Spring/spring-webflow
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

a bit more about exception handling

Browse Source
This commit is contained in:
Keith Donald
2008-11-04 13:02:54 +00:00
parent 9751f74927
commit e11805f061
2 changed files with 98 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

109
spring-webflow-reference/src/actions.xml
View File

@@ -19,8 +19,7 @@
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>
]]>
</action-state>]]>
</programlisting>
<para>
The full example below illustrates a interview flow that uses the action-state above to determine if more answers are needed to complete the interview:
@@ -64,8 +63,7 @@
<programlisting language="xml"><![CDATA[
<decision-state id="moreAnswersNeeded">
<if test="interview.moreAnswersNeeded()" then="answerQuestions" else="finish" />
</decision-state>
]]>
</decision-state>]]>
</programlisting>
</sect1>
<sect1 id="action-outcome-events">
@@ -88,6 +86,10 @@
</row>
</thead>
<tbody>
<row>
<entry>java.lang.String</entry>
<entry>the String value</entry>
</row>
<row>
<entry>java.lang.Boolean</entry>
<entry>yes (for true), no (for false)</entry>
@@ -96,10 +98,6 @@
<entry>java.lang.Enum</entry>
<entry>the Enum name</entry>
</row>
<row>
<entry>java.lang.String</entry>
<entry>the String value</entry>
</row>
<row>
<entry>any other type</entry>
<entry>success</entry>
@@ -112,15 +110,102 @@
</para>
<programlisting language="xml"><![CDATA[
<action-state id="moreAnswersNeeded">
<evaluate expression="interview.moreAnswersNeeded()"/>
<evaluate expression="interview.moreAnswersNeeded()" />
<transition on="yes" to="answerQuestions" />
<transition on="no" to="finish" />
</action-state>
]]>
</action-state>]]>
</programlisting>
</sect1>
<sect1 id="action-implementations">
<title>Action implementations</title>
<para>
While writing action code as POJO logic is the most common, there are several other action implementation options.
Sometimes you need to write action code that needs access to the flow context.
You can always invoke a POJO and pass it the flowRequestContext as an EL variable.
Alternatively, you may implement the <code>Action</code> interface or extend from the <code>MultiAction</code> base class.
These options provide stronger type safety when you have a natural coupling between your action code and Spring Web Flow APIs.
Examples of each of these approaches are shown below.
</para>
<sect2>
<title>Invoking a POJO action</title>
<programlisting language="xml"><![CDATA[
<evaluate expression="pojoAction.method(flowRequestContext)" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class PojoAction {
public String method(RequestContext context) {
...
}
}]]>
</programlisting>
</sect2>
<sect2>
<title>Invoking a custom Action implementation</title>
<programlisting language="xml"><![CDATA[
<evaluate expression="customAction" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class CustomAction implements Action {
public Event execute(RequestContext context) {
...
}
}]]>
</programlisting>
</sect2>
<sect2>
<title>Invoking a MultiAction implementation</title>
<programlisting language="xml"><![CDATA[
<evaluate expression="multiAction.actionMethod1" />
]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class CustomMultiAction extends MultiAction {
public Event actionMethod1(RequestContext context) {
...
}
public Event actionMethod2(RequestContext context) {
...
}
...
}]]>
</programlisting>
</sect2>
</sect1>
<sect1 id="action-exceptions">
<title>Action exceptions</title>
<para>
Actions often invoke services that encapsulate complex business logic.
These services may throw business exceptions that the action code should handle.
</para>
<sect2>
<title>Handling a business exception with a POJO action</title>
<para>
The following example invokes an action that catches a business exception, adds a error message to the context, and returns a result event identifier.
The result is treated as a flow event which the calling flow can then respond to.
</para>
<programlisting language="xml"><![CDATA[
<evaluate expression="bookingAction.makeBooking(booking, messageContext)" />]]>
</programlisting>
<programlisting language="java"><![CDATA[
public class BookingAction {
public String makeBooking(Booking booking, MessageContext context) {
try {
bookingService.make(booking);
return "success";
} catch (RoomNotAvailableException e) {
context.addMessage(builder.error().
.defaultText("No room is available at this hotel").build());
return "error";
}
}
}]]>
</programlisting>
</sect2>
</sect1>
<sect1 id="action-examples">
<title>Action execution examples</title>
<title>Other Action execution examples</title>
<sect2 id="action-on-start">
<title>on-start</title>
<para>

2
spring-webflow-reference/src/spring-webflow-reference.xml
View File

@@ -25,7 +25,7 @@
<title>Spring Web Flow Reference Guide</title>
<productname>Spring Web Flow</productname>
<releaseinfo>Version 2.0.4</releaseinfo>
<pubdate>October 2008</pubdate>
<pubdate>November 2008</pubdate>
<authorgroup>
<author>
<firstname>Keith</firstname>