com.google.gwt.user.server.rpc

Class RPCServletUtils

java.lang.Object

com.google.gwt.user.server.rpc.RPCServletUtils

public class RPCServletUtils
extends Object

Utility class containing helper methods used by servlets that integrate with the RPC system.

Field Summary

Fields

Modifier and Type	Field and Description
static Charset	CHARSET_UTF8 The UTF-8 Charset.
static String	CHARSET_UTF8_NAME

Method Summary

Modifier and Type	Method and Description
static boolean	acceptsGzipEncoding(javax.servlet.http.HttpServletRequest request) Returns true if the HttpServletRequest accepts Gzip encoding.
static boolean	exceedsUncompressedContentLengthLimit(String content) Returns true if the response content's estimated UTF-8 byte length exceeds 256 bytes.
static Charset	getCharset(String encoding) Get the Charset for a named character set.
static boolean	isExpectedException(Method serviceIntfMethod, Throwable cause) Returns true if the Method definition on the service is specified to throw the exception contained in the InvocationTargetException or false otherwise.
static String	readContent(javax.servlet.http.HttpServletRequest request, String expectedContentType, String expectedCharSet) Returns the content of an HttpServletRequest by decoding it using expectedCharSet, or UTF-8 if expectedCharSet is null.
static String	readContentAsGwtRpc(javax.servlet.http.HttpServletRequest request) Returns the content of an HttpServletRequest, after verifying a gwt/x-gwt-rpc; charset=utf-8 content type.
static String	readContentAsUtf8(javax.servlet.http.HttpServletRequest request) Deprecated. Use readContent(javax.servlet.http.HttpServletRequest, java.lang.String, java.lang.String) instead.
static String	readContentAsUtf8(javax.servlet.http.HttpServletRequest request, boolean checkHeaders) Deprecated. Use readContent(javax.servlet.http.HttpServletRequest, java.lang.String, java.lang.String) instead.
static void	setGzipEncodingHeader(javax.servlet.http.HttpServletResponse response) Sets the correct header to indicate that a response is gzipped.
static boolean	shouldGzipResponseContent(javax.servlet.http.HttpServletRequest request, String responseContent) Returns true if the request accepts gzip encoding and the response content's estimated UTF-8 byte length exceeds 256 bytes.
static void	writeResponse(javax.servlet.ServletContext servletContext, javax.servlet.http.HttpServletResponse response, String responseContent, boolean gzipResponse) Write the response content into the HttpServletResponse.
static void	writeResponseForUnexpectedFailure(javax.servlet.ServletContext servletContext, javax.servlet.http.HttpServletResponse response, Throwable failure) Called when the servlet itself has a problem, rather than the invoked third-party method.

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, toString

Field Detail

CHARSET_UTF8_NAME

public static final String CHARSET_UTF8_NAME

See Also:

Constant Field Values

CHARSET_UTF8

public static final Charset CHARSET_UTF8

The UTF-8 Charset. Use this to avoid concurrency bottlenecks when converting between byte arrays and Strings. See http://code.google.com/p/google-web-toolkit/issues/detail?id=6398

Method Detail

acceptsGzipEncoding

public static boolean acceptsGzipEncoding(javax.servlet.http.HttpServletRequest request)

Returns true if the HttpServletRequest accepts Gzip encoding. This is done by checking that the accept-encoding header specifies gzip as a supported encoding.

Parameters:

request - the request instance to test for gzip encoding acceptance

Returns:

true if the HttpServletRequest accepts Gzip encoding

exceedsUncompressedContentLengthLimit

public static boolean exceedsUncompressedContentLengthLimit(String content)

Returns true if the response content's estimated UTF-8 byte length exceeds 256 bytes.

Parameters:

content - the contents of the response

Returns:

true if the response content's estimated UTF-8 byte length exceeds 256 bytes

getCharset

public static Charset getCharset(String encoding)

Get the Charset for a named character set. Caches Charsets to work around a concurrency bottleneck in FastCharsetProvider. See http://code.google.com/p/google-web-toolkit/issues/detail?id=6398

Parameters:

encoding - the name of the Charset to get. If this is null the default UTF-8 character set will be returned.

Returns:

the named Charset.

See Also:

Charset#forName(String)}

isExpectedException

public static boolean isExpectedException(Method serviceIntfMethod,
                                          Throwable cause)

Returns true if the Method definition on the service is specified to throw the exception contained in the InvocationTargetException or false otherwise. NOTE we do not check that the type is serializable here. We assume that it must be otherwise the application would never have been allowed to run.

Parameters:

serviceIntfMethod - the method from the RPC request

cause - the exception that the method threw

Returns:

true if the exception's type is in the method's signature

readContent

public static String readContent(javax.servlet.http.HttpServletRequest request,
                                 String expectedContentType,
                                 String expectedCharSet)
                          throws IOException,
                                 javax.servlet.ServletException

Returns the content of an HttpServletRequest by decoding it using expectedCharSet, or UTF-8 if expectedCharSet is null.

Parameters:

request - the servlet request whose content we want to read

expectedContentType - the expected content (i.e. 'type/subtype' only) in the Content-Type request header, or null if no validation is to be performed, and you are willing to allow for some types of cross type security attacks

expectedCharSet - the expected request charset, or null if no charset validation is to be performed and UTF-8 should be assumed

Returns:

the content of an HttpServletRequest by decoding it using expectedCharSet, or UTF-8 if expectedCharSet is null

Throws:

IOException - if the request's input stream cannot be accessed, read from or closed

javax.servlet.ServletException - if the request's content type does not equal the supplied expectedContentType or expectedCharSet

readContentAsGwtRpc

public static String readContentAsGwtRpc(javax.servlet.http.HttpServletRequest request)
                                  throws IOException,
                                         javax.servlet.ServletException

Returns the content of an HttpServletRequest, after verifying a gwt/x-gwt-rpc; charset=utf-8 content type.

Parameters:

request - the servlet request whose content we want to read

Returns:

the content of an HttpServletRequest by decoding it using UTF-8

Throws:

IOException - if the request's input stream cannot be accessed, read from or closed

javax.servlet.ServletException - if the request's content type is not gwt/x-gwt-rpc; charset=utf-8, ignoring case

readContentAsUtf8

@Deprecated
public static String readContentAsUtf8(javax.servlet.http.HttpServletRequest request)
                                            throws IOException,
                                                   javax.servlet.ServletException

Deprecated. Use readContent(javax.servlet.http.HttpServletRequest, java.lang.String, java.lang.String) instead.

Returns the content of an HttpServletRequest by decoding it using the UTF-8 charset.

Parameters:

request - the servlet request whose content we want to read

Returns:

the content of an HttpServletRequest by decoding it using the UTF-8 charset

Throws:

IOException - if the requests input stream cannot be accessed, read from or closed

javax.servlet.ServletException - if the content length of the request is not specified of if the request's content type is not 'text/x-gwt-rpc' and 'charset=utf-8'

readContentAsUtf8

@Deprecated
public static String readContentAsUtf8(javax.servlet.http.HttpServletRequest request,
                                                   boolean checkHeaders)
                                            throws IOException,
                                                   javax.servlet.ServletException

Deprecated. Use readContent(javax.servlet.http.HttpServletRequest, java.lang.String, java.lang.String) instead.

Returns the content of an HttpServletRequest by decoding it using the UTF-8 charset.

Parameters:

request - the servlet request whose content we want to read

checkHeaders - Specify 'true' to check the Content-Type header to see that it matches the expected value 'text/x-gwt-rpc' and the content encoding is UTF-8. Disabling this check may allow some types of cross type security attacks.

Returns:

the content of an HttpServletRequest by decoding it using the UTF-8 charset

Throws:

IOException - if the requests input stream cannot be accessed, read from or closed

javax.servlet.ServletException - if the content length of the request is not specified of if the request's content type is not 'text/x-gwt-rpc' and 'charset=utf-8'

setGzipEncodingHeader

public static void setGzipEncodingHeader(javax.servlet.http.HttpServletResponse response)

Sets the correct header to indicate that a response is gzipped.

shouldGzipResponseContent

public static boolean shouldGzipResponseContent(javax.servlet.http.HttpServletRequest request,
                                                String responseContent)

Returns true if the request accepts gzip encoding and the response content's estimated UTF-8 byte length exceeds 256 bytes.

Parameters:

request - the request associated with the response content

responseContent - a string that will be

Returns:

true if the request accepts gzip encoding and the response content's estimated UTF-8 byte length exceeds 256 bytes

writeResponse

public static void writeResponse(javax.servlet.ServletContext servletContext,
                                 javax.servlet.http.HttpServletResponse response,
                                 String responseContent,
                                 boolean gzipResponse)
                          throws IOException

Write the response content into the HttpServletResponse. If gzipResponse is true, the response content will be gzipped prior to being written into the response.

Parameters:

servletContext - servlet context for this response

response - response instance

responseContent - a string containing the response content

gzipResponse - if true the response content will be gzip encoded before being written into the response

Throws:

IOException - if reading, writing, or closing the response's output stream fails

writeResponseForUnexpectedFailure

public static void writeResponseForUnexpectedFailure(javax.servlet.ServletContext servletContext,
                                                     javax.servlet.http.HttpServletResponse response,
                                                     Throwable failure)

Called when the servlet itself has a problem, rather than the invoked third-party method. It writes a simple 500 message back to the client.

Parameters:

servletContext -

response -

failure -