摘要：需要用到寫一個的工具，因為只有一點點基礎，但是由于好幾年不用，幾乎算是不會了，只好一點點來搞，還好能撿起來。對于下載工具，代碼如下這個工具是為了配合另外一個工具做集群上傳用的，所以里面的把和流分開了，也是為了方便另外一個工具使用。

需要用到 java 寫一個 ftp 的工具，因為只有一點點 java 基礎，但是由于好幾年不用，幾乎算是不會了，只好一點點來搞，還好能撿起來。

不過因為是在 Linux 下使用 javac 編譯，不是在 WIN 下使用 IDE 來做這些事情，所以在運行和編譯上又費了一些時間，不過正是因為這樣對 JAVA 的一些編譯、運行的知識又了解了一些。

對于 ftp 下載工具，代碼如下：

import java.io.File;   
import java.io.FileInputStream;   
import java.io.FileNotFoundException;   
import java.io.FileOutputStream;   
import java.io.IOException;   
import java.io.InputStream;   
import java.io.OutputStream;   
import java.net.SocketException;   

import org.apache.commons.net.ftp.FTPClient;   
import org.apache.commons.net.ftp.FTPReply;   


public class FtpClient {
    private String         host;   
    private int            port;   
    private String         username;   
    private String         password;   

    private boolean        binaryTransfer = true;   
    private boolean        passiveMode    = true;   
    private String         encoding       = "UTF-8";   
    private int            clientTimeout  = 3000;   
    private boolean flag=true;
    private FTPClient ftpClient = null;

    public String getHost() {   
        return host;   
    }   

    public void setHost(String host) {   
        this.host = host;   
    }   

    public int getPort() {   
        return port;   
    }   

    public void setPort(int port) {   
        this.port = port;   
    }   

    public String getUsername() {   
        return username;   
    }   

    public void setUsername(String username) {   
        this.username = username;   
    }   

    public String getPassword() {   
        return password;   
    }   

    public void setPassword(String password) {   
        this.password = password;   
    }   

    public boolean isBinaryTransfer() {   
        return binaryTransfer;   
    }   

    public void setBinaryTransfer(boolean binaryTransfer) {   
        this.binaryTransfer = binaryTransfer;   
    }   

    public boolean isPassiveMode() {   
        return passiveMode;   
    }   

    public void setPassiveMode(boolean passiveMode) {   
        this.passiveMode = passiveMode;   
    }   

    public String getEncoding() {   
        return encoding;   
    }   

    public void setEncoding(String encoding) {   
        this.encoding = encoding;   
    }   

    public int getClientTimeout() {   
        return clientTimeout;   
    }   

    public void setClientTimeout(int clientTimeout) {   
        this.clientTimeout = clientTimeout;   
    }   

    public FtpClient(String Host) {
        this.username = "anonymous";
        this.encoding = "utf-8";
        this.binaryTransfer = true;
        this.binaryTransfer = true;
        this.port = 21;
        this.host = Host;
        try {
            this.ftpClient = getFTPClient();
        } catch (Exception e) {
            System.out.println("Create FTPClient error!");
        }
    }

    private FTPClient getFTPClient() throws IOException {   
        FTPClient ftpClient = new FTPClient(); 
        ftpClient.setControlEncoding(encoding);

        connect(ftpClient);
        if (passiveMode) {   
            ftpClient.enterLocalPassiveMode();   
        }   
        setFileType(ftpClient); 

        try {   
            ftpClient.setSoTimeout(clientTimeout);   
        } catch (SocketException e) {   
            throw new IOException("Set timeout error.", e);   
        }   

        return ftpClient;   
    }   

    private void setFileType(FTPClient ftpClient) throws IOException {   
        try {   
            if (binaryTransfer) {   
                ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);   
            } else {   
                ftpClient.setFileType(FTPClient.ASCII_FILE_TYPE);   
            }   
        } catch (IOException e) {   
            throw new IOException("Could not to set file type.", e);   
        }   
    }   

    public boolean connect(FTPClient ftpClient) throws IOException {   
        try {   
            ftpClient.connect(host, port);   

            int reply = ftpClient.getReplyCode();   

            if (FTPReply.isPositiveCompletion(reply)) {   
                if (ftpClient.login(username, password)) {   
                    setFileType(ftpClient);   
                    return true;   
                }   
            } else {   
                this.ftpClient.disconnect();   
                throw new IOException("FTP server refused connection.");   
            }   
        } catch (IOException e) {   
            if (this.ftpClient.isConnected()) {   
                try {   
                    this.ftpClient.disconnect();
                } catch (IOException e1) {   
                    throw new IOException("Could not disconnect from server.", e);   
                }   

            }   
            throw new IOException("Could not connect to server.", e);   
        }   
        return false;   
    }   

    private void disconnect() throws IOException {   
        try {   
            this.ftpClient.logout();   
        } catch (IOException e) {   
            System.out.println("logout may timeout!");
        } finally {
            if (this.ftpClient.isConnected()) {   
                this.ftpClient.disconnect();   
            }   
        }  
    }   

    public InputStream getStream(String serverFile) throws IOException {
        InputStream inStream = null;
        try {
            inStream = this.ftpClient.retrieveFileStream(serverFile);
            System.out.println("inStream get over!");
            return inStream;
        } catch (IOException e) {
            System.out.println("get stream exception");
            return null;
        }
    }

    public boolean writeStream(InputStream input, String localFile) throws IOException {
        FileOutputStream fout = new FileOutputStream(localFile);
        int ch = 0;
        if(input == null){
            System.out.println("input is null");
            return false;
        }
        try {
            ch = input.read();
            while(ch != -1){
                fout.write(ch);
                ch = input.read();
            }
            System.out.println("write over!");
            return flag;
        } catch (IOException e) {
            throw new IOException("Couldn"t get file from server.", e);
        } 
    }

    public boolean isExist(String remoteFilePath)throws IOException{

        try{
            File file=new File(remoteFilePath);

            String remotePath=remoteFilePath.substring(0,(remoteFilePath.indexOf(file.getName())-1));
            String[] listNames = this.ftpClient.listNames(remotePath);   
            System.out.println(remoteFilePath);
            for(int i=0;i

這個工具是為了配合另外一個 Hadoop 工具做 集群上傳用的，所以里面的把 input 和 output 流分開了，也是為了方便另外一個工具使用。


補充一點，如何在 linux 配置運行：

如果這樣的代碼需要在 linux 下環境運行，首先要配置好響應的包，例如

import org.apache.commons.net.ftp.FTPClient; 


這個包在 apache 的網站上直接下載就行，解壓后找到對應的 jar 包，在編譯的時候進行引用：

export FTPPATH="${路徑}/xxx.jar"
javac -classpath $CLASSPATH:$FTPPATH FtpClient.java


同樣，在運行的時候也要指定 classpath：

java -classpath $CLASSPATH:$FTPPATH FtpClient


建議不要把$FTPPATH 包含在 CLASSPATH 中，用什么包就引用什么環境變量就行了，沒必要一股腦都添加進去，就像我們沒必要 import 所有的包一樣。