PathMatchingResourcePatternResolver (Grails 2.4.4)
Date: 2014-10-28

Package: org.codehaus.groovy.grails.io.support

## [Java] Class PathMatchingResourcePatternResolver

- org.codehaus.groovy.grails.io.support.PathMatchingResourcePatternResolver

- A ResourcePatternResolver implementation that is able to resolve a specified resource location path into one or more matching Resources. The source path may be a simple path which has a one-to-one mapping to a target Resource, or alternatively may contain the special "`classpath*:`" prefix and/or internal Ant-style regular expressions (matched using AntPathMatcher). Both of the latter are effectively wildcards.

  No Wildcards:

  In the simple case, if the specified location path does not start with the `"classpath*:`" prefix, and does not contain a PathMatcher pattern, this resolver will simply return a single resource via a `getResource()` call on the underlying `ResourceLoader`. Examples are real URLs such as "`file:C:/context.xml`", pseudo-URLs such as "`classpath:/context.xml`", and simple unprefixed paths such as "`/WEB-INF/context.xml`". The latter will resolve in a fashion specific to the underlying `ResourceLoader` (e.g. `ServletContextResource` for a `WebApplicationContext`).

  Ant-style Patterns:

  When the path location contains an Ant-style pattern, e.g.:

       /WEB-INF/*-context.xml
       com/mycompany/**/applicationContext.xml
       file:C:/some/path/*-context.xml
       classpath:com/mycompany/**/applicationContext.xml

  the resolver follows a more complex but defined procedure to try to resolve the wildcard. It produces a `Resource` for the path up to the last non-wildcard segment and obtains a `URL` from it. If this URL is not a "`jar:`" URL or container-specific variant (e.g. "`zip:`" in WebLogic, "`wsjar`" in WebSphere", etc.), then a `java.io.File` is obtained from it, and used to resolve the wildcard by walking the filesystem. In the case of a jar URL, the resolver either gets a `java.net.JarURLConnection` from it, or manually parses the jar URL, and then traverses the contents of the jar file, to resolve the wildcards.

  Implications on portability:

  If the specified path is already a file URL (either explicitly, or implicitly because the base `ResourceLoader` is a filesystem one, then wildcarding is guaranteed to work in a completely portable fashion.

  If the specified path is a classpath location, then the resolver must obtain the last non-wildcard path segment URL via a `Classloader.getResource()` call. Since this is just a node of the path (not the file at the end) it is actually undefined (in the ClassLoader Javadocs) exactly what sort of a URL is returned in this case. In practice, it is usually a `java.io.File` representing the directory, where the classpath resource resolves to a filesystem location, or a jar URL of some sort, where the classpath resource resolves to a jar location. Still, there is a portability concern on this operation.

  If a jar URL is obtained for the last non-wildcard segment, the resolver must be able to get a `java.net.JarURLConnection` from it, or manually parse the jar URL, to be able to walk the contents of the jar, and resolve the wildcard. This will work in most environments, but will fail in others, and it is strongly recommended that the wildcard resolution of resources coming from jars be thoroughly tested in your specific environment before you rely on it.

  `classpath*:` Prefix:

  There is special support for retrieving multiple class path resources with the same name, via the "`classpath*:`" prefix. For example, "`classpath*:META-INF/beans.xml`" will find all "beans.xml" files in the class path, be it in "classes" directories or in JAR files. This is particularly useful for autodetecting config files of the same name at the same location within each jar file. Internally, this happens via a `ClassLoader.getResources()` call, and is completely portable.

  The "classpath*:" prefix can also be combined with a PathMatcher pattern in the rest of the location path, for example "classpath*:META-INF/*-beans.xml". In this case, the resolution strategy is fairly simple: a `ClassLoader.getResources()` call is used on the last non-wildcard path segment to get all the matching resources in the class loader hierarchy, and then off each resource the same PathMatcher resolution strategy described above is used for the wildcard subpath.

  Other notes:

  WARNING: Note that "`classpath*:`" when combined with Ant-style patterns will only work reliably with at least one root directory before the pattern starts, unless the actual target files reside in the file system. This means that a pattern like "`classpath*:*.xml`" will not retrieve files from the root of jar files but rather only from the root of expanded directories. This originates from a limitation in the JDK's `ClassLoader.getResources()` method which only returns file system locations for a passed-in empty String (indicating potential roots to search).

  WARNING: Ant-style patterns with "classpath:" resources are not guaranteed to find matching resources if the root package to search is available in multiple class path locations. This is because a resource such as

           com/mycompany/package1/service-context.xml

  may be in only one location, but when a path such as

           classpath:com/mycompany/**/service-context.xml

  is used to try to resolve it, the resolver will work off the (first) URL returned by `getResource("com/mycompany");`. If this base package node exists in multiple classloader locations, the actual end resource may not be underneath. Therefore, preferably, use "`classpath*:`" with the same Ant-style pattern in such a case, which will search all class path locations that contain the root package.
  Authors:
    Juergen Hoeller
    Colin Sampaleanu
    Marius Bogoevici
    Costin Leau
  See Also:
    java.lang.ClassLoader#getResources(String)
  Since:
    1.0.2
  ``

- - ### Constructor Summary

    Constructors
    Constructor and description
    `PathMatchingResourcePatternResolver ()` Create a new PathMatchingResourcePatternResolver with a DefaultResourceLoader.
    `PathMatchingResourcePatternResolver (java.lang.ClassLoader classLoader)` Create a new PathMatchingResourcePatternResolver with a DefaultResourceLoader.
    `PathMatchingResourcePatternResolver (ResourceLoader resourceLoader)` Create a new PathMatchingResourcePatternResolver.

  - ### Methods Summary

    Methods
    Type | Name and description
    --- | ---
    `protected Resource` | `convertClassLoaderURL(java.net.URL url)` Convert the given URL as returned from the ClassLoader into a Resource object.
    `protected java.lang.String` | `determineRootDir(java.lang.String location)` Determine the root directory for the given location.
    `protected java.util.Set<Resource>` | `doFindMatchingFileSystemResources(java.io.File rootDir, java.lang.String subPattern)` Find all resources in the file system that match the given location pattern via the Ant-style PathMatcher.
    `protected java.util.Set<Resource>` | `doFindPathMatchingFileResources(Resource rootDirResource, java.lang.String subPattern)` Find all resources in the file system that match the given location pattern via the Ant-style PathMatcher.
    `protected java.util.Set<Resource>` | `doFindPathMatchingJarResources(Resource rootDirResource, java.lang.String subPattern)` Find all resources in jar files that match the given location pattern via the Ant-style PathMatcher.
    `protected void` | `doRetrieveMatchingFiles(java.lang.String fullPattern, java.io.File dir, java.util.Set<java.io.File> result)` Recursively retrieve files that match the given pattern, adding them to the given result list.
    `protected Resource[]` | `findAllClassPathResources(java.lang.String location)` Find all class location resources with the given location via the ClassLoader.
    `protected Resource[]` | `findPathMatchingResources(java.lang.String locationPattern)` Find all resources that match the given location pattern via the Ant-style PathMatcher.
    `java.lang.ClassLoader` | `getClassLoader()` Return the ClassLoader that this pattern resolver works with (never `null`).
    `protected java.util.jar.JarFile` | `getJarFile(java.lang.String jarFileUrl)` Resolve the given jar file URL into a JarFile object.
    `AntPathMatcher` | `getPathMatcher()` Return the PathMatcher that this resource pattern resolver uses.
    `Resource` | `getResource(java.lang.String location)`
    `ResourceLoader` | `getResourceLoader()` Return the ResourceLoader that this pattern resolver works with.
    `Resource[]` | `getResources(java.lang.String locationPattern)`
    `protected boolean` | `isJarResource(Resource resource)` Return whether the given resource handle indicates a jar resource that the `doFindPathMatchingJarResources` method can handle.
    `protected Resource` | `resolveRootDirResource(Resource original)` Resolve the specified resource for path matching.
    `protected java.util.Set<java.io.File>` | `retrieveMatchingFiles(java.io.File rootDir, java.lang.String pattern)` Retrieve files that match the given path pattern, checking the given directory and its subdirectories.
    `void` | `setPathMatcher(AntPathMatcher pathMatcher)` Set the PathMatcher implementation to use for this resource pattern resolver.

  - ### Inherited Methods Summary

    Inherited Methods
    Methods inherited from class | Name
    --- | ---
    `class java.lang.Object` | `java.lang.Object#wait(long, int), java.lang.Object#wait(long), java.lang.Object#wait(), java.lang.Object#equals(java.lang.Object), java.lang.Object#toString(), java.lang.Object#hashCode(), java.lang.Object#getClass(), java.lang.Object#notify(), java.lang.Object#notifyAll()`

- - ### Constructor Detail

    - #### public PathMatchingResourcePatternResolver()

      Create a new PathMatchingResourcePatternResolver with a DefaultResourceLoader.

      ClassLoader access will happen via the thread context class loader.

    - #### public PathMatchingResourcePatternResolver(java.lang.ClassLoader classLoader)

      Create a new PathMatchingResourcePatternResolver with a DefaultResourceLoader.

      Parameters:
        `classLoader` - the ClassLoader to load classpath resources with, or `null` for using the thread context class loader at the time of actual resource access

    - #### public PathMatchingResourcePatternResolver(ResourceLoader resourceLoader)

      Create a new PathMatchingResourcePatternResolver.

      ClassLoader access will happen via the thread context class loader.

      Parameters:
        `resourceLoader` - the ResourceLoader to load root directories and actual resources with

  - ### Method Detail

    - #### protected Resource convertClassLoaderURL(java.net.URL url)

      Convert the given URL as returned from the ClassLoader into a Resource object.

      The default implementation simply creates a UrlResource instance.

      Parameters:
        `url` - a URL as returned from the ClassLoader
      Returns:
        the corresponding Resource object
      See Also:
        java.lang.ClassLoader#getResources

    - #### protected java.lang.String determineRootDir(java.lang.String location)

      Determine the root directory for the given location.

      Used for determining the starting point for file matching, resolving the root directory location to a `java.io.File` and passing it into `retrieveMatchingFiles`, with the remainder of the location as pattern.

      Will return "/WEB-INF/" for the pattern "/WEB-INF/*.xml", for example.

      Parameters:
        `location` - the location to check
      Returns:
        the part of the location that denotes the root directory
      See Also:
        retrieveMatchingFiles

    - #### protected java.util.Set<Resource> doFindMatchingFileSystemResources(java.io.File rootDir, java.lang.String subPattern)

      Find all resources in the file system that match the given location pattern via the Ant-style PathMatcher.

      throws:
        IOException in case of I/O errors
      Parameters:
        `rootDir` - the root directory in the file system
        `subPattern` - the sub pattern to match (below the root directory)
      Returns:
        the Set of matching Resource instances
      See Also:
        retrieveMatchingFiles

    - #### protected java.util.Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource, java.lang.String subPattern)

      Find all resources in the file system that match the given location pattern via the Ant-style PathMatcher.

      throws:
        IOException in case of I/O errors
      Parameters:
        `rootDirResource` - the root directory as Resource
        `subPattern` - the sub pattern to match (below the root directory)
      Returns:
        the Set of matching Resource instances
      See Also:
        retrieveMatchingFiles

    - #### protected java.util.Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource, java.lang.String subPattern)

      Find all resources in jar files that match the given location pattern via the Ant-style PathMatcher.

      throws:
        IOException in case of I/O errors
      Parameters:
        `rootDirResource` - the root directory as Resource
        `subPattern` - the sub pattern to match (below the root directory)
      Returns:
        the Set of matching Resource instances
      See Also:
        java.net.JarURLConnection

    - #### protected void doRetrieveMatchingFiles(java.lang.String fullPattern, java.io.File dir, java.util.Set<java.io.File> result)

      Recursively retrieve files that match the given pattern, adding them to the given result list.

      throws:
        IOException if directory contents could not be retrieved
      Parameters:
        `fullPattern` - the pattern to match against, with prepended root directory path
        `dir` - the current directory
        `result` - the Set of matching File instances to add to

    - #### protected Resource[] findAllClassPathResources(java.lang.String location)

      Find all class location resources with the given location via the ClassLoader.

      throws:
        IOException in case of I/O errors
      Parameters:
        `location` - the absolute path within the classpath
      Returns:
        the result as Resource array
      See Also:
        java.lang.ClassLoader#getResources
        convertClassLoaderURL

    - #### protected Resource[] findPathMatchingResources(java.lang.String locationPattern)

      Find all resources that match the given location pattern via the Ant-style PathMatcher. Supports resources in jar files and zip files and in the file system.

      throws:
        IOException in case of I/O errors
      Parameters:
        `locationPattern` - the location pattern to match
      Returns:
        the result as Resource array
      See Also:
        doFindPathMatchingJarResources
        doFindPathMatchingFileResources

    - #### public java.lang.ClassLoader getClassLoader()

      Return the ClassLoader that this pattern resolver works with (never `null`).

    - #### protected java.util.jar.JarFile getJarFile(java.lang.String jarFileUrl)

      Resolve the given jar file URL into a JarFile object.

    - #### public AntPathMatcher getPathMatcher()

      Return the PathMatcher that this resource pattern resolver uses.

    - #### public Resource getResource(java.lang.String location)

    - #### public ResourceLoader getResourceLoader()

      Return the ResourceLoader that this pattern resolver works with.

    - #### public Resource[] getResources(java.lang.String locationPattern)

    - #### protected boolean isJarResource(Resource resource)

      Return whether the given resource handle indicates a jar resource that the `doFindPathMatchingJarResources` method can handle.

      The default implementation checks against the URL protocols "jar", "zip" and "wsjar" (the latter are used by BEA WebLogic Server and IBM WebSphere, respectively, but can be treated like jar files).

      Parameters:
        `resource` - the resource handle to check (usually the root directory to start path matching from)
      See Also:
        doFindPathMatchingJarResources

    - #### protected Resource resolveRootDirResource(Resource original)

      Resolve the specified resource for path matching.

      The default implementation detects an Equinox OSGi "bundleresource:" / "bundleentry:" URL and resolves it into a standard jar file URL that can be traversed using Spring's standard jar file traversal algorithm.

      throws:
        IOException in case of resolution failure
      Parameters:
        `original` - the resource to resolve
      Returns:
        the resolved resource (may be identical to the passed-in resource)

    - #### protected java.util.Set<java.io.File> retrieveMatchingFiles(java.io.File rootDir, java.lang.String pattern)

      Retrieve files that match the given path pattern, checking the given directory and its subdirectories.

      throws:
        IOException if directory contents could not be retrieved
      Parameters:
        `rootDir` - the directory to start from
        `pattern` - the pattern to match against, relative to the root directory
      Returns:
        the Set of matching File instances

    - #### public void setPathMatcher(AntPathMatcher pathMatcher)

      Set the PathMatcher implementation to use for this resource pattern resolver. Default is AntPathMatcher.