Class Resources

java.lang.Object

com.google.common.io.Resources

@GwtIncompatible
public final class Resources
extends 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.

Since:

1.0

Author:

Chris Nokleberg, Ben Yu, Colin Decker

Method Summary

Modifier and Type	Method	Description
static ByteSource	asByteSource(URL url)	Returns a ByteSource that reads from the given URL.
static CharSource	asCharSource(URL url, Charset charset)	Returns a CharSource that reads from the given URL using the given character set.
static void	copy(URL from, OutputStream to)	Copies all bytes from a URL to an output stream.
static URL	getResource(Class<?> contextClass, String resourceName)	Given a resourceName that is relative to contextClass, returns a URL pointing to the named resource.
static URL	getResource(String resourceName)	Returns a URL pointing to resourceName if the resource is found using the context class loader.
static List<String>	readLines(URL url, Charset charset)	Reads all of the lines from a URL.
static <T extends @Nullable Object> T	readLines(URL url, 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(URL url)	Reads all bytes from a URL into a byte array.
static String	toString(URL url, Charset charset)	Reads all characters from a URL into a String, using the given character set.

Methods inherited from class java.lang.Object

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

Method Details

asByteSource

public static ByteSource asByteSource(URL url)

Returns a ByteSource that reads from the given URL.

Since:

14.0

asCharSource

public static CharSource asCharSource(URL url,
 Charset charset)

Returns a CharSource that reads from the given URL using the given character set.

Since:

14.0

toByteArray

public static byte[] toByteArray(URL url)
                          throws 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:

IOException - if an I/O error occurs

toString

public static String toString(URL url,
 Charset charset)
                       throws 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 StandardCharsets for helpful predefined constants

Returns:

a string containing all the characters from the URL

Throws:

IOException - if an I/O error occurs.

readLines

@CanIgnoreReturnValue
public static <T extends @Nullable Object> T readLines(URL url,
 Charset charset,
 LineProcessor<T> callback)
                                                throws 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 StandardCharsets for helpful predefined constants

callback - the LineProcessor to use to handle the lines

Returns:

the output of processing the lines

Throws:

IOException - if an I/O error occurs

readLines

public static List<String> readLines(URL url,
 Charset charset)
                              throws 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 StandardCharsets for helpful predefined constants

Returns:

a mutable List containing all the lines

Throws:

IOException - if an I/O error occurs

copy

public static void copy(URL from,
 OutputStream to)
                 throws IOException

Copies all bytes from a URL to an output stream.

Parameters:

from - the URL to read from

to - the output stream

Throws:

IOException - if an I/O error occurs

getResource

@CanIgnoreReturnValue
public static URL getResource(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:

IllegalArgumentException - if the resource is not found

getResource

@CanIgnoreReturnValue
public static URL getResource(Class<?> contextClass,
 String resourceName)

Given a resourceName that is relative to contextClass, returns a URL pointing to the named resource.

Throws:

IllegalArgumentException - if the resource is not found