求助java中Socket问题，急。。。。！
和另一台机子做数据交换。代码如下

Java code

    public String send(String SendMessage,String clientIP,int clientPort) throws UnknownHostException, IOException{        System.out.println("------------clientIP="+clientIP+"-------------clientPort="+clientPort);        Socket s = new Socket(clientIP,clientPort);        System.out.println("s.getOutputStream()"+s.getOutputStream());                PrintStream out = new PrintStream(s.getOutputStream());        BufferedReader in = new BufferedReader(new InputStreamReader(s.getInputStream()));        InputStream is = s.getInputStream();        System.out.println("SendMessage:"+SendMessage);        out.print(SendMessage);        int b = 0;        while ((b = is.read()) != -1) {            System.out.println(b);            bos.write(b);            System.out.println(b);        }        byte[] bytes = bos.toByteArray();*/                int len = -1;        while((len=is.available()) <=8) {            len = is.available();            System.out.println("len:"+len);        }                byte[] bytes = new byte[8192];        is.read(bytes, 0 , bytes.length);        String ReceiveMessage = StringUtil.trim(new String( bytes));                System.out.println("ReceiveMessage:"+ReceiveMessage);        out.close();        s.close();        is.close();        return ReceiveMessage;    }

为什么老是在while((len=is.available()) <=8) {
len = is.available();
System.out.println("len:"+len);
}
中循环，后天总是打印len=0；端口 ip都正确，求解！

[解决办法]
类 InputStream 的 available 方法总是返回 0。

详细api文档。
[解决办法]
api文档是这么写的：
Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream。
[解决办法]
返回此输入流方法的下一个调用方可以不受阻塞地从此输入流读取（或跳过）的字节数。