How to externalize the queries to xml files using spring - spring

Question

I am using spring and their JDBC template to do read/write operations to the database. I am facing a problem in my reporting module that i have to frequently change the query sqls to cater to frequent changes.
Though using spring jdbc ORM, is there a way to externalize my query parameters such that i just change it in the XML & restart and there is no need to rebuild my source again for deployment. Any approach ORM (preferred) or simple Sql will do.
As of now i have to change the query again and again ,rebuild the source and deploy.

Answer 1

I am not sure if Spring provides some out of the box solutions to implement what you want. But here is one way to get it done, which i had implemented ones. So i will try to reduce some hardwork for you.
You might need to implement a utility to load from resources xml file. Something like this.
public final class LoadFromResourceFileUtils {
public static String loadQuery(final String libraryPath,
final String queryName) {
final InputStream is = StreamUtils
.streamFromClasspathResource(libraryPath);
if (is == null) {
throw new RuntimeException(String.format(
"The SQL Libary %s could not be found.", libraryPath));
}
final Document doc = XMLParseUtils.parse(is);
final Element qryElem = (Element) doc.selectSingleNode(String.format(
"SQLQueries/SQLQuery[#name='%s']", queryName));
final String ret = qryElem == null ? null : qryElem.getText();
return ret;
}
}
You would need to store your queries in an XML say queries.xml and keep it in your classpath, for e.g
<?xml version="1.0" encoding="UTF-8"?>
<SQLQueries>
<SQLQuery name="myQuery">
<![CDATA[
your query
]]>
</SQLQuery>
</SQLQueries>
And in your DAO you can do this to get the query
String query = LoadFromResourceFileUtils.loadQuery(
"queries.xml", "myQuery");
XMLParseUtils and StreamUtils for your reference
public final class XMLParseUtils {
public static Document parse(final InputStream inStream) {
Document ret = null;
try {
if (inStream == null) {
throw new RuntimeException(
"XML Input Stream for parsing is null");
}
final SAXReader saxReader = new SAXReader();
ret = saxReader.read(inStream);
} catch (final DocumentException exc) {
throw new RuntimeException("XML Parsing error", exc);
}
return ret;
}
}
public final class StreamUtils {
public static InputStream streamFromClasspathResource(
final String resourceClassPath) {
final Class<StreamUtils> clazz = StreamUtils.class;
final ClassLoader clLoader = clazz.getClassLoader();
final InputStream inStream = clLoader
.getResourceAsStream(resourceClassPath);
if (inStream == null) {
if(LOGGER.isDebugEnabled()){
LOGGER.debug(String.format("Resource %s NOT FOUND.",
resourceClassPath));
}
}
return inStream;
}
}