JSch：如何保持会话活跃起来 [英] JSch: How to keep the session alive and up
问题描述
我正在使用SSH编写用于静态路由管理的Java GUI程序。我的代码如下：
I'm writing Java GUI program for static route management using SSH. My code is as follows:
import com.jcraft.jsch.*;
import java.io.*;
public class Konsep {
String status;
static String username;
static String hostname;
String inputcommand;
String output;
static Session session;
JSch jsch = new JSch();
public String status(String stringstatus) {
stringstatus = status;
return stringstatus;
}
public String InputCommand(String inputcommandstatus) {
inputcommandstatus = inputcommand;
return inputcommandstatus;
}
public void connect(String usernamelokal, String hostnamelokal,
String password, int port) {
// JSch jsch=new JSch();
try {
Session sessionlokal = jsch.getSession(usernamelokal,
hostnamelokal, port);
sessionlokal.setPassword(password);
UserInfo ui = new UserInfoku.Infoku();
sessionlokal.setUserInfo(ui);
sessionlokal.setTimeout(0);
sessionlokal.connect();
status = "tersambung \n";
username = usernamelokal;
hostname = hostnamelokal;
session = sessionlokal;
System.out.println(username + " " + hostname);
} catch (Exception e) {
System.out.println(e);
status = "Exception = \n " + e + "\n";
}
}
public void disconnect() {
// JSch jsch=new JSch();
try {
Session sessionlokal = jsch.getSession(username, hostname);
// System.out.println(username +" "+ hostname);
sessionlokal.disconnect();
status = "wes pedhoott \n";
} catch (Exception e) {
System.out.println(e);
status = "Exception = \n " + e + "\n";
}
}
public void addRoute() {
// JSch jsch=new JSch();
System.out.println(username + " " + hostname);
try {
Session sessionlokal = session; // =jsch.getSession(username, hostname);
Channel channel = sessionlokal.openChannel("exec");
((ChannelExec) channel).setCommand(inputcommand);
channel.setInputStream(null);
channel.connect();
((ChannelExec) channel).setErrStream(System.err);
InputStream in = channel.getInputStream();
channel.connect();
byte[] tmp = new byte[1024];
while (true) {
while (in.available() > 0) {
int i = in.read(tmp, 0, 1024);
if (i < 0)
break;
System.out.print(new String(tmp, 0, i));
}
if (channel.isClosed()) {
System.out.println("exit-status: "
+ channel.getExitStatus());
break;
}
try {
Thread.sleep(1000);
} catch (Exception ee) {
}
}
channel.disconnect();
} catch (Exception e) {
System.out.println(e);
}
}
}
问题出在我打电话的时候connect方法然后调用addroute，程序返回
The problem is when I call the connect method and then calling the addroute, the program returns
root 192.168.50.2
root 192.168.50.2
com.jcraft.jsch.JSchException: session is down
我一直试图获得会话状态为
I've been trying to get session status with either
Session sessionlokal=session; //returns com.jcraft.jsch.JSchException: ChannelExec
或
Session sessionlokal=jsch.getSession(username, hostname); //returns session is down
我也尝试使用keepalive，但它也无效。
I've also tried to use keepalive, but its not working either.
我的目的是创建一个主持会话（登录），同时保持会话，执行一个或多个命令，然后再执行其他命令，然后关闭会话时不需要（退出）。
我一直在这个论坛上搜索，我发现了这个问题但是代码创建一个方法来定义首先执行的命令，然后创建会话，调用命令的方法并关闭会话。
My intention is to create a session to host (log in), while leaving the session up, execute a command or commands and maybe executing other commands later, and then closing the session when its not needed (log out). I've been searching on this forum and I found this question but the code is create a method to define a command to execute first, and then creating the session, call the command's method and close the session.
关于如何做的任何想法如上所述？
Any ideas about how to do as I mentioned above ?
推荐答案
尝试 Session.sendKeepAliveMsg（）没有成功，我来到以下似乎相当稳定的解决方案：
After trying Session.sendKeepAliveMsg() without success, I came to the following solution which seems to be rather stable:
private Session getSession() throws Exception {
try {
if (!session.isConnected()) {
logger.info("Session nicht konnektiert. Versuche (erneut) zu konnektieren.");
session.connect();
}
} catch (Throwable t) {
logger.info("Session kaputt. Baue neue.");
session = jsch.getSession(user, host, port);
session.setConfig(config);
session.connect();
}
return session;
}
更新：几天后失败。
我试图通过杀死服务器上的开放会话来测试它。以这种方式测试的所有先前版本都显示了完全相同的行为，无论是在等待几天或者杀死服务器进程之后问题都出现了问题，所以我认为这个测试 - 以及上述解决方案的结果 - 是有意义的。不幸的是，它不是。
I tried to test it by killing the open session on the server. All prior versions I tested this way showed the exact same behaviour, regardless wheater the problem poped up after waiting some days or killing the server process, so I thought this test - and its outcome for the above solution - to be meaningful. Unfortunately it isn't.
我将尝试其他方法来修复它并让你保持最新状态。
I'm going to try some other ways to fix it and keep you up to date.
更新2：最终解决方案，保证不受欢迎且工作正常：
private Session getSession() throws Exception {
try {
ChannelExec testChannel = (ChannelExec) session.openChannel("exec");
testChannel.setCommand("true");
testChannel.connect();
if(logger.isDebugEnabled()) {
logger.debug("Session erfolgreich getestet, verwende sie erneut");
}
testChannel.exit();
} catch (Throwable t) {
logger.info("Session kaputt. Baue neue.");
session = jsch.getSession(user, host, port);
session.setConfig(config);
session.connect();
}
return session;
}
此版本在高效环境中运行数周。我每天都会记录一下信息。
This version runs several weeks in a productive environment. Once a day I have the info message logged.
打开一个频道和执行一些do-nothing命令的成本有点烦人，但我找不到其他方法绝对肯定会议的状态。
The costs of opening a channel and performing some do-nothing-command are somewhat annoying, but I found no other way to be definitly sure about the state of the session.
这篇关于JSch：如何保持会话活跃起来的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
