Master the technical principles of the SFTP transmission framework in the Java class library
SFTP (Secure File Transfer Protocol) is a safe file transmission protocol for transmission files between computers.In the Java library, we can use the JSCH library to implement the SFTP transmission framework.Below we will introduce the technical principles of the JSCH library and provide some Java code examples.
JSCH is the abbreviation of Java Secure Channel, and is a class library of SSH2 protocol implemented by pure Java.It provides functions such as connection, authentication, and data transmission, which can be used to realize the SFTP transmission framework.
1. Configuration dependencies
To use the JSCH library, we need to add related dependencies to the project construction tool.For example, if you use Maven to build a project, you can add the following dependencies to the pom.xml file:
<dependency>
<groupId>com.jcraft</groupId>
<artifactId>jsch</artifactId>
<version>0.1.55</version>
</dependency>
2. Create SFTP connection
The first step to create a SFTP connection with the JSCH library is to create a session object.The session object represents the connection between the remote server, which requires information such as server address, port number, user name and password.The following is an example code that creates the session object:
import com.jcraft.jsch.*;
public class SFTPExample {
public static void main(String[] args) {
try {
JSch jsch = new JSch();
// Create a session object
Session session = jsch.getSession("username", "hostname", port);
session.setPassword("password");
// Set the connection attribute
session.setConfig("StrictHostKeyChecking", "no");
// establish connection
session.connect();
// Use the connection to perform the SFTP operation
// ...
// Turn off the connection
session.disconnect();
} catch (JSchException e) {
e.printStackTrace();
}
}
}
In the above code, we use the JSCH JSCH class to create a session object, and set the connected user name, host name, port number and password.Set the StricthostkeyChecking property as "NO", you can skip the host key check.Finally, build a connection with the server by calling the Connect method.
3. SFTP transmission operation
After creating the SFTP connection, we can use the Session object to perform various SFTP operations, such as uploading files, download files, creating directory, etc.Below is an example code from uploading files to remote server:
import com.jcraft.jsch.*;
public class SFTPExample {
public static void main(String[] args) {
try {
JSch jsch = new JSch();
// Create a session object
Session session = jsch.getSession("username", "hostname", port);
session.setPassword("password");
// Set the connection attribute
session.setConfig("StrictHostKeyChecking", "no");
// establish connection
session.connect();
// Create Channelsftp objects
ChannelSftp channel = (ChannelSftp) session.openChannel("sftp");
channel.connect();
// upload files
String localFilePath = "local_file.txt";
String remoteFilePath = "/path/to/remote_file.txt";
channel.put(localFilePath, remoteFilePath);
// Turn off the connection
channel.disconnect();
session.disconnect();
} catch (JSchException | SftpException e) {
e.printStackTrace();
}
}
}
In the above code, we create a ChannelSFTP object and call the Connect method to establish a connection.Then, upload the local file (Local_file.txt) to the remote server specified path (/path/to/remote_file.txt).Finally, close the connection by calling the disconnect method.
Through the above steps, we can use the JSCH library in Java to implement the SFTP transmission framework.In addition to uploading files, JSCH also provides various methods of other SFTP operations, such as downloading files, listing directory content, deleting files, etc.Developers can use the corresponding methods to complete the corresponding operations according to specific needs.
