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

java.lang.Object
  extended by com.google.gwt.user.server.rpc.RPCServletUtils

public class RPCServletUtils
extends java.lang.Object

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

Field Summary
(package private) static int BUFFER_SIZE
          Package protected for use in tests.
static java.nio.charset.Charset CHARSET_UTF8
          The UTF-8 Charset.
static java.lang.String CHARSET_UTF8_NAME
           
 
Method Summary
static boolean acceptsGzipEncoding(javax.servlet.http.HttpServletRequest request)
          Returns true if the HttpServletRequest accepts Gzip encoding.
static boolean exceedsUncompressedContentLengthLimit(java.lang.String content)
          Returns true if the response content's estimated UTF-8 byte length exceeds 256 bytes.
static java.nio.charset.Charset getCharset(java.lang.String encoding)
          Get the Charset for a named character set.
static boolean isExpectedException(java.lang.reflect.Method serviceIntfMethod, java.lang.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 java.lang.String readContent(javax.servlet.http.HttpServletRequest request, java.lang.String expectedContentType, java.lang.String expectedCharSet)
          Returns the content of an HttpServletRequest by decoding it using expectedCharSet, or UTF-8 if expectedCharSet is null.
static java.lang.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 java.lang.String readContentAsUtf8(javax.servlet.http.HttpServletRequest request)
          Deprecated. Use readContent(javax.servlet.http.HttpServletRequest, java.lang.String, java.lang.String) instead.
static java.lang.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, java.lang.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, java.lang.String responseContent, boolean gzipResponse)
          Write the response content into the HttpServletResponse.
static void writeResponseForUnexpectedFailure(javax.servlet.ServletContext servletContext, javax.servlet.http.HttpServletResponse response, java.lang.Throwable failure)
          Called when the servlet itself has a problem, rather than the invoked third-party method.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

CHARSET_UTF8_NAME

public static final java.lang.String CHARSET_UTF8_NAME
See Also:
Constant Field Values

CHARSET_UTF8

public static final java.nio.charset.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

BUFFER_SIZE

static final int BUFFER_SIZE
Package protected for use in tests.

See Also:
Constant Field Values
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(java.lang.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 java.nio.charset.Charset getCharset(java.lang.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(java.lang.reflect.Method serviceIntfMethod,
                                          java.lang.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 java.lang.String readContent(javax.servlet.http.HttpServletRequest request,
                                           java.lang.String expectedContentType,
                                           java.lang.String expectedCharSet)
                                    throws java.io.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:
java.io.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 java.lang.String readContentAsGwtRpc(javax.servlet.http.HttpServletRequest request)
                                            throws java.io.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:
java.io.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 java.lang.String readContentAsUtf8(javax.servlet.http.HttpServletRequest request)
                                          throws java.io.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:
java.io.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 java.lang.String readContentAsUtf8(javax.servlet.http.HttpServletRequest request,
                                                            boolean checkHeaders)
                                          throws java.io.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:
java.io.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,
                                                java.lang.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,
                                 java.lang.String responseContent,
                                 boolean gzipResponse)
                          throws java.io.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:
java.io.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,
                                                     java.lang.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 -
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