Polishing external contribution

This commit makes several changes to PR #24651.

- Add byte[] getContentAsByteArray() on Resource.
- Remove getContentAsString() from Resource, as it relied on the default
charset which is not reliable.
- Add getContentAsString() to EncodedResource, as a charset is provided
through the constructor.

See gh-24651

spring-core/src/main/java/org/springframework/core/io/AbstractFileResolvingResource.java

@@ -26,10 +26,7 @@ import java.net.URL;
 import java.net.URLConnection;
 import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
-import java.nio.charset.Charset;
-import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
-import java.nio.file.Paths;
 import java.nio.file.StandardOpenOption;
 import java.util.jar.JarEntry;
 
@@ -323,39 +320,6 @@ public abstract class AbstractFileResolvingResource extends AbstractResource {
 	protected void customizeConnection(HttpURLConnection con) throws IOException {
 	}
 
-	/**
-	 * This implementation returns the contents of a file as a string using the
-	 * system default Charset. Provided the resource exists and the context has
-	 * access to it, the contents will be returned as a single string with line
-	 * feed characters retained.
-	 * @return the contents of the requested file as a {@code String}.
-	 * @throws FileNotFoundException in the event the file path is invalid.
-	 * @throws IOException if the file can not be read or cannot be serialzied.
-	 */
-	@Override
-	public String getContentAsString() throws IOException {
-
-		if( !exists() ) {
-			throw new FileNotFoundException(getDescription() + " cannot be found.");
-		}
-		if ( !isReadable() ) {
-			throw new IOException(getDescription() + " cannot be opened for reading.");
-		}
-		return new String(Files.readAllBytes(Paths.get(getFile().getAbsolutePath())), Charset.defaultCharset());
-	}
-
-	@Override
-	public String getContentAsString(Charset charset) throws IOException {
-
-		if( !exists() ) {
-			throw new FileNotFoundException(getDescription() + " cannot be found.");
-		}
-		if ( !isReadable() ) {
-			throw new IOException(getDescription() + " cannot be opened for reading.");
-		}
-		return new String(Files.readAllBytes(Paths.get(getFile().getAbsolutePath())), charset);
-
-	}
 
 	/**
 	 * Inner delegate class, avoiding a hard JBoss VFS API dependency at runtime.

spring-core/src/main/java/org/springframework/core/io/ByteArrayResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ package org.springframework.core.io;
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.charset.Charset;
 import java.util.Arrays;
 
 import org.springframework.lang.Nullable;
@@ -100,6 +101,19 @@ public class ByteArrayResource extends AbstractResource {
 		return new ByteArrayInputStream(this.byteArray);
 	}
 
+	@Override
+	public byte[] getContentAsByteArray() throws IOException {
+		int length = this.byteArray.length;
+		byte[] result = new byte[length];
+		System.arraycopy(this.byteArray, 0, result, 0, length);
+		return result;
+	}
+
+	@Override
+	public String getContentAsString(Charset charset) throws IOException {
+		return new String(this.byteArray, charset);
+	}
+
 	/**
 	 * This implementation returns a description that includes the passed-in
 	 * {@code description}, if any.

spring-core/src/main/java/org/springframework/core/io/FileSystemResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,6 +27,7 @@ import java.net.URL;
 import java.nio.channels.FileChannel;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.WritableByteChannel;
+import java.nio.charset.Charset;
 import java.nio.file.FileSystem;
 import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
@@ -196,6 +197,26 @@ public class FileSystemResource extends AbstractResource implements WritableReso
 		}
 	}
 
+	@Override
+	public byte[] getContentAsByteArray() throws IOException {
+		try {
+			return Files.readAllBytes(this.filePath);
+		}
+		catch (NoSuchFileException ex) {
+			throw new FileNotFoundException(ex.getMessage());
+		}
+	}
+
+	@Override
+	public String getContentAsString(Charset charset) throws IOException {
+		try {
+			return Files.readString(this.filePath, charset);
+		}
+		catch (NoSuchFileException ex) {
+			throw new FileNotFoundException(ex.getMessage());
+		}
+	}
+
 	/**
 	 * This implementation checks whether the underlying file is marked as writable
 	 * (and corresponds to an actual file with content, not to a directory).

spring-core/src/main/java/org/springframework/core/io/PathResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -25,6 +25,7 @@ import java.net.URI;
 import java.net.URL;
 import java.nio.channels.ReadableByteChannel;
 import java.nio.channels.WritableByteChannel;
+import java.nio.charset.Charset;
 import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.OpenOption;
@@ -141,6 +142,26 @@ public class PathResource extends AbstractResource implements WritableResource {
 		return Files.newInputStream(this.path);
 	}
 
+	@Override
+	public byte[] getContentAsByteArray() throws IOException {
+		try {
+			return Files.readAllBytes(this.path);
+		}
+		catch (NoSuchFileException ex) {
+			throw new FileNotFoundException(ex.getMessage());
+		}
+	}
+
+	@Override
+	public String getContentAsString(Charset charset) throws IOException {
+		try {
+			return Files.readString(this.path, charset);
+		}
+		catch (NoSuchFileException ex) {
+			throw new FileNotFoundException(ex.getMessage());
+		}
+	}
+
 	/**
 	 * This implementation checks whether the underlying file is marked as writable
 	 * (and corresponds to an actual file with content, not to a directory).

spring-core/src/main/java/org/springframework/core/io/Resource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,9 +17,9 @@
 package org.springframework.core.io;
 
 import java.io.File;
-import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.io.InputStreamReader;
 import java.net.URI;
 import java.net.URL;
 import java.nio.channels.Channels;
@@ -27,6 +27,7 @@ import java.nio.channels.ReadableByteChannel;
 import java.nio.charset.Charset;
 
 import org.springframework.lang.Nullable;
+import org.springframework.util.FileCopyUtils;
 
 /**
  * Interface for a resource descriptor that abstracts from the actual
@@ -179,40 +180,29 @@ public interface Resource extends InputStreamSource {
 	String getDescription();
 
 	/**
-	 * Return a {@link ReadableByteChannel}.
-	 * <p>It is expected that each call creates a <i>fresh</i> channel.
-	 * <p>The default implementation returns {@link Channels#newChannel(InputStream)}
-	 * with the result of {@link #getInputStream()}.
-	 * @return the byte channel for the underlying resource (must not be {@code null})
-	 * @throws java.io.FileNotFoundException if the underlying resource doesn't exist
-	 * @throws IOException if the content channel could not be opened
-	 * @since 5.0
-	 * @see #getInputStream()
+	 * Return the contents of this resource as a byte array.
+	 * @return the contents of this resource as byte array
+	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as
+	 * absolute file path, i.e. if the resource is not available in a file system
+	 * @throws IOException in case of general resolution/reading failures
+	 * @since 6.0.5
 	 */
-
-	/**
-	 * Returns the contents of a file as a string using the system default Charset.
-	 * <p>The default implementation returns a {@link Object#toString()} representation of the resource.
-	 * @return the contents of the requested file as a {@code String}.
-	 * @throws FileNotFoundException in the event the file path is invalid.
-	 * @throws IOException if the file can not be read or cannot be accessed.
-	 * @since 5.2.5
-	 */
-	default String getContentAsString() throws IOException{
-		return toString();
+	default byte[] getContentAsByteArray() throws IOException {
+		return FileCopyUtils.copyToByteArray(getInputStream());
 	}
 
 	/**
-	 * Returns the contents of a file as a string using the specified Charset.
-	 * <p>The default implementation returns a {@link Object#toString()} representation of the resource.
-	 * @param charset the {@code Charset} to use to deserialize the content. Defaults to system default.
-	 * @return the contents of the requested file as a {@code String}.
-	 * @throws FileNotFoundException in the event the file path is invalid.
-	 * @throws IOException if the file can not be read or cannot be accessed.
-	 * @since 5.2.5
+	 * Returns the contents of this resource as a string, using the specified
+	 * charset.
+	 * @param charset the charset to use for decoding
+	 * @return the contents of this resource as a {@code String}
+	 * @throws java.io.FileNotFoundException if the resource cannot be resolved as
+	 * absolute file path, i.e. if the resource is not available in a file system
+	 * @throws IOException in case of general resolution/reading failures
+	 * @since 6.0.5
 	 */
-	default String getContentAsString(Charset charset) throws IOException{
-		return toString();
+	default String getContentAsString(Charset charset) throws IOException {
+		return FileCopyUtils.copyToString(new InputStreamReader(getInputStream(), charset));
 	}
 
 }

spring-core/src/main/java/org/springframework/core/io/support/EncodedResource.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -159,6 +159,27 @@ public class EncodedResource implements InputStreamSource {
 		return this.resource.getInputStream();
 	}
 
+	/**
+	 * Returns the contents of the specified resource as a string, using the specified
+	 * {@link #getCharset() Charset} or {@linkplain #getEncoding() encoding}
+	 * (if any).
+	 * @throws IOException if opening the resource failed
+	 * @since 6.0.5
+	 */
+	public String getContentAsString() throws IOException {
+		Charset charset;
+		if (this.charset != null) {
+			charset = this.charset;
+		}
+		else if (this.encoding != null) {
+			charset = Charset.forName(this.encoding);
+		}
+		else {
+			charset = Charset.defaultCharset();
+		}
+		return this.resource.getContentAsString(charset);
+	}
+
 
 	@Override
 	public boolean equals(@Nullable Object other) {

spring-core/src/test/java/org/springframework/core/io/ResourceTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,6 +29,8 @@ import java.net.URISyntaxException;
 import java.net.URL;
 import java.nio.ByteBuffer;
 import java.nio.channels.ReadableByteChannel;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.stream.Stream;
@@ -49,6 +51,7 @@ import org.springframework.util.FileCopyUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
 
 /**
  * Unit tests for various {@link Resource} implementations.
@@ -69,6 +72,7 @@ class ResourceTests {
 		assertThat(resource.isReadable()).isTrue();
 		assertThat(resource.contentLength() > 0).isTrue();
 		assertThat(resource.lastModified() > 0).isTrue();
+		assertThat(resource.getContentAsByteArray()).containsExactly(Files.readAllBytes(Path.of(resource.getURI())));
 	}
 
 	@ParameterizedTest(name = "{index}: {0}")
@@ -113,24 +117,13 @@ class ResourceTests {
 		Resource relative4 = resource.createRelative("X.class");
 		assertThat(relative4.exists()).isFalse();
 		assertThat(relative4.isReadable()).isFalse();
+		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(relative4::contentLength);
+		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(relative4::lastModified);
+		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(relative4::getInputStream);
+		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(relative4::readableChannel);
+		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(relative4::getContentAsByteArray);
 		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(
-				relative4::contentLength);
-		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(
-				relative4::lastModified);
-	}
-
-	@ParameterizedTest(name = "{index}: {0}")
-	@MethodSource("resource")
-	void loadingMissingResourceFails(Resource resource) {
-		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(() ->
-				resource.createRelative("X").getInputStream());
-	}
-
-	@ParameterizedTest(name = "{index}: {0}")
-	@MethodSource("resource")
-	void readingMissingResourceFails(Resource resource) {
-		assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(() ->
-				resource.createRelative("X").readableChannel());
+				() -> relative4.getContentAsString(StandardCharsets.UTF_8));
 	}
 
 	private static Stream<Arguments> resource() throws URISyntaxException {
@@ -153,12 +146,18 @@ class ResourceTests {
 
 		@Test
 		void hasContent() throws Exception {
-			Resource resource = new ByteArrayResource("testString".getBytes());
+			String testString = "testString";
+			byte[] testBytes = testString.getBytes();
+			Resource resource = new ByteArrayResource(testBytes);
 			assertThat(resource.exists()).isTrue();
 			assertThat(resource.isOpen()).isFalse();
-			String content = FileCopyUtils.copyToString(new InputStreamReader(resource.getInputStream()));
-			assertThat(content).isEqualTo("testString");
-			assertThat(new ByteArrayResource("testString".getBytes())).isEqualTo(resource);
+			byte[] contentBytes = resource.getContentAsByteArray();
+			assertThat(contentBytes).containsExactly(testBytes);
+			String contentString = resource.getContentAsString(StandardCharsets.US_ASCII);
+			assertThat(contentString).isEqualTo(testString);
+			contentString = FileCopyUtils.copyToString(new InputStreamReader(resource.getInputStream()));
+			assertThat(contentString).isEqualTo(testString);
+			assertThat(new ByteArrayResource(testBytes)).isEqualTo(resource);
 		}
 
 		@Test
@@ -181,11 +180,22 @@ class ResourceTests {
 
 		@Test
 		void hasContent() throws Exception {
-			InputStream is = new ByteArrayInputStream("testString".getBytes());
-			Resource resource = new InputStreamResource(is);
-			String content = FileCopyUtils.copyToString(new InputStreamReader(resource.getInputStream()));
-			assertThat(content).isEqualTo("testString");
-			assertThat(new InputStreamResource(is)).isEqualTo(resource);
+			String testString = "testString";
+			byte[] testBytes = testString.getBytes();
+			InputStream is = new ByteArrayInputStream(testBytes);
+			Resource resource1 = new InputStreamResource(is);
+			String content = FileCopyUtils.copyToString(new InputStreamReader(resource1.getInputStream()));
+			assertThat(content).isEqualTo(testString);
+			assertThat(new InputStreamResource(is)).isEqualTo(resource1);
+			assertThatIllegalStateException().isThrownBy(resource1::getInputStream);
+
+			Resource resource2 = new InputStreamResource(new ByteArrayInputStream(testBytes));
+			assertThat(resource2.getContentAsByteArray()).containsExactly(testBytes);
+			assertThatIllegalStateException().isThrownBy(resource2::getContentAsByteArray);
+
+			Resource resource3 = new InputStreamResource(new ByteArrayInputStream(testBytes));
+			assertThat(resource3.getContentAsString(StandardCharsets.US_ASCII)).isEqualTo(testString);
+			assertThatIllegalStateException().isThrownBy(() -> resource3.getContentAsString(StandardCharsets.US_ASCII));
 		}
 
 		@Test
@@ -435,6 +445,9 @@ class ResourceTests {
 					.withMessageContaining(name);
 			assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(() ->
 					resource.createRelative("/testing")).withMessageContaining(name);
+			assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(resource::getContentAsByteArray);
+			assertThatExceptionOfType(FileNotFoundException.class).isThrownBy(
+					() -> resource.getContentAsString(StandardCharsets.US_ASCII));
 			assertThat(resource.getFilename()).isNull();
 		}
 
@@ -456,25 +469,4 @@ class ResourceTests {
 
 	}
 
-	@Test
-	void getContentAsString_givenValidFile_ShouldReturnFileContent() throws IOException {
-		String expectedString = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
-				+ "<!DOCTYPE properties SYSTEM \"http://java.sun.com/dtd/properties.dtd\">\n"
-				+ "<properties version=\"1.0\">\n"
-				+ "\t<entry key=\"foo\">bar</entry>\n"
-				+ "</properties>";
-
-		String fileDirString =
-				new ClassPathResource("org/springframework/core/io/example.xml").getContentAsString();
-		assertThat(fileDirString).isNotBlank();
-		assertThat(fileDirString).isEqualTo(expectedString);
-	}
-
-	@Test
-	void getContentAsString_givenAnInvalidFile_ShouldThrowFileNotFoundException(){
-		assertThatExceptionOfType(FileNotFoundException.class)
-				.isThrownBy(new ClassPathResource("nonExistantFile")::getContentAsString);
-
-	}
-
 }

spring-core/src/test/resources/org/springframework/core/io/example.xml

@@ -2,4 +2,5 @@
 <!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
 <properties version="1.0">
 	<entry key="foo">bar</entry>
-</properties>
+</properties>
+

spring-webflux/src/main/java/org/springframework/web/reactive/resource/EncodedResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.URI;
 import java.net.URL;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -269,6 +270,16 @@ public class EncodedResourceResolver extends AbstractResourceResolver {
 			return this.encoded.getDescription();
 		}
 
+		@Override
+		public byte[] getContentAsByteArray() throws IOException {
+			return this.encoded.getContentAsByteArray();
+		}
+
+		@Override
+		public String getContentAsString(Charset charset) throws IOException {
+			return this.encoded.getContentAsString(charset);
+		}
+
 		@Override
 		public HttpHeaders getResponseHeaders() {
 			HttpHeaders headers;

spring-webflux/src/main/java/org/springframework/web/reactive/resource/VersionResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.URI;
 import java.net.URL;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
@@ -308,6 +309,16 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 			return this.original.getDescription();
 		}
 
+		@Override
+		public byte[] getContentAsByteArray() throws IOException {
+			return this.original.getContentAsByteArray();
+		}
+
+		@Override
+		public String getContentAsString(Charset charset) throws IOException {
+			return this.original.getContentAsString(charset);
+		}
+
 		@Override
 		public InputStream getInputStream() throws IOException {
 			return this.original.getInputStream();

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/EncodedResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.URI;
 import java.net.URL;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -266,6 +267,16 @@ public class EncodedResourceResolver extends AbstractResourceResolver {
 			return this.encoded.getDescription();
 		}
 
+		@Override
+		public byte[] getContentAsByteArray() throws IOException {
+			return this.encoded.getContentAsByteArray();
+		}
+
+		@Override
+		public String getContentAsString(Charset charset) throws IOException {
+			return this.encoded.getContentAsString(charset);
+		}
+
 		@Override
 		public HttpHeaders getResponseHeaders() {
 			HttpHeaders headers;

spring-webmvc/src/main/java/org/springframework/web/servlet/resource/VersionResourceResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.net.URI;
 import java.net.URL;
+import java.nio.charset.Charset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Comparator;
@@ -304,6 +305,16 @@ public class VersionResourceResolver extends AbstractResourceResolver {
 			return this.original.getDescription();
 		}
 
+		@Override
+		public byte[] getContentAsByteArray() throws IOException {
+			return this.original.getContentAsByteArray();
+		}
+
+		@Override
+		public String getContentAsString(Charset charset) throws IOException {
+			return this.original.getContentAsString(charset);
+		}
+
 		@Override
 		public InputStream getInputStream() throws IOException {
 			return this.original.getInputStream();