Java中的URL连接（FTP） - 简单问题 [英] URL Connection (FTP) in Java - Simple Question

问题描述

我有一个简单的问题。我试图用Java将文件上传到我的ftp服务器。

我在我的电脑上有一个文件，我想复制该文件并上传它。我尝试手动将文件的每个字节写入输出流，但对于复杂文件（如zip文件或pdf文件）无效。

 文件文件=我电脑上的某个文件; 
 String name = file.getName（）; 
 URL url =新的URL（ftp：// user：[e-mail]/+ name +; type = i）; 
 URLConnection urlc = url.openConnection（）; 
 OutputStream os = urlc.getOutputStream（）; 
 
 //然后我该怎么办？ 
  

只是为了踢腿，这是我试图做的：

  OutputStream os = urlc.getOutputStream（）; 
 BufferedReader br = new BufferedReader（new FileReader（file））; 
 String line = br.readLine（）; 
 while（line！= null&&（！line.equals（）））{
 os.write（line.getBytes（））; 
 os.write（\\\
.getBytes（））; 
 line = br.readLine（）; 
} 
 os.close（）; 
  

例如，当我用pdf执行此操作时，然后尝试打开我运行的PDF这个程序，它说，试图打开PDF时发生错误。我猜是因为我正在写一个\\\
到文件中？如何在不执行此操作的情况下复制文件？ code>或 Writer 类，当你试图复制一个二进制文件的byte-to-byte精确内容时。只能用于纯文本！相反，使用 InputStream 和 OutputStream 类;它们根本不解释数据，而 Reader 和 Writer 类将数据解释为字符。例如

  OutputStream os = urlc.getOutputStream（）; 
 FileInputStreamReader fis = new FileInputStream（file）; 
 byte [] buffer = new byte [1000]; 
 int count = 0; （（count = fis.read（buffer））> 0）{
 os.write（buffer，0，count）; 
。 
 
 $ / code> 

无论您的 URLConnection 这里的用法是正确的，我不知道;使用Apache Commons FTP（如其他地方所建议的）将是一个很好的主意。无论如何，这将是读取文件的方式。

I have a simple question. I'm trying to upload a file to my ftp server in Java.

I have a file on my computer, and I want to make a copy of that file and upload it. I tried manually writing each byte of the file to the output stream, but that doesn't work for complicated files, like zip files or pdf files.

File file = some file on my computer;
String name = file.getName();
URL url = new URL("ftp://user:[e-mail]/" + name +";type=i");
URLConnection urlc = url.openConnection();
OutputStream os = urlc.getOutputStream();

//then what do I do?

Just for kicks, here is what I tried to do:

OutputStream os = urlc.getOutputStream();
BufferedReader br = new BufferedReader(new FileReader(file));
String line = br.readLine();
while(line != null && (!line.equals(""))) {
    os.write(line.getBytes());
    os.write("\n".getBytes());
    line = br.readLine();
}
os.close();

For example, when I do this with a pdf and then try and open the pdf that I run with this program, it says an error occurred when trying to open the pdf. I'm guessing because I am writing a "\n" to the file? How do I copy the file without doing this?

解决方案

Do not use any of the Reader or Writer classes when you're trying to copy the byte-for-byte exact contents of a binary file. Use these only for plain text! Instead, use the InputStream and OutputStream classes; they do not interpret the data at all, while the Reader and Writer classes interpret the data as characters. For example

OutputStream os = urlc.getOutputStream();
FileInputStreamReader fis = new FileInputStream(file);
byte[] buffer = new byte[1000];
int count = 0;
while((count = fis.read(buffer)) > 0) {
    os.write(buffer, 0, count);
}

Whether your URLConnection usage is correct here, I don't know; using Apache Commons FTP (as suggested elsewhere) would be an excellent idea. Regardless, this would be the way to read the file.

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