增强 SSH/SFTP 稳定性并完善安全校验与前端交互

backend/src/main/java/com/sshmanager/service/ConnectionService.java

@@ -16,11 +16,14 @@ public class ConnectionService {
 
     private final ConnectionRepository connectionRepository;
     private final EncryptionService encryptionService;
+    private final SshService sshService;
 
     public ConnectionService(ConnectionRepository connectionRepository,
-                             EncryptionService encryptionService) {
+                             EncryptionService encryptionService,
+                             SshService sshService) {
         this.connectionRepository = connectionRepository;
         this.encryptionService = encryptionService;
+        this.sshService = sshService;
     }
 
     public List<ConnectionDto> listByUserId(Long userId) {
@@ -130,4 +133,18 @@ public class ConnectionService {
         return conn.getPassphrase() != null ?
             encryptionService.decrypt(conn.getPassphrase()) : null;
     }
+
+    public Connection testConnection(Connection conn, String password, String privateKey, String passphrase) {
+        SshService.SshSession session = null;
+        try {
+            session = sshService.createShellSession(conn, password, privateKey, passphrase);
+            return conn;
+        } catch (Exception e) {
+            throw new RuntimeException("Connection test failed: " + e.getMessage(), e);
+        } finally {
+            if (session != null) {
+                session.disconnect();
+            }
+        }
+    }
 }