Class ServletInputStream
- All Implemented Interfaces:
- Closeable,- AutoCloseable
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 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 Also:
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Constructor SummaryConstructorsModifierConstructorDescriptionprotectedDoes nothing, because this is an abstract class.
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Method SummaryModifier and TypeMethodDescriptionabstract booleanHas the end of this InputStream been reached?abstract booleanisReady()Returnstrueif it is allowable to call aread()method.intread(ByteBuffer buffer) Reads from the input stream into the given buffer.byte[]intreadLine(byte[] b, int off, int len) Reads the input stream, one line at a time.intreadNBytes(byte[] b, int off, int len) byte[]readNBytes(int len) abstract voidsetReadListener(ReadListener listener) Sets theReadListenerfor thisServletInputStreamand thereby switches to non-blocking IO.Methods inherited from class java.io.InputStreamavailable, close, mark, markSupported, nullInputStream, read, read, read, reset, skip, skipNBytes, transferTo
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Constructor Details- 
ServletInputStreamprotected ServletInputStream()Does nothing, because this is an abstract class.
 
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Method Details- 
readReads from the input stream into the given buffer.If the input stream is in non-blocking mode, before each invocation of this method isReady()must be called and must returntrueor theReadListener.onDataAvailable()call back must indicate that data is available to read else anIllegalStateExceptionmust be thrown.Otherwise, if this method is called when bufferhas no space remaining, the method returns0immediately andbufferis unchanged.If the input stream is in blocking mode and bufferhas 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 -1if 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. - Parameters:
- buffer- The buffer into which the data is read.
- Returns:
- The number of bytes read or -1if the end of the stream has been reached.
- Throws:
- IllegalStateException- If the input stream is in non-blocking mode and this method is called without first calling- isReady()and that method has returned- trueor- ReadListener.onDataAvailable()has not signalled that data is available to read.
- 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.
- NullPointerException- If buffer is null.
- Since:
- Servlet 6.1
 
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readLineReads 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. This method may only be used when the input stream is in blocking mode. - Parameters:
- b- an array of bytes into which data is read
- off- an integer specifying the character at which this method begins reading
- len- an integer specifying the maximum number of bytes to read
- Returns:
- an integer specifying the actual number of bytes read, or -1 if the end of the stream is reached
- Throws:
- IllegalStateException- If this method is called when the input stream is in non-blocking mode.
- IOException- if an input or output exception has occurred
 
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isFinishedpublic abstract boolean isFinished()Has the end of this InputStream been reached?- Returns:
- trueif all the data has been read from the stream, else- false
- Since:
- Servlet 3.1
 
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isReadypublic abstract boolean isReady()Returnstrueif it is allowable to call aread()method. In blocking mode, this method will always returntrue, but a subsequent call to aread()method may block awaiting data. In non-blocking mode this method may returnfalse, in which case it is illegal to call aread()method and anIllegalStateExceptionMUST be thrown. WhenReadListener.onDataAvailable()is called, a call to this method that returnedtrueis implicit.If this method returns falseand aReadListenerhas been set viasetReadListener(ReadListener), then the container will subsequently invokeReadListener.onDataAvailable()(orReadListener.onAllDataRead()) once data (or EOF) has become available. Other than the initial callReadListener.onDataAvailable()will only be called if and only if this method is called and returns false.- Returns:
- trueif data can be obtained without blocking, otherwise returns- false.
- Since:
- Servlet 3.1
 
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setReadListenerSets theReadListenerfor thisServletInputStreamand thereby switches to non-blocking IO. It is only valid to switch to non-blocking IO within async processing or HTTP upgrade processing.- Parameters:
- 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- ReadListenerhas already been set
- NullPointerException- If listener is null
- Since:
- Servlet 3.1
 
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readAllBytesThis method may only be used when the input stream is in blocking mode. - Overrides:
- readAllBytesin class- InputStream
- Throws:
- IllegalStateException- If this method is called when the input stream is in non-blocking mode.
- IOException
 
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readNBytesThis method may only be used when the input stream is in blocking mode. - Overrides:
- readNBytesin class- InputStream
- Throws:
- IllegalStateException- If this method is called when the input stream is in non-blocking mode.
- IOException
 
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readNBytesThis method may only be used when the input stream is in blocking mode. - Overrides:
- readNBytesin class- InputStream
- Throws:
- IllegalStateException- If this method is called when the input stream is in non-blocking mode.
- IOException
 
 
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