实现Firefox扩展程序，和Java RMI Client端进行通信。

在Firefox工具栏注册按钮，点击按钮后弹出Popup.html页面，引用Popup.js脚本，通过脚本向Java RMI client发送消息，Java RMI Client接收消息后转发到Java RMI Server。

Popup.js中的发送代码：

btnSend.addEventListener("click", function(event) {

    const sending = browser.runtime.sendNativeMessage("native.host", url.value);
  
    sending.then(function(resp) {
        txtResult.textContent = resp.message;
                
    }, function(err) {
        txtResult.textContent = err;
    });
});

注册的native.json配置文件

{
    "name": "native.host",
    "description": "Example host for native messaging",
    "path": "native.bat",
    "type": "stdio",
    "allowed_extensions": ["hook@native"]
  }

执行的native.bat代码

@echo off 
rem  echo off -> close stdout 
call java -cp "C:\Users\cc\OneDrive\src\java\RMIClient\bin" net.RMIClient

Java RMI client程序

public class RMIClient  {
	
	public static String read() throws IOException {
		byte[] _len = new byte[4];
		System.in.read(_len);

		ByteBuffer bb = ByteBuffer.wrap(_len);
		bb.order(ByteOrder.LITTLE_ENDIAN);
		int length = bb.getInt(0);
		byte[] message = new byte[length];
		System.in.read(message);
		
		return new String(message, "UTF-8");
	}
	
	public static void write(String s) throws IOException {
		byte[] utf = s.getBytes("UTF-8");
		
		ByteBuffer bb = ByteBuffer.allocate(utf.length + 4);
		bb.order(ByteOrder.LITTLE_ENDIAN);
		bb.putInt(0, utf.length);
		bb.put(4, utf);
		
		byte[] bs = bb.array();
		System.out.write(bs);
		System.out.flush();
	}

	public static void main(String[] args) throws IOException, InterruptedException, NotBoundException {
		Registry registry = LocateRegistry.getRegistry("127.0.0.1", 1099);
		IReceive receiver = (IReceive) registry.lookup("Receiver");
		
			String data =  read();
			String result = receiver.receive(data);
			write(" { \"message\":\"ok\" }" );
	}

}

运行效果，浏览器弹出框，点击"Send"发送浏览器当前地址

Java RMI Server收到的消息：