编写MainActivity.java中的源代码。该文件中重要的源代码如下：
创建Socket线程：
//创建Socket连接线程
public class connectThread extends Thread{
public void run(){
Message msg=new Message();
try {
socket = new Socket();
SocketAddress socketAddress = new
InetSocketAddress(IP.getText().toString(),Integer.parseInt(port.g etText().toString()));
socket.connect(socketAddress, 5000); //设置连接超时时间为5秒
if(socket.isConnected())
{
readIsRun=true;
msg.arg1=1;
socketConnectError.sendMessage(msg);
System.out.println(“Socket连接目标IP成功!”);
}else{
//不会执行到此处！
}
} catch (NumberFormatException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(“IP地址转化出错!”);
}catch(SocketTimeoutException e) { //连接超时
// TODO Auto-generated catch block
Toast.makeText(MainActivity.this, “连接超时”,
Toast.LENGTH_SHORT).show();
e.printStackTrace();
}catch (UnknownHostException e) {//域名不正确
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(“目标IP错误，连接失败!”);
}catch (ConnectException e) { //服务器未响应或端口未打开// TODO Auto-generated catch block
Toast.makeText(MainActivity.this, “服务器未响应，连接失败!”, Toast.LENGTH_SHORT).show();
System.out.println(“服务器未响应，连接失败!”);
//e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();