FTP和SFTP的区别和工作原理：
很详细：http://blog.csdn.net/cuker919/article/details/6403925
可以根据自己的实际情况选择使用FTP或者SFTP，使用FTP时要安装FTP，而SFTP不需要安装。
效率：FTP>SFTP
安全：SFTP>FTP
这儿只是比较SFTP 读取image和URL读取image效率：适用文件服务和系统服务是不同服务器。
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
| public class SFTP {
public static void testSftp() throws Exception{
ChannelSftp sftp = ChannelSFTPImpl.getSFTP();
String directory = "/data/apps/c2m/release/images-src";
String downloadFile = "/2S8959_20180114162259.jpg";
long s = System.currentTimeMillis();
InputStream is = sftp.get(directory+downloadFile);
BufferedImage image = ImageIO.read(is);
long e = System.currentTimeMillis();
System.out.println(e-s);
}
public static void testUrl() throws Exception{
String str = "http://h5.jinzhiyun.net/images-src/2S8959_20180114162259.jpg";
URL url = new URL(str);
long s = System.currentTimeMillis();
BufferedImage image = ImageIO.read(url);
long e = System.currentTimeMillis();
System.out.println(e-s);
}
public static void main(String[] args) throws Exception {
testSftp();
testUrl();
}
}
|
//执行结果
ChannelSFTPImpl.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
| public class ChannelSFTPImpl {
private static final String host = "";
private static final int port = 22;
private static final String username = "";
private static String password = "";
public static ChannelSftp sftp = null;
private ChannelSFTPImpl() {
}
public static ChannelSftp getSFTP() {
if(null == sftp){
MySFTP sf = new MySFTP();
sftp = sf.connect(host, port, username, password);
}
return sftp;
}
}
|
MySFTP.java connect()
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
| public ChannelSftp connect(String host, int port, String username, String password) {
ChannelSftp sftp = null;
try {
JSch jsch = new JSch();
jsch.getSession(username, host, port);
Session sshSession = jsch.getSession(username, host, port);
sshSession.setPassword(password);
Properties sshConfig = new Properties();
sshConfig.put("StrictHostKeyChecking", "no");
sshSession.setConfig(sshConfig);
sshSession.connect();
com.jcraft.jsch.Channel channel = sshSession.openChannel("sftp");
channel.connect();
sftp = (ChannelSftp) channel;
} catch (Exception e) {
}
return sftp;
}
|
FTP：从FTP服务器下载文件：
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
| public class FtpUtil {
public static void main(String[] args) {
String url = "";
int port = 21;
String username = "";
String password = "";
String remotePath = "/data/apps/c2m/release/images-src";
String fileName = "";
downFile(url, port, username, password, remotePath, fileName);
}
public static boolean downFile(String url, int port, String username, String password, String remotePath, String fileName) {
boolean success = false;
FTPClient ftp = new FTPClient();
int reply;
try {
ftp.enterLocalPassiveMode();
ftp.connect(url, port);
ftp.login(username, password);
ftp.setFileType(FTPClient.BINARY_FILE_TYPE);
reply = ftp.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply)) {
ftp.disconnect();
return success;
}
ftp.changeWorkingDirectory(remotePath);
FTPFile[] fs = ftp.listFiles();
for (FTPFile ff : fs) {
if (ff.getName().equals(fileName)) {
}
}
ftp.logout();
success = true;
} catch (SocketException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (ftp.isConnected()) {
try {
ftp.disconnect();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return success;
}
}
|