4.2 Using Resource

Using Resource

1. ByteArrayResource

Junit test:

import org.junit.Test;
import org.springframework.core.io.ByteArrayResource;
import org.springframework.core.io.Resource;

public class ResourceTest {

	@Test
	public void testByteArraryResorce() {
		Resource resource = new ByteArrayResource("Hello World!".getBytes());
		if (resource.exists()) {
			dumpStream(resource);
		}
		Assert.assertEquals(false, resource.isOpen());
	}

	private void dumpStream(Resource resource) {
		InputStream inputStream = null;
		try {
			inputStream = resource.getInputStream();
			byte [] descByte = new byte [inputStream.available()];
			inputStream.read(descByte);
			System.out.println(new String(descByte));
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				inputStream.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
	}
}

NOTE: ByteArrayResource can be used repeatedly, because isOpen() always returns false.

2. InputStreamResource:

@Test
public void testInputStreamResource() {
		ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream("Hello World!".getBytes());
		Resource resource = new InputStreamResource(byteArrayInputStream);
		if (resource.exists()) {
			dumpStream(resource);
		}
		Assert.assertEquals(true, resource.isOpen());
}

NOTE: InputStreamResource can be used only one time, because isOpen() always returns true.

3. FileSystemResource:

@Test
public void testFileResource() {
		File file = new File("d:/test.txt");
		Resource resource = new FileSystemResource(file);
		if (resource.exists()) {
			dumpStream(resource);
		}
		Assert.assertEquals(false, resource.isOpen());
}

NOTE: FileSystemResource can be used repeatedly, because isOpen() always returns false.

4. ClassPathResource:

ClassPathResource replaces Class and ClassLoader to give a uniform implement. The resource can be used repeatedly, because isOpen() always returns false.

Here are three constructors in ClassPathResource:

• public ClassPathResource(String path): using default ClassLoader to load resource.

• public ClassPathResource(String path, ClassLoader classLoader): using specified ClassLoader to load path resource.

• _ public ClassPathResource(String path, Class<?> clazz)_: using Class path to load resource.

For example, if the Class path is “cn.javass.spring.ResourceTest”, the path is “cn/javass/spring/ResourceTest”.

1. public ClassPathResource(String path):

@Test
public void testClasspathResourceBydefaultClassLoader() throws IOException {
		Resource resource = new ClassPathResource("cn/javass/spring/chapter4/test.properties");
		if (resource.exists()) {
			dumpStream(resource);
		}
		System.out.println("path:" + resource.getFile().getAbsolutePath());
		Assert.assertEquals(false, resource.isOpen());
}

1. public ClassPathResource(String path, ClassLoader classLoader):

@Test
public void testClasspathResourceByClassLoader() throws IOException {
		ClassLoader classLoader = this.getClass().getClassLoader();
		Resource resource = new ClassPathResource("cn/javass/spring/chapter4/test.properties", classLoader);
		if (resource.exists()) {
			dumpStream(resource);
		}
		System.out.println("path:" + resource.getFile().getAbsolutePath());
		Assert.assertEquals(false, resource.isOpen());
}

1. _ public ClassPathResource(String path, Class<?> clazz)_:

@Test
public void testClasspathResourceByClass() throws IOException {
		Class clazz = this.getClass();
		Resource resource1 = new ClassPathResource("cn/javass/spring/chapter4/test.properties", clazz);
		if (resource1.exists()) {
			dumpStream(resource1);
		}
		System.out.println("path:" + resource1.getFile().getAbsolutePath());
		Assert.assertEquals(false, resource1.isOpen());

		Resource resource2 = new ClassPathResource("cn/javass/spring/chapter4/test.properties", this.getClass());
		if (resource2.exists()) {
			dumpStream(resource2);
		}
		System.out.println("path:" + resource2.getFile().getAbsolutePath());
		Assert.assertEquals(false, resource1.isOpen());
}

If not provide the full path, it will search in the resource folder. If not found in the resource folder, it will search in other package folders.

@Test
public void classpathResourceTestFromJar() throws IOException {
		Resource resource = new ClassPathResource("overview.html");
		if (resource.exists()) {
			dumpStream(resource);
		}
		System.out.println("path:" + resource.getURL().getPath());
		Assert.assertEquals(false, resource.isOpen());
}

5. UrlResource:

isOpen() always return false. Supporting three ways to load resources:

• http

• ftp

• file: For example, new UrlResource(“file:d:/test.txt“).

6. ServletContextResource:

To simplize the ServletContext of servlet.

7. VfsResource:

JBoss AS is now provide on http://wildfly.org/downloads/.

@Test
public void testVfsResourceForRealFileSystem() throws IOException {
		//New virtual path
		VirtualFile home = VFS.getChild("/home");
		//Mapping physical path
		VFS.mount(home, new RealFileSystem(new File("d:")));
		//Load resource from virtual path
		VirtualFile virtualFile = home.getChild("test.txt");
		Resource resource = new VfsResource(virtualFile);
		if (resource.exists()) {
			dumpStream(resource);
		}
		System.out.println(resource.getFile().getAbsolutePath());
		Assert.assertEquals(false, resource.isOpen());
}