ServletOutputStream.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package jakarta.servlet;
import java.io.CharConversionException;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.text.MessageFormat;
import java.util.Objects;
import java.util.ResourceBundle;
/**
* Provides an output stream for sending binary data to the client. A <code>ServletOutputStream</code> object is
* normally retrieved via the {@link ServletResponse#getOutputStream} method.
* <p>
* This is an abstract class that the servlet container implements. Subclasses of this class must implement the
* <code>java.io.OutputStream.write(int)</code> method.
*
* @see ServletResponse
*/
public abstract class ServletOutputStream extends OutputStream {
private static final String LSTRING_FILE = "jakarta.servlet.LocalStrings";
private static final ResourceBundle lStrings = ResourceBundle.getBundle(LSTRING_FILE);
/**
* Does nothing, because this is an abstract class.
*/
protected ServletOutputStream() {
// NOOP
}
/**
* Writes from the given buffer to the output stream.
* <p>
* If the output steam is in non-blocking mode, before each invocation of this method {@link #isReady()} must be
* called and must return {@code true} or the {@link WriteListener#onWritePossible()} call back must indicate that
* data may be written else an {@link IllegalStateException} must be thrown.
* <p>
* Otherwise, if this method is called when {@code buffer} has no data remaining, the method returns immediately and
* {@code buffer} is unchanged.
* <p>
* If the output stream is in non-blocking mode, neither the position, limit nor content of the buffer passed to
* this method may be modified until a subsequent call to {@link #isReady()} returns true or the
* {@link WriteListener#onWritePossible()} call back indicates data may be written again. At this point the buffer's
* limit will be unchanged from the value when passed to this method and the position will be the same as the limit.
* <p>
* If the output stream is in blocking mode and {@code buffer} has space remaining, this method blocks until all the
* remaining data in the buffer has been written. When the method returns, and if data has been written, the
* buffer's limit will be unchanged from the value when passed to this method and the position will be the same as
* the limit.
* <p>
* Subclasses are strongly encouraged to override this method and provide a more efficient implementation.
*
* @param buffer The buffer from which the data is written.
*
* @exception IllegalStateException If the output stream is in non-blocking mode and this method is called without
* first calling {@link #isReady()} and that method has returned {@code true}
* or {@link WriteListener#onWritePossible()} has not signalled that data may
* be written.
* @exception IOException If the output stream has been closed or if some other I/O error occurs.
* @exception NullPointerException If buffer is null.
*
* @since Servlet 6.1
*/
public void write(ByteBuffer buffer) throws IOException {
Objects.requireNonNull(buffer);
if (!isReady()) {
throw new IllegalStateException();
}
if (buffer.remaining() == 0) {
return;
}
byte[] b = new byte[buffer.remaining()];
buffer.get(b);
write(b);
}
/**
* Writes a <code>String</code> to the client, without a carriage return-line feed (CRLF) character at the end.
*
* @param s the <code>String</code> to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(String s) throws IOException {
if (s == null) {
s = "null";
}
int len = s.length();
byte[] buffer = new byte[len];
for (int i = 0; i < len; i++) {
char c = s.charAt(i);
//
// XXX NOTE: This is clearly incorrect for many strings,
// but is the only consistent approach within the current
// servlet framework. It must suffice until servlet output
// streams properly encode their output.
//
if ((c & 0xff00) != 0) { // high order byte must be zero
String errMsg = lStrings.getString("err.not_iso8859_1");
Object[] errArgs = new Object[1];
errArgs[0] = Character.valueOf(c);
errMsg = MessageFormat.format(errMsg, errArgs);
throw new CharConversionException(errMsg);
}
buffer[i] = (byte) (c & 0xFF);
}
write(buffer);
}
/**
* Writes a <code>boolean</code> value to the client, with no carriage return-line feed (CRLF) character at the end.
*
* @param b the <code>boolean</code> value to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(boolean b) throws IOException {
String msg;
if (b) {
msg = lStrings.getString("value.true");
} else {
msg = lStrings.getString("value.false");
}
print(msg);
}
/**
* Writes a character to the client, with no carriage return-line feed (CRLF) at the end.
*
* @param c the character to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(char c) throws IOException {
print(String.valueOf(c));
}
/**
* Writes an int to the client, with no carriage return-line feed (CRLF) at the end.
*
* @param i the int to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(int i) throws IOException {
print(String.valueOf(i));
}
/**
* Writes a <code>long</code> value to the client, with no carriage return-line feed (CRLF) at the end.
*
* @param l the <code>long</code> value to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(long l) throws IOException {
print(String.valueOf(l));
}
/**
* Writes a <code>float</code> value to the client, with no carriage return-line feed (CRLF) at the end.
*
* @param f the <code>float</code> value to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(float f) throws IOException {
print(String.valueOf(f));
}
/**
* Writes a <code>double</code> value to the client, with no carriage return-line feed (CRLF) at the end.
*
* @param d the <code>double</code> value to send to the client
*
* @exception IOException if an input or output exception occurred
*/
public void print(double d) throws IOException {
print(String.valueOf(d));
}
/**
* Writes a carriage return-line feed (CRLF) to the client.
*
* @exception IOException if an input or output exception occurred
*/
public void println() throws IOException {
print("\r\n");
}
/**
* Writes a <code>String</code> to the client, followed by a carriage return-line feed (CRLF).
*
* @param s the <code>String</code> to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(String s) throws IOException {
StringBuilder sb = new StringBuilder();
sb.append(s);
sb.append("\r\n");
print(sb.toString());
}
/**
* Writes a <code>boolean</code> value to the client, followed by a carriage return-line feed (CRLF).
*
* @param b the <code>boolean</code> value to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(boolean b) throws IOException {
StringBuilder sb = new StringBuilder();
if (b) {
sb.append(lStrings.getString("value.true"));
} else {
sb.append(lStrings.getString("value.false"));
}
sb.append("\r\n");
print(sb.toString());
}
/**
* Writes a character to the client, followed by a carriage return-line feed (CRLF).
*
* @param c the character to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(char c) throws IOException {
println(String.valueOf(c));
}
/**
* Writes an int to the client, followed by a carriage return-line feed (CRLF) character.
*
* @param i the int to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(int i) throws IOException {
println(String.valueOf(i));
}
/**
* Writes a <code>long</code> value to the client, followed by a carriage return-line feed (CRLF).
*
* @param l the <code>long</code> value to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(long l) throws IOException {
println(String.valueOf(l));
}
/**
* Writes a <code>float</code> value to the client, followed by a carriage return-line feed (CRLF).
*
* @param f the <code>float</code> value to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(float f) throws IOException {
println(String.valueOf(f));
}
/**
* Writes a <code>double</code> value to the client, followed by a carriage return-line feed (CRLF).
*
* @param d the <code>double</code> value to write to the client
*
* @exception IOException if an input or output exception occurred
*/
public void println(double d) throws IOException {
println(String.valueOf(d));
}
/**
* Returns {@code true} if it is allowable to call any method that may write data (e.g. {@code write()},
* {@code print()} or {@code flush}). In blocking mode, this method will always return {@code true}, but a
* subsequent call to a method that writes data may block. In non-blocking mode this method may return
* {@code false}, in which case it is illegal to call a method that writes data and an {@link IllegalStateException}
* MUST be thrown. When {@link WriteListener#onWritePossible()} is called, a call to this method that returned
* {@code true} is implicit.
* <p>
* If this method returns {@code false} and a {@link WriteListener} has been set via
* {@link #setWriteListener(WriteListener)}, then container will subsequently invoke
* {@link WriteListener#onWritePossible()} once a write operation becomes possible without blocking. Other than the
* initial call, {@link WriteListener#onWritePossible()} will only be called if and only if this method is called
* and returns false.
*
* @return {@code true} if data can be written without blocking, otherwise returns {@code false}.
*
* @since Servlet 3.1
*/
public abstract boolean isReady();
/**
* Sets the {@link WriteListener} for this {@link ServletOutputStream} and thereby switches to non-blocking IO. It
* is only valid to switch to non-blocking IO within async processing or HTTP upgrade processing.
*
* @param listener The non-blocking IO write listener
*
* @throws IllegalStateException If this method is called if neither async nor HTTP upgrade is in progress or if the
* {@link WriteListener} has already been set
* @throws NullPointerException If listener is null
*
* @since Servlet 3.1
*/
public abstract void setWriteListener(WriteListener listener);
/**
* {@inheritDoc}
* <p>
* If this method is called when the output stream is in non-blocking mode, it will immediately return with the
* stream effectively closed, even if the stream contains buffered data that is yet to be written to client. The
* container will write this data out in the background. If this process fails the
* {@link WriteListener#onError(Throwable)} method will be invoked as normal.
*/
@Override
public void close() throws IOException {
super.close();
}
}