HADOOP-16790: Add Write Convenience Methods

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FileUtil.java

@@ -21,23 +21,28 @@
 import java.io.BufferedInputStream;
 import java.io.BufferedOutputStream;
 import java.io.BufferedReader;
+import java.io.BufferedWriter;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
+import java.io.OutputStreamWriter;
 import java.net.InetAddress;
 import java.net.URI;
 import java.net.UnknownHostException;
 import java.nio.charset.Charset;
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.AccessDeniedException;
 import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -1633,4 +1638,235 @@ public static boolean compareFs(FileSystem srcFs, FileSystem destFs) {
     // check for ports
     return srcUri.getPort()==dstUri.getPort();
   }
+
+  /**
+   * Writes bytes to a file. This utility method opens the file for writing,
+   * creating the file if it does not exist, or overwrites an existing file. All
+   * bytes in the byte array are written to the file.
+   *
+   * @param fs the file system with which to create the file
+   * @param path the path to the file
+   * @param bytes the byte array with the bytes to write
+   *
+   * @return the file system
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileSystem write(final FileSystem fs, final Path path,
+      final byte[] bytes) throws IOException {
+
+    Objects.requireNonNull(path);
+    Objects.requireNonNull(bytes);
+
+    try (FSDataOutputStream out = fs.createFile(path).overwrite(true).build()) {
+      out.write(bytes);
+    }
+
+    return fs;
+  }
+
+  /**
+   * Writes bytes to a file. This utility method opens the file for writing,
+   * creating the file if it does not exist, or overwrites an existing file. All
+   * bytes in the byte array are written to the file.
+   *
+   * @param fileContext the file context with which to create the file
+   * @param path the path to the file
+   * @param bytes the byte array with the bytes to write
+   *
+   * @return the file context
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileContext write(final FileContext fileContext,
+      final Path path, final byte[] bytes) throws IOException {
+
+    Objects.requireNonNull(path);
+    Objects.requireNonNull(bytes);
+
+    try (FSDataOutputStream out =
+        fileContext.create(path).overwrite(true).build()) {
+      out.write(bytes);
+    }
+
+    return fileContext;
+  }
+
+  /**
+   * Write lines of text to a file. Each line is a char sequence and is written
+   * to the file in sequence with each line terminated by the platform's line
+   * separator, as defined by the system property {@code
+   * line.separator}. Characters are encoded into bytes using the specified
+   * charset. This utility method opens the file for writing, creating the file
+   * if it does not exist, or overwrites an existing file.
+   *
+   * @param fs the file system with which to create the file
+   * @param path the path to the file
+   * @param lines a Collection to iterate over the char sequences
+   * @param cs the charset to use for encoding
+   *
+   * @return the file system
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileSystem write(final FileSystem fs, final Path path,
+      final Iterable<? extends CharSequence> lines, final Charset cs)
+      throws IOException {
+
+    Objects.requireNonNull(path);
+    Objects.requireNonNull(lines);
+    Objects.requireNonNull(cs);
+
+    CharsetEncoder encoder = cs.newEncoder();
+    try (FSDataOutputStream out = fs.createFile(path).overwrite(true).build();
+        BufferedWriter writer =
+            new BufferedWriter(new OutputStreamWriter(out, encoder))) {
+      for (CharSequence line : lines) {
+        writer.append(line);
+        writer.newLine();
+      }
+    }
+    return fs;
+  }
+
+  /**
+   * Write lines of text to a file. Each line is a char sequence and is written
+   * to the file in sequence with each line terminated by the platform's line
+   * separator, as defined by the system property {@code
+   * line.separator}. Characters are encoded into bytes using the specified
+   * charset. This utility method opens the file for writing, creating the file
+   * if it does not exist, or overwrites an existing file.
+   *
+   * @param fileContext the file context with which to create the file
+   * @param path the path to the file
+   * @param lines a Collection to iterate over the char sequences
+   * @param cs the charset to use for encoding
+   *
+   * @return the file context
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileContext write(final FileContext fileContext,
+      final Path path, final Iterable<? extends CharSequence> lines,
+      final Charset cs) throws IOException {
+
+    Objects.requireNonNull(path);
+    Objects.requireNonNull(lines);
+    Objects.requireNonNull(cs);
+
+    CharsetEncoder encoder = cs.newEncoder();
+    try (FSDataOutputStream out = fileContext.create(path).overwrite(true).build();
+        BufferedWriter writer =
+            new BufferedWriter(new OutputStreamWriter(out, encoder))) {
+      for (CharSequence line : lines) {
+        writer.append(line);
+        writer.newLine();
+      }
+    }
+    return fileContext;
+  }
+
+  /**
+   * Write a line of text to a file. Characters are encoded into bytes using the
+   * specified charset. This utility method opens the file for writing, creating
+   * the file if it does not exist, or overwrites an existing file.
+   *
+   * @param fs the file system with which to create the file
+   * @param path the path to the file
+   * @param charseq the char sequence to write to the file
+   * @param cs the charset to use for encoding
+   *
+   * @return the file system
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileSystem write(final FileSystem fs, final Path path,
+      final CharSequence charseq, final Charset cs) throws IOException {
+
+    Objects.requireNonNull(path);
+    Objects.requireNonNull(charseq);
+    Objects.requireNonNull(cs);
+
+    CharsetEncoder encoder = cs.newEncoder();
+    try (FSDataOutputStream out = fs.createFile(path).overwrite(true).build();
+        BufferedWriter writer =
+            new BufferedWriter(new OutputStreamWriter(out, encoder))) {
+      writer.append(charseq);
+    }
+    return fs;
+  }
+
+  /**
+   * Write a line of text to a file. Characters are encoded into bytes using the
+   * specified charset. This utility method opens the file for writing, creating
+   * the file if it does not exist, or overwrites an existing file.
+   *
+   * @param FileContext the file context with which to create the file
+   * @param path the path to the file
+   * @param charseq the char sequence to write to the file
+   * @param cs the charset to use for encoding
+   *
+   * @return the file context
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileContext write(final FileContext fs, final Path path,
+      final CharSequence charseq, final Charset cs) throws IOException {
+
+    Objects.requireNonNull(path);
+    Objects.requireNonNull(charseq);
+    Objects.requireNonNull(cs);
+
+    CharsetEncoder encoder = cs.newEncoder();
+    try (FSDataOutputStream out = fs.create(path).overwrite(true).build();
+        BufferedWriter writer =
+            new BufferedWriter(new OutputStreamWriter(out, encoder))) {
+      writer.append(charseq);
+    }
+    return fs;
+  }
+
+  /**
+   * Write a line of text to a file. Characters are encoded into bytes using
+   * UTF-8. This utility method opens the file for writing, creating the file if
+   * it does not exist, or overwrites an existing file.
+   *
+   * @param fs the files system with which to create the file
+   * @param path the path to the file
+   * @param charseq the char sequence to write to the file
+   *
+   * @return the file system
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileSystem write(final FileSystem fs, final Path path,
+      final CharSequence charseq) throws IOException {
+    return write(fs, path, charseq, StandardCharsets.UTF_8);
+  }
+
+  /**
+   * Write a line of text to a file. Characters are encoded into bytes using
+   * UTF-8. This utility method opens the file for writing, creating the file if
+   * it does not exist, or overwrites an existing file.
+   *
+   * @param fileContext the files system with which to create the file
+   * @param path the path to the file
+   * @param charseq the char sequence to write to the file
+   *
+   * @return the file context
+   *
+   * @throws NullPointerException if any of the arguments are {@code null}
+   * @throws IOException if an I/O error occurs creating or writing to the file
+   */
+  public static FileContext write(final FileContext fileContext,
+      final Path path, final CharSequence charseq) throws IOException {
+    return write(fileContext, path, charseq, StandardCharsets.UTF_8);
+  }
 }