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Error writing file from Java applet

I created a simple Java class for checking file write from applets:
update appeared

public class localfile extends Applet{
public localfile(){
    try {
        File f = new File("testfile.txt");
        BufferedWriter out = new BufferedWriter(new FileWriter(f,true));
        out.write("test");
        out.close();
    }
    catch(Exception x)
       System.err.println(x.toString());
   }
}

I created and signed the bank:

jar cvf localfile.jar localfile.java
jarsigner localfile.jar yourkey

html looks like this:    <applet code="localfile.class" archive="localfile.jar", width=300, height=600>

The error I get every time I run this applet:

java.lang.SecurityException: trusted loader attempted to load sandboxed resource from file:/home/w/test/
at com.sun.deploy.security.CPCallbackHandler$ParentCallback.check(CPCallbackHandler.java:308)
at com.sun.deploy.security.CPCallbackHandler$ParentCallback.access$1400(CPCallbackHandler.java:121)
at com.sun.deploy.security.CPCallbackHandler$ChildElement.checkResource(CPCallbackHandler.java:473)
at sun.plugin2.applet.Plugin2ClassLoader.checkResource(Plugin2ClassLoader.java:701)
at sun.plugin2.applet.Applet2ClassLoader.findClass(Applet2ClassLoader.java:206)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Plugin2ClassLoader.java:520)
at sun.plugin2.applet.Plugin2Manager.createApplet(Plugin2Manager.java:2940)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Plugin2Manager.java:1444)
at java.lang.Thread.run(Thread.java:619)
Exception: java.lang.SecurityException: trusted loader attempted to load sandboxed resource from file:/home/w/test/

Which is strange: I created a similar applet for reading files, and it works fine.

Any thoughts?

I ran this applet in both the browser and the applet. It is strange that this applet does not work with the applet viewer and throws an exception, but this is fine in the browser.

java.security.AccessControlException: access denied (java.util.PropertyPermission java.security.policy write)
at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323)
at java.security.AccessController.checkPermission(AccessController.java:546)
at java.lang.SecurityManager.checkPermission(SecurityManager.java:532)
at java.lang.System.setProperty(System.java:725)
at localfile.<init>(localfile.java:15)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at java.lang.Class.newInstance0(Class.java:355)
at java.lang.Class.newInstance(Class.java:308)
at sun.applet.AppletPanel.createApplet(AppletPanel.java:785)
at sun.applet.AppletPanel.runLoader(AppletPanel.java:714)
at sun.applet.AppletPanel.run(AppletPanel.java:368)
at java.lang.Thread.run(Thread.java:619)

So, besides this strange behavior, I believe that my problem is resolved. Thanks everyone :)

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5 answers

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+2

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Ant, , java-comm.jar ..

<target name="applet.sign" description="Sign the applet jar">
<signjar jar="${applet.dir}/*.jar"
         storepass="${applet.key.password}"
         keystore="${applet.keystore}"
         alias="${applet.key.alias}"
         keypass="${applet.key.password}" />

jar .

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. :

Resource resource = acquire();
try {
     use(resource);
} finally {
     resource.release();
}

:

final FileOutputStream rawOut = new FileOutputStream(file);
try {
    ...
    out.flush();
} finally {
    rawOut.close();
}
0

Source: https://habr.com/ru/post/1751084/

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