关于socket 通信 客户端如何校验是否连接？

function SocketStart(Socket_par) {
if(plus.os.name == "Android") {
//导入Android原生包
var Socket = plus.android.importClass("java.net.Socket");
var PrintWriter = plus.android.importClass("java.io.PrintWriter");
var BufferedWriter = plus.android.importClass("java.io.BufferedWriter");
var OutputStreamWriter = plus.android.importClass("java.io.OutputStreamWriter");
var BufferedReader = plus.android.importClass("java.io.BufferedReader");
var InputStreamReader = plus.android.importClass("java.io.InputStreamReader");
//新建一个socket链接
var socket = new Socket(Socket_PORT, IP_ADDR);
var date1 = new Date(); //开始时间

    var outputStreamWriter = new OutputStreamWriter(socket.getOutputStream());  
    var bufferWriter = new BufferedWriter(outputStreamWriter);  
    var out = new PrintWriter(bufferWriter, true);  
    console.log("请求的数据为-----"+Socket_par);   
    out.println(Socket_par); //发送请求数据  
    out.flush();  
    socket.shutdownOutput();  
    var inputStreamReader = new InputStreamReader(socket.getInputStream()); //接收请求数据  
    var br = new BufferedReader(inputStreamReader);  
    var data = br.readLine();  
    var date2 = new Date(); //结束时间  
    {  
        if(data != null) {  
            var date3 = date2.getTime() - date1.getTime() //时间差的毫秒数  
            console.log("请求耗时为:(毫秒)-----" + date3);  
            console.log("返回的数据为-----"+data);  
            var datajson = eval('(' + data + ')'); //请求数据字符串转化为json对象  
            return datajson; //返回json对象  
        } else {  
            alert("socket链接错误");  
            return false; //返回失败  
        }  
    }  
}  

}