## org.springframework.remoting.httpinvoker
Class HttpInvokerServiceExporter

    java.lang.Object
      org.springframework.remoting.support.RemotingSupport
          org.springframework.remoting.support.RemoteExporter
              org.springframework.remoting.support.RemoteInvocationBasedExporter
                  org.springframework.remoting.rmi.RemoteInvocationSerializingExporter
                      org.springframework.remoting.httpinvoker.HttpInvokerServiceExporter

All Implemented Interfaces:
  BeanClassLoaderAware, InitializingBean, HttpRequestHandler

    public class HttpInvokerServiceExporter

extends RemoteInvocationSerializingExporter
implements HttpRequestHandler

Servlet-API-based HTTP request handler that exports the specified service bean as HTTP invoker service endpoint, accessible via an HTTP invoker proxy.

Note: Spring also provides an alternative version of this exporter, for Sun's JRE 1.6 HTTP server: `SimpleHttpInvokerServiceExporter`.

Deserializes remote invocation objects and serializes remote invocation result objects. Uses Java serialization just like RMI, but provides the same ease of setup as Caucho's HTTP-based Hessian and Burlap protocols.

HTTP invoker is the recommended protocol for Java-to-Java remoting. It is more powerful and more extensible than Hessian and Burlap, at the expense of being tied to Java. Nevertheless, it is as easy to set up as Hessian and Burlap, which is its main advantage compared to RMI.

Since:
  1.1
Author:
  Juergen Hoeller
See Also:
  `HttpInvokerClientInterceptor`, `HttpInvokerProxyFactoryBean`, `RmiServiceExporter`, `HessianServiceExporter`, `BurlapServiceExporter`

Field Summary

Fields inherited from class org.springframework.remoting.rmi.RemoteInvocationSerializingExporter
`CONTENT_TYPE_SERIALIZED_OBJECT`

Fields inherited from class org.springframework.remoting.support.RemotingSupport
`logger`

Constructor Summary
`HttpInvokerServiceExporter()`

Method Summary
`protected InputStream` `decorateInputStream(HttpServletRequest request, InputStream is)` Return the InputStream to use for reading remote invocations, potentially decorating the given original InputStream.
`protected OutputStream` `decorateOutputStream(HttpServletRequest request, HttpServletResponse response, OutputStream os)` Return the OutputStream to use for writing remote invocation results, potentially decorating the given original OutputStream.
`void` `handleRequest(HttpServletRequest request, HttpServletResponse response)` Reads a remote invocation from the request, executes it, and writes the remote invocation result to the response.
`protected RemoteInvocation` `readRemoteInvocation(HttpServletRequest request)` Read a RemoteInvocation from the given HTTP request.
`protected RemoteInvocation` `readRemoteInvocation(HttpServletRequest request, InputStream is)` Deserialize a RemoteInvocation object from the given InputStream.
`protected void` `writeRemoteInvocationResult(HttpServletRequest request, HttpServletResponse response, RemoteInvocationResult result)` Write the given RemoteInvocationResult to the given HTTP response.
`protected void` `writeRemoteInvocationResult(HttpServletRequest request, HttpServletResponse response, RemoteInvocationResult result, OutputStream os)` Serialize the given RemoteInvocation to the given OutputStream.

Methods inherited from class org.springframework.remoting.rmi.RemoteInvocationSerializingExporter
`afterPropertiesSet, createObjectInputStream, createObjectOutputStream, doReadRemoteInvocation, doWriteRemoteInvocationResult, getContentType, getProxy, isAcceptProxyClasses, prepare, setAcceptProxyClasses, setContentType`

Methods inherited from class org.springframework.remoting.support.RemoteInvocationBasedExporter
`getRemoteInvocationExecutor, invoke, invokeAndCreateResult, setRemoteInvocationExecutor`

Methods inherited from class org.springframework.remoting.support.RemoteExporter
`checkService, checkServiceInterface, getExporterName, getProxyForService, getService, getServiceInterface, setInterceptors, setRegisterTraceInterceptor, setService, setServiceInterface`

Methods inherited from class org.springframework.remoting.support.RemotingSupport
`getBeanClassLoader, overrideThreadContextClassLoader, resetThreadContextClassLoader, setBeanClassLoader`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### HttpInvokerServiceExporter

    public HttpInvokerServiceExporter()

Method Detail

### handleRequest

    public void handleRequest(HttpServletRequest request,
                              HttpServletResponse response)
                       throws ServletException,
                              IOException

  Reads a remote invocation from the request, executes it, and writes the remote invocation result to the response.

  Specified by:
    `handleRequest` in interface `HttpRequestHandler`
  Parameters:
    `request` - current HTTP request
    `response` - current HTTP response
  Throws:
    `ServletException` - in case of general errors
    `IOException` - in case of I/O errors
  See Also:
    `readRemoteInvocation(HttpServletRequest)`, `RemoteInvocationBasedExporter.invokeAndCreateResult(org.springframework.remoting.support.RemoteInvocation, Object)`, `writeRemoteInvocationResult(HttpServletRequest, HttpServletResponse, RemoteInvocationResult)`

### readRemoteInvocation

    protected RemoteInvocation readRemoteInvocation(HttpServletRequest request)
                                             throws IOException,
                                                    ClassNotFoundException

  Read a RemoteInvocation from the given HTTP request.

  Delegates to `readRemoteInvocation(javax.servlet.http.HttpServletRequest, java.io.InputStream)` with the `servlet request's input stream`.

  Parameters:
    `request` - current HTTP request
  Returns:
    the RemoteInvocation object
  Throws:
    `IOException` - in case of I/O failure
    `ClassNotFoundException` - if thrown by deserialization

### readRemoteInvocation

    protected RemoteInvocation readRemoteInvocation(HttpServletRequest request,
                                                    InputStream is)
                                             throws IOException,
                                                    ClassNotFoundException

  Deserialize a RemoteInvocation object from the given InputStream.

  Gives `decorateInputStream(javax.servlet.http.HttpServletRequest, java.io.InputStream)` a chance to decorate the stream first (for example, for custom encryption or compression). Creates a `CodebaseAwareObjectInputStream` and calls `RemoteInvocationSerializingExporter.doReadRemoteInvocation(java.io.ObjectInputStream)` to actually read the object.

  Can be overridden for custom serialization of the invocation.

  Parameters:
    `request` - current HTTP request
    `is` - the InputStream to read from
  Returns:
    the RemoteInvocation object
  Throws:
    `IOException` - in case of I/O failure
    `ClassNotFoundException` - if thrown during deserialization

### decorateInputStream

    protected InputStream decorateInputStream(HttpServletRequest request,
                                              InputStream is)
                                       throws IOException

  Return the InputStream to use for reading remote invocations, potentially decorating the given original InputStream.

  The default implementation returns the given stream as-is. Can be overridden, for example, for custom encryption or compression.

  Parameters:
    `request` - current HTTP request
    `is` - the original InputStream
  Returns:
    the potentially decorated InputStream
  Throws:
    `IOException` - in case of I/O failure

### writeRemoteInvocationResult

    protected void writeRemoteInvocationResult(HttpServletRequest request,
                                               HttpServletResponse response,
                                               RemoteInvocationResult result)
                                        throws IOException

  Write the given RemoteInvocationResult to the given HTTP response.

  Parameters:
    `request` - current HTTP request
    `response` - current HTTP response
    `result` - the RemoteInvocationResult object
  Throws:
    `IOException` - in case of I/O failure

### writeRemoteInvocationResult

    protected void writeRemoteInvocationResult(HttpServletRequest request,
                                               HttpServletResponse response,
                                               RemoteInvocationResult result,
                                               OutputStream os)
                                        throws IOException

  Serialize the given RemoteInvocation to the given OutputStream.

  The default implementation gives `decorateOutputStream(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.io.OutputStream)` a chance to decorate the stream first (for example, for custom encryption or compression). Creates an `ObjectOutputStream` for the final stream and calls `RemoteInvocationSerializingExporter.doWriteRemoteInvocationResult(org.springframework.remoting.support.RemoteInvocationResult, java.io.ObjectOutputStream)` to actually write the object.

  Can be overridden for custom serialization of the invocation.

  Parameters:
    `request` - current HTTP request
    `response` - current HTTP response
    `result` - the RemoteInvocationResult object
    `os` - the OutputStream to write to
  Throws:
    `IOException` - in case of I/O failure
  See Also:
    `decorateOutputStream(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, java.io.OutputStream)`, `RemoteInvocationSerializingExporter.doWriteRemoteInvocationResult(org.springframework.remoting.support.RemoteInvocationResult, java.io.ObjectOutputStream)`

### decorateOutputStream

    protected OutputStream decorateOutputStream(HttpServletRequest request,
                                                HttpServletResponse response,
                                                OutputStream os)
                                         throws IOException

  Return the OutputStream to use for writing remote invocation results, potentially decorating the given original OutputStream.

  The default implementation returns the given stream as-is. Can be overridden, for example, for custom encryption or compression.

  Parameters:
    `request` - current HTTP request
    `response` - current HTTP response
    `os` - the original OutputStream
  Returns:
    the potentially decorated OutputStream
  Throws:
    `IOException` - in case of I/O failure