

MIT