Class WebappClassLoaderBase

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Lifecycle, WebappProperties, InstrumentableClassLoader, PermissionCheck
    Direct Known Subclasses:
    ParallelWebappClassLoader, WebappClassLoader

    public abstract class WebappClassLoaderBase
    extends URLClassLoader
    implements Lifecycle, InstrumentableClassLoader, WebappProperties, PermissionCheck
    Specialized web application class loader.

    This class loader is a full reimplementation of the URLClassLoader from the JDK. It is designed to be fully compatible with a normal URLClassLoader, although its internal behavior may be completely different.

    IMPLEMENTATION NOTE - By default, this class loader follows the delegation model required by the specification. The bootstrap class loader will be queried first, then the local repositories, and only then delegation to the parent class loader will occur. This allows the web application to override any shared class except the classes from J2SE. Special handling is provided from the JAXP XML parser interfaces, the JNDI interfaces, and the classes from the servlet API, which are never loaded from the webapp repositories. The delegate property allows an application to modify this behavior to move the parent class loader ahead of the local repositories.

    IMPLEMENTATION NOTE - Due to limitations in Jasper compilation technology, any repository which contains classes from the servlet API will be ignored by the class loader.

    IMPLEMENTATION NOTE - The class loader generates source URLs which include the full JAR URL when a class is loaded from a JAR file, which allows setting security permission at the class level, even when a class is contained inside a JAR.

    IMPLEMENTATION NOTE - Local repositories are searched in the order they are added via the initial constructor.

    IMPLEMENTATION NOTE - No check for sealing violations or security is made unless a security manager is present.

    IMPLEMENTATION NOTE - As of 8.0, this class loader implements InstrumentableClassLoader, permitting web application classes to instrument other classes in the same web application. It does not permit instrumentation of system or container classes or classes in other web apps.

    Author:
    Remy Maucherat, Craig R. McClanahan
    • Field Detail

      • sm

        protected static final StringManager sm
        The string manager for this package.
      • resources

        protected WebResourceRoot resources
        Associated web resources for this webapp.
      • resourceEntries

        protected final Map<String,​ResourceEntry> resourceEntries
        The cache of ResourceEntry for classes and resources we have loaded, keyed by resource path, not binary name. Path is used as the key since resources may be requested by binary name (classes) or path (other resources such as property files) and the mapping from binary name to path is unambiguous but the reverse mapping is ambiguous.
      • delegate

        protected boolean delegate
        Should this class loader delegate to the parent class loader before searching its own repositories (i.e. the usual Java2 delegation model)? If set to false, this class loader will search its own repositories first, and delegate to the parent only if the class or resource is not found locally. Note that the default, false, is the behavior called for by the servlet specification.
      • permissionList

        protected final ArrayList<Permission> permissionList
        A list of read File Permission's required if this loader is for a web application context.
      • securityManager

        protected final SecurityManager securityManager
        Instance of the SecurityManager installed.
      • parent

        protected final ClassLoader parent
        The parent class loader.
    • Constructor Detail

      • WebappClassLoaderBase

        protected WebappClassLoaderBase()
        Construct a new ClassLoader with no defined repositories and no parent ClassLoader.
      • WebappClassLoaderBase

        protected WebappClassLoaderBase​(ClassLoader parent)
        Construct a new ClassLoader with no defined repositories and the given parent ClassLoader.

        Method is used via reflection - see WebappLoader.createClassLoader()

        Parameters:
        parent - Our parent class loader
    • Method Detail

      • getResources

        @Deprecated
        public WebResourceRoot getResources()
        Deprecated.
        This will be removed in Tomcat 10.1.x onwards
        Unused. Always returns null.
        Returns:
        associated resources.
      • setResources

        public void setResources​(WebResourceRoot resources)
        Set associated resources.
        Parameters:
        resources - the resources from which the classloader will load the classes
      • getContextName

        public String getContextName()
        Returns:
        the context name for this class loader.
      • getDelegate

        public boolean getDelegate()
        Return the "delegate first" flag for this class loader.
        Returns:
        true if the class lookup will delegate to the parent first. The default in Tomcat is false.
      • setDelegate

        public void setDelegate​(boolean delegate)
        Set the "delegate first" flag for this class loader. If this flag is true, this class loader delegates to the parent class loader before searching its own repositories, as in an ordinary (non-servlet) chain of Java class loaders. If set to false (the default), this class loader will search its own repositories first, and delegate to the parent only if the class or resource is not found locally, as per the servlet specification.
        Parameters:
        delegate - The new "delegate first" flag
      • getClearReferencesRmiTargets

        public boolean getClearReferencesRmiTargets()
      • setClearReferencesRmiTargets

        public void setClearReferencesRmiTargets​(boolean clearReferencesRmiTargets)
      • getClearReferencesStopThreads

        public boolean getClearReferencesStopThreads()
        Returns:
        the clearReferencesStopThreads flag for this Context.
      • setClearReferencesStopThreads

        public void setClearReferencesStopThreads​(boolean clearReferencesStopThreads)
        Set the clearReferencesStopThreads feature for this Context.
        Parameters:
        clearReferencesStopThreads - The new flag value
      • getClearReferencesStopTimerThreads

        public boolean getClearReferencesStopTimerThreads()
        Returns:
        the clearReferencesStopTimerThreads flag for this Context.
      • setClearReferencesStopTimerThreads

        public void setClearReferencesStopTimerThreads​(boolean clearReferencesStopTimerThreads)
        Set the clearReferencesStopTimerThreads feature for this Context.
        Parameters:
        clearReferencesStopTimerThreads - The new flag value
      • getClearReferencesLogFactoryRelease

        public boolean getClearReferencesLogFactoryRelease()
        Returns:
        the clearReferencesLogFactoryRelease flag for this Context.
      • setClearReferencesLogFactoryRelease

        public void setClearReferencesLogFactoryRelease​(boolean clearReferencesLogFactoryRelease)
        Set the clearReferencesLogFactoryRelease feature for this Context.
        Parameters:
        clearReferencesLogFactoryRelease - The new flag value
      • getClearReferencesHttpClientKeepAliveThread

        public boolean getClearReferencesHttpClientKeepAliveThread()
        Returns:
        the clearReferencesHttpClientKeepAliveThread flag for this Context.
      • setClearReferencesHttpClientKeepAliveThread

        public void setClearReferencesHttpClientKeepAliveThread​(boolean clearReferencesHttpClientKeepAliveThread)
        Set the clearReferencesHttpClientKeepAliveThread feature for this Context.
        Parameters:
        clearReferencesHttpClientKeepAliveThread - The new flag value
      • getClearReferencesObjectStreamClassCaches

        public boolean getClearReferencesObjectStreamClassCaches()
      • setClearReferencesObjectStreamClassCaches

        public void setClearReferencesObjectStreamClassCaches​(boolean clearReferencesObjectStreamClassCaches)
      • getClearReferencesThreadLocals

        public boolean getClearReferencesThreadLocals()
      • setClearReferencesThreadLocals

        public void setClearReferencesThreadLocals​(boolean clearReferencesThreadLocals)
      • getSkipMemoryLeakChecksOnJvmShutdown

        public boolean getSkipMemoryLeakChecksOnJvmShutdown()
      • setSkipMemoryLeakChecksOnJvmShutdown

        public void setSkipMemoryLeakChecksOnJvmShutdown​(boolean skipMemoryLeakChecksOnJvmShutdown)
      • addTransformer

        public void addTransformer​(ClassFileTransformer transformer)
        Adds the specified class file transformer to this class loader. The transformer will then be able to modify the bytecode of any classes loaded by this class loader after the invocation of this method.
        Specified by:
        addTransformer in interface InstrumentableClassLoader
        Parameters:
        transformer - The transformer to add to the class loader
      • removeTransformer

        public void removeTransformer​(ClassFileTransformer transformer)
        Removes the specified class file transformer from this class loader. It will no longer be able to modify the byte code of any classes loaded by the class loader after the invocation of this method. However, any classes already modified by this transformer will remain transformed.
        Specified by:
        removeTransformer in interface InstrumentableClassLoader
        Parameters:
        transformer - The transformer to remove
      • copyStateWithoutTransformers

        protected void copyStateWithoutTransformers​(WebappClassLoaderBase base)
      • modified

        public boolean modified()
        Have one or more classes or resources been modified so that a reload is appropriate?
        Returns:
        true if there's been a modification
      • doDefineClass

        protected final Class<?> doDefineClass​(String name,
                                               byte[] b,
                                               int off,
                                               int len,
                                               ProtectionDomain protectionDomain)
      • findResource

        public URL findResource​(String name)
        Find the specified resource in our local repository, and return a URL referring to it, or null if this resource cannot be found.
        Overrides:
        findResource in class URLClassLoader
        Parameters:
        name - Name of the resource to be found
      • findResources

        public Enumeration<URL> findResources​(String name)
                                       throws IOException
        Return an enumeration of URLs representing all of the resources with the given name. If no resources with this name are found, return an empty enumeration.
        Overrides:
        findResources in class URLClassLoader
        Parameters:
        name - Name of the resources to be found
        Throws:
        IOException - if an input/output error occurs
      • getResource

        public URL getResource​(String name)
        Find the resource with the given name. A resource is some data (images, audio, text, etc.) that can be accessed by class code in a way that is independent of the location of the code. The name of a resource is a "/"-separated path name that identifies the resource. If the resource cannot be found, return null.

        This method searches according to the following algorithm, returning as soon as it finds the appropriate URL. If the resource cannot be found, returns null.

        • If the delegate property is set to true, call the getResource() method of the parent class loader, if any.
        • Call findResource() to find this resource in our locally defined repositories.
        • Call the getResource() method of the parent class loader, if any.
        Overrides:
        getResource in class ClassLoader
        Parameters:
        name - Name of the resource to return a URL for
      • getResourceAsStream

        public InputStream getResourceAsStream​(String name)
        Find the resource with the given name, and return an input stream that can be used for reading it. The search order is as described for getResource(), after checking to see if the resource data has been previously cached. If the resource cannot be found, return null.
        Overrides:
        getResourceAsStream in class URLClassLoader
        Parameters:
        name - Name of the resource to return an input stream for
      • loadClass

        public Class<?> loadClass​(String name)
                           throws ClassNotFoundException
        Load the class with the specified name. This method searches for classes in the same manner as loadClass(String, boolean) with false as the second argument.
        Overrides:
        loadClass in class ClassLoader
        Parameters:
        name - The binary name of the class to be loaded
        Throws:
        ClassNotFoundException - if the class was not found
      • loadClass

        public Class<?> loadClass​(String name,
                                  boolean resolve)
                           throws ClassNotFoundException
        Load the class with the specified name, searching using the following algorithm until it finds and returns the class. If the class cannot be found, returns ClassNotFoundException.
        • Call findLoadedClass(String) to check if the class has already been loaded. If it has, the same Class object is returned.
        • If the delegate property is set to true, call the loadClass() method of the parent class loader, if any.
        • Call findClass() to find this class in our locally defined repositories.
        • Call the loadClass() method of our parent class loader, if any.
        If the class was found using the above steps, and the resolve flag is true, this method will then call resolveClass(Class) on the resulting Class object.
        Overrides:
        loadClass in class ClassLoader
        Parameters:
        name - The binary name of the class to be loaded
        resolve - If true then resolve the class
        Throws:
        ClassNotFoundException - if the class was not found
      • getPermissions

        protected PermissionCollection getPermissions​(CodeSource codeSource)
        Get the Permissions for a CodeSource. If this instance of WebappClassLoaderBase is for a web application context, add read FilePermission for the appropriate resources.
        Overrides:
        getPermissions in class URLClassLoader
        Parameters:
        codeSource - where the code was loaded from
        Returns:
        PermissionCollection for CodeSource
      • check

        public boolean check​(Permission permission)
        Description copied from interface: PermissionCheck
        Does this component have the given permission?
        Specified by:
        check in interface PermissionCheck
        Parameters:
        permission - The permission to test
        Returns:
        false if a SecurityManager is enabled and the component does not have the given permission, otherwise true
      • getURLs

        public URL[] getURLs()

        Note that list of URLs returned by this method may not be complete. The web application class loader accesses class loader resources via the WebResourceRoot which supports the arbitrary mapping of additional files, directories and contents of JAR files under WEB-INF/classes. Any such resources will not be included in the URLs returned here.

        Overrides:
        getURLs in class URLClassLoader
      • addLifecycleListener

        public void addLifecycleListener​(LifecycleListener listener)
        Add a lifecycle event listener to this component.
        Specified by:
        addLifecycleListener in interface Lifecycle
        Parameters:
        listener - The listener to add
      • findLifecycleListeners

        public LifecycleListener[] findLifecycleListeners()
        Get the lifecycle listeners associated with this lifecycle. If this Lifecycle has no listeners registered, a zero-length array is returned.
        Specified by:
        findLifecycleListeners in interface Lifecycle
        Returns:
        An array containing the life cycle listeners associated with this life cycle. If this component has no listeners registered, a zero-length array is returned.
      • removeLifecycleListener

        public void removeLifecycleListener​(LifecycleListener listener)
        Remove a lifecycle event listener from this component.
        Specified by:
        removeLifecycleListener in interface Lifecycle
        Parameters:
        listener - The listener to remove
      • getState

        public LifecycleState getState()
        Obtain the current state of the source component.
        Specified by:
        getState in interface Lifecycle
        Returns:
        The current state of the source component.
      • getStateName

        public String getStateName()
        Obtain a textual representation of the current component state. Useful for JMX. The format of this string may vary between point releases and should not be relied upon to determine component state. To determine component state, use Lifecycle.getState().
        Specified by:
        getStateName in interface Lifecycle
        Returns:
        The name of the current component state.
      • init

        public void init()
        Description copied from interface: Lifecycle
        Prepare the component for starting. This method should perform any initialization required post object creation. The following LifecycleEvents will be fired in the following order:
        1. INIT_EVENT: On the successful completion of component initialization.
        Specified by:
        init in interface Lifecycle
      • destroy

        public void destroy()
        Description copied from interface: Lifecycle
        Prepare to discard the object. The following LifecycleEvents will be fired in the following order:
        1. DESTROY_EVENT: On the successful completion of component destruction.
        Specified by:
        destroy in interface Lifecycle
      • getJavaseClassLoader

        protected ClassLoader getJavaseClassLoader()
      • setJavaseClassLoader

        protected void setJavaseClassLoader​(ClassLoader classLoader)
      • clearReferences

        protected void clearReferences()
        Clear references.
      • findClassInternal

        protected Class<?> findClassInternal​(String name)
        Find specified class in local repositories.
        Parameters:
        name - The binary name of the class to be loaded
        Returns:
        the loaded class, or null if the class isn't found
      • isPackageSealed

        protected boolean isPackageSealed​(String name,
                                          Manifest man)
        Returns true if the specified package name is sealed according to the given manifest.
        Parameters:
        name - Path name to check
        man - Associated manifest
        Returns:
        true if the manifest associated says it is sealed
      • findLoadedClass0

        protected Class<?> findLoadedClass0​(String name)
        Finds the class with the given name if it has previously been loaded and cached by this class loader, and return the Class object. If this class has not been cached, return null.
        Parameters:
        name - The binary name of the resource to return
        Returns:
        a loaded class
      • refreshPolicy

        protected void refreshPolicy()
        Refresh the system policy file, to pick up eventual changes.
      • filter

        protected boolean filter​(String name,
                                 boolean isClassName)
        Filter classes.
        Parameters:
        name - class name
        isClassName - true if name is a class name, false if name is a resource name
        Returns:
        true if the class should be filtered
      • getWebappName

        public String getWebappName()
        Description copied from interface: WebappProperties
        Returns a name for the logging system to use for the web application, if any, associated with the class loader.
        Specified by:
        getWebappName in interface WebappProperties
        Returns:
        The name to use for the web application or null if none is available.
      • getHostName

        public String getHostName()
        Description copied from interface: WebappProperties
        Returns a name for the logging system to use for the Host where the web application, if any, associated with the class loader is deployed.
        Specified by:
        getHostName in interface WebappProperties
        Returns:
        The name to use for the Host where the web application is deployed or null if none is available.
      • getServiceName

        public String getServiceName()
        Description copied from interface: WebappProperties
        Returns a name for the logging system to use for the Service where the Host, if any, associated with the class loader is deployed.
        Specified by:
        getServiceName in interface WebappProperties
        Returns:
        The name to use for the Service where the Host is deployed or null if none is available.
      • hasLoggingConfig

        public boolean hasLoggingConfig()
        Description copied from interface: WebappProperties
        Enables JULI to determine if the web application includes a local configuration without JULI having to look for the file which it may not have permission to do when running under a SecurityManager.
        Specified by:
        hasLoggingConfig in interface WebappProperties
        Returns:
        true if the web application includes a logging configuration at the standard location of /WEB-INF/classes/logging.properties.