JSch基本使用

JSch 是SSH2的一个纯Java实现。它允许你连接到一个sshd 服务器,使用端口转发,X11转发,文件传输等等。你可以将它的功能集成到你自己的 程序中。同时该项目也提供一个J2ME版本用来在手机上直连SSHD服务器。

官网:http://www.jcraft.com/jsch/中有很多例子http://www.jcraft.com/jsch/examples/,这里先采用(已做修改)其中2个来进行简单论述,希望对大家有所帮助。
本文采用的jsch版本是0.1.51. 下载地址:http://sourceforge.net/projects/jsch/files/jsch/0.1.54/jsch-0.1.54.zip/download
本文采用的Linux操作系统是CentOS6.5.

TIPS: 查看Linux操作系统(内核)版本可以使用:uname -a; uname -r; cat /etc/issue; cat /etc/redhat-release等命令。

第一个例子:采用Java模拟shell操作。
这里涉及到几个参数,会在下面的代码中有所体现:

  • USER:所连接的Linux主机登录时的用户名
  • PASSWORD:登录密码
  • HOST:主机地址
  • DEFAULT_SSH_PROT=端口号,默认为22
package com.test.jsch;

/**
 * This program enables you to connect to sshd server and get the shell prompt.
 * You will be asked username, hostname and passwd.
 * If everything works fine, you will get the shell prompt. Output may
 * be ugly because of lacks of terminal-emulation, but you can issue commands.
 */

import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.UserInfo;
import com.jcraft.jsch.Channel;

public class Shell{
    private static final String USER="root";
    private static final String PASSWORD="********";
    private static final String HOST="localhost";
    private static final int DEFAULT_SSH_PORT=22;

    public static void main(String[] arg){

        try{
            JSch jsch=new JSch();
            Session session = jsch.getSession(USER,HOST,DEFAULT_SSH_PORT);
            session.setPassword(PASSWORD);

            UserInfo userInfo = new UserInfo() {
                @Override
                public String getPassphrase() {
                    System.out.println("getPassphrase");
                    return null;
                }
                @Override
                public String getPassword() {
                    System.out.println("getPassword");
                    return null;
                }
                @Override
                public boolean promptPassword(String s) {
                    System.out.println("promptPassword:"+s);
                    return false;
                }
                @Override
                public boolean promptPassphrase(String s) {
                    System.out.println("promptPassphrase:"+s);
                    return false;
                }
                @Override
                public boolean promptYesNo(String s) {
                    System.out.println("promptYesNo:"+s);
                    return true;//notice here!
                }
                @Override
                public void showMessage(String s) {
                    System.out.println("showMessage:"+s);
                }
            };

            session.setUserInfo(userInfo);

            // It must not be recommended, but if you want to skip host-key check,
            // invoke following,
            // session.setConfig("StrictHostKeyChecking", "no");

            //session.connect();
            session.connect(30000);   // making a connection with timeout.

            Channel channel=session.openChannel("shell");

            // Enable agent-forwarding.
            //((ChannelShell)channel).setAgentForwarding(true);

            channel.setInputStream(System.in);
      /*
      // a hack for MS-DOS prompt on Windows.
      channel.setInputStream(new FilterInputStream(System.in){
          public int read(byte[] b, int off, int len)throws IOException{
            return in.read(b, off, (len>1024?1024:len));
          }
        });
       */

            channel.setOutputStream(System.out);

      /*
      // Choose the pty-type "vt102".
      ((ChannelShell)channel).setPtyType("vt102");
      */

      /*
      // Set environment variable "LANG" as "ja_JP.eucJP".
      ((ChannelShell)channel).setEnv("LANG", "ja_JP.eucJP");
      */

            //channel.connect();
            channel.connect(3*1000);
        }
        catch(Exception e){
            System.out.println(e);
        }
    }
}

运行结果:

promptYesNo:
The authenticity of host '10.101.139.5' can't be established.
RSA key fingerprint is 59:0f:32:fc:7b:54:3d:90:c0:ef:5a:6b:fb:11:55:e1.
Are you sure you want to continue connecting?
trueLast login: Thu Sep 29 18:40:56 2016 from 10.101.48.240
[root@hidden ~]#

输入ls查看:

(省略一些....)
[root@hidden ~]# ls
ls
1.txt            install.log.syslog  vmware-tools-distrib  模板  文档  桌面
anaconda-ks.cfg  logs                workspace             视频  下载
install.log      util                公共的                图片  音乐
[root@hidden ~]#

这样就和在原linux系统中一样使用shell功能了。

如果需要跳过如下的检测:

The authenticity of host '10.101.139.5' can't be established.
RSA key fingerprint is 59:0f:32:fc:7b:54:3d:90:c0:ef:5a:6b:fb:11:55:e1.
Are you sure you want to continue connecting?

只需要在程序中加入相应的代码:

session.setConfig("StrictHostKeyChecking", "no");

运行结果:

Last login: Thu Sep 29 18:39:18 2016 from 10.101.48.240
[root@hidden ~]#

第二个例子:运行一条shell指令,这里就那“ls”做例子好了。

No more talk, show you the code:

package com.test.jsch;

import com.jcraft.jsch.*;
import java.io.*;

public class Exec{
    private static final String USER="root";
    private static final String PASSWORD="********";
    private static final String HOST="localhost";
    private static final int DEFAULT_SSH_PORT=22;

    public static void main(String[] arg){
        try{
            JSch jsch=new JSch();

            Session session = jsch.getSession(USER,HOST,DEFAULT_SSH_PORT);
            session.setPassword(PASSWORD);

            // username and password will be given via UserInfo interface.
            session.setUserInfo(new MyUserInfo());
            session.connect();

            String command="ls";

            Channel channel=session.openChannel("exec");
            ((ChannelExec)channel).setCommand(command);

            // X Forwarding
            // channel.setXForwarding(true);

            //channel.setInputStream(System.in);
            channel.setInputStream(null);

            //channel.setOutputStream(System.out);

            //FileOutputStream fos=new FileOutputStream("/tmp/stderr");
            //((ChannelExec)channel).setErrStream(fos);
            ((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()){
                    if(in.available()>0) continue;
                    System.out.println("exit-status: "+channel.getExitStatus());
                    break;
                }
                try{Thread.sleep(1000);}catch(Exception ee){}
            }
            channel.disconnect();
            session.disconnect();
        }
        catch(Exception e){
            System.out.println(e);
        }
    }

    private static class MyUserInfo implements UserInfo{
        @Override
        public String getPassphrase() {
            System.out.println("getPassphrase");
            return null;
        }
        @Override
        public String getPassword() {
            System.out.println("getPassword");
            return null;
        }
        @Override
        public boolean promptPassword(String s) {
            System.out.println("promptPassword:"+s);
            return false;
        }
        @Override
        public boolean promptPassphrase(String s) {
            System.out.println("promptPassphrase:"+s);
            return false;
        }
        @Override
        public boolean promptYesNo(String s) {
            System.out.println("promptYesNo:"+s);
            return true;//notice here!
        }
        @Override
        public void showMessage(String s) {
            System.out.println("showMessage:"+s);
        }
    }
}

运行结果:

promptYesNo:The authenticity of host '10.101.139.5' can't be established.
RSA key fingerprint is 59:0f:32:fc:7b:54:3d:90:c0:ef:5a:6b:fb:11:55:e1.
Are you sure you want to continue connecting?
1.txt
anaconda-ks.cfg
install.log
install.log.syslog
logs
util
vmware-tools-distrib
workspace
公共的
模板
视频
图片
文档
下载
音乐
桌面
exit-status: 0

第二个例子相比于第一个例子来说将UserInfo采用static class的方式提取出来,这样更直观一点。

JSch是以多线程方式一下,所以代码在connect后如果不disconnect channel和session,以及相关stream, 程序会一直等待,直到关闭。

需要注意的一个问题,相关的Stream和Channel是一定要关闭的,那么应该在什么时候来关?执行connect后,JSch接受客户端结果需要一定的时间(以秒计),如果马上关闭session就会发现什么都没接受到或内容不全。

还有一点注意,使用shell时,看到执行后没有结果,解决办法是在命令行后加上”\n”字符,server端就认为是一条完整的命令了。

最后将第一个和第二个例子合并,并提取一些公用模块,以便更好的理解和使用:

package com.test.jsch;

import com.jcraft.jsch.*;

import java.io.*;
import java.util.concurrent.TimeUnit;

import static java.lang.String.format;

/**
 * Created by hidden on 2016/9/29.
 */
public class SSHExecutor {
    private static long INTERVAL = 100L;
    private static int SESSION_TIMEOUT = 30000;
    private static int CHANNEL_TIMEOUT = 3000;
    private JSch jsch = null;
    private Session session = null;

    private SSHExecutor(SSHInfo sshInfo) throws JSchException {
        jsch =new JSch();
        session = jsch.getSession(sshInfo.getUser(),sshInfo.getHost(),sshInfo.getPort());
        session.setPassword(sshInfo.getPassword());
        session.setUserInfo(new MyUserInfo());
        session.connect(SESSION_TIMEOUT);
    }

    /*
    * 在这里修改访问入口,当然可以把这个方法弄到SSHExecutor外面,这里是方便操作才这么做的
    * */
    public static SSHExecutor newInstance() throws JSchException {
        SSHInfo sshInfo = new SSHInfo("root","******","locahost",22);
        return new SSHExecutor(sshInfo);
    }

    /*
    * 注意编码转换
    * */
    public long shell(String cmd, String outputFileName) throws JSchException, IOException, InterruptedException {
        long start = System.currentTimeMillis();
        Channel channel = session.openChannel("shell");
        PipedInputStream pipeIn = new PipedInputStream();
        PipedOutputStream pipeOut = new PipedOutputStream( pipeIn );
        FileOutputStream fileOut = new FileOutputStream( outputFileName, true);
        channel.setInputStream(pipeIn);
        channel.setOutputStream(fileOut);
        channel.connect(CHANNEL_TIMEOUT);

        pipeOut.write(cmd.getBytes());
        Thread.sleep( INTERVAL );
        pipeOut.close();
        pipeIn.close();
        fileOut.close();
        channel.disconnect();
        return System.currentTimeMillis() - start;
    }

    public int exec(String cmd) throws IOException, JSchException, InterruptedException {
        ChannelExec channelExec = (ChannelExec)session.openChannel( "exec" );
        channelExec.setCommand( cmd );
        channelExec.setInputStream( null );
        channelExec.setErrStream( System.err );
        InputStream in = channelExec.getInputStream();
        channelExec.connect();

        int res = -1;
        StringBuffer buf = new StringBuffer( 1024 );
        byte[] tmp = new byte[ 1024 ];
        while ( true ) {
            while ( in.available() > 0 ) {
                int i = in.read( tmp, 0, 1024 );
                if ( i < 0 ) break;
                buf.append( new String( tmp, 0, i ) );
            }
            if ( channelExec.isClosed() ) {
                res = channelExec.getExitStatus();
                System.out.println( format( "Exit-status: %d", res ) );
                break;
            }
            TimeUnit.MILLISECONDS.sleep(100);
        }
        System.out.println( buf.toString() );
        channelExec.disconnect();
        return res;
    }

    public Session getSession(){
        return session;
    }

    public void close(){
        getSession().disconnect();
    }

    /*
    * SSH连接信息
    * */
    public static class SSHInfo{
        private String user;
        private String password;
        private String host;
        private int port;

        public SSHInfo(String user, String password, String host, int port) {
            this.user = user;
            this.password = password;
            this.host = host;
            this.port = port;
        }

        public String getUser() {
            return user;
        }

        public String getPassword() {
            return password;
        }

        public String getHost() {
            return host;
        }

        public int getPort() {
            return port;
        }
    }

    /*
    * 自定义UserInfo
    * */
    private static class MyUserInfo implements UserInfo{

        @Override public String getPassphrase() { return null; }

        @Override public String getPassword() { return null; }

        @Override public boolean promptPassword(String s) { return false; }

        @Override public boolean promptPassphrase(String s) { return false; }

        @Override
        public boolean promptYesNo(String s) {
            System.out.println(s);
            System.out.println("true");
            return true;
        }

        @Override public void showMessage(String s) { }
    }
}

测试代码:

        SSHExecutor ssh =  SSHExecutor.newInstance();
        System.out.println("================");
        long shell1 = ssh.shell("ls\n","C:\\Users\\hidden\\Desktop\\shell.txt");
        long shell2 = ssh.shell("pwd\n","C:\\Users\\hidden\\Desktop\\shell.txt");
        System.out.println("shell 1 执行了"+shell1+"ms");
        System.out.println("shell 2 执行了"+shell2+"ms");
        System.out.println("================");
        int cmd1 = ssh.exec("ls\n");
        ssh.close();

测试结果:

The authenticity of host '10.101.139.5' can't be established.
RSA key fingerprint is 59:0f:32:fc:7b:54:3d:90:c0:ef:5a:6b:fb:11:55:e1.
Are you sure you want to continue connecting?
true
================
shell 1 执行了142ms
shell 2 执行了132ms
================
Exit-status: 0
1.txt
anaconda-ks.cfg
install.log
install.log.syslog
logs
util
vmware-tools-distrib
workspace
公共的
模板
视频
图片
文档
下载
音乐
桌面

还有解释查看一下左边是否有个shell.txt以及shell.txt是否有相应的内容。



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