javax.servlet

## Class ServletOutputStream

- java.lang.Object
- - java.io.OutputStream
  - - javax.servlet.ServletOutputStream

- All Implemented Interfaces:
    java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

      public abstract class ServletOutputStream
      extends java.io.OutputStream

  Provides an output stream for sending binary data to the client. A `ServletOutputStream` object is normally retrieved via the `ServletResponse.getOutputStream()` method.

  This is an abstract class that the servlet container implements. Subclasses of this class must implement the `java.io.OutputStream.write(int)` method.

  See Also:
    `ServletResponse`

- - ### Constructor Summary

    Constructors
    Modifier | Constructor and Description
    --- | ---
    `protected` | `ServletOutputStream()` Does nothing, because this is an abstract class.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `abstract boolean` | `isReady()` Checks if a non-blocking write will succeed.
    `void` | `print(boolean b)` Writes a `boolean` value to the client, with no carriage return-line feed (CRLF) character at the end.
    `void` | `print(char c)` Writes a character to the client, with no carriage return-line feed (CRLF) at the end.
    `void` | `print(double d)` Writes a `double` value to the client, with no carriage return-line feed (CRLF) at the end.
    `void` | `print(float f)` Writes a `float` value to the client, with no carriage return-line feed (CRLF) at the end.
    `void` | `print(int i)` Writes an int to the client, with no carriage return-line feed (CRLF) at the end.
    `void` | `print(long l)` Writes a `long` value to the client, with no carriage return-line feed (CRLF) at the end.
    `void` | `print(java.lang.String s)` Writes a `String` to the client, without a carriage return-line feed (CRLF) character at the end.
    `void` | `println()` Writes a carriage return-line feed (CRLF) to the client.
    `void` | `println(boolean b)` Writes a `boolean` value to the client, followed by a carriage return-line feed (CRLF).
    `void` | `println(char c)` Writes a character to the client, followed by a carriage return-line feed (CRLF).
    `void` | `println(double d)` Writes a `double` value to the client, followed by a carriage return-line feed (CRLF).
    `void` | `println(float f)` Writes a `float` value to the client, followed by a carriage return-line feed (CRLF).
    `void` | `println(int i)` Writes an int to the client, followed by a carriage return-line feed (CRLF) character.
    `void` | `println(long l)` Writes a `long` value to the client, followed by a carriage return-line feed (CRLF).
    `void` | `println(java.lang.String s)` Writes a `String` to the client, followed by a carriage return-line feed (CRLF).
    `abstract void` | `setWriteListener(WriteListener listener)` Sets the `WriteListener` for this `ServletOutputStream` and thereby switches to non-blocking IO.

    - ### Methods inherited from class java.io.OutputStream

      `close, flush, write, write, write`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### ServletOutputStream

          protected ServletOutputStream()

      Does nothing, because this is an abstract class.

  - ### Method Detail

    - #### print

          public void print(java.lang.String s)
                     throws java.io.IOException

      Writes a `String` to the client, without a carriage return-line feed (CRLF) character at the end.
      Parameters:
        `s` - the `String` to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### print

          public void print(boolean b)
                     throws java.io.IOException

      Writes a `boolean` value to the client, with no carriage return-line feed (CRLF) character at the end.
      Parameters:
        `b` - the `boolean` value to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### print

          public void print(char c)
                     throws java.io.IOException

      Writes a character to the client, with no carriage return-line feed (CRLF) at the end.
      Parameters:
        `c` - the character to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### print

          public void print(int i)
                     throws java.io.IOException

      Writes an int to the client, with no carriage return-line feed (CRLF) at the end.
      Parameters:
        `i` - the int to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### print

          public void print(long l)
                     throws java.io.IOException

      Writes a `long` value to the client, with no carriage return-line feed (CRLF) at the end.
      Parameters:
        `l` - the `long` value to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### print

          public void print(float f)
                     throws java.io.IOException

      Writes a `float` value to the client, with no carriage return-line feed (CRLF) at the end.
      Parameters:
        `f` - the `float` value to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### print

          public void print(double d)
                     throws java.io.IOException

      Writes a `double` value to the client, with no carriage return-line feed (CRLF) at the end.
      Parameters:
        `d` - the `double` value to send to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println()
                       throws java.io.IOException

      Writes a carriage return-line feed (CRLF) to the client.
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(java.lang.String s)
                       throws java.io.IOException

      Writes a `String` to the client, followed by a carriage return-line feed (CRLF).
      Parameters:
        `s` - the `String` to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(boolean b)
                       throws java.io.IOException

      Writes a `boolean` value to the client, followed by a carriage return-line feed (CRLF).
      Parameters:
        `b` - the `boolean` value to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(char c)
                       throws java.io.IOException

      Writes a character to the client, followed by a carriage return-line feed (CRLF).
      Parameters:
        `c` - the character to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(int i)
                       throws java.io.IOException

      Writes an int to the client, followed by a carriage return-line feed (CRLF) character.
      Parameters:
        `i` - the int to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(long l)
                       throws java.io.IOException

      Writes a `long` value to the client, followed by a carriage return-line feed (CRLF).
      Parameters:
        `l` - the `long` value to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(float f)
                       throws java.io.IOException

      Writes a `float` value to the client, followed by a carriage return-line feed (CRLF).
      Parameters:
        `f` - the `float` value to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### println

          public void println(double d)
                       throws java.io.IOException

      Writes a `double` value to the client, followed by a carriage return-line feed (CRLF).
      Parameters:
        `d` - the `double` value to write to the client
      Throws:
        `java.io.IOException` - if an input or output exception occurred

    - #### isReady

          public abstract boolean isReady()

      Checks if a non-blocking write will succeed. If this returns `false`, it will cause a callback to `WriteListener.onWritePossible()` when the buffer has emptied. If this method returns `false` no further data must be written until the contain calls `WriteListener.onWritePossible()`.
      Returns:
        `true` if data can be written, else `false`
      Since:
        Servlet 3.1

    - #### setWriteListener

          public abstract void setWriteListener(WriteListener listener)

      Sets the `WriteListener` for this `ServletOutputStream` and 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 write listener
      Throws:
        `java.lang.IllegalStateException` - If this method is called if neither async nor HTTP upgrade is in progress or if the `WriteListener` has already been set
        `java.lang.NullPointerException` - If listener is null
      Since:
        Servlet 3.1

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