java实操之使用jcraft进行sftp上传下载文件

　　sftp作为临时的文件存储位置，在某些场合还是有其应景的，比如对账文件存放。需要提供一个上传的工具类。实现方法参考下：

pom.xml中引入类库：

        <dependency>
            <groupId>com.jcraft</groupId>
            <artifactId>jsch</artifactId>
            <version>0.1.54</version>
        </dependency>

sftp工具类和使用命令行是一样的操作方法，上传下载如下：

public class SftpUploadTest {

    private ChannelSftp sftp = null;

    private Session sshSession = null;

    private String username;

    private String password;

    private String host;

    private int port;

    public SftpUploadTest(String username, String password, String host, int port) {
        this.username = username;
        this.password = password;
        this.host = host;
        this.port = port;
    }

    /**
     * 连接sftp服务器
     *
     * @return ChannelSftp sftp连接实例
     */
    public ChannelSftp connect() {
        info("-->sftp连接开始>>>>>> " + host + ":" + port + " >>>username=" + username);
        JSch jsch = new JSch();
        try {
            jsch.getSession(username, host, port);
            sshSession = jsch.getSession(username, host, port);
            sshSession.setPassword(password);
            Properties properties = new Properties();
            properties.put("StrictHostKeyChecking", "no");
            sshSession.setConfig(properties);
            sshSession.connect();
            Channel channel = sshSession.openChannel("sftp");
            channel.connect();
            sftp = (ChannelSftp) channel;
            info(" ftp Connected to " + host + ":" + port);
        } catch (JSchException e) {
            throw new RuntimeException("sftp连接失败", e);
        }
        return sftp;
    }

    /**
     * 下载单个文件，如果指定文件名，则下载到文件名否则保持原有文件名
     *
     * @param remoteFilePath    远程文件路径 /tmp/xxx.txt || xxx.txt.zip
     * @param localFilePath     本地文件路径 如 D:\xxx.txt
     * @return 下载的文件
     */
    public File downloadFile(String remoteFilePath, String localFilePath) {
        info(">>>>>>>>>downloadFile--ftp下载文件" + remoteFilePath + "开始>>>>>>>>>>>>>");
        connect();
        String remoteFileName = "";
        // 远端目录确定以 / 作为目录格式
        String rFileSeparator = "/";
        int rDirNameSepIndex = remoteFilePath.lastIndexOf(rFileSeparator) + 1;
        String rDir = remoteFilePath.substring(0, rDirNameSepIndex);
        remoteFileName = remoteFilePath.substring(rDirNameSepIndex);
        if(localFilePath.endsWith(File.separator)) {
            localFilePath = localFilePath + (localFilePath.endsWith(File.separator) ? remoteFileName : "/" + remoteFileName);
        }
        File file = null;
        OutputStream output = null;
        try {
            file = new File(localFilePath);
            if (file.exists()) {
                file.delete();
            }
            file.createNewFile();
            sftp.cd(rDir);
            output = new FileOutputStream(file);
            sftp.get(remoteFileName, output);
            info("===DownloadFile:" + remoteFileName + " success from sftp.");
        } catch (SftpException e) {
            error("ftp下载文件失败", e);
        } catch (FileNotFoundException e) {
            error("本地目录异常，请检查" + file.getPath(), e);
        } catch (IOException e) {
            error("创建本地文件失败" + file.getPath(), e);
        } finally {
            if (output != null) {
                try {
                    output.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            disconnect();
        }

        info(">>>>>>>>>downloadFile--ftp下载文件结束>>>>>>>>>>>>>");
        return file;
    }

    /**
     * 上传单个文件，如果指正下载文件名则使用，否则保留原有文件名
     *
     * @param remoteFilePath    远程文件路径 /tmp/xxx.txt ||xxx.txt.zip
     * @param uploadFilePath    要上传的文件 如：D:\test\xxx.txt
     */
    public void uploadFile(String remoteFilePath, String uploadFilePath) {
        info(" begin uploadFile from:" + uploadFilePath +
                ", to: " + remoteFilePath);
        FileInputStream in = null;
        connect();
        String remoteFileName = "";
        String remoteDir = remoteFilePath;
        String localFileName = "";
        // 远端目录确定以 / 作为目录格式
        String rFileSeparator = "/";
        if(remoteFilePath.endsWith(rFileSeparator)) {
            localFileName = uploadFilePath.substring(uploadFilePath.lastIndexOf(File.separator) + 1);
            remoteFileName = localFileName;
        } else {
            int fileNameDirSep = remoteFilePath.lastIndexOf(rFileSeparator) + 1;
            remoteDir = remoteFilePath.substring(0, fileNameDirSep);
            remoteFileName = remoteFilePath.substring(fileNameDirSep);
        }
        try {
            sftp.cd(remoteDir);
        } catch (SftpException e) {
            try {
                sftp.mkdir(remoteDir);
                sftp.cd(remoteDir);
            } catch (SftpException e1) {
                error("ftp创建文件路径失败，路径为" + remoteDir);
                throw new RuntimeException("ftp创建文件路径失败" + remoteDir);
            }
        }
        File file = new File(uploadFilePath);
        try {
            in = new FileInputStream(file);
            sftp.put(in, remoteFileName);
        } catch (FileNotFoundException e) {
            error("文件不存在-->" + uploadFilePath);
        } catch (SftpException e) {
            error("sftp异常-->", e);
        } finally {
            if (in != null) {
                try {
                    in.close();
                } catch (IOException e) {
                    info("Close stream error." + e.getMessage());
                }
            }
            disconnect();
        }
        info(">>>>>>>>>uploadFile--ftp上传文件结束>>>>>>>>>>>>>");
    }

    /**
     * 关闭连接
     */
    public void disconnect() {
        if (this.sftp != null) {
            if (this.sftp.isConnected()) {
                this.sftp.disconnect();
                this.sftp = null;
                info("sftp 连接已关闭！");
            }
        }
        if (this.sshSession != null) {
            if (this.sshSession.isConnected()) {
                this.sshSession.disconnect();
                this.sshSession = null;
                info("sshSession 连接已关闭！");
            }
        }
    }
    private void info(String msg) {
        System.out.println("info: " + msg);
    }

    private void error(String msg) {
        error(msg, null);
    }

    private void error(String msg, Throwable e) {
        System.out.println("error: " + msg);
        if(e != null) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) throws Exception {
        SftpUploadTest uploadTest = new SftpUploadTest("root", "123", "10.40.10.17", 52766);
        uploadTest.uploadFile("/tmp/" + "readme-" + System.currentTimeMillis() + ".txt", "C:\Users\xx\Desktop\sample\readme.txt");
        uploadTest.downloadFile("/tmp/readme.txt", "C:\Users\xx\Desktop\sample\readme-" + System.currentTimeMillis() + ".txt");
    }
}

　　使用时，可根据需要进行连接的适时释放！也可能为了安全需要，添加一些额外的安全指令！

　　sftp文件操作的命令罗列如下参考：

sftp常用的为上传下载

# get
# 从远程服务器上下载一个文件存放到本地，如下：
# 先通过lcd切换到本地那个目录下，然后通过get file
>> lcd d: #表示切换到本地的d盘下
>> get ./test.sql　　 #这样就将当前文件下载本地的d盘下
# put
# 是将本地的文件上传到远程服务器上，如下：
>> put #在windows下弹出选择文件的窗口
# lcd
# 先通过lcd切换到本地那个目录下
>> lcd c: #表示切换到本地的c盘下
# lls
#显示当前目录下的所有文件
>> pwd        #显示当前目录