JSch库中SCP协议实现的解释

Question

JSch库中SCP协议实现的解释

javasshsftpscpjsch

5

我正在思考JSch库使用的一个示例，可以在这里找到：
http://www.jcraft.com/jsch/examples/ScpFrom.java.html

我无法理解这个示例中的几个代码模式。它们是：

Is there any reasons to prefer SCP over SFTP, which can be ran using the same library?
Why we run scp -f <remote file> on remote host instead of running simply scp source_file_path destination_file_path? Why execution on remote host is better?
In the beginning of the transfer there is a line
```
while(true){
int c=checkAck(in);
if(c!='C'){
    break;
}
...
```
what is the meaning of this magical C letter? Why C?

Why to send this signal all the time?

// send '\0'
buf[0]=0; out.write(buf, 0, 1); out.flush();

how this can read filesize?

long filesize=0L;
while(true){
    if(in.read(buf, 0, 1)<0){
        // error
        break; 
    }
    if(buf[0]==' ')break;
    filesize=filesize*10L+(long)(buf[0]-'0'); //What is this??
}

- MiamiBeach

1个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Martin Prikryl · Accepted Answer

C<filesize> <filename>

So the size of the file is explicitly sent as part of the command, allowing the receiving end to know the expected size of the following transfer.

C permissions size filename

例如：

C 0644 153634 index.php

代码中的循环将字符串"153634"转换为数字153634。看起来实现有点复杂，但它有效。

另请参阅SCP（安全拷贝协议）文件传输是如何工作的？