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：
復制代碼代碼如下:
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<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();
}
}
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
復制代碼代碼如下:
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：
復制代碼代碼如下:
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：
復制代碼代碼如下:
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。
以上所述就是本文的全部內容了，希望能夠對大家學習java有所幫助。
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