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 * 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
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 *     http://www.apache.org/licenses/LICENSE-2.0
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package jakarta.servlet;

import java.io.IOException;
import java.io.InputStream;

Provides an input stream for reading binary data from a client request, including an efficient readLine method for reading data one line at a time. With some protocols, such as HTTP POST and PUT, a ServletInputStream object can be used to read data sent from the client.

A ServletInputStream object is normally retrieved via the ServletRequest.getInputStream method.

This is an abstract class that a servlet container implements. Subclasses of this class must implement the java.io.InputStream.read() method.

See Also:
/** * Provides an input stream for reading binary data from a client request, * including an efficient <code>readLine</code> method for reading data one line * at a time. With some protocols, such as HTTP POST and PUT, a * <code>ServletInputStream</code> object can be used to read data sent from the * client. * <p> * A <code>ServletInputStream</code> object is normally retrieved via the * {@link ServletRequest#getInputStream} method. * <p> * This is an abstract class that a servlet container implements. Subclasses of * this class must implement the <code>java.io.InputStream.read()</code> method. * * @see ServletRequest */
public abstract class ServletInputStream extends InputStream {
Does nothing, because this is an abstract class.
/** * Does nothing, because this is an abstract class. */
protected ServletInputStream() { // NOOP }
Reads the input stream, one line at a time. Starting at an offset, reads bytes into an array, until it reads a certain number of bytes or reaches a newline character, which it reads into the array as well.

This method returns -1 if it reaches the end of the input stream before reading the maximum number of bytes.

Params:
  • b – an array of bytes into which data is read
  • off – an integer specifying the character at which this method begins reading
  • len – an integer specifying the maximum number of bytes to read
Throws:
  • IOException – if an input or output exception has occurred
Returns:an integer specifying the actual number of bytes read, or -1 if the end of the stream is reached
/** * Reads the input stream, one line at a time. Starting at an offset, reads * bytes into an array, until it reads a certain number of bytes or reaches * a newline character, which it reads into the array as well. * <p> * This method returns -1 if it reaches the end of the input stream before * reading the maximum number of bytes. * * @param b * an array of bytes into which data is read * @param off * an integer specifying the character at which this method * begins reading * @param len * an integer specifying the maximum number of bytes to read * @return an integer specifying the actual number of bytes read, or -1 if * the end of the stream is reached * @exception IOException * if an input or output exception has occurred */
public int readLine(byte[] b, int off, int len) throws IOException { if (len <= 0) { return 0; } int count = 0, c; while ((c = read()) != -1) { b[off++] = (byte) c; count++; if (c == '\n' || count == len) { break; } } return count > 0 ? count : -1; }
Has the end of this InputStream been reached?
Returns:true if all the data has been read from the stream, else false
Since:Servlet 3.1
/** * Has the end of this InputStream been reached? * * @return <code>true</code> if all the data has been read from the stream, * else <code>false</code> * * @since Servlet 3.1 */
public abstract boolean isFinished();
Can data be read from this InputStream without blocking? Returns If this method is called and returns false, the container will invoke ReadListener.onDataAvailable() when data is available.
Returns:true if data can be read without blocking, else false
Since:Servlet 3.1
/** * Can data be read from this InputStream without blocking? * Returns If this method is called and returns false, the container will * invoke {@link ReadListener#onDataAvailable()} when data is available. * * @return <code>true</code> if data can be read without blocking, else * <code>false</code> * * @since Servlet 3.1 */
public abstract boolean isReady();
Sets the ReadListener for this ServletInputStream 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 read listener
Throws:
Since:Servlet 3.1
/** * Sets the {@link ReadListener} for this {@link ServletInputStream} 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 read listener * * @throws IllegalStateException If this method is called if neither * async nor HTTP upgrade is in progress or * if the {@link ReadListener} has already * been set * @throws NullPointerException If listener is null * * @since Servlet 3.1 */
public abstract void setReadListener(ReadListener listener); }