This article contains some code snippets that I commonly use for Java I/O.
Create temp file
Create a temp file inside a specified folder
/** max index reached with temp files */ public static int MAX_INDEX = 100; /** * Create a temporary file in specified folder. To create the file * use prefix and postfix passed as parameters. Temporary files * are numbered according to an internal index. * * @param baseDir path of base directory that will contain file * @param prefix file prefix * @param postfix file postfix * @return temporary File or null */ public static File createTempFile(String baseDir, String prefix, String postfix) throws Exception { File parentDir = new File(baseDir); File tempFile = null; if (parentDir != null) { for (int index = 0; index < MAX_INDEX; index++) { tempFile = new File(parentDir, prefix + "_" + index + postfix); if (!tempFile.exists()) { if (tempFile.createNewFile()) return tempFile; } } } return null; }
Write String to File
Write String content inside a specified file.
public static void writeToFile(String content, File outFile) { try { // Create file FileWriter fstream = new FileWriter( outFile ); BufferedWriter out = new BufferedWriter(fstream); out.write( content ); // Close the output stream out.close(); } catch (Exception e) { // Catch exception if any System.err.println("Error: " + e.getMessage()); } }
Read String from File, by Filesystem
Read Textual content of a file starting from file path, given on filesystem. The method raises exceptions
public static String tryReadFromFile(String filepath) throws Exception { // leggo risorsa da stream InputStream inStream = new FileInputStream(filepath); byte[] content = new byte[inStream.available()]; inStream.read(content); inStream.close(); // l'array di byte diventa stringa return new String(content); }
Lettura String da File, tramite Classpath
Read textual content of a file starting from file path, given on classpath. The method raises exceptions
public static String tryReadFromResource(String classpath) throws Exception { // leggo risorsa da stream InputStream inStream = CLASSLOADER.getResourceAsStream(classpath); byte[] content = new byte[inStream.available()]; inStream.read(content); inStream.close(); // l'array di byte diventa stringa return new String(content); }
Lettura String da File, tramite URL
Read textual content from a resource referenced by an URL, given as parameter. The methos raises exceptions
public static String tryReadFromURL(String urlString) throws Exception { // lettura risorsa URL url = new URL(urlString); InputStream inStream = url.openStream(); byte[] content = new byte[inStream.available()]; inStream.read(content); inStream.close(); // l'array di byte diventa stringa return new String(content); }
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