javax.servlet.ServletInputStream Maven / Gradle / Ivy
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* Copyright 2004 The Apache Software Foundation
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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 {@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.
*
* @return true if data can be obtained without blocking,
* otherwise returns false.
*
* @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);
}