Java tutorial
package com.baeldung.file; import org.apache.commons.io.FileUtils; import org.hamcrest.CoreMatchers; import org.hamcrest.Matchers; import org.junit.Assert; import org.junit.Test; import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.net.URISyntaxException; import java.net.URL; import java.net.URLConnection; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.Paths; import java.util.stream.Stream; import static org.junit.Assert.assertEquals; import static org.junit.Assert.assertThat; public class FileOperationsManualTest { @Test public void givenFileName_whenUsingClassloader_thenFileData() throws IOException { String expectedData = "Hello World from fileTest.txt!!!"; ClassLoader classLoader = getClass().getClassLoader(); File file = new File(classLoader.getResource("fileTest.txt").getFile()); InputStream inputStream = new FileInputStream(file); String data = readFromInputStream(inputStream); assertEquals(expectedData, data.trim()); } @Test public void givenFileNameAsAbsolutePath_whenUsingClasspath_thenFileData() throws IOException { String expectedData = "Hello World from fileTest.txt!!!"; Class clazz = FileOperationsManualTest.class; InputStream inputStream = clazz.getResourceAsStream("/fileTest.txt"); String data = readFromInputStream(inputStream); assertEquals(expectedData, data.trim()); } @Test public void givenFileName_whenUsingJarFile_thenFileData() throws IOException { String expectedData = "BSD License"; Class clazz = Matchers.class; InputStream inputStream = clazz.getResourceAsStream("/LICENSE.txt"); String data = readFromInputStream(inputStream); assertThat(data.trim(), CoreMatchers.containsString(expectedData)); } @Test public void givenURLName_whenUsingURL_thenFileData() throws IOException { String expectedData = "Example Domain"; URL urlObject = new URL("http://www.example.com/"); URLConnection urlConnection = urlObject.openConnection(); InputStream inputStream = urlConnection.getInputStream(); String data = readFromInputStream(inputStream); assertThat(data.trim(), CoreMatchers.containsString(expectedData)); } @Test public void givenFileName_whenUsingFileUtils_thenFileData() throws IOException { String expectedData = "Hello World from fileTest.txt!!!"; ClassLoader classLoader = getClass().getClassLoader(); File file = new File(classLoader.getResource("fileTest.txt").getFile()); String data = FileUtils.readFileToString(file); assertEquals(expectedData, data.trim()); } @Test public void givenFilePath_whenUsingFilesReadAllBytes_thenFileData() throws IOException, URISyntaxException { String expectedData = "Hello World from fileTest.txt!!!"; Path path = Paths.get(getClass().getClassLoader().getResource("fileTest.txt").toURI()); byte[] fileBytes = Files.readAllBytes(path); String data = new String(fileBytes); assertEquals(expectedData, data.trim()); } @Test public void givenFilePath_whenUsingFilesLines_thenFileData() throws IOException, URISyntaxException { String expectedData = "Hello World from fileTest.txt!!!"; Path path = Paths.get(getClass().getClassLoader().getResource("fileTest.txt").toURI()); StringBuilder data = new StringBuilder(); Stream<String> lines = Files.lines(path); lines.forEach(line -> data.append(line).append("\n")); lines.close(); assertEquals(expectedData, data.toString().trim()); } private String readFromInputStream(InputStream inputStream) throws IOException { StringBuilder resultStringBuilder = new StringBuilder(); try (BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream))) { String line; while ((line = bufferedReader.readLine()) != null) { resultStringBuilder.append(line).append("\n"); } } return resultStringBuilder.toString(); } }