java使用ftp下载文件到本地（只是下载）
1.添加依赖
camel-ftp依赖与commons-net依赖两者取其中一个即可
2.辅助类
package com.zq.util;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;
import java.io.*;
import java.net.SocketException;
/**
* Created by java1 on 2018/1/23 0031.
*/
public class FtpUtil {
private final static Log logger = LogFactory.getLog(FtpUtil.class);
/**
* 获取FTPClient对象
*
* @param ftpHost
* FTP主机服务器
* @param ftpPassword
* FTP 登录密码
* @param ftpUserName
* FTP登录用户名
* @param ftpPort
* FTP端口 默认为21
* @return
*/
public static FTPClient getFTPClient(String ftpHost, String ftpUserName,
String ftpPassword, int ftpPort) {
FTPClient ftpClient = new FTPClient();
try {
ftpClient = new FTPClient();
ftpClient.connect(ftpHost, ftpPort);// 连接FTP服务器
ftpClient.login(ftpUserName, ftpPassword);// 登陆FTP服务器
if (!FTPReply.isPositiveCompletion(ftpClient.getReplyCode())) {
logger.info("未连接到FTP，用户名或密码错误。");
ftpClient.disconnect();
} else {
logger.info("FTP连接成功。");
}
} catch (SocketException e) {
e.printStackTrace();
logger.info("FTP的IP地址可能错误，请正确配置。");
} catch (IOException e) {
e.printStackTrace();
logger.info("FTP的端口错误,请正确配置。");
}
return ftpClient;
}
/*
* 从FTP服务器下载文件
*
* @param ftpHost FTP IP地址
*
* @param ftpUserName FTP 用户名
*
* @param ftpPassword FTP用户名密码
*
* @param ftpPort FTP端口
*
* @param ftpPath FTP服务器中文件所在路径 格式： zq/ftp路劲 fdfd/aa
*
* @param localPath 下载到本地的位置 格式：H:/download
*
* @param fileName 文件名称
*/
public static void downloadFtpFile(String ftpHost, String ftpUserName,
String ftpPassword, int ftpPort, String ftpPath, String localPath,
String fileName) {
FTPClient ftpClient = null;
try {
ftpClient = getFTPClient(ftpHost, ftpUserName, ftpPassword, ftpPort);
ftpClient.setControlEncoding("UTF-8"); // 中文支持
ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
ftpClient.enterLocalPassiveMode();
ftpClient.changeWorkingDirectory(ftpPath);
File localFile = new File(localPath + File.separatorChar + fileName);
OutputStream os = new FileOutputStream(localFile);
ftpClient.retrieveFile(fileName, os);
os.close();
ftpClient.logout();
} catch (FileNotFoundException e) {
logger.error("没有找到" + ftpPath + "文件");
e.printStackTrace();
} catch (SocketException e) {
logger.error("连接FTP失败.");
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
logger.error("文件读取错误。");
e.printStackTrace();
}
}
}
3.测试（这一步测试其实是把文件从ftp上拉到（或复制到）本地自定义的文件夹下面）
package com.zq.down;
import com.zq.util.FtpUtil;
/**
* Created by java1 on 2018/1/23 0023.
*/
public class FtpDownloadTestScriptTest {
public static void main(String[] args) {
String ftpHost = "10.1.1.123";
String ftpUserName = "123";
String ftpPassword = "123456";
int ftpPort = 21;
String ftpPath = "/";//ftp根目录
String localPath = "E:\\TestTxt";
String fileName = "c4.zip";
FtpUtil.downloadFtpFile(ftpHost, ftpUserName, ftpPassword, ftpPort, ftpPath, localPath, fileName);
}
}
4. （1,2,3步骤是把文件拉到本地，如果说在界面想出现下载界面的话可以发送ajax请求。下面是我写的，仅供参考）
$.ajax({
type: 'POST',
dataType: 'json',
url: "/device/exportLog",
data: { 'deviceSn': deviceSn } ,
timeout: 10000,
success: function ( data ) {
if(data.status){
Messenger().post({
message: data.info,
type: 'success',
showCloseButton: true
}) ;
var FileName = deviceSn.toLowerCase()+".zip";
var url = window.location.protocol + "//" + window.location.host + "/device/deviceLogdownFromHttp?fileName="+FileName;
window.location.href = url;
}else{
Messenger().post({
message: data.info,
type: 'error',
showCloseButton: true
}) ;
}
}
});
5.后台：
/**
* 下载zip文件
* */
@RequestMapping("/deviceLogdownFromHttp")
public void deviceLogdownFromHttp(HttpServletRequest request, HttpServletResponse response)throws Exception{
String fileName = request.getParameter("fileName");
try{
String resultPath =PropertyUtil.getProperty("tasksave.filePath")+"/"+fileName;// "E://AllTxt//zqzipzipzipzipzip.rar";
String zipName = resultPath.substring(0,resultPath.lastIndexOf(".")) + ".zip";
File zipFile = new File(zipName);
//读写zip文件
InputStream fis = new BufferedInputStream(new FileInputStream(zipFile));
byte[] buffer = new byte[fis.available()];
fis.read(buffer);
fis.close();
response.reset();
String targetName = zipName.substring(zipName.lastIndexOf("/")+1);
targetName = new String(targetName.getBytes("UTF-8"), "ISO-8859-1");
response.setHeader("Content-Disposition", "attachment; filename=\"" + targetName + "\"");
response.addHeader("Content-lenth", "" + buffer.length);
response.setContentType("application/octet-stream;charset=UTF-8");
OutputStream os = new BufferedOutputStream(response.getOutputStream());
os.write(buffer);
os.flush();
os.close();
response.flushBuffer();
String cc=fileName.substring(0,fileName.lastIndexOf(".")).toUpperCase();
sysLogMapper.deleteDownloadLogTaskByDeviceSn(fileName.substring(0,fileName.lastIndexOf(".")).toUpperCase());
}catch(Exception e){
e.printStackTrace();
}
}
6.（4,5步骤仅供参考，每个人写的不一样。）
主要是：
var FileName = deviceSn.toLowerCase()+".zip";
var url = window.location.protocol + "//" + window.location.host + "/device/deviceLogdownFromHttp?fileName="+FileName;
window.location.href = url;（前台）
(后台):deviceLogdownFromHttp这个方法