com.alipay.api.internal.util.file.FileUtils Maven / Gradle / Ivy
package com.alipay.api.internal.util.file;
import java.io.*;
import java.nio.charset.Charset;
public class FileUtils {
/**
* Reads the contents of a file into a String using the default encoding for the VM. The file is always closed.
*
* @param file the file to read, must not be {@code null}
* @return the file contents, never {@code null}
* @throws IOException in case of an I/O error
* @since 1.3.1
* @deprecated 2.5 use {@link #readFileToString(File, Charset)} instead
*/
@Deprecated
public static String readFileToString(final File file) throws IOException {
return readFileToString(file, Charset.defaultCharset());
}
/**
* Reads the contents of a file into a String. The file is always closed.
*
* @param file the file to read, must not be {@code null}
* @param encoding the encoding to use, {@code null} means platform default
* @return the file contents, never {@code null}
* @throws IOException in case of an I/O error
* @since 2.3
*/
public static String readFileToString(final File file, final Charset encoding) throws IOException {
InputStream in = null;
try {
in = openInputStream(file);
return IOUtils.toString(in, Charsets.toCharset(encoding));
} finally {
IOUtils.closeQuietly(in);
}
}
/**
* Opens a {@link FileInputStream} for the specified file, providing better error messages than simply calling new
* FileInputStream(file).
*
* At the end of the method either the stream will be successfully opened, or an exception will have been thrown.
*
* An exception is thrown if the file does not exist. An exception is thrown if the file object exists but is a directory. An exception
* is thrown if the file exists but cannot be read.
*
* @param file the file to open for input, must not be {@code null}
* @return a new {@link FileInputStream} for the specified file
* @throws FileNotFoundException if the file does not exist
* @throws IOException if the file object is a directory
* @throws IOException if the file cannot be read
* @since 1.3
*/
public static FileInputStream openInputStream(final File file) throws IOException {
if (file.exists()) {
if (file.isDirectory()) {
throw new IOException("File '" + file + "' exists but is a directory");
}
if (file.canRead() == false) {
throw new IOException("File '" + file + "' cannot be read");
}
} else {
throw new FileNotFoundException("File '" + file + "' does not exist");
}
return new FileInputStream(file);
}
}