javax.servlet.ServletInputStream Maven / Gradle / Ivy
/*
* 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 javax.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.
*
* @see ServletRequest
*/
public abstract class ServletInputStream extends InputStream {
/**
* 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.
*
* @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?
*
* @return true if all the data has been read from the stream, else false
*
* @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 {@link ReadListener#onDataAvailable()} when data is available.
*
* @return true if data can be read without blocking, else 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);
}