30 /** 31 * This abstract class is the superclass of all classes representing 32 * an output stream of bytes. An output stream accepts output bytes 33 * and sends them to some sink. 34 * <p> 35 * Applications that need to define a subclass of 36 * <code>OutputStream</code> must always provide at least a method 37 * that writes one byte of output. 38 * 39 * @author Arthur van Hoff 40 * @see java.io.BufferedOutputStream 41 * @see java.io.ByteArrayOutputStream 42 * @see java.io.DataOutputStream 43 * @see java.io.FilterOutputStream 44 * @see java.io.InputStream 45 * @see java.io.OutputStream#write(int) 46 * @since 1.0 47 */ 48 public abstract class OutputStream implements Closeable, Flushable { 49 /** 50 * Writes the specified byte to this output stream. The general 51 * contract for <code>write</code> is that one byte is written 52 * to the output stream. The byte to be written is the eight 53 * low-order bits of the argument <code>b</code>. The 24 54 * high-order bits of <code>b</code> are ignored. 55 * <p> 56 * Subclasses of <code>OutputStream</code> must provide an 57 * implementation for this method. 58 * 59 * @param b the <code>byte</code>. 60 * @exception IOException if an I/O error occurs. In particular, 61 * an <code>IOException</code> may be thrown if the 62 * output stream has been closed. 63 */ 64 public abstract void write(int b) throws IOException; 65 66 /** 67 * Writes <code>b.length</code> bytes from the specified byte array 68 * to this output stream. The general contract for <code>write(b)</code> 69 * is that it should have exactly the same effect as the call | 30 /** 31 * This abstract class is the superclass of all classes representing 32 * an output stream of bytes. An output stream accepts output bytes 33 * and sends them to some sink. 34 * <p> 35 * Applications that need to define a subclass of 36 * <code>OutputStream</code> must always provide at least a method 37 * that writes one byte of output. 38 * 39 * @author Arthur van Hoff 40 * @see java.io.BufferedOutputStream 41 * @see java.io.ByteArrayOutputStream 42 * @see java.io.DataOutputStream 43 * @see java.io.FilterOutputStream 44 * @see java.io.InputStream 45 * @see java.io.OutputStream#write(int) 46 * @since 1.0 47 */ 48 public abstract class OutputStream implements Closeable, Flushable { 49 /** 50 * Returns a new {@code OutputStream} which discards all bytes. The 51 * returned stream is initially open. The stream is closed by calling 52 * the {@code close()} method. Subsequent calls to {@code close()} have 53 * no effect. 54 * 55 * <p> While the stream is open, the {@code write(int)}, {@code 56 * write(byte[])}, and {@code write(byte[], int, int)} methods do nothing. 57 * After the stream has been closed, these methods all throw {@code 58 * IOException}. 59 * 60 * <p> The {@code flush()} method does nothing. 61 * 62 * @return an {@code OutputStream} which discards all bytes 63 * 64 * @since 10 65 */ 66 public static OutputStream nullStream() { 67 return new OutputStream() { 68 private volatile boolean closed; 69 70 private void ensureOpen() throws IOException { 71 if (closed) { 72 throw new IOException("Stream closed"); 73 } 74 } 75 76 @Override 77 public void write(int b) throws IOException { 78 ensureOpen(); 79 } 80 81 @Override 82 // overridden for efficiency 83 public void write(byte b[], int off, int len) throws IOException { 84 Objects.requireNonNull(b); 85 Objects.checkFromIndexSize(off, len, b.length); 86 ensureOpen(); 87 } 88 89 @Override 90 public void close() { 91 closed = true; 92 } 93 }; 94 } 95 96 /** 97 * Writes the specified byte to this output stream. The general 98 * contract for <code>write</code> is that one byte is written 99 * to the output stream. The byte to be written is the eight 100 * low-order bits of the argument <code>b</code>. The 24 101 * high-order bits of <code>b</code> are ignored. 102 * <p> 103 * Subclasses of <code>OutputStream</code> must provide an 104 * implementation for this method. 105 * 106 * @param b the <code>byte</code>. 107 * @exception IOException if an I/O error occurs. In particular, 108 * an <code>IOException</code> may be thrown if the 109 * output stream has been closed. 110 */ 111 public abstract void write(int b) throws IOException; 112 113 /** 114 * Writes <code>b.length</code> bytes from the specified byte array 115 * to this output stream. The general contract for <code>write(b)</code> 116 * is that it should have exactly the same effect as the call |