Question

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

能帮我吗？代码写了第一张图片，然后完全停止了写。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。这实际上是一种方法。

    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）

以退出代码1退出的进程。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（在这种情况下，您可以检查回复代码以确定失败的确切原因）。 < / p>

因此您的代码应该执行以下操作：

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

在我看来，原因是

550权限被拒绝。

在我的情况下，可以通过编辑/etc/vsftpd.conf来治愈

并更改为

write_enable = YES

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

此处是完整的示例

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();
        }
    }

无法在FTP服务器上写入多个文件

1 个答案: