在Java Web Start中运行JNLP时发生NullPointerException（jar用作stardardlone）

Question

I wrote my first application and I sill can't fix one issue. When running application using Eclipse - everything works ok. After export to runnable jar (using Export required libraries into generated JAR), when running jar in Windows - everything works ok.

When I'm trying to run application using jnlp file and Java Web Start - it throws:

Exception in thread "AWT-EventQueue-2" java.lang.NullPointerException    
   at javax.swing.ImageIcon.<init>(Unknown Source)
   at MedicalOffice.MedicalOfficeView.<init>(MedicalOfficeView.java:122)

The point is that following code:

imgURL = MedicalOfficeView.class.getResource("/patientsListSmall.jpg");
patientsList.setIcon(new ImageIcon(imgURL));

throws NullPointerException.

I have image folder in my project, added it to classpath and used the code above. It works only in Eclipse and standardlone jar file. I checked jar file and image exists in main jar folder.

This is my jnlp code:

<?xml version="1.0" encoding="UTF-8"?>
<jnlp spec="1.0" codbase="http://localhost:8081/MOS/"
href="MedicalOfficeSoftware.jnlp">
    <information>
        <title>Small Medical Office Management Software</title>
        <vendor>Pawel Raczy</vendor>
        <description>MedicalOfficeManagement</description>
        <offline-allowed/>
    </information>
    <resources>
        <j2se version="1.8+"/>
        <jar href="MedicalOfficeSoftware.jar"/>
    </resources>
    <application-desc main-class="MedicalOffice.MVCMedicalOffice"/> 
</jnlp>

I also tried to use following code in my application:

URL imgURL = Thread.currentThread().getContextClassLoader().getResource("patientsListSmall.jpg");
patientsList.setIcon(new ImageIcon(imgURL));

as well as this one:

URL imgURL = getClass().getClassLoader().getResource("patientsListSmall.jpg");
patientsList.setIcon(new ImageIcon(imgURL));

Effect is the same - works only in eclipse and standardlone jar file.

Answer 1

您的签名jar清单文件中是否具有Trusted-Library属性？