[英]Java - Getting corrupted JPG while uploading using FTP connection?
以下代碼用於在JAVA中使用FTP上載三個JPG-Image文件。 文件上傳並通過“成功”消息確認，但文件已損壞。 小的小縮略圖文件部分可讀（前四分之一）。
我試着在網上搜索並補充道
setFileType(FTPClient.BINARY_FILE_TYPE);
但問題仍然存在:(
有人可以看看它並給我一個暗示或建議嗎？
碼：
package de.immozukunft.programs;
import java.io.*;
import java.util.Locale;
import java.util.ResourceBundle;
import org.apache.commons.net.ftp.FTPClient;
/**
* This class enables the ability to connect and trasfer data to the FTP server
*/
public class FtpUpDown {
static Locale locale = new Locale("de"); // Locale is set to "de" for
// Germany
static ResourceBundle r = ResourceBundle.getBundle("Strings", locale); // ResourceBundle
// for
// different
// languages
// and
// String
// Management
// FTP-Connection properties
static String host = "IP-address"; //Host
static String username = "username"; // Username
static int port = 21; //Port
static String password = "password"; // Password
/**
* <h3>FTP-connection tester</h3>
*
*/
public static boolean connect() {
FTPClient ftpClient = new FTPClient();
try {
ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
ftpClient.connect(host, port);
ftpClient.login(username, password);
ftpClient.logout();
ftpClient.disconnect();
} catch (Exception e) {
// e.printStackTrace();
System.err.println("Unable to connect"); // TODO String einfügen
return (false);
}
System.out.println("Connection established"); // TODO String einfügen
return (true);
}
/**
* <h3>FTP-Status</h3>
*
* @return
* @throws IOException
*/
static public String getStatus() {
if (connect()) {
return (r.getString("successConnectFTP"));
} else {
return (r.getString("unableToConnectFTP"));
}
}
/**
* <h3>FTP-filelist</h3>
*
* @return String-Array der Dateinamen auf dem FTP-Server
*/
public static String[] list() throws IOException {
FTPClient ftpClient = new FTPClient();
String[] filenameList;
try {
ftpClient.connect(host, port);
ftpClient.login(username, password);
filenameList = ftpClient.listNames();
ftpClient.logout();
} finally {
ftpClient.disconnect();
}
return filenameList;
}
/**
* <h3>FTP-Client-Download:</h3>
*
* @return true falls ok
*/
public static boolean download(String localResultFile,
String remoteSourceFile, boolean showMessages) throws IOException {
FTPClient ftpClient = new FTPClient();
FileOutputStream fos = null;
boolean resultOk = true;
try {
ftpClient.connect(host, port);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.login(username, password);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
fos = new FileOutputStream(localResultFile);
resultOk &= ftpClient.retrieveFile(remoteSourceFile, fos);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.logout();
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
} finally {
try {
if (fos != null) {
fos.close();
}
} catch (IOException e) {/* nothing to do */
}
ftpClient.disconnect();
}
return resultOk;
}
/**
* <h3>FTP-Client-Upload:</h3>
*
* @param localSourceFile
* The source of local file
* @param remoteResultFile
* Set the destination of the file
* @param showMessages
* If set on TRUE messages will be displayed on the console
* @return true Returns If successfully transfered it will return TRUE, else
* FALSE
*/
public static boolean upload(String localSourceFile,
String remoteResultFile, boolean showMessages) throws IOException {
FTPClient ftpClient = new FTPClient();
FileInputStream fis = null;
boolean resultOk = true;
try {
ftpClient.connect(host, port);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.login(username, password);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
fis = new FileInputStream(localSourceFile);
resultOk &= ftpClient.storeFile(remoteResultFile, fis);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.logout();
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
} finally {
try {
if (fis != null) {
fis.close();
}
} catch (IOException e) {/* nothing to do */
}
ftpClient.disconnect();
}
return resultOk;
}
// Setter and Getter-methods
public static String getHost() {
return host;
}
public static void setHost(String host) {
FtpUpDown.host = host;
}
public static String getUsername() {
return username;
}
public static void setUsername(String username) {
FtpUpDown.username = username;
}
public static int getPort() {
return port;
}
public static void setPort(int port) {
FtpUpDown.port = port;
}
public static String getPassword() {
return password;
}
public static void setPassword(String password) {
FtpUpDown.password = password;
}
}
招呼
THE-E
所以我終於弄明白了問題所在。
問題是由setFileType(FTPClient.BINARY_FILE_TYPE)的順序引起的。 它需要在fis = new FileInputStream(localSourceFile)和ftpClient.storeFile(remoteResultFile, fis) fis = new FileInputStream(localSourceFile)之前定位在upload() - ftpClient.storeFile(remoteResultFile, fis)
所以完整的工作代碼是：
import java.io.*;
import java.util.Locale;
import java.util.ResourceBundle;
import org.apache.commons.net.ftp.FTPClient;
/**
* This class enables the ability to connect and trasfer data to the FTP server
*/
public class FtpUpDown {
static Locale locale = new Locale("de"); // Locale is set to "de" for
// Germany
static ResourceBundle r = ResourceBundle.getBundle("Strings", locale); // ResourceBundle
// for
// different
// languages
// and
// String
// Management
// FTP-Connection properties
static String host = "IP-Address"; // IP-address
static String username = "username"; // Username
static int port = 21; // Port
static String password = "password"; // Password
/**
* <h3>FTP-connection tester</h3>
*
*/
public static boolean connect() {
FTPClient ftpClient = new FTPClient();
try {
ftpClient.connect(host, port);
ftpClient.login(username, password);
ftpClient.logout();
ftpClient.disconnect();
} catch (Exception e) {
// e.printStackTrace();
System.err.println("Unable to connect"); // TODO String einfügen
return (false);
}
System.out.println("Connection established"); // TODO String einfügen
return (true);
}
/**
* <h3>FTP-Status</h3>
*
* @return
* @throws IOException
*/
static public String getStatus() {
if (connect()) {
return (r.getString("successConnectFTP"));
} else {
return (r.getString("unableToConnectFTP"));
}
}
/**
* <h3>FTP-filelist</h3>
*
* @return String-Array der Dateinamen auf dem FTP-Server
*/
public static String[] list() throws IOException {
FTPClient ftpClient = new FTPClient();
String[] filenameList;
try {
ftpClient.connect(host, port);
ftpClient.login(username, password);
filenameList = ftpClient.listNames();
ftpClient.logout();
} finally {
ftpClient.disconnect();
}
return filenameList;
}
/**
* <h3>FTP-Client-Download:</h3>
*
* @return true falls ok
*/
public static boolean download(String localResultFile,
String remoteSourceFile, boolean showMessages) throws IOException {
FTPClient ftpClient = new FTPClient();
FileOutputStream fos = null;
boolean resultOk = true;
try {
ftpClient.connect(host, port);
ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.login(username, password);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
fos = new FileOutputStream(localResultFile);
resultOk &= ftpClient.retrieveFile(remoteSourceFile, fos);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.logout();
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
} finally {
try {
if (fos != null) {
fos.close();
}
} catch (IOException e) {/* nothing to do */
}
ftpClient.disconnect();
}
return resultOk;
}
/**
* <h3>FTP-Client-Upload:</h3>
*
* @param localSourceFile
* The source of local file
* @param remoteResultFile
* Set the destination of the file
* @param showMessages
* If set on TRUE messages will be displayed on the console
* @return true Returns If successfully transfered it will return TRUE, else
* FALSE
*/
public static boolean upload(String localSourceFile,
String remoteResultFile, boolean showMessages) throws IOException {
FTPClient ftpClient = new FTPClient();
FileInputStream fis = null;
boolean resultOk = true;
try {
ftpClient.connect(host, port);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.login(username, password);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
fis = new FileInputStream(localSourceFile);
ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
resultOk &= ftpClient.storeFile(remoteResultFile, fis);
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
resultOk &= ftpClient.logout();
if (showMessages) {
System.out.println(ftpClient.getReplyString());
}
} finally {
try {
if (fis != null) {
fis.close();
}
ftpClient.disconnect();
} catch (IOException e) {/* nothing to do */
}
}
return resultOk;
}
// Setter and Getter-methods
public static String getHost() {
return host;
}
public static void setHost(String host) {
FtpUpDown.host = host;
}
public static String getUsername() {
return username;
}
public static void setUsername(String username) {
FtpUpDown.username = username;
}
public static int getPort() {
return port;
}
public static void setPort(int port) {
FtpUpDown.port = port;
}
public static String getPassword() {
return password;
}
public static void setPassword(String password) {
FtpUpDown.password = password;
}
}
您為每個操作創建一個新連接，並且某些代碼路徑不設置“二進制文件”標志（即上載和下載方法）。
setFileType(FTPClient.BINARY_FILE_TYPE)是正確的做法，但在你提供的代碼中，它只在connect() ，而在download()沒有調用。
即使在download() disconnect()中調用它，也會調用disconnect()來結束會話。
結論：你需要在download()方法中調用setFileType(FTPClient.BINARY_FILE_TYPE)在setFileType(FTPClient.BINARY_FILE_TYPE) ftpClient.connect(host, port)之后調用upload()方法
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