java - 无法在 FTP 服务器上写入多个文件

Question

您好，我在 OutputStream out = ftp.storeFileStream(path); 上遇到了诸如 java.lang.NullPointerException 之类的错误。当我写入一个文件后，无法继续在 FTP 服务器上写入第二个文件。

你能帮我一下吗？代码写了第一张图片并完全停止了写。这是我的方法代码........

    public void getIncidentPhotoByID(int incidentid, int photoId) {
    String base64Image = null;
    WebSSLClient client = new WebSSLClient();
    String photo_Id= "incident_"+incidentid;
    String jsonResponse,jsonResImg; 
    Response response =client.createRequest(PropertiesUtil.getOracleCloudRestUrL() + "/mobile/platform/storage/collections/dev_cre_incident_photos_collection/objects").get();
    jsonResponse = response.readEntity(String.class); 
    Map<String,String> imgMap = new HashMap<>();     
    try {
        JSONObject jsonObj = new JSONObject(jsonResponse);
        JSONArray jsonArr = jsonObj.getJSONArray("items");
        for (int i = 0; i < jsonArr.length(); ++i) {
            JSONObject rec = jsonArr.getJSONObject(i);
            String name = rec.getString("name");             
            String name_id = removeStr(name);
            if(name_id.equals(photo_Id)){ 
                Response response1 =client.createRequest(PropertiesUtil.getOracleCloudRestUrL() + "/mobile/platform/storage/collections/dev_cre_incident_photos_collection/objects/"+name).get();
                jsonResImg = response1.readEntity(String.class); 
                imgMap.put(name, jsonResImg);
            }           
        }            
    } catch (JSONException e) {
        e.getMessage();
    }

我将发布 2 个单独的代码。其实也是一种方法。

    FTPClient ftp = new FTPClient();  
    FileInputStream fis = null;
     try  {                 
          ftp.connect("link.myjpl.com");
          ftp.login("user", "password");
          ftp.setFileType(FTPClient.BINARY_FILE_TYPE);
            Set set;
            set = imgMap.entrySet();
            Iterator iterator = set.iterator();
            while(iterator.hasNext()) {
                Map.Entry mentry = (Map.Entry)iterator.next();

                base64Image = mentry.getValue().toString();
                      System.out.println(base64Image);
                String filename =  mentry.getKey().toString();
                     System.out.println(filename);
                String[] strings = base64Image.split(",");
                String extension;
                   switch (strings[0]) {//check image's extension
                       case "data:image/jpeg;base64":
                           extension = "jpeg";
                           break;
                       case "data:image/png;base64":
                           extension = "png";
                           break;
                       default://should write cases for more images types
                           extension = "jpg";
                           break;
                   }   
                       byte[] data1 = Base64.decodeBase64(strings[1]);
                       String dirPath ="ReportImages/test/";
                       String dir = dirPath+photo_Id;
                       boolean dirExists = ftp.changeWorkingDirectory(dir);
                       if(!dirExists){
                           ftp.makeDirectory(dir);  
                       }
                       String path = dir+"/"+filename+"."+ extension;                        

                       OutputStream out = ftp.storeFileStream(path);
                       out.write(data1); 
                       ftp.completePendingCommand();
                       out.flush();
             }
                    ftp.disconnect();                             
        } catch (IOException e) {
            System.out.print(e);
            e.printStackTrace();
            System.out.println("Error while FTP'ing ");   
        } 
} 

这是 NPE 错误!

SEVERE: 

java.lang.NullPointerException 在 com.scm.cre.cloud.model.services.CareCloudDbAppModuleImpl.getIncidentPhotoByID(CareCloudDbAppModuleImpl.java:144) 在 com.scm.cre.batch.job.ConnectTest.callRestAip(ConnectTest.java:20) 在 com.scm.cre.batch.CareExecutor.main(CareExecutor.java:84)

进程已退出，退出代码为 1。这是一个屏幕截图...... enter image description here

Answer 1

看看javadocs

它说:

如果无法打开数据连接(例如文件不存在)，则返回null(此时可以检查回复码以确定失败的具体原因)。

因此你的代码应该这样做:

if (out == null) {
    System.out.println(ftp.getReplyCode());
    System.out.println (ftp.getReplyString());
}

就我而言，原因是

550 权限被拒绝。

就我而言，可以通过编辑/etc/vsftpd.conf 来解决

并更改为

write_enable=YES

保存文件并使用 sudo service vsftpd restart 重新启动 vsftpd。

这里是一个更完整的示例

FTPClient ftp = new FTPClient();

try {
    ftp.connect("somehost");
    ftp.login("user", "pw");
    ftp.enterLocalPassiveMode();

    OutputStream out = ftp.storeFileStream("dump1");
    if (out == null) {
        System.out.println(ftp.getReplyCode());
        System.out.println (ftp.getReplyString());
        return;
    }
    out.write("test is a test".getBytes());
    out.flush();
    out.close();
    System.out.println (ftp.getReplyString());
    ftp.completePendingCommand();
    System.out.println (ftp.getReplyString());

    out = ftp.storeFileStream("dump2");
    if (out == null) {
        System.out.println(ftp.getReplyCode());
        System.out.println (ftp.getReplyString());
        return;
    }
    out.write("test is a test2".getBytes());
    out.flush();
    out.close();
    System.out.println (ftp.getReplyString());
    ftp.completePendingCommand();
    System.out.println (ftp.getReplyString());

} catch (IOException e) {
    e.printStackTrace();
}
    finally {
        try {
            ftp.disconnect();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }