SFTP Trust Public key configuration and Jsch Library

1. SFTP Credit Public key configuration
1.1 Client-generated key pair

Take the DSA Example:

Ssh-keygen–t DSA

After the command is executed, ID_DSA and id_dsa.pub two files are generated under the home/user name/.ssh directory

1.2 will id_dsa.pub the public key file is uploaded to the server home/ User name /.ssh directory under

SCP id_dsa.pub username @ server-side ip:/home/user name/.ssh

You also need to enter a password

1.3 Adding a trusted public key to the server

Log on to the server, enter the/home/user name/.ssh directory, and add the contents of the Id_dsa.pub file that you just copied to the Authorized_keys file

Cat Id_dsa.pub >> Authorized_keys

1.4 Service side modified separately Authorized_key files and . SSH the permissions for - and the the

chmod Authorized_keys

chmod. SSH

1.5 Testing

Execute on client:

sftp–oport= port User name @ server-side IP

If you do not need to enter a password to connect, then the configuration is successful

2. Jsch Library-based SFTP operation Java code

2. public class Sftputil {
4. Private final static Logger log = Loggerfactory.getlogger (Sftputil.class);
8. /** SFTP */
10. public static final String sftp = "SFTP";
12. /** Channel */
14. Private CHANNELSFTP channel;
16. /** Session */
18. Private session session;
22. /** Avoiding multithreading concurrency */
24. private static threadlocal<sftputil> sftplocal = new threadlocal<sftputil> ();
28. /**
30. * Get Sftpchannel
32. *
34. * @param connectconfig Connection Configuration
36. * @return
38. * @throws Exception
40. * @throws jschexception
42. */
44. private void init (Connectconfig connectconfig) throws Exception {
46. String host = Connectconfig.gethost ();
48. int port = Connectconfig.getport ();
52. String userName = Connectconfig.getusername ();
56. Create a Jsch object
58. Jsch Jsch = new Jsch ();
62. Add private key (trust login mode)
64. if (Stringutils.isnotblank (Connectconfig.getprivatekey ())) {
66. Jsch.addidentity (Connectconfig.getprivatekey ());
68. }
72. Session = Jsch.getsession (UserName, host, Port);
74. if (log.isinfoenabled ()) {
76. Log.info ("Jsch Session created,sftphost = {}, sftpusername={}", host, UserName);
78. }
82. Set Password
84. if (Stringutils.isnotblank (Connectconfig.getpassword ())) {
86. Session.setpassword (Connectconfig.getpassword ());
88. }
92. Properties Config = new properties ();
94. Config.put ("stricthostkeychecking", "no");
96. Session.setconfig (config);
98. Set timeout
100. Session.settimeout (Connectconfig.gettimeout ());
102. Establish a connection
104. Session.connect ();
106. if (log.isinfoenabled ()) {
108. Log.info ("Jsch Session connected.sftphost = {}, sftpusername={}", host, UserName);
110. }
114. Open the SFTP Channel
116. Channel = (CHANNELSFTP) session.openchannel (SFTP);
118. Establishing the connection to the SFTP channel
120. Channel.connect ();
122. if (log.isinfoenabled ()) {
124. Log.info ("Connected successfully to Sftphost = {}, sftpusername={}", host, UserName);
126. }
128. }
132. /**
134. * is connected
136. *
138. * @return
140. */
142. Private Boolean isconnected () {
144. return null! = Channel && channel.isconnected ();
146. }
150. /**
152. * Get the SFTP client for local thread storage
154. *
156. * @return
158. * @throws Exception
160. */
162. public static Sftputil Getsftputil (Connectconfig connectconfig) throws Exception {
164. Sftputil sftputil = Sftplocal.get ();
166. if (null = = Sftputil | |!sftputil.isconnected ()) {
168. Sftplocal.set (New Sftputil (Connectconfig));
170. }
172. return Sftplocal.get ();
174. }
178. /**
180. * Release the SFTP client for local thread storage
182. */
184. public static void release () {
186. if (null! = Sftplocal.get ()) {
188. Sftplocal.get (). Closechannel ();
190. Sftplocal.set (NULL);
192. }
194. }
198. /**
200. * Constructor function
202. * <p>
204. * Non-thread safe, so permissions are private
206. * </p>
208. *
210. * @throws Exception
212. */
214. Private Sftputil (Connectconfig connectconfig) throws Exception {
216. Super ();
218. Init (connectconfig);
220. }
224. /**
226. * Close the Channel
228. *
230. * @throws Exception
232. */
234. public void Closechannel () {
236. if (null! = Channel) {
238. try {
240. Channel.disconnect ();
242. } catch (Exception e) {
244. Log.error ("An exception occurred while closing the SFTP channel:", e);
246. }
248. }
250. if (null! = session) {
252. try {
254. Session.disconnect ();
256. } catch (Exception e) {
258. Log.error ("Sftp off Session Exception:", E);
260. }
262. }
264. }
268. /**
270. * Download File
272. *
274. * @param downdir Download catalogue
276. * @param src source file
278. * @param the file name or directory after DST is saved
280. * @throws Exception
282. */
284. public void Downfile (string downdir, string src, string dst) throws Exception {
286. CHANNEL.CD (Downdir);
288. Channel.get (SRC, DST);
290. }
294. /**
296. * Delete Files
298. *
300. * @param filePath File full path
302. * @throws sftpexception
304. */
306. public void DeleteFile (String filePath) throws Sftpexception {
308. CHANNEL.RM (FilePath);
310. }
314. @SuppressWarnings ("Unchecked")
316. Public list<string> listfiles (String dir) throws Sftpexception {
318. vector<lsentry> files = channel.ls (dir);
320. if (null! = files) {
322. list<string> fileNames = new arraylist<string> ();
324. Iterator<lsentry> iter = Files.iterator ();
326. while (Iter.hasnext ()) {
328. String fileName = Iter.next (). GetFileName ();
330. if (Stringutils.equals (".", FileName) | | Stringutils.equals ("..", FileName)) {
332. Continue
334. }
336. Filenames.add (FileName);
338. }
340. return fileNames;
342. }
344. return null;
346. }
348. }

Description:

2.1 Connectconfig contains all the parameter information needed to establish an SFTP connection

2.2 If the trusted public key configuration for SFTP is followed by the first step, you need to set the private key ID_DSA in the key pair into Java code by calling the Addidentity method of Jsch

1. Add private key (trust login mode)
2. if (Stringutils.isnotblank (Connectconfig.getprivatekey ())) {
3. Jsch.addidentity (Connectconfig.getprivatekey ());
4. }

2.3 In order to avoid frequent connection establishment and connection release operations, it is generally defined as a singleton pattern, but there are some business scenarios that need to be freed after the same thread has performed several successive complete business operations. In the case of a singleton, there is a concurrency problem with shared resource contention in multiple-threaded scenarios, such as a thread releasing a connection during the execution of a business by a B thread. Therefore, you can use threadlocal to avoid this problem. Java code

2. /**
4. * Get the SFTP client for local thread storage
6. *
8. * @return
10. * @throws Exception
12. */
14. public static Sftputil Getsftputil (Connectconfig connectconfig) throws Exception {
16. Sftputil sftputil = Sftplocal.get ();
18. if (null = = Sftputil | |!sftputil.isconnected ()) {
20. Sftplocal.set (New Sftputil (Connectconfig));
22. }
24. return Sftplocal.get ();
26. }
30. /**
32. * Release the SFTP client for local thread storage
34. */
36. public static void release () {
38. if (null! = Sftplocal.get ()) {
40. Sftplocal.get (). Closechannel ();
42. Sftplocal.set (NULL);
44. }
46. }