一，简介
创建Socket，连接服务器地址和端口号，进行发送信息。

二，实现
启动线程发送信息

  data = et.getText().toString();
                if(data == null){
                    Toast.makeText(MainActivity.this,"please input Sending Data", Toast.LENGTH_SHORT).show();
                }else {
                    //在后面加上 '\0' ,是为了在服务端方便我们去解析；
                    data = data + '\0';
                }

                Thread thread = new Thread(){
                    @Override
                    public void run() {
                        super.run();

                            try {
                                sockets = new Socket(ip,8000);

                                outputStream = sockets.getOutputStream();
                                outputStream.write(data.getBytes());
                            } catch (IOException e) {
                                e.printStackTrace();
                            }


                    }
                };
                thread.start();

源码：ChatAPP ----- 客户端