https://tomcat.apache.org/: jakarta.servlet package 
/*
 * 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.text.MessageFormat;
import java.util.ResourceBundle;


Provides an output stream for sending binary data to the client. A
ServletOutputStream object is normally retrieved via the ServletResponse.getOutputStream method. 

This is an abstract class that the servlet container implements. Subclasses
of this class must implement the java.io.OutputStream.write(int)
method.

See Also:
/**
 * 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.

/**
     * Does nothing, because this is an abstract class.
     */
    protected ServletOutputStream() {
        // NOOP
    }

    
Writes a String to the client, without a carriage
return-line feed (CRLF) character at the end.

Params:
  • s – 
           the String to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 boolean value to the client, with no carriage
return-line feed (CRLF) character at the end.

Params:
  • b – 
           the boolean value to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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.

Params:
  • c – 
           the character to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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.

Params:
  • i – 
           the int to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 long value to the client, with no carriage
return-line feed (CRLF) at the end.

Params:
  • l – 
           the long value to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 float value to the client, with no carriage
return-line feed (CRLF) at the end.

Params:
  • f – 
           the float value to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 double value to the client, with no carriage
return-line feed (CRLF) at the end.

Params:
  • d – 
           the double value to send to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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.

Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 String to the client, followed by a carriage
return-line feed (CRLF).

Params:
  • s – 
           the String to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 boolean value to the client, followed by a carriage
return-line feed (CRLF).

Params:
  • b – 
           the boolean value to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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).

Params:
  • c – 
           the character to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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.

Params:
  • i – 
           the int to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 long value to the client, followed by a carriage
return-line feed (CRLF).

Params:
  • l – 
           the long value to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 float value to the client, followed by a carriage
return-line feed (CRLF).

Params:
  • f – 
           the float value to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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 double value to the client, followed by a carriage
return-line feed (CRLF).

Params:
  • d – 
           the double value to write to the client
Throws:
  • IOException – 
               if an input or output exception occurred
/**
     * 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));
    }

    
Checks if a non-blocking write will succeed. If this returns
false, it will cause a callback to WriteListener.onWritePossible() when the buffer has emptied. If this method returns false no further data must be written until the contain calls WriteListener.onWritePossible(). 
Returns:true if data can be written, else false
Since:Servlet 3.1
/**
     * Checks if a non-blocking write will succeed. If this returns
     * <code>false</code>, it will cause a callback to
     * {@link WriteListener#onWritePossible()} when the buffer has emptied. If
     * this method returns <code>false</code> no further data must be written
     * until the contain calls {@link WriteListener#onWritePossible()}.
     *
     * @return <code>true</code> if data can be written, else <code>false</code>
     *
     * @since Servlet 3.1
     */
    public abstract boolean isReady();

    
Sets the WriteListener for this 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. 
Params:
  • listener –  The non-blocking IO write listener
Throws:
Since:Servlet 3.1
/**
     * 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(jakarta.servlet.WriteListener listener);
}