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25 
26 package java.net;
27 
28 import java.io.FileDescriptor;
29 import java.io.FileOutputStream;
30 import java.io.IOException;
31 import java.nio.channels.FileChannel;
32 
33 /**
34  * This stream extends FileOutputStream to implement a
35  * SocketOutputStream. Note that this class should <b>NOT</b> be
36  * public.
37  *
38  * @author      Jonathan Payne
39  * @author      Arthur van Hoff
40  */
41 class SocketOutputStream extends FileOutputStream {
42     static {
init()43         init();
44     }
45 
46     private AbstractPlainSocketImpl impl = null;
47     private byte temp[] = new byte[1];
48 
49     /**
50      * Creates a new SocketOutputStream. Can only be called
51      * by a Socket. This method needs to hang on to the owner Socket so
52      * that the fd will not be closed.
53      * @param impl the socket output stream implemented
54      */
SocketOutputStream(AbstractPlainSocketImpl impl)55     SocketOutputStream(AbstractPlainSocketImpl impl) throws IOException {
56         super(impl.getFileDescriptor());
57         this.impl = impl;
58     }
59 
60     /**
61      * Returns the unique {@link java.nio.channels.FileChannel FileChannel}
62      * object associated with this file output stream. </p>
63      *
64      * The {@code getChannel} method of {@code SocketOutputStream}
65      * returns {@code null} since it is a socket based stream.</p>
66      *
67      * @return  the file channel associated with this file output stream
68      *
69      * @since 1.4
70      */
getChannel()71     public final FileChannel getChannel() {
72         return null;
73     }
74 
75     /**
76      * Writes to the socket.
77      * @param fd the FileDescriptor
78      * @param b the data to be written
79      * @param off the start offset in the data
80      * @param len the number of bytes that are written
81      * @throws    IOException If an I/O error has occurred.
82      */
socketWrite0(FileDescriptor fd, byte[] b, int off, int len)83     private native void socketWrite0(FileDescriptor fd, byte[] b, int off,
84                                      int len) throws IOException;
85 
86     /**
87      * Writes to the socket with appropriate locking of the
88      * FileDescriptor.
89      * @param b the data to be written
90      * @param off the start offset in the data
91      * @param len the number of bytes that are written
92      * @throws    IOException If an I/O error has occurred.
93      */
socketWrite(byte b[], int off, int len)94     private void socketWrite(byte b[], int off, int len) throws IOException {
95 
96 
97         if (len <= 0 || off < 0 || len > b.length - off) {
98             if (len == 0) {
99                 return;
100             }
101             throw new ArrayIndexOutOfBoundsException("len == " + len
102                     + " off == " + off + " buffer length == " + b.length);
103         }
104 
105         FileDescriptor fd = impl.acquireFD();
106         try {
107             socketWrite0(fd, b, off, len);
108         } catch (SocketException se) {
109             if (impl.isClosedOrPending()) {
110                 throw new SocketException("Socket closed");
111             } else {
112                 throw se;
113             }
114         } finally {
115             impl.releaseFD();
116         }
117     }
118 
119     /**
120      * Writes a byte to the socket.
121      * @param b the data to be written
122      * @throws    IOException If an I/O error has occurred.
123      */
write(int b)124     public void write(int b) throws IOException {
125         temp[0] = (byte)b;
126         socketWrite(temp, 0, 1);
127     }
128 
129     /**
130      * Writes the contents of the buffer <i>b</i> to the socket.
131      * @param b the data to be written
132      * @throws    SocketException If an I/O error has occurred.
133      */
write(byte b[])134     public void write(byte b[]) throws IOException {
135         socketWrite(b, 0, b.length);
136     }
137 
138     /**
139      * Writes <i>length</i> bytes from buffer <i>b</i> starting at
140      * offset <i>len</i>.
141      * @param b the data to be written
142      * @param off the start offset in the data
143      * @param len the number of bytes that are written
144      * @throws    SocketException If an I/O error has occurred.
145      */
write(byte b[], int off, int len)146     public void write(byte b[], int off, int len) throws IOException {
147         socketWrite(b, off, len);
148     }
149 
close()150     public void close() throws IOException {
151         // No longer used. Socket.getOutputStream returns an
152         // OutputStream which calls Socket.close directly
153         assert false;
154     }
155 
156     /**
157      * Overrides finalize, the fd is closed by the Socket.
158      */
159     @SuppressWarnings({"deprecation", "removal"})
finalize()160     protected void finalize() {}
161 
162     /**
163      * Perform class load-time initializations.
164      */
init()165     private static native void init();
166 
167 }
168