java ssh2 连接并执行 linux命令

<!-- https://mvnrepository.com/artifact/ch.ethz.ganymed/ganymed-ssh2 -->
<dependency>
  <groupId>ch.ethz.ganymed</groupId>
  <artifactId>ganymed-ssh2</artifactId>
  <version>build210</version>
</dependency>

或者官方下载: http://www.ganymed.ethz.ch/ssh2/

package ;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import ch.ethz.ssh2.Connection;
import ch.ethz.ssh2.Session;
import ch.ethz.ssh2.StreamGobbler;

/**
 * @Description 远程执行linux命令
 */
public class SSHUtil {

    private String host; // ip
    private String username;
    private String password;

    /**
     * @param host(ip)
     * @param username(用户名)
     * @param password(密码)
     */
    public SSHUtil(String host, String username, String password) {
        this.host = host;
        this.username = username;
        this.password = password;
    }

    private Connection conn = null;

    /**
     * 连接
     */
    private boolean connect() {
        conn = new Connection(host);
        try {
            conn.connect();
            if (conn.authenticateWithPassword(username, password)) {
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }

    /**
     * 执行命令
     */
    public String execute(String command) {
        if (command == null || "null".equals(command)) {
            return "传入命令为空!!!";
        }
        if (!connect()) {
            return "连接服务器失败!!!";
        }
        Session session = null;
        try {
            session = conn.openSession();
            session.execCommand(command);
            InputStream stdout = new StreamGobbler(session.getStdout());
            BufferedReader br = new BufferedReader(new InputStreamReader(stdout));
            StringBuffer sb = new StringBuffer();

            // ExitCode正常为0
            // 1:报错、2:误用命令、126:命令不得执行、127:没找到命令、130:ctrl+c结束、255:返回码超出范围  
            sb.append("ExitCode: " + session.getExitStatus() + "\n");
            while (true) {  
                String line = br.readLine();
                if (line == null)
                    break;
                sb.append(line + "\n");
            }
            return sb.toString();
        } catch (IOException e) {
            e.printStackTrace();
            return "error";
        } finally {
            if (conn != null) {
                conn.close();
            }
            if (session != null) {
                session.close();
            }
        }
    }
}

关于返回值(ExitCode)，具体看这个。
http://www.tldp.org/LDP/abs/html/exitcodes.html

每次执行不同的对象的时候都会重新连接一次，懒得判断。
execCommand(cmd) 方法好像可以传进去一个String数组，懒得测。

我执行的命令经常给我返回ExitCode： null
反正正确执行了也懒得查什么原因了。