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BaseCommandController (Spring Framework API 2.1) - Spring Framework 2.1.0 API 文档英文版

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org.springframework.web.servlet.mvc
Class BaseCommandController

java.lang.Object
  org.springframework.context.support.ApplicationObjectSupport
      org.springframework.web.context.support.WebApplicationObjectSupport
          org.springframework.web.servlet.support.WebContentGenerator
              org.springframework.web.servlet.mvc.AbstractController
                  org.springframework.web.servlet.mvc.BaseCommandController

All Implemented Interfaces:

ApplicationContextAware, ServletContextAware, Controller

Direct Known Subclasses:

AbstractCommandController, AbstractFormController

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public abstract class BaseCommandController
extends AbstractController

Controller implementation which creates an object (the command object) on receipt of a request and attempts to populate this object with request parameters.

This controller is the base for all controllers wishing to populate JavaBeans based on request parameters, validate the content of such JavaBeans using Validators and use custom editors (in the form of PropertyEditors) to transform objects into strings and vice versa, for example. Three notions are mentioned here:

Command class:
An instance of the command class will be created for each request and populated with request parameters. A command class can basically be any Java class; the only requirement is a no-arg constructor. The command class should preferably be a JavaBean in order to be able to populate bean properties with request parameters.

Populating using request parameters and PropertyEditors:
Upon receiving a request, any BaseCommandController will attempt to fill the command object using the request parameters. This is done using the typical and well-known JavaBeans property notation. When a request parameter named 'firstName' exists, the framework will attempt to call setFirstName([value]) passing the value of the parameter. Nested properties are of course supported. For instance a parameter named 'address.city' will result in a getAddress().setCity([value]) call on the command class.

It's important to realise that you are not limited to String arguments in your JavaBeans. Using the PropertyEditor-notion as supplied by the java.beans package, you will be able to transform Strings to Objects and the other way around. For instance setLocale(Locale loc) is perfectly possible for a request parameter named locale having a value of en, as long as you register the appropriate PropertyEditor in the Controller (see initBinder() for more information on that matter.

Validators: After the controller has successfully populated the command object with parameters from the request, it will use any configured validators to validate the object. Validation results will be put in a Errors object which can be used in a View to render any input problems.

Workflow (and that defined by superclass):
Since this class is an abstract base class for more specific implementation, it does not override the handleRequestInternal() method and also has no actual workflow. Implementing classes like AbstractFormController, AbstractcommandController, SimpleFormController and AbstractWizardFormController provide actual functionality and workflow. More information on workflow performed by superclasses can be found here.

Exposed configuration properties (and those defined by superclass):

name	default	description
commandName	command	the name to use when binding the instantiated command class to the request
commandClass	null	the class to use upon receiving a request and which to fill using the request parameters. What object is used and whether or not it should be created is defined by extending classes and their configuration properties and methods.
validators	null	Array of Validator beans. The validator will be called at appropriate places in the workflow of subclasses (have a look at those for more info) to validate the command object.
validator	null	Short-form property for setting only one Validator bean (usually passed in using a <ref bean="beanId"/> property.
validateOnBinding	true	Indicates whether or not to validate the command object after the object has been populated with request parameters.

Author:

Rod Johnson, Juergen Hoeller

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Field Summary
static String	DEFAULT_COMMAND_NAME           Default command name used for binding command objects: "command"

 

Fields inherited from class org.springframework.web.servlet.support.WebContentGenerator
METHOD_GET, METHOD_HEAD, METHOD_POST

 

Fields inherited from class org.springframework.context.support.ApplicationObjectSupport
logger

 

Constructor Summary
BaseCommandController()

 

Method Summary
protected  ServletRequestDataBinder	bindAndValidate(HttpServletRequest request, Object command)           Bind the parameters of the given request to the given command object.
protected  boolean	checkCommand(Object command)           Check if the given command object is a valid for this controller, i.e. its command class.
protected  ServletRequestDataBinder	createBinder(HttpServletRequest request, Object command)           Create a new binder instance for the given command and request.
protected  Object	createCommand()           Create a new command instance for the command class of this controller.
BindingErrorProcessor	getBindingErrorProcessor()           Return the strategy to use for processing binding errors.
protected  Object	getCommand(HttpServletRequest request)           Retrieve a command object for the given request.
Class	getCommandClass()           Return the command class for this controller.
String	getCommandName()           Return the name of the command in the model.
MessageCodesResolver	getMessageCodesResolver()           Return the strategy to use for resolving errors into message codes.
PropertyEditorRegistrar[]	getPropertyEditorRegistrars()           Return the PropertyEditorRegistrars to be applied to every DataBinder that this controller uses.
Validator	getValidator()           Return the primary Validator for this controller.
Validator[]	getValidators()           Return the Validators for this controller.
protected  void	initApplicationContext()           Subclasses can override this for custom initialization behavior.
protected  void	initBinder(HttpServletRequest request, ServletRequestDataBinder binder)           Initialize the given binder instance, for example with custom editors.
boolean	isValidateOnBinding()           Return if the Validator should get applied when binding.
protected  void	onBind(HttpServletRequest request, Object command)           Callback for custom post-processing in terms of binding.
protected  void	onBind(HttpServletRequest request, Object command, BindException errors)           Callback for custom post-processing in terms of binding.
protected  void	onBindAndValidate(HttpServletRequest request, Object command, BindException errors)           Callback for custom post-processing in terms of binding and validation.
protected  void	prepareBinder(ServletRequestDataBinder binder)           Prepare the given binder, applying the specified MessageCodesResolver, BindingErrorProcessor and PropertyEditorRegistrars (if any).
void	setBindingErrorProcessor(BindingErrorProcessor bindingErrorProcessor)           Set the strategy to use for processing binding errors, that is, required field errors and PropertyAccessExceptions.
void	setCommandClass(Class commandClass)           Set the command class for this controller.
void	setCommandName(String commandName)           Set the name of the command in the model.
void	setMessageCodesResolver(MessageCodesResolver messageCodesResolver)           Set the strategy to use for resolving errors into message codes.
void	setPropertyEditorRegistrar(PropertyEditorRegistrar propertyEditorRegistrar)           Specify a single PropertyEditorRegistrar to be applied to every DataBinder that this controller uses.
void	setPropertyEditorRegistrars(PropertyEditorRegistrar[] propertyEditorRegistrars)           Specify multiple PropertyEditorRegistrars to be applied to every DataBinder that this controller uses.
void	setValidateOnBinding(boolean validateOnBinding)           Set if the Validator should get applied when binding.
void	setValidator(Validator validator)           Set the primary Validator for this controller.
void	setValidators(Validator[] validators)           Set the Validators for this controller.
protected  boolean	suppressBinding(HttpServletRequest request)           Return whether to suppress binding for the given request.
protected  boolean	suppressValidation(HttpServletRequest request)           Deprecated. as of Spring 2.0.4, in favor of the suppressValidation(HttpServletRequest, Object) variant
protected  boolean	suppressValidation(HttpServletRequest request, Object command)           Return whether to suppress validation for the given request.
protected  boolean	suppressValidation(HttpServletRequest request, Object command, BindException errors)           Return whether to suppress validation for the given request.
protected  boolean	useDirectFieldAccess()           Determine whether to use direct field access instead of bean property access.

 

Methods inherited from class org.springframework.web.servlet.mvc.AbstractController
handleRequest, handleRequestInternal, isSynchronizeOnSession, setSynchronizeOnSession

 

Methods inherited from class org.springframework.web.servlet.support.WebContentGenerator
applyCacheSeconds, applyCacheSeconds, cacheForSeconds, cacheForSeconds, checkAndPrepare, checkAndPrepare, getCacheSeconds, getSupportedMethods, isRequireSession, isUseCacheControlHeader, isUseExpiresHeader, preventCaching, setCacheSeconds, setRequireSession, setSupportedMethods, setUseCacheControlHeader, setUseExpiresHeader

 

Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport
getServletContext, getTempDir, getWebApplicationContext, isContextRequired, setServletContext

 

Methods inherited from class org.springframework.context.support.ApplicationObjectSupport
getApplicationContext, getMessageSourceAccessor, requiredContextClass, setApplicationContext

 

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

 

Field Detail

DEFAULT_COMMAND_NAME

public static final String DEFAULT_COMMAND_NAME

Default command name used for binding command objects: "command"

See Also:

Constant Field Values

Constructor Detail

BaseCommandController

public BaseCommandController()

Method Detail

setCommandName

public final void setCommandName(String commandName)

Set the name of the command in the model. The command object will be included in the model under this name.

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getCommandName

public final String getCommandName()

Return the name of the command in the model.

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setCommandClass

public final void setCommandClass(Class commandClass)

Set the command class for this controller. An instance of this class gets populated and validated on each request.

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getCommandClass

public final Class getCommandClass()

Return the command class for this controller.

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setValidator

public final void setValidator(Validator validator)

Set the primary Validator for this controller. The Validator must support the specified command class. If there are one or more existing validators set already when this method is called, only the specified validator will be kept. Use setValidators(Validator[]) to set multiple validators.

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getValidator

public final Validator getValidator()

Return the primary Validator for this controller.

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setValidators

public final void setValidators(Validator[] validators)

Set the Validators for this controller. The Validator must support the specified command class.

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getValidators

public final Validator[] getValidators()

Return the Validators for this controller.

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setValidateOnBinding

public final void setValidateOnBinding(boolean validateOnBinding)

Set if the Validator should get applied when binding.

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isValidateOnBinding

public final boolean isValidateOnBinding()

Return if the Validator should get applied when binding.

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setMessageCodesResolver

public final void setMessageCodesResolver(MessageCodesResolver messageCodesResolver)

Set the strategy to use for resolving errors into message codes. Applies the given strategy to all data binders used by this controller.

Default is null, i.e. using the default strategy of the data binder.

See Also:

createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object), DataBinder.setMessageCodesResolver(org.springframework.validation.MessageCodesResolver)

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getMessageCodesResolver

public final MessageCodesResolver getMessageCodesResolver()

Return the strategy to use for resolving errors into message codes.

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setBindingErrorProcessor

public final void setBindingErrorProcessor(BindingErrorProcessor bindingErrorProcessor)

Set the strategy to use for processing binding errors, that is, required field errors and PropertyAccessExceptions.

Default is null, that is, using the default strategy of the data binder.

See Also:

createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object), DataBinder.setBindingErrorProcessor(org.springframework.validation.BindingErrorProcessor)

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getBindingErrorProcessor

public final BindingErrorProcessor getBindingErrorProcessor()

Return the strategy to use for processing binding errors.

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setPropertyEditorRegistrar

public final void setPropertyEditorRegistrar(PropertyEditorRegistrar propertyEditorRegistrar)

Specify a single PropertyEditorRegistrar to be applied to every DataBinder that this controller uses.

Allows for factoring out the registration of PropertyEditors to separate objects, as an alternative to initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder).

See Also:

initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder)

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setPropertyEditorRegistrars

public final void setPropertyEditorRegistrars(PropertyEditorRegistrar[] propertyEditorRegistrars)

Specify multiple PropertyEditorRegistrars to be applied to every DataBinder that this controller uses.

Allows for factoring out the registration of PropertyEditors to separate objects, as an alternative to initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder).

See Also:

initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder)

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getPropertyEditorRegistrars

public final PropertyEditorRegistrar[] getPropertyEditorRegistrars()

Return the PropertyEditorRegistrars to be applied to every DataBinder that this controller uses.

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initApplicationContext

protected void initApplicationContext()

Description copied from class: ApplicationObjectSupport

Subclasses can override this for custom initialization behavior. Gets called by setApplicationContext after setting the context instance.

Note: Does not get called on reinitialization of the context but rather just on first initialization of this object's context reference.

Overrides:

initApplicationContext in class ApplicationObjectSupport

See Also:

ApplicationObjectSupport.setApplicationContext(org.springframework.context.ApplicationContext)

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getCommand

protected Object getCommand(HttpServletRequest request)
                     throws Exception

Retrieve a command object for the given request.

The default implementation calls createCommand(). Subclasses can override this.

Parameters:

request - current HTTP request

Returns:

object command to bind onto

Throws:

Exception - if the command object could not be obtained

See Also:

createCommand()

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createCommand

protected final Object createCommand()
                              throws Exception

Create a new command instance for the command class of this controller.

This implementation uses BeanUtils.instantiateClass, so the command needs to have a no-arg constructor (supposed to be public, but not required to).

Returns:

the new command instance

Throws:

Exception - if the command object could not be instantiated

See Also:

BeanUtils.instantiateClass(Class)

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checkCommand

protected final boolean checkCommand(Object command)

Check if the given command object is a valid for this controller, i.e. its command class.

Parameters:

command - the command object to check

Returns:

if the command object is valid for this controller

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bindAndValidate

protected final ServletRequestDataBinder bindAndValidate(HttpServletRequest request,
                                                         Object command)
                                                  throws Exception

Bind the parameters of the given request to the given command object.

Parameters:

request - current HTTP request

command - the command to bind onto

Returns:

the ServletRequestDataBinder instance for additional custom validation

Throws:

Exception - in case of invalid state or arguments

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suppressBinding

protected boolean suppressBinding(HttpServletRequest request)

Return whether to suppress binding for the given request.

The default implementation always returns "false". Can be overridden in subclasses to suppress validation, for example, if a special request parameter is set.

Parameters:

request - current HTTP request

Returns:

whether to suppress binding for the given request

See Also:

suppressValidation(javax.servlet.http.HttpServletRequest, java.lang.Object, org.springframework.validation.BindException)

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createBinder

protected ServletRequestDataBinder createBinder(HttpServletRequest request,
                                                Object command)
                                         throws Exception

Create a new binder instance for the given command and request.

Called by bindAndValidate(javax.servlet.http.HttpServletRequest, java.lang.Object). Can be overridden to plug in custom ServletRequestDataBinder instances.

The default implementation creates a standard ServletRequestDataBinder and invokes prepareBinder(org.springframework.web.bind.ServletRequestDataBinder) and initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder).

Note that neither prepareBinder(org.springframework.web.bind.ServletRequestDataBinder) nor initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder) will be invoked automatically if you override this method! Call those methods at appropriate points of your overridden method.

Parameters:

request - current HTTP request

command - the command to bind onto

Returns:

the new binder instance

Throws:

Exception - in case of invalid state or arguments

See Also:

bindAndValidate(javax.servlet.http.HttpServletRequest, java.lang.Object), prepareBinder(org.springframework.web.bind.ServletRequestDataBinder), initBinder(javax.servlet.http.HttpServletRequest, org.springframework.web.bind.ServletRequestDataBinder)

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prepareBinder

protected final void prepareBinder(ServletRequestDataBinder binder)

Prepare the given binder, applying the specified MessageCodesResolver, BindingErrorProcessor and PropertyEditorRegistrars (if any). Called by createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object).

Parameters:

binder - the new binder instance

See Also:

createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object), setMessageCodesResolver(org.springframework.validation.MessageCodesResolver), setBindingErrorProcessor(org.springframework.validation.BindingErrorProcessor)

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useDirectFieldAccess

protected boolean useDirectFieldAccess()

Determine whether to use direct field access instead of bean property access. Applied by prepareBinder(org.springframework.web.bind.ServletRequestDataBinder).

Default is "false". Can be overridden in subclasses.

Returns:

whether to use direct field access (true) or bean property access (false)

See Also:

prepareBinder(org.springframework.web.bind.ServletRequestDataBinder), DataBinder.initDirectFieldAccess()

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initBinder

protected void initBinder(HttpServletRequest request,
                          ServletRequestDataBinder binder)
                   throws Exception

Initialize the given binder instance, for example with custom editors. Called by createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object).

This method allows you to register custom editors for certain fields of your command class. For instance, you will be able to transform Date objects into a String pattern and back, in order to allow your JavaBeans to have Date properties and still be able to set and display them in an HTML interface.

The default implementation is empty.

Parameters:

request - current HTTP request

binder - the new binder instance

Throws:

Exception - in case of invalid state or arguments

See Also:

createBinder(javax.servlet.http.HttpServletRequest, java.lang.Object), DataBinder.registerCustomEditor(java.lang.Class, java.beans.PropertyEditor), CustomDateEditor

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onBind

protected void onBind(HttpServletRequest request,
                      Object command,
                      BindException errors)
               throws Exception

Callback for custom post-processing in terms of binding. Called on each submit, after standard binding but before validation.

The default implementation delegates to onBind(HttpServletRequest, Object).

Parameters:

request - current HTTP request

command - the command object to perform further binding on

errors - validation errors holder, allowing for additional custom registration of binding errors

Throws:

Exception - in case of invalid state or arguments

See Also:

bindAndValidate(javax.servlet.http.HttpServletRequest, java.lang.Object), onBind(HttpServletRequest, Object)

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onBind

protected void onBind(HttpServletRequest request,
                      Object command)
               throws Exception

Callback for custom post-processing in terms of binding.

Called by the default implementation of the onBind(HttpServletRequest, Object, BindException) variant with all parameters, after standard binding but before validation.

The default implementation is empty.

Parameters:

request - current HTTP request

command - the command object to perform further binding on

Throws:

Exception - in case of invalid state or arguments

See Also:

onBind(HttpServletRequest, Object, BindException)

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suppressValidation

protected boolean suppressValidation(HttpServletRequest request,
                                     Object command,
                                     BindException errors)

Return whether to suppress validation for the given request.

The default implementation delegates to suppressValidation(HttpServletRequest, Object).

Parameters:

request - current HTTP request

command - the command object to validate

errors - validation errors holder, allowing for additional custom registration of binding errors

Returns:

whether to suppress validation for the given request

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suppressValidation

protected boolean suppressValidation(HttpServletRequest request,
                                     Object command)

Return whether to suppress validation for the given request.

Called by the default implementation of the suppressValidation(HttpServletRequest, Object, BindException) variant with all parameters.

The default implementation delegates to suppressValidation(HttpServletRequest).

Parameters:

request - current HTTP request

command - the command object to validate

Returns:

whether to suppress validation for the given request

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suppressValidation

protected boolean suppressValidation(HttpServletRequest request)

Deprecated. as of Spring 2.0.4, in favor of the suppressValidation(HttpServletRequest, Object) variant

Return whether to suppress validation for the given request.

Called by the default implementation of the suppressValidation(HttpServletRequest, Object) variant with all parameters.

The default implementation is empty.

Parameters:

request - current HTTP request

Returns:

whether to suppress validation for the given request

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onBindAndValidate

protected void onBindAndValidate(HttpServletRequest request,
                                 Object command,
                                 BindException errors)
                          throws Exception

Callback for custom post-processing in terms of binding and validation. Called on each submit, after standard binding and validation, but before error evaluation.

The default implementation is empty.

Parameters:

request - current HTTP request

command - the command object, still allowing for further binding

errors - validation errors holder, allowing for additional custom validation

Throws:

Exception - in case of invalid state or arguments

See Also:

bindAndValidate(javax.servlet.http.HttpServletRequest, java.lang.Object), Errors

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