org.cloudbus.cloudsim.util.ResourceLoader Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of cloudsim-plus Show documentation
Show all versions of cloudsim-plus Show documentation
CloudSim Plus: A modern, highly extensible and easier-to-use Java 8 Framework for Modeling and Simulation of Cloud Computing Infrastructures and Services
package org.cloudbus.cloudsim.util;
import java.io.*;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.FileSystem;
import java.nio.file.*;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;
/**
* An utility class that loads a resource file/directory that is contained inside
* the directory of a given class.
*
* @author Manoel Campos da Silva Filho
*/
public final class ResourceLoader {
/**
* A private constructor to avoid class instantiation.
*/
private ResourceLoader(){}
/**
* Gets a {@link FileReader}
* @param filePath the path to the file
* @return the {@link FileReader} instance.
*/
public static FileReader getFileReader(final String filePath){
try {
return new FileReader(filePath);
} catch (FileNotFoundException e) {
throw new UncheckedIOException(e);
}
}
/**
* Gets the absolute path of a resource (a file or sub-directory) inside the resources directory.
*
* @param klass a class from the project which will be used just to assist in getting the path
* of the given resource. It can can any class inside the project
* where a resource you are trying to get from the resources directory
* @param name the name of the resource to get its path
* (that can be a file or a sub-directory inside the resources directory)
* @return the absolute path of the resource
*/
public static String getResourcePath(final Class klass, final String name) {
final URL resource = getResourceUrl(klass, name);
return resource == null || resource.getPath() == null ? "" : resource.getFile();
}
/**
* Gets the {@link URL} of a resource (a file or sub-directory) inside the resources directory.
*
* @param klass a class from the project which will be used just to assist in getting the path
* of the given resource. It can can any class inside the project
* where a resource you are trying to get from the resources directory
* @param name the name of the resource to get its path
* (that can be a file or a sub-directory inside the resources directory)
* @return the {@link URL} of the resource
*/
public static URL getResourceUrl(final Class klass, final String name) {
return klass.getClassLoader().getResource(name);
}
/**
* Gets the list of files contained inside a given resource directory.
*
* @param klass a class from the project which will be used just to assist in getting the path
* of the given resource. It can can any class inside the project
* where a resource you are trying to get from the resources directory
* @param resourceDir the name of the resource directory to get the list of files from
* @return
*/
public static List getResourceList(final Class klass, final String resourceDir){
final URI uri;
try {
uri = getResourceUrl(klass, resourceDir).toURI();
} catch (URISyntaxException e) {
throw new IllegalArgumentException(e);
}
try {
final Path fullPath = uriToPath(resourceDir, uri);
final List list =
Files.walk(fullPath, 1)
.map(path -> resourceDir + "/" + path.getFileName().toString())
.collect(Collectors.toList());
//Removes the first element which is the name of the containing directory
if(!list.isEmpty()) {
list.remove(0);
}
return list;
} catch (IOException e) {
throw new UncheckedIOException(e);
}
}
private static Path uriToPath(final String resourceDir, final URI uri) throws IOException {
if (uri.getScheme().equals("jar")) {
final FileSystem fileSystem = FileSystems.newFileSystem(uri, Collections.emptyMap());
return fileSystem.getPath(resourceDir);
}
return Paths.get(uri);
}
/**
* Gets a {@link BufferedReader} to read a resource (a file or sub-directory inside the resources directory)
* from its absolute path.
*
* @param klass a class from the project that will be used just to assist in getting the path of the given resource
* @param resourceName the name of the resource to get a {@link BufferedReader} for it
* @return a {@link BufferedReader} to read the resource
* @throws FileNotFoundException when the file doesn't exist
*/
public static BufferedReader getBufferedReader(final Class klass, final String resourceName) {
return new BufferedReader(new InputStreamReader(getInputStream(resourceName, klass)));
}
/**
* Try to load the resource from a jar file, in case the user is running simulations
* from a jar instead of directly from the IDE.
* If the input is null, the simulation is not being executed from a jar file,
* so try to load the resource from a directory in the filesystem.
*
* @param resourceName the name of the resource to get a {@link BufferedReader} for it
* @param klass a class from the project that will be used just to assist in getting the path of the given resource
* @return a {@link InputStream} to read the resource
* @throws UncheckedIOException when the file cannot be accessed (such as when it doesn't exist)
*/
public static InputStream getInputStream(final String resourceName, final Class klass) {
//Try to load the resource from the resource directory in the filesystem
InputStream input = klass.getClassLoader().getResourceAsStream("/"+resourceName);
if(input != null){
return input;
}
//Try to load the resource from a jar file
input = klass.getResourceAsStream("/"+resourceName);
if(input != null){
return input;
}
//Try to load the resource from anywhere else than the resource directory
try {
return new FileInputStream(resourceName);
} catch (FileNotFoundException e) {
throw new UncheckedIOException(e);
}
}
}