JsonCommandServlet (json-command-servlet 1.9.1 API)

com.cedarsoftware.servlet.JsonCommandServlet

```
@groovy.util.logging.Slf4j
@groovy.transform.CompileStatic
class JsonCommandServlet
extends javax.servlet.http.HttpServlet
```
This class will accept JSON REST requests, find the named Spring Bean, find the method, and then invoke the method. Once complete, it will convert the return object to JSON and then send that back to the client. The requests are typically made from a Javascript client, although they could easily be made from Python, Java, or Objective C. The request comes in with http://yoursite.com/context/cmd/controllerName/methodName. The "cmd" part can be whatever name you map to this servlet in web.xml. The arguments are sent as the HTTP POST body, or they can be sent via query params like this:
http://yoursite.com/json/Controller/methodName?json=[arg1, arg2,...]
When calling the JsonServlet, it will always return an object in the form:
{"data":v,"status":false|true|null}
where the value 'v' is the return value of the Controller method called. The status is 'true' if the method call properly succeeded. Use the return value 'v' when status === true. If status === false then the communications reach the server, however, there was an exception. A Controller method threw an exception, invalid JSON was passed in, the name of the controller targeted was wrong, the controller targeted was not a BaseController, or the method on the controller was not found. The value 'v' when the the status === false will indicate the error. If the status === null then the call() method within the browser never reached the server. The value 'v' is a message indicating a network communications issue.
The returned JSON is gzip compressed if the caller indicates that it accepts Content-Encoding of gzip AND the return message is greater than 512 bytes. The return stream from methods that return large arrays and/or object graphs compresses especially well.

Authors:
John DeRegnaucourt (jdereg@gmail.com)
Copyright (c) Cedar Software LLC

Licensed under the Apache License, Version 2.0 (the "License") you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Field Summary

Fields
Modifiers	Name	Description
`static java.lang.ThreadLocal<HttpServletRequest>`	`servletRequest`
`static java.lang.ThreadLocal<HttpServletResponse>`	`servletResponse`

Constructor Summary

Constructors
Constructor and description
`JsonCommandServlet ()`

Methods Summary

Methods
Type Params	Return Type	Name and description
	`protected void`	`doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` Handle JSON GET style request.
	`protected void`	`doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` Process JSON POST style where the controller, method, and arguments are passed in as the POST data.
	`static java.lang.Throwable`	`getDeepestException(java.lang.Throwable e)` Get the deepest (original cause) of the exception chain.
	`void`	`init()`
	`void`	`route(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` If using UrlRewrite from tuckey.org, then route HTTP Json commands via this 'route' method and list it in the urlrewrite.xml.

Inherited Methods Summary

Inherited Methods
Methods inherited from class	Name
`class javax.servlet.http.HttpServlet`	javax.servlet.http.HttpServlet#service(javax.servlet.ServletRequest, javax.servlet.ServletResponse), javax.servlet.http.HttpServlet#getServletConfig(), javax.servlet.http.HttpServlet#getServletInfo(), javax.servlet.http.HttpServlet#getServletName(), javax.servlet.http.HttpServlet#getServletContext(), javax.servlet.http.HttpServlet#getInitParameter(java.lang.String), javax.servlet.http.HttpServlet#getInitParameterNames(), javax.servlet.http.HttpServlet#log(java.lang.String), javax.servlet.http.HttpServlet#log(java.lang.String, java.lang.Throwable), javax.servlet.http.HttpServlet#init(javax.servlet.ServletConfig), javax.servlet.http.HttpServlet#init(), javax.servlet.http.HttpServlet#destroy(), javax.servlet.http.HttpServlet#wait(long), javax.servlet.http.HttpServlet#wait(long, int), javax.servlet.http.HttpServlet#wait(), javax.servlet.http.HttpServlet#equals(java.lang.Object), javax.servlet.http.HttpServlet#toString(), javax.servlet.http.HttpServlet#hashCode(), javax.servlet.http.HttpServlet#getClass(), javax.servlet.http.HttpServlet#notify(), javax.servlet.http.HttpServlet#notifyAll()

- Field Detail
  - public static final java.lang.ThreadLocal<HttpServletRequest> servletRequest
  - public static final java.lang.ThreadLocal<HttpServletResponse> servletResponse
- Constructor Detail
  - JsonCommandServlet()
- Method Detail
  - protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
    
    Handle JSON GET style request. In this case, 'controller', 'method', and 'json' are specified as URL parameters. Example: http://cedarsoftware.com/coolApp/CoolController/coolMethod?json=[args...]
  - protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
    
    Process JSON POST style where the controller, method, and arguments are passed in as the POST data. Example: http://cedarsoftware.com/coolApp/CoolController/coolMethod Post body contains the arguments in JSON format.
  - static java.lang.Throwable getDeepestException(java.lang.Throwable e)
    
    Get the deepest (original cause) of the exception chain.
    Parameters:
    e - Throwable exception that occurred.
    Returns:
    Throwable original (causal) exception
  - void init()
  - void route(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
    
    If using UrlRewrite from tuckey.org, then route HTTP Json commands via this 'route' method and list it in the urlrewrite.xml.

Summary:
Field
Constructor
Method

| Detail:
Field
Constructor
Method

Groovy Documentation

[Groovy] Class JsonCommandServlet

Field Summary

Constructor Summary

Methods Summary

Inherited Methods Summary

Field Detail

public static final java.lang.ThreadLocal<HttpServletRequest> servletRequest

public static final java.lang.ThreadLocal<HttpServletResponse> servletResponse

Constructor Detail

JsonCommandServlet()

Method Detail

protected void doGet(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)

protected void doPost(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)

static java.lang.Throwable getDeepestException(java.lang.Throwable e)

void init()

void route(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)