import ch.ethz.ssh2.Connection;
import ch.ethz.ssh2.Session;
import ch.ethz.ssh2.StreamGobbler;
import com.io.Debug;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;

public class ChangeEmailPassword {
    private String username = "";
    private String oldpassword = "";
    private Connection conn = null;
    private boolean hasError = false;
    private String ErrorMessage = "";
    private boolean isSuccessfully = false;
    private String SystemMessage = "";
   
    public static final String HOST = "127.0.0.1"; //server ip
    public boolean isSuccessfully(){
        return isSuccessfully;
    }
    public boolean isHasError(){
        return hasError;
    }
    public String getErrorMessage(){
        return ErrorMessage;
    }
    public void setErrorMessage(String msg){
        hasError = true;
        this.ErrorMessage =  msg;
    }
   
    public ChangeEmailPassword(String username,String oldpassword) {
        this.username = username;
        this.oldpassword = oldpassword;
         try{
             conn = new Connection(HOST);
             conn.connect();
           
            boolean isAuthenticated = conn.authenticateWithPassword(username, oldpassword);
            if (isAuthenticated == false) {
                setErrorMessage("Authentication failed.");
                conn=null;
            }
         }catch(Exception e){
             conn.close();
             conn = null;
             System.out.println(e);
         }
    }
    public void setNewPassword(String newpassword) {
        if(hasError){
            return;
        }
        if (conn==null){
            return;
        }
        try{
            Session sess = conn.openSession();
            sess.execCommand("passwd");
            InputStream so = sess.getStdout();
            InputStream err = sess.getStderr();
            OutputStream out = sess.getStdin();
           
            byte[] buffer = new byte[500];//其实没有必要这么大.130就差不多了.怕万一有什么提示.
            int length = 0;
            length = err.read(buffer);
//            if (length > 0) {
//                System.out.println("#1:"+ new String(buffer, 0, length));
//                //(current) UNIX password:
//            }
            String coldpassword = oldpassword+"\n";
            out.write(coldpassword.getBytes());
            length = err.read(buffer);
//            if (length > 0) {
//                System.out.println("#2:"+ new String(buffer, 0, length));
//                //(current) UNIX password:
//            }
            String cnewpass = newpassword +"\n";
            out.write(cnewpass.getBytes());
            length = err.read(buffer);
            if (length > 0) {
                String rs = new String(buffer, 0, length);
                //System.out.println("#3:"+rs);
                if(rs.indexOf("BAD")>-1){
                    sess.close();
                    conn.close();
                    setErrorMessage(rs);
                    return;
                }
            }
            out.write(cnewpass.getBytes());
            length = so.read(buffer);
            if (length > 0) {
                String rs = new String(buffer, 0, length);
                if(rs.indexOf("successfully")>-1){
                    this.isSuccessfully = true;
                    this.SystemMessage = rs;
                }
            }
           
            sess.close();
           
            conn.close();
        } catch (IOException e) {
            e.printStackTrace(System.err);
        }
    }
   
    public static void main(String[] args) {
        ChangeEmailPassword cep = new ChangeEmailPassword("username", "oldpassword");
        if(cep.isHasError()){
            System.out.println(cep.getErrorMessage());
            cep = null;
            return;
        }
        cep.setNewPassword("newpassword");
        if(cep.isHasError()){
            System.out.println(cep.getErrorMessage());
            cep = null;
            return;
        }
        if(cep.isSuccessfully){
            System.out.println(cep.getSystemMessage());
        }
    }
   
    public String getSystemMessage() {
        return SystemMessage;
    }
}
 
//把里面注解掉的System.out.println打开可以看到系统提示的信息.我只保留了最关键的信息提示