oracle.dbtools.plugin.api.servlet

Interface EntityTags

public interface EntityTags

Provides services for validating "If-Match" and "If-None-Match" request headers. Also provides a facility for generating an "ETag" header automatically from a secure digest of a HttpServletResponse.

Author:

cdivilly

Field Summary

Fields

Modifier and Type	Field and Description
static String	ETAG
static String	IF_MATCH
static String	IF_NONE_MATCH

Method Summary

Modifier and Type	Method and Description
EntityTag.Builder	builder() Return a new instance of an EntityTag.Builder
EntityTag	entityTag(javax.servlet.http.HttpServletRequest request, String headerName) Parses an EntityTag value from the specified header.
EntityTag	entityTag(String text) This method formats a textual value into a digested, strong EntityTag value.
boolean	etag(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response, HasGetMethod servlet) Adapt a HttpServletResponse to produce a strong "ETag" generated from a secure digest of the response headers and body.
boolean	hasPrecondition(javax.servlet.http.HttpServletRequest request) Determine if the specified request is a conditional HTTP request.
EntityTag	parse(CharSequence text) Parses text into an EntityTag value.
void	validatePrecondition(javax.servlet.http.HttpServletRequest request, CharSequence currentEntityTag) Validate whether the pre-condition in the request matches the current "ETag" value of the requested resource.

Field Detail

IF_MATCH

static final String IF_MATCH

See Also:

RFC 2616 Section 14.24, Constant Field Values

IF_NONE_MATCH

static final String IF_NONE_MATCH

See Also:

RFC 2616 Section 14.26, Constant Field Values

ETAG

static final String ETAG

See Also:

RFC 2616 Section 14.19, Constant Field Values

Method Detail

hasPrecondition

boolean hasPrecondition(javax.servlet.http.HttpServletRequest request)

Determine if the specified request is a conditional HTTP request. A request is conditional if it contains IF_MATCH for a PUT,POST,PATCH or DELETE method, and IF_NONE_MATCH for a GET or HEAD method

Parameters:

request - The HTTP request to check for presence of a pre-condition

Returns:

true if request has a precondition, false otherwise

validatePrecondition

void validatePrecondition(javax.servlet.http.HttpServletRequest request,
                          CharSequence currentEntityTag)

Validate whether the pre-condition in the request matches the current "ETag" value of the requested resource.

Parameters:

request - The request to be validated

currentEntityTag - The current "ETag" value of the requested resource

parse

EntityTag parse(CharSequence text)

Parses text into an EntityTag value. The value must be correctly formatted as a quoted ETag value.

Parameters:

text - The text value to parse

Returns:

EntityTag instance, or null if the supplied parameter is null

Throws:

IllegalArgumentException - if the value is not correctly formatted

entityTag

EntityTag entityTag(String text)

This method formats a textual value into a digested, strong EntityTag value. This method is equivalent to:

  String text = ...;
  EntityTags tags = ...;
  EntityTag tag = tags.builder().append(text).build();
 

Parameters:

text - The textual representation of the EntityTag

Returns:

Parsed EntityTag instance

entityTag

EntityTag entityTag(javax.servlet.http.HttpServletRequest request,
                    String headerName)

Parses an EntityTag value from the specified header. If the header is "If-Match" or IF_NONE_MATCH and the value is * then a null value will be returned.

Parameters:

request - The request to examine

headerName - The name of the HTTP Header

Returns:

The EntityTag value or null if the header is absent or has no value

builder

EntityTag.Builder builder()

Return a new instance of an EntityTag.Builder

Returns:

EntityTag.Builder instance

etag

boolean etag(javax.servlet.http.HttpServletRequest request,
             javax.servlet.http.HttpServletResponse response,
             HasGetMethod servlet)
      throws javax.servlet.ServletException,
             IOException

Adapt a HttpServletResponse to produce a strong "ETag" generated from a secure digest of the response headers and body. This method also performs any validation This provides a simple mechanism to produce a guaranteed correct "ETag", however the simplicity has some costs:

• The CPU overhead of generating the secure digest
• The memory overhead of buffering the entire response in order to produce the digest

This method SHOULD NOT be used for large responses. Servlets that wish to use this method must implement the HasGetMethod interface and pass a reference to themselves as the final parameter.

Parameters:

request - The request being processed

response - The response object provided by the servlet container

servlet - The servlet which will produce the response

Returns:

true if the servlet should proceed with processing the request, false otherwise

Throws:

javax.servlet.ServletException - if the HTTP request cannot be handled

IOException - if an input or output error occurs while the request is being handled

See Also:

HasGetMethod