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Spring batch dynamic file writer

Does spring batch provide any dynamic/generic file writers? For example, if i have multiple requirements of generating a file and i have one view created for each purpose, all i want to do is specify the view name and i want spring-batch to extract the data from the view to a flat file with column headings. This is as simple as if you have used dbviz or sql developer, just export the result of a query to a file.
Recently i had 4 different requirements of extracting data to file, and i have repeated the config file and created a record bean and record mapper to map the bean to the columns of view for each file. Rather than repeating this entire process every time, i am looking to see if Spring batch or any other java frameworks provides a generic approach to extracting a file based on the table and its columns without writing result set mappers or dealing with field extractors.
I can build a generic spring batch file extractor but wanted to check if spring-batch already does that, which seems like a basic thing?
Also if i create a generic extractor then the attributes of the bean will be kinda dynamic based on the columns names of the view. So in that scenario, if i have about 50 columns i dont want to specify each attribute in fieldExtractor, i want all the attributes to be extracted. Currently i am specifying attributes in spring config as given below, but i don't want to spefiy the attribute names. I just want to say extract all attributes. Is that possible?
<bean id="CsvItemWriter" class="some.class.FileWriter" scope="step">
<property name="resource" value="file://#{jobParameters['file.name']}"/>
<property name="shouldDeleteIfExists" value="true" />
<property name="lineAggregator">
<bean class="org.springframework.batch.item.file.transform.DelimitedLineAggregator">
<property name="delimiter">
<util:constant static-field="org.springframework.batch.item.file.transform.DelimitedLineTokenizer.DELIMITER_TAB" />
</property>
<property name="fieldExtractor"> <bean class="org.springframework.batch.item.file.transform.BeanWrapperFieldExtractor">
<property name="names" value="name.last, name.first, name.middle, birthDate, gender, homePhone, cellPhone"/>
</bean>
</property>
</bean>
</property>

In case some one needs it, i found a similar question in SO that was difficult to find. I am using columnMapRowMapper as mentioned here

Spring REST | MappingJacksonHttpMessageConverter produces invalid JSON

I've implemented a RESTful web service with Spring. The service responds in XML or JSON based on the Accept header. Here's the context.xml mapping:
<bean id="xstreamMarshaller" class="org.springframework.oxm.xstream.XStreamMarshaller"/>
<bean id="xmlMessageConverter"
class="org.springframework.http.converter.xml.MarshallingHttpMessageConverter">
<constructor-arg ref="xstreamMarshaller"/>
<property name="supportedMediaTypes" value="application/xml"/>
</bean>
<bean id="jsonHttpMessageConverter"
class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter">
<property name="prefixJson" value="false"/>
<property name="supportedMediaTypes" value="application/json"/>
</bean>
<bean
class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
<property name="messageConverters">
<util:list id="beanList">
<ref bean="xmlMessageConverter"/>
<ref bean="jsonHttpMessageConverter"/>
</util:list>
</property>
</bean>
Here is my controller method:
#Controller
#RequestMapping(value = "/entityService")
class RestfulEntityService {
#Resource
private EntityService entityService;
#ResponseBody
#RequestMapping(value = "/getAllEntities", method = RequestMethod.GET)
public List<Entity> getAllEntities() {
return entityService.getAllEntities();
}
}
The XML response is valid, however, when the client sets the Accept header to application/json, the response is invalid JSON.
Here is the JSON response sample:
[{"id":3,"attributes":[{"id":18,"attributeValue":null,"attributeName":"mobile","attributeType":"varchar(40)","entity":{"id":3,"attributes":[{"id":18,"attributeValue":null,"attributeName":"mobile","attributeType":"varchar(40)","entity":{"id":3,"attributes":[{"id":18,"attributeValue":null,"attributeName":"mobile","attributeType":"varchar(40)","entity":{"id":3,"attributes": ..... repeats for a while and then stops..

You're using XStream to serialize XML responses and Jackson JSON to serialize JSON responses. Looking at the JSON output you posted, it seems like there's a circular reference issue at hand. I'm guessing Entity has a list of attributes, each pointing to their respective entity. XStream handles circular references transparently by using XPath, this allows to preserve references when deserializing back to objects. Jackson is able to handle circular references since v1.6, but you need to help it by annotating your serialized entities with #JsonManagedReference and #JsonBackReference. I think Jackson is unique in allowing back references in JSON serialization.
See Jackson's documentation on handling bi-directional references using declarative methods for reference.

Spring syntax for setting a Class object?

Is there a way to set a property in spring to, not an instance of a class, but the class object itself? i.e.
Rather than
<bean>
<property name="prototype" class="a.b.c.Foo">...
giving you an instance of "Foo", something like:
<bean>
<property name="prototype" class="java.lang.Class" value="a.b.c.Foo.class"...
edit:
best (working) solution so far - use the normal instantiation and derive the class in the setter. In terms of solutions I think this we'd describe this as "cheating":
<bean class="Bar">
<property name="prototype" class="a.b.c.Foo">...
public class Bar{
public void setPrototype(Object o){
this.prototypeClass=o.getClass();
edit:
dtsazza's method works as well.
edit:
pedromarce's method works as well.

<bean>
<property name="x">
<value type="java.lang.Class">a.b.c.Foo</value>
</property>
</bean>
That should work.

You could certainly use the static factory method Class.forName(), if there's no more elegant syntax (and I don't believe there is):
<property name="x">
<bean class="java.lang.Class" factory-method="forName">
<constructor-arg value="a.b.c.Foo"/>
</bean>
</property>

No. With a bean tag you instruct Spring on how to instantiate a class.

Would <property name="x" class="a.b.c.Foo.class"> work? That should be an instance of a Class object...

"Recycling" names within a spring application context

lets say, I have a lot of stuff within my spring application context which looks like that
<bean name="foo.0001" class="com.example.MyClass">
<property name="name" value="foo.name.0001"/>
<property name="zap">
<bean class="com.example.Other">
<property name="name" value="foo.name.0001"/>
</bean>
</property>
<property name="bar">
<bean class="com.example.NextOther">
<property name="name" value="foo.name.0001"/>
</bean>
</property>
</bean>
so the string foo.name.0001 appears within the bean definition several times. Because it is a larger system with several blocks of this configuration, it is quite annoying to modify each of those ids. Ideally I would want to set it only once within a block. Is there a possibility to set some kind of property which exists only in a local scope of a bean definition?

I'm not sure how that would logically work, as you would still have to reference that value somehow to pass it to the nested beans. If you are worried about defining it multiple times, you can have a look at Springs PropertyPlaceholderConfigurer. It will allow you to the following:
<property name="bar">
<bean class="com.example.NextOther">
<property name="name" value="${foo.name.001}"/>
</bean>
</property>
This would allow you to define it once, and reference it from multiple locations.

It depends how much effort you want to put into to this but your requirements could be fufilled by a spring custom namespace. These are ideal when you have lots of identical blocks of beans each configured differently.
Basically you'd define the xml schema then write a bean definition parser that sets up the beans as required.
See here for more details:
http://www.javaworld.com/javaworld/jw-02-2008/jw-02-springcomponents.html
This is how Spring security simplified its xml configuration.

Is it possible to have multiple PropertyPlaceHolderConfigurer in my applicationContext?

I need to load a specific applicationContext.xml file according to a given system property. This itself loads a file with the actual configuration. Therefore I need two PropertyPlaceHolderConfigurer, one which resolves the system param, and the other one within the actual configuration.
Any ideas how to do this?

Yes you can do more than one. Be sure to set ignoreUnresolvablePlaceholders so that the first will ignore any placeholders that it can't resolve.
<bean id="ppConfig1" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<property name="locations">
<list>
<value>classpath*:/my.properties</value>
</list>
</property>
</bean>
<bean id="ppConfig2" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="false"/>
<property name="locations">
<list>
<value>classpath*:/myOther.properties</value>
</list>
</property>
</bean>
Depending on your application, you should investigate systemPropertiesMode, it allows you to load properties from a file, but allow the system properties to override values in the property file if set.

Another solution is to use placeholderPrefix property of PropertyPlaceholderConfigurer. You specify it for the second (third, fourth...) configurer, and then prefix all your corresponding placeholders, thus there will be no conflict.
<bean id="mySecondConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"
p:location="classpath:/myprops.properties"
p:placeholderPrefix="myprefix-"/>
<bean class="com.mycompany.MyClass" p:myprop="${myprefix-value.from.myprops}"/>

Beware -- there might be a bug related to multiple configurers. See http://jira.spring.io/browse/SPR-5719 for more details.
I'm unable to get multiple to work locally... but I'm not yet blaming anyone but myself.

On my own side, playing with PropertyPlaceholderConfigurer both properties :
order (should be lower for first accessed/parsed PPC)
ignoreUnresolvablePlaceholders ("false" for first accessed/parsed PPC, "true" for next one)
and also give 2 distinct id(s) to both PPC (to avoid one to be overwritten by the other)
works perfectly
Hope it helps

You can't do this directly, and this JIRA issue from Spring explains why (check the comment from Chris Beams for a detailed explanation):
https://jira.springsource.org/browse/SPR-6428
However, he does provide a workaround using Spring 3.1 or later, which is to use the PropertySourcesPlaceholderConfigurer class instead of PropertyPlaceholderConfigurer class.
You can download a Maven-based project that demonstrates the problem and the solution from the Spring framework issues github:
https://github.com/SpringSource/spring-framework-issues
Look for the issue number, SPR-6428, in the downloaded projects.

We have the following approach working:
<util:properties id="defaultProperties">
<prop key="stand.name">DEV</prop>
<prop key="host">localhost</prop>
</util:properties>
<context:property-placeholder
location="file:${app.properties.path:app.properties}"
properties-ref="defaultProperties"/>
System property app.properties.path can be used to override path to config file.
And application bundles some default values for placeholders that cannot be defined with defaults in common modules.

Just giving 2 distinct ids worked for me. I am using spring 3.0.4.
Hope that helps.

In case, you need to define two PPC's (like in my situation) and use them independently. By setting property placeholderPrefix, you can retrieve values from desired PPC. This will be handy when both set of PPC's properties has same keys, and if you don't use this the property of ppc2 will override ppc1.
Defining your xml:
<bean name="ppc1"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="properties" ref="ref to your props1" />
<property name="placeholderPrefix" value="$prefix1-{" />
</bean>
<bean name="ppc2"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="properties" ref="ref to your props2" />
<property name="placeholderPrefix" value="$prefix2-{" />
</bean>
Retrieving during Run time:
#Value(value = "$prefix1-{name}")
private String myPropValue1;
#Value(value = "$prefix2-{name}")
private String myPropValue2;