in framework/src/main/java/org/apache/felix/framework/BundleWiringImpl.java [2624:2878]
private static String diagnoseClassLoadError(
StatefulResolver resolver, BundleRevision revision, String name)
{
// We will try to do some diagnostics here to help the developer
// deal with this exception.
// Get package name.
String pkgName = Util.getClassPackage(name);
if (pkgName.length() == 0)
{
return null;
}
// First, get the bundle string of the revision doing the class loader.
String importer = revision.getBundle().toString();
// Next, check to see if the revision imports the package.
List<BundleWire> wires = (revision.getWiring() == null)
? null : revision.getWiring().getProvidedWires(null);
for (int i = 0; (wires != null) && (i < wires.size()); i++)
{
if (wires.get(i).getCapability().getNamespace().equals(BundleRevision.PACKAGE_NAMESPACE) &&
wires.get(i).getCapability().getAttributes().get(BundleRevision.PACKAGE_NAMESPACE).equals(pkgName))
{
String exporter = wires.get(i).getProviderWiring().getBundle().toString();
StringBuilder sb = new StringBuilder("*** Package '");
sb.append(pkgName);
sb.append("' is imported by bundle ");
sb.append(importer);
sb.append(" from bundle ");
sb.append(exporter);
sb.append(", but the exported package from bundle ");
sb.append(exporter);
sb.append(" does not contain the requested class '");
sb.append(name);
sb.append("'. Please verify that the class name is correct in the importing bundle ");
sb.append(importer);
sb.append(" and/or that the exported package is correctly bundled in ");
sb.append(exporter);
sb.append(". ***");
return sb.toString();
}
}
// Next, check to see if the package was optionally imported and
// whether or not there is an exporter available.
List<BundleRequirement> reqs = revision.getWiring().getRequirements(null);
/*
* TODO: RB - Fix diagnostic message for optional imports.
for (int i = 0; (reqs != null) && (i < reqs.length); i++)
{
if (reqs[i].getName().equals(pkgName) && reqs[i].isOptional())
{
// Try to see if there is an exporter available.
IModule[] exporters = getResolvedExporters(reqs[i], true);
exporters = (exporters.length == 0)
? getUnresolvedExporters(reqs[i], true) : exporters;
// An exporter might be available, but it may have attributes
// that do not match the importer's required attributes, so
// check that case by simply looking for an exporter of the
// desired package without any attributes.
if (exporters.length == 0)
{
IRequirement pkgReq = new Requirement(
ICapability.PACKAGE_NAMESPACE, "(package=" + pkgName + ")");
exporters = getResolvedExporters(pkgReq, true);
exporters = (exporters.length == 0)
? getUnresolvedExporters(pkgReq, true) : exporters;
}
long expId = (exporters.length == 0)
? -1 : Util.getBundleIdFromModuleId(exporters[0].getId());
StringBuilder sb = new StringBuilder("*** Class '");
sb.append(name);
sb.append("' was not found, but this is likely normal since package '");
sb.append(pkgName);
sb.append("' is optionally imported by bundle ");
sb.append(impId);
sb.append(".");
if (exporters.length > 0)
{
sb.append(" However, bundle ");
sb.append(expId);
if (reqs[i].isSatisfied(
Util.getExportPackage(exporters[0], reqs[i].getName())))
{
sb.append(" does export this package. Bundle ");
sb.append(expId);
sb.append(" must be installed before bundle ");
sb.append(impId);
sb.append(" is resolved or else the optional import will be ignored.");
}
else
{
sb.append(" does export this package with attributes that do not match.");
}
}
sb.append(" ***");
return sb.toString();
}
}
*/
// Next, check to see if the package is dynamically imported by the revision.
if (resolver.isAllowedDynamicImport(revision, pkgName))
{
// Try to see if there is an exporter available.
Map<String, String> dirs = Collections.emptyMap();
Map<String, Object> attrs = Collections.singletonMap(
BundleRevision.PACKAGE_NAMESPACE, (Object) pkgName);
BundleRequirementImpl req = new BundleRequirementImpl(
revision, BundleRevision.PACKAGE_NAMESPACE, dirs, attrs);
List<BundleCapability> exporters = resolver.findProviders(req, false);
BundleRevision provider = null;
try
{
provider = resolver.resolve(revision, pkgName);
}
catch (Exception ex)
{
provider = null;
}
String exporter = (exporters.isEmpty())
? null : exporters.iterator().next().toString();
StringBuilder sb = new StringBuilder("*** Class '");
sb.append(name);
sb.append("' was not found, but this is likely normal since package '");
sb.append(pkgName);
sb.append("' is dynamically imported by bundle ");
sb.append(importer);
sb.append(".");
if ((exporters.size() > 0) && (provider == null))
{
sb.append(" However, bundle ");
sb.append(exporter);
sb.append(" does export this package with attributes that do not match.");
}
sb.append(" ***");
return sb.toString();
}
// Next, check to see if there are any exporters for the package at all.
Map<String, String> dirs = Collections.emptyMap();
Map<String, Object> attrs = Collections.singletonMap(
BundleRevision.PACKAGE_NAMESPACE, (Object) pkgName);
BundleRequirementImpl req = new BundleRequirementImpl(
revision, BundleRevision.PACKAGE_NAMESPACE, dirs, attrs);
List<BundleCapability> exports = resolver.findProviders(req, false);
if (exports.size() > 0)
{
boolean classpath = false;
try
{
BundleRevisionImpl.getSecureAction()
.getClassLoader(BundleClassLoader.class).loadClass(name);
classpath = true;
}
catch (NoClassDefFoundError | Exception ex)
{
// Ignore
}
String exporter = exports.iterator().next().toString();
StringBuilder sb = new StringBuilder("*** Class '");
sb.append(name);
sb.append("' was not found because bundle ");
sb.append(importer);
sb.append(" does not import '");
sb.append(pkgName);
sb.append("' even though bundle ");
sb.append(exporter);
sb.append(" does export it.");
if (classpath)
{
sb.append(" Additionally, the class is also available from the system class loader. There are two fixes: 1) Add an import for '");
sb.append(pkgName);
sb.append("' to bundle ");
sb.append(importer);
sb.append("; imports are necessary for each class directly touched by bundle code or indirectly touched, such as super classes if their methods are used. ");
sb.append("2) Add package '");
sb.append(pkgName);
sb.append("' to the '");
sb.append(Constants.FRAMEWORK_BOOTDELEGATION);
sb.append("' property; a library or VM bug can cause classes to be loaded by the wrong class loader. The first approach is preferable for preserving modularity.");
}
else
{
sb.append(" To resolve this issue, add an import for '");
sb.append(pkgName);
sb.append("' to bundle ");
sb.append(importer);
sb.append(".");
}
sb.append(" ***");
return sb.toString();
}
// Next, try to see if the class is available from the system
// class loader.
try
{
BundleRevisionImpl.getSecureAction()
.getClassLoader(BundleClassLoader.class).loadClass(name);
StringBuilder sb = new StringBuilder("*** Package '");
sb.append(pkgName);
sb.append("' is not imported by bundle ");
sb.append(importer);
sb.append(", nor is there any bundle that exports package '");
sb.append(pkgName);
sb.append("'. However, the class '");
sb.append(name);
sb.append("' is available from the system class loader. There are two fixes: 1) Add package '");
sb.append(pkgName);
sb.append("' to the '");
sb.append(Constants.FRAMEWORK_SYSTEMPACKAGES_EXTRA);
sb.append("' property and modify bundle ");
sb.append(importer);
sb.append(" to import this package; this causes the system bundle to export class path packages. 2) Add package '");
sb.append(pkgName);
sb.append("' to the '");
sb.append(Constants.FRAMEWORK_BOOTDELEGATION);
sb.append("' property; a library or VM bug can cause classes to be loaded by the wrong class loader. The first approach is preferable for preserving modularity.");
sb.append(" ***");
return sb.toString();
}
catch (Exception ex2)
{
}
// Finally, if there are no imports or exports for the package
// and it is not available on the system class path, simply
// log a message saying so.
StringBuilder sb = new StringBuilder("*** Class '");
sb.append(name);
sb.append("' was not found. Bundle ");
sb.append(importer);
sb.append(" does not import package '");
sb.append(pkgName);
sb.append("', nor is the package exported by any other bundle or available from the system class loader.");
sb.append(" ***");
return sb.toString();
}