ServletResponse (Java(TM) EE 8 Specification APIs)

All Known Subinterfaces:

HttpServletResponse

All Known Implementing Classes:

HttpServletResponseWrapper, ServletResponseWrapper
```
public interface ServletResponse
```
Defines an object to assist a servlet in sending a response to the client. The servlet container creates a ServletResponse object and passes it as an argument to the servlet's service method.
To send binary data in a MIME body response, use the ServletOutputStream returned by getOutputStream(). To send character data, use the PrintWriter object returned by getWriter(). To mix binary and text data, for example, to create a multipart response, use a ServletOutputStream and manage the character sections manually.
The charset for the MIME body response can be specified explicitly using any of the following techniques: per request, per web-app (using ServletContext.setRequestCharacterEncoding(java.lang.String), deployment descriptor), and per container (for all web applications deployed in that container, using vendor specific configuration). If multiple of the preceding techniques have been employed, the priority is the order listed. For per request, the charset for the response can be specified explicitly using the setCharacterEncoding(java.lang.String) and setContentType(java.lang.String) methods, or implicitly using the setLocale(java.util.Locale) method. Explicit specifications take precedence over implicit specifications. If no charset is explicitly specified, ISO-8859-1 will be used. The setCharacterEncoding, setContentType, or setLocale method must be called before getWriter and before committing the response for the character encoding to be used.
See the Internet RFCs such as RFC 2045 for more information on MIME. Protocols such as SMTP and HTTP define profiles of MIME, and those standards are still evolving.

Author:

Various

See Also:

ServletOutputStream

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`flushBuffer()` Forces any content in the buffer to be written to the client.
`int`	`getBufferSize()` Returns the actual buffer size used for the response.
`String`	`getCharacterEncoding()` Returns the name of the character encoding (MIME charset) used for the body sent in this response.
`String`	`getContentType()` Returns the content type used for the MIME body sent in this response.
`Locale`	`getLocale()` Returns the locale specified for this response using the `setLocale(java.util.Locale)` method.
`ServletOutputStream`	`getOutputStream()` Returns a `ServletOutputStream` suitable for writing binary data in the response.
`PrintWriter`	`getWriter()` Returns a `PrintWriter` object that can send character text to the client.
`boolean`	`isCommitted()` Returns a boolean indicating if the response has been committed.
`void`	`reset()` Clears any data that exists in the buffer as well as the status code, headers.
`void`	`resetBuffer()` Clears the content of the underlying buffer in the response without clearing headers or status code.
`void`	`setBufferSize(int size)` Sets the preferred buffer size for the body of the response.
`void`	`setCharacterEncoding(String charset)` Sets the character encoding (MIME charset) of the response being sent to the client, for example, to UTF-8.
`void`	`setContentLength(int len)` Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.
`void`	`setContentLengthLong(long len)` Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.
`void`	`setContentType(String type)` Sets the content type of the response being sent to the client, if the response has not been committed yet.
`void`	`setLocale(Locale loc)` Sets the locale of the response, if the response has not been committed yet.

- Method Detail
  - getCharacterEncoding
```
String getCharacterEncoding()
```
    Returns the name of the character encoding (MIME charset) used for the body sent in this response. The following methods for specifying the response character encoding are consulted, in decreasing order of priority: per request, perweb-app (using ServletContext.setResponseCharacterEncoding(java.lang.String), deployment descriptor), and per container (for all web applications deployed in that container, using vendor specific configuration). The first one of these methods that yields a result is returned. Per-request, the charset for the response can be specified explicitly using the setCharacterEncoding and setContentType methods, or implicitly using the setLocale(java.util.Locale) method. Explicit specifications take precedence over implicit specifications. Calls made to these methods after getWriter has been called or after the response has been committed have no effect on the character encoding. If no character encoding has been specified, ISO-8859-1 is returned.
    See RFC 2047 (http://www.ietf.org/rfc/rfc2047.txt) for more information about character encoding and MIME.
    
    Returns:
    
    a String specifying the name of the character encoding, for example, UTF-8
  - getContentType
```
String getContentType()
```
    Returns the content type used for the MIME body sent in this response. The content type proper must have been specified using setContentType(java.lang.String) before the response is committed. If no content type has been specified, this method returns null. If a content type has been specified, and a character encoding has been explicitly or implicitly specified as described in getCharacterEncoding() or getWriter() has been called, the charset parameter is included in the string returned. If no character encoding has been specified, the charset parameter is omitted.
    
    Returns:
    
    a String specifying the content type, for example, text/html; charset=UTF-8, or null
    
    Since:
    
    Servlet 2.4
  - getOutputStream
```
ServletOutputStream getOutputStream()
                             throws IOException
```
    Returns a ServletOutputStream suitable for writing binary data in the response. The servlet container does not encode the binary data.
    Calling flush() on the ServletOutputStream commits the response. Either this method or getWriter() may be called to write the body, not both, except when reset() has been called.
    
    Returns:
    
    a ServletOutputStream for writing binary data
    
    Throws:
    
    IllegalStateException - if the getWriter method has been called on this response
    
    IOException - if an input or output exception occurred
    
    See Also:
    
    getWriter(), reset()
  - getWriter
```
PrintWriter getWriter()
               throws IOException
```
    Returns a PrintWriter object that can send character text to the client. The PrintWriter uses the character encoding returned by getCharacterEncoding(). If the response's character encoding has not been specified as described in getCharacterEncoding (i.e., the method just returns the default value ISO-8859-1), getWriter updates it to ISO-8859-1.
    Calling flush() on the PrintWriter commits the response.
    Either this method or getOutputStream() may be called to write the body, not both, except when reset() has been called.
    
    Returns:
    
    a PrintWriter object that can return character data to the client
    
    Throws:
    
    UnsupportedEncodingException - if the character encoding returned by getCharacterEncoding cannot be used
    
    IllegalStateException - if the getOutputStream method has already been called for this response object
    
    IOException - if an input or output exception occurred
    
    See Also:
    
    getOutputStream(), setCharacterEncoding(java.lang.String), reset()
  - setCharacterEncoding
```
void setCharacterEncoding(String charset)
```
    Sets the character encoding (MIME charset) of the response being sent to the client, for example, to UTF-8. If the response character encoding has already been set by the ServletContext.setResponseCharacterEncoding(java.lang.String), deployment descriptor, or using the setContentType() or setLocale() methods, the value set in this method overrides any of those values. Calling setContentType(java.lang.String) with the String of text/html and calling this method with the String of UTF-8 is equivalent with calling setContentType with the String of text/html; charset=UTF-8.
    This method can be called repeatedly to change the character encoding. This method has no effect if it is called after getWriter has been called or after the response has been committed.
    Containers must communicate the character encoding used for the servlet response's writer to the client if the protocol provides a way for doing so. In the case of HTTP, the character encoding is communicated as part of the Content-Type header for text media types. Note that the character encoding cannot be communicated via HTTP headers if the servlet does not specify a content type; however, it is still used to encode text written via the servlet response's writer.
    
    Parameters:
    
    charset - a String specifying only the character set defined by IANA Character Sets (http://www.iana.org/assignments/character-sets)
    
    Since:
    
    Servlet 2.4
    
    See Also:
    
    setContentType(java.lang.String), setLocale(java.util.Locale)
  - setContentLength
```
void setContentLength(int len)
```
    Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.
    
    Parameters:
    
    len - an integer specifying the length of the content being returned to the client; sets the Content-Length header
  - setContentLengthLong
```
void setContentLengthLong(long len)
```
    Sets the length of the content body in the response In HTTP servlets, this method sets the HTTP Content-Length header.
    
    Parameters:
    
    len - a long specifying the length of the content being returned to the client; sets the Content-Length header
    
    Since:
    
    Servlet 3.1
  - setContentType
```
void setContentType(String type)
```
    Sets the content type of the response being sent to the client, if the response has not been committed yet. The given content type may include a character encoding specification, for example, text/html;charset=UTF-8. The response's character encoding is only set from the given content type if this method is called before getWriter is called.
    This method may be called repeatedly to change content type and character encoding. This method has no effect if called after the response has been committed. It does not set the response's character encoding if it is called after getWriter has been called or after the response has been committed.
    Containers must communicate the content type and the character encoding used for the servlet response's writer to the client if the protocol provides a way for doing so. In the case of HTTP, the Content-Type header is used.
    
    Parameters:
    
    type - a String specifying the MIME type of the content
    
    See Also:
    
    setLocale(java.util.Locale), setCharacterEncoding(java.lang.String), getOutputStream(), getWriter()
  - setBufferSize
```
void setBufferSize(int size)
```
    Sets the preferred buffer size for the body of the response. The servlet container will use a buffer at least as large as the size requested. The actual buffer size used can be found using getBufferSize.
    A larger buffer allows more content to be written before anything is actually sent, thus providing the servlet with more time to set appropriate status codes and headers. A smaller buffer decreases server memory load and allows the client to start receiving data more quickly.
    This method must be called before any response body content is written; if content has been written or the response object has been committed, this method throws an IllegalStateException.
    
    Parameters:
    
    size - the preferred buffer size
    
    Throws:
    
    IllegalStateException - if this method is called after content has been written
    
    See Also:
    
    getBufferSize(), flushBuffer(), isCommitted(), reset()
  - getBufferSize
```
int getBufferSize()
```
    Returns the actual buffer size used for the response. If no buffering is used, this method returns 0.
    
    Returns:
    
    the actual buffer size used
    
    See Also:
    
    setBufferSize(int), flushBuffer(), isCommitted(), reset()
  - flushBuffer
```
void flushBuffer()
          throws IOException
```
    Forces any content in the buffer to be written to the client. A call to this method automatically commits the response, meaning the status code and headers will be written.
    
    Throws:
    
    IOException - if the act of flushing the buffer cannot be completed.
    
    See Also:
    
    setBufferSize(int), getBufferSize(), isCommitted(), reset()
  - resetBuffer
```
void resetBuffer()
```
    Clears the content of the underlying buffer in the response without clearing headers or status code. If the response has been committed, this method throws an IllegalStateException.
    
    Since:
    
    Servlet 2.3
    
    See Also:
    
    setBufferSize(int), getBufferSize(), isCommitted(), reset()
  - isCommitted
```
boolean isCommitted()
```
    Returns a boolean indicating if the response has been committed. A committed response has already had its status code and headers written.
    
    Returns:
    
    a boolean indicating if the response has been committed
    
    See Also:
    
    setBufferSize(int), getBufferSize(), flushBuffer(), reset()
  - reset
```
void reset()
```
    Clears any data that exists in the buffer as well as the status code, headers. The state of calling getWriter() or getOutputStream() is also cleared. It is legal, for instance, to call getWriter(), reset() and then getOutputStream(). If getWriter() or getOutputStream() have been called before this method, then the corrresponding returned Writer or OutputStream will be staled and the behavior of using the stale object is undefined. If the response has been committed, this method throws an IllegalStateException.
    
    Throws:
    
    IllegalStateException - if the response has already been committed
    
    See Also:
    
    setBufferSize(int), getBufferSize(), flushBuffer(), isCommitted()
  - setLocale
```
void setLocale(Locale loc)
```
    Sets the locale of the response, if the response has not been committed yet. It also sets the response's character encoding appropriately for the locale, if the character encoding has not been explicitly set using setContentType(java.lang.String) or setCharacterEncoding(java.lang.String), getWriter hasn't been called yet, and the response hasn't been committed yet. If the deployment descriptor contains a locale-encoding-mapping-list element, and that element provides a mapping for the given locale, that mapping is used. Otherwise, the mapping from locale to character encoding is container dependent.
    This method may be called repeatedly to change locale and character encoding. The method has no effect if called after the response has been committed. It does not set the response's character encoding if it is called after setContentType(java.lang.String) has been called with a charset specification, after setCharacterEncoding(java.lang.String) has been called, after getWriter has been called, or after the response has been committed.
    Containers must communicate the locale and the character encoding used for the servlet response's writer to the client if the protocol provides a way for doing so. In the case of HTTP, the locale is communicated via the Content-Language header, the character encoding as part of the Content-Type header for text media types. Note that the character encoding cannot be communicated via HTTP headers if the servlet does not specify a content type; however, it is still used to encode text written via the servlet response's writer.
    
    Parameters:
    
    loc - the locale of the response
    
    See Also:
    
    getLocale(), setContentType(java.lang.String), setCharacterEncoding(java.lang.String)
  - getLocale
```
Locale getLocale()
```
    Returns the locale specified for this response using the setLocale(java.util.Locale) method. Calls made to setLocale after the response is committed have no effect. If no locale has been specified, the container's default locale is returned.
    
    Returns:
    
    the Locale for this response.
    
    See Also:
    
    setLocale(java.util.Locale)

Interface ServletResponse

Method Summary

Method Detail

getCharacterEncoding

getContentType

getOutputStream

getWriter

setCharacterEncoding

setContentLength

setContentLengthLong

setContentType

setBufferSize

getBufferSize

flushBuffer

resetBuffer

isCommitted

reset

setLocale

getLocale