org.nuiton.web.filter

Class JpaTransactionFilter

java.lang.Object

org.nuiton.web.filter.JpaTransactionFilter

All Implemented Interfaces:

javax.servlet.Filter

public abstract class JpaTransactionFilter
extends Object
implements javax.servlet.Filter

Purpose of this filter

This filter purpose is to inject in the request a entityManager from EntityManager and deal with the complete lifecycle of a JPA entityManager while a request.

The injected JPA entityManager will be closed (if was really opened) at the end of the request.

Configuration of the filter

The filter accepts two configuration parameters:

• excludeMethods: This parameters configure a set of method names which should never be called on the proxied entityManager. When a such method is called on the entityManager then the filter will pass in the hook onExcludeMethod(Object, Method, Object[]).

  Default implementation of this hook is to throw an exception.

• unusedMethods: This parameters configure a set of method names which should be by-pass when the proxied entityManager was not still open (via a EntityManager#. When a such method is called on the entityManager then the filter will pass in the hook onUnusedMethod(Object, Method, Object[]).

  Default implementation of this hook is to not return null values.

Obtain the entityManager

The (proxied) entityManager is pushed as an attribute in the servlet request.

The attribute name is defined by field requestAttributeName (default value is JPA_TRANSACTION_REQUEST_ATTRIBUTE) and can be changed.

A convience method is created here to obtain the entityManager getTransaction(ServletRequest) :

 EntityManager em = JpaTransactionFilter.getTransaction(ServletRequest);
 

If you prefer to not use this nice method, you can also do this:

 EntityManager em = (EntityManager) request.getAttribute(JpaTransactionFilter#JPA_TRANSACTION_REQUEST_ATTRIBUTE);
 

Or

 EntityManager em = (EntityManager) request.getAttribute(modifiedAttributeName);
 

Since:

1.13

Author:

tchemit, bleny

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	JpaTransactionFilter.JpaTransactionProxyInvocationHandler Handler of a proxy on a EntityManager.

Field Summary

Fields

Modifier and Type	Field and Description
static String[]	DEFAULT_EXCLUDE_METHODS
static String[]	DEFAULT_UNUSED_METHODS
protected Set<String>	excludeMethods names of methods to forbid access while using proxy.
static String	JPA_TRANSACTION_REQUEST_ATTRIBUTE
protected String	requestAttributeName Name of the request attribute where to push the entityManager.
protected Set<String>	unusedMethods names of methods to by-pass if no entityManager opened on proxy.

Constructor Summary

Constructors

Constructor and Description
JpaTransactionFilter()

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract javax.persistence.EntityManager	createEntityManager(javax.servlet.ServletRequest request) Method to open a new entityManager.
void	destroy()
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain)
Set<String>	getExcludeMethods()
static javax.persistence.EntityManager	getTransaction(javax.servlet.ServletRequest request)
Set<String>	getUnusedMethods()
void	init(javax.servlet.FilterConfig filterConfig)
protected void	onCloseTransaction(javax.persistence.EntityManager entityManager) Hook method to close the topia entityManager of the request at the end of the request when all filter has been consumed.
protected Object	onExcludeMethod(Object proxy, Method method, Object[] args) Hook method called when a method with his name in excludeMethods was invoked on the proxied entityManager.
protected Object	onUnusedMethod(Object proxy, Method method, Object[] args) Hook method called when a method with his name in unusedMethods was invoked on the proxied entityManager while the underlying entityManager is still not opened.
void	setRequestAttributeName(String requestAttributeName) to change the requestAttributeName.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

JPA_TRANSACTION_REQUEST_ATTRIBUTE

public static final String JPA_TRANSACTION_REQUEST_ATTRIBUTE

See Also:

Constant Field Values

DEFAULT_EXCLUDE_METHODS

public static final String[] DEFAULT_EXCLUDE_METHODS

DEFAULT_UNUSED_METHODS

public static final String[] DEFAULT_UNUSED_METHODS

excludeMethods

protected Set<String> excludeMethods

names of methods to forbid access while using proxy.

unusedMethods

protected Set<String> unusedMethods

names of methods to by-pass if no entityManager opened on proxy.

requestAttributeName

protected String requestAttributeName

Name of the request attribute where to push the entityManager.

By default will use value of JPA_TRANSACTION_REQUEST_ATTRIBUTE.

Constructor Detail

JpaTransactionFilter

public JpaTransactionFilter()

Method Detail

getExcludeMethods

public Set<String> getExcludeMethods()

getUnusedMethods

public Set<String> getUnusedMethods()

setRequestAttributeName

public void setRequestAttributeName(String requestAttributeName)

to change the requestAttributeName.

Parameters:

requestAttributeName - new name of the request attribute where to push the entityManager.

getTransaction

public static javax.persistence.EntityManager getTransaction(javax.servlet.ServletRequest request)

createEntityManager

protected abstract javax.persistence.EntityManager createEntityManager(javax.servlet.ServletRequest request)

Method to open a new entityManager.

Parameters:

request - incoming request

Returns:

the new freshly opened entityManager

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Filter

init

public void init(javax.servlet.FilterConfig filterConfig)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Filter

Throws:

javax.servlet.ServletException

doFilter

public void doFilter(javax.servlet.ServletRequest request,
            javax.servlet.ServletResponse response,
            javax.servlet.FilterChain chain)
              throws IOException,
                     javax.servlet.ServletException

Specified by:

doFilter in interface javax.servlet.Filter

Throws:

IOException

javax.servlet.ServletException

onExcludeMethod

protected Object onExcludeMethod(Object proxy,
                     Method method,
                     Object[] args)
                          throws Throwable

Hook method called when a method with his name in excludeMethods was invoked on the proxied entityManager.

Parameters:

proxy - proxied entityManager

method - method invoked

args - arguments of the invoked method

Returns:

the return code of the method

Throws:

Throwable - if any error to do.

onCloseTransaction

protected void onCloseTransaction(javax.persistence.EntityManager entityManager)

Hook method to close the topia entityManager of the request at the end of the request when all filter has been consumed.

Parameters:

entityManager - the entityManager to close (can be null if entityManager was not required while the current request)

onUnusedMethod

protected Object onUnusedMethod(Object proxy,
                    Method method,
                    Object[] args)
                         throws Throwable

Hook method called when a method with his name in unusedMethods was invoked on the proxied entityManager while the underlying entityManager is still not opened.

Parameters:

proxy - the proxy itself

method - method invoked

args - arguments of the invoked method

Returns:

the return code of the method

Throws:

Throwable - if any error to do.