java编写ftp下载工具

需要用到 java 写一个 ftp 的工具，因为只有一点点 java 基础，但是由于好几年不用，几乎算是不会了，只好一点点来搞，还好能捡起来。

不过因为是在 Linux 下使用 javac 编译，不是在 WIN 下使用 IDE 来做这些事情，所以在运行和编译上又费了一些时间，不过正是因为这样对 JAVA 的一些编译、运行的知识又了解了一些。

对于 ftp 下载工具，代码如下：

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<listNames.length;i++){
                System.out.println(listNames[i]);
                if(remoteFilePath.equals(listNames[i])){
                    flag=true;
                    System.out.println("file:"+file.getName()+" existed");
                    break;
                }else {
                    flag=false;
                }
            }
        } catch (IOException e) {  
            throw new IOException("FILE EXCEPTION", e);  
        }
        return flag;
    }
    //main for testing
    public static void main(String[] args) throws IOException {  
        String hostname = "cp01-testing-ps7130.cp01.baidu.com";
        String serverFile="/home/work/check_disk.sh";
        String localFile="/home/work/workspace/project/dhc2-0/dhc/base/ftp/task_get";
        FtpClient ftp = new FtpClient(hostname);  
        System.out.println(ftp.isExist(serverFile));
        ftp.writeStream(ftp.getStream(serverFile), localFile);
        ftp.disconnect();
    }  
}

这个工具是为了配合另外一个 Hadoop 工具做 集群上传用的，所以里面的把 input 和 output 流分开了，也是为了方便另外一个工具使用。

补充一点，如何在 linux 配置运行：

如果这样的代码需要在 linux 下环境运行，首先要配置好响应的包，例如

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

这个包在 apache 的网站上直接下载就行，解压后找到对应的 jar 包，在编译的时候进行引用：

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

同样，在运行的时候也要指定 classpath：

java -classpath $CLASSPATH:$FTPPATH FtpClient

建议不要把$FTPPATH 包含在 CLASSPATH 中，用什么包就引用什么环境变量就行了，没必要一股脑都添加进去，就像我们没必要 import 所有的包一样。

以上所述就是本文的全部内容了，希望能够对大家学习java有所帮助。

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