/*
 * Copyright (c) 1997-2018 Oracle and/or its affiliates and others.
 * All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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.
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package javax.servlet;

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

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.

Author:Various
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. * * * @author Various * * @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() { }
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; }
Returns true when all the data from the stream has been read else it returns false.
Returns:true when all data for this particular request has been read, otherwise returns false.
Since:Servlet 3.1
/** * Returns true when all the data from the stream has been read else it returns false. * * @return <code>true</code> when all data for this particular request has been read, otherwise returns * <code>false</code>. * * @since Servlet 3.1 */
public abstract boolean isFinished();
Returns true if data can be read without blocking else returns false.
Returns:true if data can be obtained without blocking, otherwise returns false.
Since:Servlet 3.1
/** * Returns true if data can be read without blocking else returns false. * * @return <code>true</code> if data can be obtained without blocking, otherwise returns <code>false</code>. * * @since Servlet 3.1 */
public abstract boolean isReady();
Instructs the ServletInputStream to invoke the provided ReadListener when it is possible to read
Params:
  • readListener – the ReadListener that should be notified when it's possible to read.
Throws:
  • IllegalStateException – if one of the following conditions is true
    • the associated request is neither upgraded nor the async started
    • setReadListener is called more than once within the scope of the same request.
  • NullPointerException – if readListener is null
Since:Servlet 3.1
/** * Instructs the <code>ServletInputStream</code> to invoke the provided {@link ReadListener} when it is possible to * read * * @param readListener the {@link ReadListener} that should be notified when it's possible to read. * * @exception IllegalStateException if one of the following conditions is true * <ul> * <li>the associated request is neither upgraded nor the async started * <li>setReadListener is called more than once within the scope of the same * request. * </ul> * * @throws NullPointerException if readListener is null * * @since Servlet 3.1 * */
public abstract void setReadListener(ReadListener readListener); }