jakarta.servlet.ServletInputStream Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2023 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.
*/
package jakarta.servlet;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.util.Objects;
/**
*
* 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 {@link 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 ServletRequest
*
*/
public abstract class ServletInputStream extends InputStream {
/**
* Does nothing, because this is an abstract class.
*
*/
protected ServletInputStream() {
}
/**
* Reads from the input stream into the given buffer.
*
* If the input stream is in non-blocking mode, before each invocation of this method {@link #isReady()} must be called
* and must return {@code true} or the {@link ReadListener#onDataAvailable()} call back must indicate that data is
* available to read else an {@link IllegalStateException} must be thrown.
*
* Otherwise, if this method is called when {@code buffer} has no space remaining, the method returns {@code 0}
* immediately and {@code buffer} is unchanged.
*
* If the input stream is in blocking mode and {@code buffer} has space remaining, this method blocks until at least one
* byte has been read, end of stream is reached or an exception is thrown.
*
* Returns the number of bytes read or {@code -1} if the end of stream is reached without reading any data.
*
* When the method returns, and if data has been read, the buffer's position will be unchanged from the value when
* passed to this method and the limit will be the position incremented by the number of bytes read.
*
* Subclasses are strongly encouraged to override this method and provide a more efficient implementation.
*
* @param buffer The buffer into which the data is read.
*
* @return The number of bytes read or {@code -1} if the end of the stream has been reached.
*
* @exception IllegalStateException If the input 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 ReadListener#onDataAvailable()} has
* not signalled that data is available to read.
*
* @exception IOException If data cannot be read for any reason other than the end of stream being reached, the input
* stream has been closed or if some other I/O error occurs.
*
* @exception NullPointerException If buffer is null.
*
* @since Servlet 6.1
*/
public int read(ByteBuffer buffer) throws IOException {
Objects.requireNonNull(buffer);
if (!isReady()) {
throw new IllegalStateException();
}
if (buffer.remaining() == 0) {
return 0;
}
byte[] b = new byte[buffer.remaining()];
int result = read(b);
if (result == -1) {
return -1;
}
int position = buffer.position();
buffer.put(b, 0, result);
buffer.position(position);
buffer.limit(position + result);
return result;
}
/**
* 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 {@code -1} if it reaches the end of the input stream before reading the maximum number of bytes.
*
* This method may only be used when the input stream is in blocking mode.
*
* @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 IllegalStateException If this method is called when the input stream is in non-blocking mode.
*
* @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.
*
* @return true when all data for this particular request has been read, otherwise returns
* false.
*
* @since Servlet 3.1
*/
public abstract boolean isFinished();
/**
* Returns {@code true} if it is allowable to call a {@code read()} method. In blocking mode, this method will always
* return {@code true}, but a subsequent call to a {@code read()} method may block awaiting data. In non-blocking mode
* this method may return {@code false}, in which case it is illegal to call a {@code read()} method and an
* {@link IllegalStateException} MUST be thrown. When {@link ReadListener#onDataAvailable()} is called, a call to this
* method that returned {@code true} is implicit.
*
* If this method returns {@code false} and a {@link ReadListener} has been set via
* {@link #setReadListener(ReadListener)}, then the container will subsequently invoke
* {@link ReadListener#onDataAvailable()} (or {@link ReadListener#onAllDataRead()}) once data (or EOF) has become
* available. Other than the initial call, {@link ReadListener#onDataAvailable()} will only be called if and only if
* this method is called and returns false.
*
* @return {@code true} if data can be obtained without blocking, otherwise returns {@code false}.
* @see ReadListener
* @since Servlet 3.1
*/
public abstract boolean isReady();
/**
* Instructs the ServletInputStream 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
*
* - the associated request is neither upgraded nor the async started
*
- setReadListener is called more than once within the scope of the same request.
*
*
* @throws NullPointerException if readListener is null
*
* @since Servlet 3.1
*
*/
public abstract void setReadListener(ReadListener readListener);
/**
* {@inheritDoc}
*
* This method may only be used when the input stream is in blocking mode.
*
* @exception IllegalStateException If this method is called when the input stream is in non-blocking mode.
*/
@Override
public byte[] readAllBytes() throws IOException {
return super.readAllBytes();
}
/**
* {@inheritDoc}
*
* This method may only be used when the input stream is in blocking mode.
*
* @exception IllegalStateException If this method is called when the input stream is in non-blocking mode.
*/
@Override
public byte[] readNBytes(int len) throws IOException {
return super.readNBytes(len);
}
/**
* {@inheritDoc}
*
* This method may only be used when the input stream is in blocking mode.
*
* @exception IllegalStateException If this method is called when the input stream is in non-blocking mode.
*/
@Override
public int readNBytes(byte[] b, int off, int len) throws IOException {
return super.readNBytes(b, off, len);
}
}