nodejs中v8插件c++和js参数转换--二进制参数

nodejs中c++和js交换二进制数据，采用  buffer。同时以下列子展示了v8常用到的一些其他类型转换技巧.

项目中#include <zlib.h>  是zlib库，在linux下编译时候注意带上 -lz参数，比如vi ./build/***.target.mk  修改这个文件，找到LIBS :=
然后修改为 LIBS := -lz 即可编译运行。
binary-v8-buffer.rar   可参考用例。

#include <string.h>
#include <string>
#include <v8.h>
#include <node.h>
#include <node_buffer.h>
#include <zlib.h> //zlib库
using namespace node;
using namespace v8;
using namespace std;

Handle<Value> lz_uncompress(const Arguments& args) {
    HandleScope scope;
    if(args.Length() < 1) {
      ThrowException(Exception::TypeError(String::New("Wrong number of arguments")));
      return scope.Close(Undefined());
    }

    //String, Number, Boolean, Object, Array等对象都是从Value继承而来,
    //所以很好判断类型,通过 "Is系列函数"，如 IsNumber
    //另外通过“To系列函数”,如ToNumber
    //
    Local<Value> arg1 = args[0];
    if (Buffer::HasInstance(arg1)) {
        size_t size = Buffer::Length(arg1->ToObject());
        char* bufferdata = Buffer::Data(arg1->ToObject());

        unsigned char  buf [1024] = {'\0'};
        uLong  bufLen = sizeof(buf);
        int ret = uncompress(buf, &bufLen, (const Bytef*)(bufferdata), (uLong)size);
        if(ret != Z_OK){
            ThrowException(Exception::TypeError(String::New("destination memory too little")));
            return scope.Close(Undefined());
        }
        return scope.Close(String::New((const char*)buf,bufLen));
    }
    else{
        ThrowException(Exception::TypeError(String::New("input is not Buffer data")));
        return scope.Close(Undefined());
    }

 }

// Convert a JavaScript string to a std::string.
// To not bother too much with string encodings
//we just use ascii.
string ObjectToString(Local<Value> value) {
  String::Utf8Value utf8_value(value);
  return string(*utf8_value);
}

Handle<Value> lz_compress(const Arguments& args) {
    HandleScope scope;
    if(args.Length() < 1) {
      ThrowException(Exception::TypeError(String::New("Wrong number of arguments")));
      return scope.Close(Undefined());
    }


  //v8::String::Utf8Value param1(args[0]->ToString());
  //std::string rawStr = std::string(*param1);
  Local<Value> arg1 = args[0];
    std::string rawStr = ObjectToString(arg1);

  unsigned char  buf [1024] = {'\0'};
    uLong  bufLen = sizeof(buf);
  int ret = compress(buf, &bufLen, (const Bytef*)(rawStr.c_str()), (uLong)rawStr.length());
    if(ret != Z_OK){
        ThrowException(Exception::TypeError(String::New("destination memory too little")));
    return scope.Close(Undefined());
    }

     Buffer *outBuf = Buffer::New ((const char*)buf, bufLen);
  return scope.Close(outBuf->handle_);
}


void init(Handle<Object> target) {

  NODE_SET_METHOD(target, "compress", lz_compress);
  NODE_SET_METHOD(target, "uncompress", lz_uncompress);
}

NODE_MODULE(LZzlib, init);