这个示例主要是模拟一个Shell程序，通过输入一些命令，执行操作。源代码来自官网。
这个示例的特点：
1. 接收用户的输入；
2. 通过字符解析和判断；
3. 利用VFS自带的一些功能进行功能实现；
package test.ffm83.commons.VFS;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.DateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.StringTokenizer;
import org.apache.commons.vfs2.FileContent;
import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.FileSystemManager;
import org.apache.commons.vfs2.FileType;
import org.apache.commons.vfs2.FileUtil;
import org.apache.commons.vfs2.Selectors;
import org.apache.commons.vfs2.VFS;
/**
* A simple command-line shell for performing file operations.
* @author <a href="mailto:adammurdoch@apache.org">AdamMurdoch</a>
* @author Gary D. Gregory,范芳铭整理和添加注释
*/
public classShell
{
private static final String CVS_ID = "$Id:Shell.java 232419 2005-08-13 07:23:40 +0200(Sa, 13 Aug 2005) imario $";
private final FileSystemManager mgr;
privateFileObject cwd;
privateBufferedReader reader;
public static void main(final String[] args)
{
try
{
(new Shell()).go();
}
catch (Exception e)
{
e.printStackTrace();
System.exit(1);
}
System.exit(0);
}
privateShell() throwsFileSystemException
{
mgr = VFS.getManager();
cwd = mgr.resolveFile(System.getProperty("user.dir"));//获取当前文件夹
reader = new BufferedReader(new InputStreamReader(System.in));//接收输入内容
}
private void go() throws Exception
{
System.out.println("VFS Shell [" + CVS_ID + "]");
while (true)
{
final String[] cmd = nextCommand();
if (cmd == null)
{
return;
}
if (cmd.length == 0)
{
continue;
}
final String cmdName = cmd[0];
if (cmdName.equalsIgnoreCase("exit") ||cmdName.equalsIgnoreCase("quit"))
{
return;
}
try
{
handleCommand(cmd);
}
catch (final Exception e)
{
System.err.println("Command failed:");
e.printStackTrace(System.err);
}
}
}
/**
* Handles a command.
*/
private void handleCommand(final String[] cmd) throws Exception
{
final String cmdName = cmd[0];
if (cmdName.equalsIgnoreCase("cat"))
{
cat(cmd);
}
else if (cmdName.equalsIgnoreCase("cd"))
{
cd(cmd);
}
else if (cmdName.equalsIgnoreCase("cp"))
{
cp(cmd);
}
else if (cmdName.equalsIgnoreCase("help"))
{
help();
}
else if (cmdName.equalsIgnoreCase("ls"))
{
ls(cmd);
}
else if (cmdName.equalsIgnoreCase("pwd"))
{
pwd();
}
else if (cmdName.equalsIgnoreCase("rm"))
{
rm(cmd);
}
else if (cmdName.equalsIgnoreCase("touch"))
{
touch(cmd);
}
else
{
System.err.println("Unknown command \""+ cmdName + "\".");
}
}
/**
* Does a ‘help‘ command.
*/
private void help()
{
System.out.println("Commands:");
System.out.println("cat <file> Displays the contents of a file.");
System.out.println("cd [folder] Changescurrent folder.");
System.out.println("cp <src> <dest> Copies a file or folder.");
System.out.println("help Shows thismessage.");
System.out.println("ls [-R] [path] Listscontents of a file or folder.");
System.out.println("pwd Displayscurrent folder.");
System.out.println("rm <path> Deletes a file or folder.");
System.out.println("touch <path> Setsthe last-modified time of a file.");
System.out.println("exit Exits thisprogram.");
System.out.println("quit Exits thisprogram.");
}
/**
* Does an ‘rm‘ command.
*/
private void rm(final String[] cmd) throws Exception
{
if (cmd.length < 2)
{
throw new Exception("USAGE: rm <path>");
}
final FileObject file = mgr.resolveFile(cwd, cmd[1]);
file.delete(Selectors.SELECT_SELF);
}
/**
* Does a ‘cp‘ command.
*/
private void cp(final String[] cmd) throws Exception
{
if (cmd.length < 3)
{
throw new Exception("USAGE: cp <src><dest>");
}
final FileObject src = mgr.resolveFile(cwd, cmd[1]);
FileObject dest = mgr.resolveFile(cwd, cmd[2]);
if (dest.exists() && dest.getType() ==FileType.FOLDER)
{
dest =dest.resolveFile(src.getName().getBaseName());
}
dest.copyFrom(src, Selectors.SELECT_ALL);
}
/**
* Does a ‘cat‘ command.
*/
private void cat(final String[] cmd) throws Exception
{
if (cmd.length < 2)
{
throw new Exception("USAGE: cat<path>");
}
// Locate the file
final FileObject file = mgr.resolveFile(cwd, cmd[1]);
// Dump the contents to System.out
FileUtil.writeContent(file,System.out);
System.out.println();
}
/**
* Does a ‘pwd‘ command.
*/
private void pwd()
{
System.out.println("Current folder is " + cwd.getName());
}
/**
* Does a ‘cd‘ command.
* If the taget directory does notexist, a message is printed to <code>System.err</code>.
*/
private void cd(final String[] cmd) throws Exception
{
final String path;
if (cmd.length > 1)
{
path = cmd[1];
}
else
{
path = System.getProperty("user.home");
}
// Locate and validate the folder
FileObject tmp = mgr.resolveFile(cwd, path);
if (tmp.exists())
{
cwd = tmp;
}
else
{
System.out.println("Folder does not exist: "+ tmp.getName());
}
System.out.println("Current folder is " + cwd.getName());
}
/**
* Does an ‘ls‘ command.
*/
private void ls(final String[] cmd) throws FileSystemException
{
int pos = 1;
final boolean recursive;
if (cmd.length > pos && cmd[pos].equals("-R"))
{
recursive = true;
pos++;
}
else
{
recursive = false;
}
final FileObject file;
if (cmd.length > pos)
{
file = mgr.resolveFile(cwd, cmd[pos]);
}
else
{
file = cwd;
}
if (file.getType() == FileType.FOLDER)
{
// List the contents
System.out.println("Contents of " + file.getName());
listChildren(file, recursive, "");
}
else
{
// Stat the file
System.out.println(file.getName());
final FileContent content = file.getContent();
System.out.println("Size: " + content.getSize() + " bytes.");
final DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.MEDIUM, DateFormat.MEDIUM);
final String lastMod = dateFormat.format(newDate(content.getLastModifiedTime()));
System.out.println("Last modified: " + lastMod);
}
}
/**
* Does a ‘touch‘ command.
*/
private void touch(final String[] cmd) throws Exception
{
if (cmd.length < 2)
{
throw new Exception("USAGE: touch<path>");
}
final FileObject file = mgr.resolveFile(cwd, cmd[1]);
if (!file.exists())
{
file.createFile();
}
file.getContent().setLastModifiedTime(System.currentTimeMillis());
}
/**
* Lists the children of a folder.
*/
private void listChildren(final FileObject dir,
final boolean recursive,
final String prefix)
throws FileSystemException
{
final FileObject[] children = dir.getChildren();
for (int i = 0; i < children.length; i++)
{
final FileObject child = children[i];
System.out.print(prefix);
System.out.print(child.getName().getBaseName());
if (child.getType() == FileType.FOLDER)
{
System.out.println("/");
if (recursive)
{
listChildren(child,recursive, prefix + " ");
}
}
else
{
System.out.println();
}
}
}
/**
* Returns the next command, split intotokens.
*/
privateString[] nextCommand() throws IOException
{
System.out.print("> ");
final String line = reader.readLine();
if (line == null)
{
return null;
}
final ArrayList<String> cmd = newArrayList<String>();
final StringTokenizer tokens = new StringTokenizer(line);
while (tokens.hasMoreTokens())
{
cmd.add(tokens.nextToken());
}
return cmd.toArray(new String[cmd.size()]);
}
}
运行结果如下：
VFS Shell [$Id:Shell.java 2324192005-08-13 07:23:40 +0200 (Sa, 13 Aug 2005) imario $]
> pwd
Current folder isfile:///D:/develop/eclipse/Workspaces/test_all
原文地址：http://blog.csdn.net/ffm83/article/details/42080351
