jakarta.servlet.ServletInputStream Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2022 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;
/**
*
* 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 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.
*
*
*
* @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.
*
* @return true when all data for this particular request has been read, otherwise returns
* false.
*
* @since Servlet 3.1
*/
public abstract boolean isFinished();
/**
* Returns true if data can be read without blocking else returns false.
*
* If this method returns 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 true if data can be obtained without blocking, otherwise returns 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);
}