ServletInputStream.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.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 <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.
*/
protected ServletInputStream() {
// NOOP
}
/**
* Reads from the input stream into the given buffer.
* <p>
* 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.
* <p>
* Otherwise, if this method is called when {@code buffer} has no space remaining, the method returns {@code 0}
* immediately and {@code buffer} is unchanged.
* <p>
* 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.
* <p>
* Returns the number of bytes read or {@code -1} if the end of stream is reached without reading any data.
* <p>
* 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.
* <p>
* 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.
* <p>
* This method returns -1 if it reaches the end of the input stream before reading the maximum number of bytes.
* <p>
* 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;
}
/**
* 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();
/**
* 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.
* <p>
* 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}.
*
* @since Servlet 3.1
*/
public abstract boolean isReady();
/**
* 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);
/**
* {@inheritDoc}
* <p>
* 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}
* <p>
* 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}
* <p>
* 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);
}
}