ftp中ftpClient类的API--

珀耳塞福建

org.apache.commons.net.ftp
Class FTPClient类FTPClient
java.lang.Object java.lang.Object继承
   org.apache.commons.net.SocketClient org.apache.commons.net.SocketClient
       org.apache.commons.net.ftp.FTP org.apache.commons.net.ftp.FTP
           org.apache.commons.net.ftp.FTPClient org.apache.commons.net.ftp.FTPClient
All Implemented Interfaces: 所有已实现的接口：
Configurable 可配置
Direct Known Subclasses: 直接已知子类：
FTPHTTPClient , FTPSClient FTPHTTPClient ， FTPSClient

public class FTPClient公共类FTPClient
extends FTP延伸的FTP
implements Configurable实现了可配置
FTPClient encapsulates all the functionality necessary to store and retrieve files from an FTP server. FTPClient封装了所有必要的功能来存储和检索从FTP服务器上的文件。 This class takes care of all low level details of interacting with an FTP server and provides a convenient higher level interface.这个类负责所有与FTP服务器交互的底层细节，并提供了便捷的更高层次的接口。 As with all classes derived from SocketClient , you must first connect to the server with connect before doing anything, and finally disconnect after you're completely finished interacting with the server.正如来自所有类SocketClient ，您必须首先连接到与服务器connect做任何事之前，最后disconnect完成后，你完全与服务器交互。 Then you need to check the FTP reply code to see if the connection was successful.然后，你需要检查的FTP答复代码，看看是否连接成功。 For example:例如：
    boolean error = false;布尔错误= 0;
    try {尝试{
      int reply;诠释答复;
      ftp.connect("ftp.foobar.com"); ftp.connect（“ftp.foobar.com”）;
      System.out.println("Connected to " + server + "."); System.out.println（“连接到”+服务器+ ".");
      System.out.print(ftp.getReplyString()); System.out.print（ftp.getReplyString（））;

      // After connection attempt, you should check the reply code to verify / /连接尝试后，你应该检查代码以验证答复
      // success. / /成功。
      reply = ftp.getReplyCode();答复= ftp.getReplyCode（）;

      if(!FTPReply.isPositiveCompletion(reply)) {如果（！FTPReply.isPositiveCompletion（回复））{
        ftp.disconnect(); ftp.disconnect（）;
        System.err.println("FTP server refused connection."); System.err.println（“FTP服务器拒绝连接。”）;
        System.exit(1); System.exit（1）;
      } }
      ... ... // transfer files / /传送文件
      ftp.logout(); ftp.logout（）;
    } catch(IOException e) { }捕捉（IOException异常五）{
      error = true;误差为真;
      e.printStackTrace(); e.printStackTrace（）;
    } finally {最后} {
      if(ftp.isConnected()) {如果（ftp.isConnected（））{
        try {尝试{
          ftp.disconnect(); ftp.disconnect（）;
        } catch(IOException ioe) { }捕捉（IOException异常雇主组织）{
          // do nothing / /什么也不做
        } }
      } }
      System.exit(error ? 1 : 0); System.exit（错误1：0？）;
    } }

Immediately after connecting is the only real time you need to check the reply code (because connect is of type void).连接后立即是唯一真正的时候你需要检查答复代码（因为是连接类型为void）。 The convention for all the FTP command methods in FTPClient is such that they either return a boolean value or some other value.对于所有的FTP FTPClient指挥方法的公约就是这样，他们要么返回一个布尔值或其他值。 The boolean methods return true on a successful completion reply from the FTP server and false on a reply resulting in an error condition or failure.该方法返回一个布尔从FTP服务器成功完成答辩，假假真真的错误条件中的一个或故障而导致的答复。 The methods returning a value other than boolean return a value containing the higher level data produced by the FTP command, or null if a reply resulted in an error condition or failure.该方法返回一个布尔值返回值比含有较高水平的FTP命令，或者为null，如果产生一个错误条件答复或故障导致其他数据。 If you want to access the exact FTP reply code causing a success or failure, you must call getReplyCode after a success or failure.如果您要访问的FTP的确切答复代码导致成功或失败，你必须调用getReplyCode后，成功或失败。
The default settings for FTPClient are for it to use FTP.ASCII_FILE_TYPE , FTP.NON_PRINT_TEXT_FORMAT , FTP.STREAM_TRANSFER_MODE , and FTP.FILE_STRUCTURE . FTPClient的默认设置是它使用FTP.ASCII_FILE_TYPE ， FTP.NON_PRINT_TEXT_FORMAT ， FTP.STREAM_TRANSFER_MODE和FTP.FILE_STRUCTURE 。 The only file types directly supported are FTP.ASCII_FILE_TYPE and FTP.BINARY_FILE_TYPE .唯一的文件直接支持的类型是FTP.ASCII_FILE_TYPE和FTP.BINARY_FILE_TYPE 。 Because there are at least 4 different EBCDIC encodings, we have opted not to provide direct support for EBCDIC.因为至少有4种不同的EBCDIC编码，我们还选择了不提供直接支持的EBCDIC。 To transfer EBCDIC and other unsupported file types you must create your own filter InputStreams and OutputStreams and wrap them around the streams returned or required by the FTPClient methods.为了转移EBCDIC和其他不支持的文件类型，你必须创建自己的过滤InputStreams和OutputStreams和总结他们周围的流退回或由FTPClient方法所需。 FTPClient uses the NetASCII filter streams to provide transparent handling of ASCII files. FTPClient使用NetASCII过滤器流提供ASCII文件透明处理。 We will consider incorporating EBCDIC support if there is enough demand.我们会考虑把EBCDIC码的支持，如果有足够的需求。
FTP.NON_PRINT_TEXT_FORMAT , FTP.STREAM_TRANSFER_MODE , and FTP.FILE_STRUCTURE are the only supported formats, transfer modes, and file structures. FTP.NON_PRINT_TEXT_FORMAT ， FTP.STREAM_TRANSFER_MODE和FTP.FILE_STRUCTURE是唯一支持的格式，传输模式和文件结构。
Because the handling of sockets on different platforms can differ significantly, the FTPClient automatically issues a new PORT (or EPRT) command prior to every transfer requiring that the server connect to the client's data port.由于在不同平台上插座处理可以显着差异，在FTPClient自动发出一个新的端口（或EPRT）命令之前，每次传输要求的服务器连接到客户端的数据端口。 This ensures identical problem-free behavior on Windows, Unix, and Macintosh platforms.这将确保相同的Windows，Unix和Macintosh平台无故障的行为。 Additionally, it relieves programmers from having to issue the PORT (or EPRT) command themselves and dealing with platform dependent issues.此外，它解除不必发出端口（或EPRT）命令自己和与平台有关问题的程序员。
Additionally, for security purposes, all data connections to the client are verified to ensure that they originated from the intended party (host and port).此外，为了安全起见，所有的数据连接到客户端进行验证，以确保他们打算从党（主机和端口）起源。 If a data connection is initiated by an unexpected party, the command will close the socket and throw an IOException.如果一个数据连接是由党发起的一个意外，该命令将关闭套接字并抛出一个IOException异常。 You may disable this behavior with setRemoteVerificationEnabled() .您可以禁用此行为setRemoteVerificationEnabled()
You should keep in mind that the FTP server may choose to prematurely close a connection if the client has been idle for longer than a given time period (usually 900 seconds).你应该记住，在FTP服务器可以选择过早关闭连接，如果客户已超过给定的时间较长时期（通常为900秒）闲置。 The FTPClient class will detect a premature FTP server connection closing when it receives a FTPReply.SERVICE_NOT_AVAILABLE response to a command.将检测的FTPClient类FTP服务器连接过早关闭，当它收到FTPReply.SERVICE_NOT_AVAILABLE响应命令。 When that occurs, the FTP class method encountering that reply will throw an FTPConnectionClosedException . FTPConnectionClosedException is a subclass of IOException and therefore need not be caught separately, but if you are going to catch it separately, its catch block must appear before the more general IOException catch block.一旦这种情况发生时，FTP类方法遇到的答复将抛出一个FTPConnectionClosedException 。 FTPConnectionClosedException是一个子类IOException ，因此不必分别被捕获，但如果你要抓住它分开，它的catch块必须出现在更一般的IOException catch块。 When you encounter an FTPConnectionClosedException , you must disconnect the connection with disconnect() to properly clean up the system resources used by FTPClient.当你遇到一个FTPConnectionClosedException ，必须断开与连接disconnect()妥善清理，系统资源使用FTPClient。 Before disconnecting, you may check the last reply code and text with getReplyCode , getReplyString , and getReplyStrings .在断开，你可以检查代码和文本的最后答复与getReplyCode ， getReplyString和getReplyStrings 。 You may avoid server disconnections while the client is idle by periodically sending NOOP commands to the server.您可能会避免服务器断开，而客户端闲置的空操作指令通过定期发送到服务器。
Rather than list it separately for each method, we mention here that every method communicating with the server and throwing an IOException can also throw a MalformedServerReplyException , which is a subclass of IOException.它不是单独列出每个方法，我们在这里提到的每个方法与服务器通信，并抛出一个IOException异常也可引发MalformedServerReplyException ，这是一个IOException异常子类。 A MalformedServerReplyException will be thrown when the reply received from the server deviates enough from the protocol specification that it cannot be interpreted in a useful manner despite attempts to be as lenient as possible.将抛出一个MalformedServerReplyException答复时，从服务器收到的偏离足够的协议规范，它不能在一个有用的方式解释尽管试图尽可能宽松。
Listing API Examples Both paged and unpaged examples of directory listings are available, as follows:上市API的两个例子的目录列表分页和无页数的范例，如下：
Unpaged (whole list) access, using a parser accessible by auto-detect:无页数（全名单）访问，使用分析器可经自动检测：
    FTPClient f = new FTPClient(); FTPClient f =new FTPClient（）;
    f.connect(server); f.connect（服务器）;
    f.login(username, password); f.login（用户名，密码）;
    FTPFile[] files = listFiles(directory); FTPFile []文件= listfiles