Package org.apache.catalina.loader

Class WebappClassLoaderBase

java.lang.Object
java.lang.ClassLoader
java.security.SecureClassLoader
java.net.URLClassLoader
org.apache.catalina.loader.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 Details

    • 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.

    • loaderPC

      protected final HashMap<String,PermissionCollection> loaderPC
      The PermissionCollection for each CodeSource for a web application context.

    • securityManager

      protected final SecurityManager securityManager
      Instance of the SecurityManager installed.

    • parent

      protected final ClassLoader parent
      The parent class loader.

    • allPermission

      @Deprecated protected final Permission allPermission
      Deprecated.
      Unused. This will be removed in Tomcat 9.
      All permission.

  • Constructor Details

    • 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 Details

    • 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

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • doDefineClass

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

    • findClass

      public Class<?> findClass(String name) throws ClassNotFoundException
      Find the specified class in our local repositories, if possible. If not found, throw ClassNotFoundException.
      Overrides:
      findClass in class URLClassLoader
      Parameters:
      name - The binary name of the class to be loaded
      Throws:
      ClassNotFoundException - if the class was not found

    • 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

    • getResources

      public Enumeration<URL> getResources(String name) throws IOException
      Overrides:
      getResources in class ClassLoader
      Throws:
      IOException

    • 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

    • checkStateForClassLoading

      protected void checkStateForClassLoading(String className) throws ClassNotFoundException
      Throws:
      ClassNotFoundException

    • checkStateForResourceLoading

      protected void checkStateForResourceLoading(String resource) throws IllegalStateException
      Throws:
      IllegalStateException

    • 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()
      Description copied from interface: Lifecycle
      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

    • start

      public void start() throws LifecycleException
      Start the class loader.
      Specified by:
      start in interface Lifecycle
      Throws:
      LifecycleException - if a lifecycle error occurs

    • stop

      public void stop() throws LifecycleException
      Stop the class loader.
      Specified by:
      stop in interface Lifecycle
      Throws:
      LifecycleException - if a lifecycle error occurs

    • 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

    • filter

      @Deprecated protected boolean filter(String name)
      Deprecated.
      Use filter(String, boolean) This will be removed in Tomcat 9
      Filter classes.
      Parameters:
      name - class name
      Returns:
      true if the class should be filtered

    • addURL

      protected void addURL(URL url)
      Overrides:
      addURL in class URLClassLoader

    • 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.