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FTP网络文件传输

技术2022-05-11  0


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需要用到JAVA API提供的FtpClient,TelnetInputStream,RandomAccessFile等几个类. (1)FtpClient类 负责客户端与服务器端的通讯,实现了客户端FTP传输的功能. (2)TelnetInputStream类 负责辅助完成FTP的传输,是一种输入流类 (3)RandomAccessFile类 文件随机访问 下面实现一个FTP客户端程序,用来下载FTP服务端的文件,实现步骤如下: (1)输入服务器名以及用于登录的用户名和密码,登录FTP服务器 (2)登录成功后,列出服务器端的目录和文件名 (3)选择要下载的文件和存储的本机目录完成文件下载 创建一个包含main()方法的客户端FtpClientFrame类 package ftpclient; import java.awt.*; import java.awt.event.*; import javax.swing.*; import sun.net.ftp.*; import sun.net.*; import java.io.*; public class FtpClientFrame extends JFrame{ JPanel contentPane; Label labelPrompt=new Label(); Label labelHost=new Label(); TextField textFieldHost=new TextField(); Label labelUser=new Label(); TextField textFieldUser=new TextField(); Label labelPassword=new Label(); TextField textFieldPassword=new TextField(); Button buttonLink=new Button(); Button buttonDisconnect=new Button(); Label labelFileShow=new Label(); TextArea textAreaContent=new TextArea(); Label labelFile=new Label(); TextField textFieldFile=new TextField(); Label labelDir=new Label(); TextField textFieldDir=new TextField(); Button buttonDownload=new Button(); FtpClient myFtp=null; TelnetInputStream inStream=null; public FtpClientFrame(){ try{ jbInit(); } catch(Exception e){ e.printStackTrace(); } } private void jbInit() throws Exception{ contentPane=(JPanel)this.getContentPane(); contentPane.setLayout(null); labelPrompt.setBounds(new Rectangle(25,6,180,22)); labelHost.setText("主机名"); labelHost.setBounds(new Rectangle(25,38,50,22)); textFieldHost.setBounds(new Rectangle(78,38,280,22)); labelUser.setText("用户名"); labelUser.setBounds(new Rectangle(25,70,50,22)); textFieldUser.setBounds(new Rectangle(78,70,114,22)); labelPassword.setText("密码:"); labelPassword.setBounds(new Rectangle(205,70,37,22)); textFieldPassword.setBounds(new Rectangle(244,70,114,22)); textFieldPassword.setEchoChar('*'); buttonLink.setLabel("连接"); buttonLink.setBounds(new Rectangle(375,38,70,22)); buttonLink.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ buttonLink_actionPerformed(e); } }); buttonLink.setEnabled(true); buttonDisconnect.setLabel("断开"); buttonDisconnect.setBounds(new Rectangle(375,70,70,22)); buttonDisconnect.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ buttonDisconnect_actionPerformed(e); } }); buttonDisconnect.setEnabled(false); labelFileShow.setText("目录列表"); labelFileShow.setBounds(new Rectangle(25,105,140,22)); textAreaContent.setBounds(new Rectangle(25,135,420,235)); textAreaContent.setEditable(false); labelFile.setText("欲下载的文件"); labelFile.setBounds(new Rectangle(25,380,100,22)); textFieldFile.setBounds(new Rectangle(128,380,230,22)); labelDir.setText("存放文件的路径"); labelDir.setBounds(new Rectangle(25,412,100,22)); textFieldDir.setBounds(new Rectangle(1285,412,230,22)); buttonDownload.setLabel("下载"); buttonDownload.setBounds(new Rectangle(375,412,70,22)); buttonDownload.addActionListener(new ActionListener(){ public void actionPerformed(ActionEvent e){ buttonDownload_actionPerformed(e); } }); buttonDownload.setEnabled(false); contentPane.add(labelPrompt,null); contentPane.add(labelHost,null); contentPane.add(textFieldHost,null); contentPane.add(labelUser,null); contentPane.add(textFieldUser,null); contentPane.add(labelPassword,null); contentPane.add(textFieldPassword,null); contentPane.add(buttonLink,null); contentPane.add(buttonDisconnect,null); contentPane.add(labelFileShow,null); contentPane.add(textAreaContent,null); contentPane.add(textFieldFile,null); contentPane.add(labelFile,null); contentPane.add(labelDir,null); contentPane.add(textFieldDir,null); contentPane.add(buttonDownload,null); enableEvents(AWTEvent.WINDOW_EVENT_MASK); this.setSize(new Dimension(480,485)); this.setResizable(false); this.setTitle("ftp客户端"); this.setVisible(true); } void buttonLink_actionPerformed(ActionEvent e){ String hostname=textFieldHost.getText(); labelPrompt.setText("正在连接..."); try{ myFtp=new FtpClient(hostname); myFtp.login(textFieldUser.getText(), textFieldPassword.getText()); myFtp.binary(); showFileContents(); } catch(FtpLoginException e1){ String strPrompt="用户名密码错误"; labelPrompt.setText(strPrompt); } catch(IOException e1){ String strPrompt="连接主机"+hostname+"失败"; labelPrompt.setText(strPrompt); } catch(SecurityException e1){ String strPrompt="无权限与主机:"+hostname+"连接"; labelPrompt.setText(strPrompt); } labelPrompt.setText("连接主机:"+hostname+"成功"); buttonDisconnect.setEnabled(true); buttonDownload.setEnabled(true); buttonLink.setEnabled(false); } void buttonDisconnect_actionPerformed(ActionEvent e){ try{ myFtp.closeServer(); textAreaContent.setText(""); labelPrompt.setText("与主机断开"); } catch(IOException e1){ System.out.println("Error: "+e1); } buttonLink.setEnabled(true); buttonDownload.setEnabled(false); buttonDisconnect.setEnabled(false); } public void showFileContents(){ int ch; StringBuffer buf=new StringBuffer(); try{ inStream=myFtp.list(); while((ch=inStream.read())>=0){ buf.append((char)ch); } textAreaContent.append(buf.toString()); inStream.close(); } catch(Exception e){ System.out.println("Error: "+e); } } void buttonDownload_actionPerformed(ActionEvent e){ int ch; StringBuffer buf=new StringBuffer(); buf.setLength(0); try{ File dir=new File(textFieldDir.getText()); File f=new File(dir,textFieldFile.getText()); RandomAccessFile file=new RandomAccessFile(f,"rw"); inStream=myFtp.get(textFieldFile.getText()); while((ch=inStream.read())>=0){ buf.append((char)ch); } file.writeBytes(buf.toString()); file.close(); JOptionPane.showMessageDialog(FtpClientFrame.this, "下载成功","下载成功!",1); } catch(Exception e1){ System.out.println("Error:"+e1); } } protected void processWindowEvent(WindowEvent e){ super.processWindowEvent(e); if(e.getID()==WindowEvent.WINDOW_CLOSING){ try{ if(inStream!=null) inStream.close(); } catch(IOException e1){ System.out.println("Error: "+e1); } System.exit(0); } } public static void main(String[] args){ new FtpClientFrame(); } }

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