简单replaceAll（）上的java.lang.NullPointerException

我尝试用java编写一个简单的strin替换。这是java代码。在我的测试环境LinuxUbuntu12.04LTS中，tomcat工作得很好。在生产环境中，它会导致空点异常

如何避免此情况…在System.out中正确显示字符串。错误是一致的

fo=fo.replaceAll("##idEelemento##", mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_NAME).toString());

这是一节课：

    /**
     * 
 */
package mdtFOP;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.util.List;
import java.util.UUID;

import org.alfresco.model.ContentModel;
import org.alfresco.service.cmr.model.FileInfo;
import org.alfresco.service.cmr.repository.ContentReader;
import org.alfresco.service.cmr.repository.ContentWriter;
import org.alfresco.service.cmr.repository.NodeRef;
import org.alfresco.service.cmr.search.ResultSet;
import org.alfresco.service.cmr.search.SearchService;
import org.alfresco.service.namespace.QName;

/**
 * @author marcello
 *
 */
public class fopMDT {
    private static String fo="";

    /** 
     * 
     */
    public fopMDT() {
        // TODO Auto-generated constructor stub
    }

    public static void GenerateLabelPaper(NodeRef nodeRef){

        ContentReader reader=null;
        System.out.println("MDT - Begin Generate label paper procedure . Class: mdtFOP. Method : GenerateLabelPaper(nodeRef) ...");
        if(mdt.mdtBehaviours.fileFolderService.getFileInfo(nodeRef).isFolder()==true){
            System.out.println("MDT - Try to generate A4 QR label PDF file for just created folder.");
            System.out.println("MDT - Loading mdtQR stylesheet for FO transformations");

            try {
                System.out.println("MDT - Reading content of barcodeFile XML file");
                String barcode= readBarcodeXML();
                System.out.println("MDT - Locate and Iterate trought fo files in mdtAdmin site");
                ResultSet fopFolder = mdt.mdtBehaviours.searchService.query(mdt.mdtBehaviours.storeRef, SearchService.LANGUAGE_XPATH, "/app:company_home/st:sites/cm:mdtadmin/cm:documentLibrary/cm:xmlTemplate/cm:FOP/cm:fo");
                List<FileInfo> foFiles = mdt.mdtBehaviours.fileFolderService.listFiles(fopFolder.getNodeRef(0));
                System.out.println("MDT - find " + foFiles.size() +" .fo files in mdtAdmin site folder: " +mdt.mdtBehaviours.fileFolderService.getFileInfo(fopFolder.getNodeRef(0)).getName());
                for (FileInfo foFile:foFiles){System.out.println("MDT - " + foFile.getName());}
                for (FileInfo foFile:foFiles){
                    System.out.println("MDT - Begin label creation for file "+ foFile.getName()+". Read content...");
                    reader = mdt.mdtBehaviours.contentService.getReader(foFile.getNodeRef(), ContentModel.PROP_CONTENT);
                    fo = reader.getContentString();
                    System.out.println("MDT - DEBUG - fo content: " + "\r" + fo);
                    System.out.println("MDT - Inject folder data before PDF creation from folder: " + mdt.mdtBehaviours.fileFolderService.getFileInfo(nodeRef).getName());
                    System.out.println("MDT - Inject idElemento: " + mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_NAME).toString());
                    fo=fo.replaceAll("##idEelemento##", mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_NAME).toString());
                    System.out.println("MDT - Inject descrizione: " + mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_DESCRIPTION).toString());
                    fo=fo.replaceAll("##descrizione##", mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_DESCRIPTION).toString());
                    System.out.println("MDT - Inject articolo: "+ mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_DESCRIPTION).toString());
                    fo=fo.replaceAll("##articolo##", mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_DESCRIPTION).toString());
                    System.out.println("MDT - Inject barcode data before PDF creation...");
                    fo=fo.replaceAll("<fo:inline>mdtQRCODE</fo:inline>", barcode.replaceAll("MDTQRMDTQR", mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_NAME).toString()));
                    String tempFileName = String.valueOf(UUID.randomUUID())+".fo";
                    System.out.println("MDT - Begin fo transfomation on disk for file: " + foFile.getName());
                    try{
                        System.out.println("MDT - TempFileName: " + tempFileName);
                        File tempFile = new File(tempFileName);
                        FileWriter file = new FileWriter(tempFile);
                        BufferedWriter out = new BufferedWriter (file);
                        out.write(fo);
                        out.close();
                        System.out.println("MDT - Starting FOP from command line: ");
                        Process fop;
                        String fopCommand = "/opt/fop-1.1/fop -fo "+tempFileName+" -pdf "+tempFileName+".pdf";
                        System.out.println("MDT - " + fopCommand);
                        fop= Runtime.getRuntime().exec(fopCommand);
                        int fopExit =fop.waitFor();
                        if (fopExit==0){
                            System.out.println("MDT - Conversion with FOP terminate WITHOUT error.");
                            QName contentQName = QName.createQName("{http://www.alfresco.org/model/content/1.0}content");
                            FileInfo pdfFile = mdt.mdtBehaviours.fileFolderService.create(nodeRef,"QR-"+tempFileName+"-"+mdt.mdtBehaviours.nodeService.getProperty(nodeRef, ContentModel.PROP_NAME).toString()+".pdf", contentQName);
                            NodeRef pdf = pdfFile.getNodeRef();
                            ContentWriter writer = mdt.mdtBehaviours.contentService.getWriter(pdf, ContentModel.PROP_CONTENT, true);
                            System.out.println("MDT - Put PDF label file, " +pdfFile.getName()+" in MDT folder: " + mdt.mdtBehaviours.fileFolderService.getFileInfo(nodeRef).getName() );
                            writer.setMimetype("application/pdf");
                            writer.guessEncoding();
                            tempFile= new File(tempFileName+".pdf");
                            writer.putContent(tempFile);
                        }
                    }catch (Exception e){
                        System.out.println("MDT - Something went wrong during FOP conversion: error Stack: "+ e.getMessage());
                        e.printStackTrace();
                    } finally {
                        System.out.println("MDT - Delete .fo and .pdf temporary files from disk.");
                        File f = new File(tempFileName);
                        if (f.exists()){f.delete();};
                        f=  new File(tempFileName+".pdf");
                        if (f.exists()){f.delete();};   
                        System.out.println("MDT - Temporary file deleted");

                    }
                }

            } catch (Exception e){
                System.out.println("MDT - Something went wrong in FOP conversion routine: error Stack: "+ e.getMessage());
                e.printStackTrace();

            }

        } else { System.out.println("MDT - Skip QR creation on this behaviours because node is type:content");
        }
    }





public static String readBarcodeXML(){
    ContentReader reader=null;
    ResultSet barcodeConfigFile= mdt.mdtBehaviours.searchService.query(mdt.mdtBehaviours.storeRef, SearchService.LANGUAGE_XPATH, "/app:company_home/st:sites/cm:mdtadmin/cm:documentLibrary/cm:xmlTemplate/cm:FOP/cm:barcodeConfig.properties");
    reader = mdt.mdtBehaviours.contentService.getReader(barcodeConfigFile.getNodeRefs().get(0), ContentModel.PROP_CONTENT);
    String barcodeXMLFileName = reader.getContentString();
    System.out.println("MDT - Barcode file name from : "+ mdt.mdtBehaviours.fileFolderService.getFileInfo(barcodeConfigFile.getNodeRef(0)).getName());

    ResultSet barcodeFile= mdt.mdtBehaviours.searchService.query(mdt.mdtBehaviours.storeRef, SearchService.LANGUAGE_XPATH, "/app:company_home/st:sites/cm:mdtadmin/cm:documentLibrary/cm:xmlTemplate/cm:FOP/cm:"+barcodeXMLFileName);
    System.out.println("MDT - Using Barcode file name : "+ mdt.mdtBehaviours.fileFolderService.getFileInfo(barcodeFile.getNodeRef(0)).getName());
    reader = mdt.mdtBehaviours.contentService.getReader(barcodeFile.getNodeRef(0), ContentModel.PROP_CONTENT);
    String barcode = reader.getContentString();
    System.out.println("MDT - DEBUG : QR barcode XML file content: " + "\r" + barcode);
    return barcode;
}



    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub

    }

}

在应用该方法之前进行空检查

if(fo!=null)
 fo=fo.replaceAll("##idEelemento##", mdt.mdtBehaviours.nodeService.getProperty(nodeRef,      ContentModel.PROP_NAME).toString());
}

---

所以，您知道错误在哪一行。你有没有弄清楚哪个变量没有引用一个值？这是第一步。你能在130行以内复制它吗？我怀疑问题中90%的代码是不相关的。很简单：fo为null，或者mdt为null，或者mdt.mdtBehaviours为null，或者mdt.mdtBehaviours.nodeService为null，或者mdt.mdtBehaviours.nodeService.getPropertynodeRef，ContentModel.PROP_NAME为null，或者getProperty方法中的某些内容为null确定fo为null？