Package com.google.common.io

Class Resources

  • @Beta
public final class Resources
extends java.lang.Object
    Provides utility methods for working with resources in the classpath. Note that even though these methods use URL parameters, they are usually not appropriate for HTTP or other non-classpath resources.

    All method parameters must be non-null unless documented otherwise.

    Since:
    1.0

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static ByteSource asByteSource​(java.net.URL url)
      Returns a ByteSource that reads from the given URL.
      static CharSource asCharSource​(java.net.URL url, java.nio.charset.Charset charset)
      Returns a CharSource that reads from the given URL using the given character set.
      static void copy​(java.net.URL from, java.io.OutputStream to)
      Copies all bytes from a URL to an output stream.
      static java.net.URL getResource​(java.lang.Class<?> contextClass, java.lang.String resourceName)
      Given a resourceName that is relative to contextClass, returns a URL pointing to the named resource.
      static java.net.URL getResource​(java.lang.String resourceName)
      Returns a URL pointing to resourceName if the resource is found using the context class loader.
      static InputSupplier<java.io.InputStream> newInputStreamSupplier​(java.net.URL url)
      Returns a factory that will supply instances of InputStream that read from the given URL.
      static InputSupplier<java.io.InputStreamReader> newReaderSupplier​(java.net.URL url, java.nio.charset.Charset charset)
      Returns a factory that will supply instances of InputStreamReader that read a URL using the given character set.
      static java.util.List<java.lang.String> readLines​(java.net.URL url, java.nio.charset.Charset charset)
      Reads all of the lines from a URL.
      static <T> T readLines​(java.net.URL url, java.nio.charset.Charset charset, LineProcessor<T> callback)
      Streams lines from a URL, stopping when our callback returns false, or we have read all of the lines.
      static byte[] toByteArray​(java.net.URL url)
      Reads all bytes from a URL into a byte array.
      static java.lang.String toString​(java.net.URL url, java.nio.charset.Charset charset)
      Reads all characters from a URL into a String, using the given character set.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Method Detail

      • newInputStreamSupplier

        public static InputSupplier<java.io.InputStream> newInputStreamSupplier​(java.net.URL url)
        Returns a factory that will supply instances of InputStream that read from the given URL.
        Parameters:
        url - the URL to read from
        Returns:
        the factory

      • asByteSource

        public static ByteSource asByteSource​(java.net.URL url)
        Returns a ByteSource that reads from the given URL.
        Since:
        14.0

      • newReaderSupplier

        public static InputSupplier<java.io.InputStreamReader> newReaderSupplier​(java.net.URL url,
                                                                         java.nio.charset.Charset charset)
        Returns a factory that will supply instances of InputStreamReader that read a URL using the given character set.
        Parameters:
        url - the URL to read from
        charset - the charset used to decode the input stream; see Charsets for helpful predefined constants
        Returns:
        the factory

      • asCharSource

        public static CharSource asCharSource​(java.net.URL url,
                                      java.nio.charset.Charset charset)
        Returns a CharSource that reads from the given URL using the given character set.
        Since:
        14.0

      • toByteArray

        public static byte[] toByteArray​(java.net.URL url)
                          throws java.io.IOException
        Reads all bytes from a URL into a byte array.
        Parameters:
        url - the URL to read from
        Returns:
        a byte array containing all the bytes from the URL
        Throws:
        java.io.IOException - if an I/O error occurs

      • toString

        public static java.lang.String toString​(java.net.URL url,
                                        java.nio.charset.Charset charset)
                                 throws java.io.IOException
        Reads all characters from a URL into a String, using the given character set.
        Parameters:
        url - the URL to read from
        charset - the charset used to decode the input stream; see Charsets for helpful predefined constants
        Returns:
        a string containing all the characters from the URL
        Throws:
        java.io.IOException - if an I/O error occurs.

      • readLines

        public static <T> T readLines​(java.net.URL url,
                              java.nio.charset.Charset charset,
                              LineProcessor<T> callback)
                       throws java.io.IOException
        Streams lines from a URL, stopping when our callback returns false, or we have read all of the lines.
        Parameters:
        url - the URL to read from
        charset - the charset used to decode the input stream; see Charsets for helpful predefined constants
        callback - the LineProcessor to use to handle the lines
        Returns:
        the output of processing the lines
        Throws:
        java.io.IOException - if an I/O error occurs

      • readLines

        public static java.util.List<java.lang.String> readLines​(java.net.URL url,
                                                         java.nio.charset.Charset charset)
                                                  throws java.io.IOException
        Reads all of the lines from a URL. The lines do not include line-termination characters, but do include other leading and trailing whitespace.

        This method returns a mutable List. For an ImmutableList, use Resources.asCharSource(url, charset).readLines().

        Parameters:
        url - the URL to read from
        charset - the charset used to decode the input stream; see Charsets for helpful predefined constants
        Returns:
        a mutable List containing all the lines
        Throws:
        java.io.IOException - if an I/O error occurs

      • copy

        public static void copy​(java.net.URL from,
                        java.io.OutputStream to)
                 throws java.io.IOException
        Copies all bytes from a URL to an output stream.
        Parameters:
        from - the URL to read from
        to - the output stream
        Throws:
        java.io.IOException - if an I/O error occurs

      • getResource

        public static java.net.URL getResource​(java.lang.String resourceName)
        Returns a URL pointing to resourceName if the resource is found using the context class loader. In simple environments, the context class loader will find resources from the class path. In environments where different threads can have different class loaders, for example app servers, the context class loader will typically have been set to an appropriate loader for the current thread.

        In the unusual case where the context class loader is null, the class loader that loaded this class (Resources) will be used instead.

        Throws:
        java.lang.IllegalArgumentException - if the resource is not found

      • getResource

        public static java.net.URL getResource​(java.lang.Class<?> contextClass,
                                       java.lang.String resourceName)
        Given a resourceName that is relative to contextClass, returns a URL pointing to the named resource.
        Throws:
        java.lang.IllegalArgumentException - if the resource is not found