How to get spring configuration from database - spring

Question

I'm using Eclipse Juno, JDK 7, tomcat 7.0.29, hibernate 4.1.5 and Spring 3.1.2.
I'm trying to load Spring configuration info from database. This is what I could do until now:
WEB.XML
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/context-beans.xml
</param-value>
</context-param>
jdbc.properties
jdbc.driver_class=com.microsoft.sqlserver.jdbc.SQLServerDriver
jdbc.url=jdbc:sqlserver://localhost;databaseName=mydbname;
jdbc.username=<my_usr>
jdbc.password=<my_pwd>
context-beans.xml
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:oxm="http://www.springframework.org/schema/oxm"
xmlns:security="http://www.springframework.org/schema/security"
xsi:schemaLocation="http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.1.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsd
http://www.springframework.org/schema/oxm http://www.springframework.org/schema/oxm/spring-oxm-3.1.xsd">
<!-- Configure which package will contain our components -->
<context:component-scan base-package="com.xxx" />
<context:annotation-config />
<mvc:annotation-driven />
<mvc:resources mapping="/static/**" location="/static/" />
<tx:annotation-driven />
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitName" value="appPersistenceUnit" />
</bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<bean id="dataSource" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource" p:driverClassName="com.microsoft.sqlserver.jdbc.SQLServerDriver"
p:url="jdbc:sqlserver://localhost;databaseName=appDB" p:username="theUserName" p:password="thePassword" destroy-method="close"/>
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate" lazy-init="false" >
<property name="dataSource" ref="dataSource" />
<property name="lazyInit" value="false" />
</bean>
<bean id="appProperties" class="com.xxx.web.util.MyAppPropertyPlaceholderConfigurer">
<property name="nameColumn" value="key" />
<property name="valueColumn" value="value" />
<property name="tableName" value="app_params" />
<property name="whereClause" value="param_type = 'GLOBAL'" />
<property name="jdbcTemplate" ref="jdbcTemplate" />
</bean>
<!-- Files path configuration -->
<mvc:resources mapping="/iconfiles/**" location="file:/${PATH.ICON_FILES}" />
</beans>
Please consider table app_params contains 1 record where key="PATH.ICON_FILES", value="c:/temp/icons/" and param_type="GLOBAL".
MyAppPropertyPlaceholderConfigurer
package com.xxx.web.util;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowCallbackHandler;
public class MyAppPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
private JdbcTemplate jdbcTemplate;
private String nameColumn;
private String valueColumn;
private String tableName;
private String whereClause;
public MyAppPropertyPlaceholderConfigurer() {
super();
setPlaceholderPrefix("${");
}
#Override
protected void loadProperties(final Properties props) throws IOException {
if (null == props) {
throw new IOException("No properties passed by Spring framework - cannot proceed.");
}
String sql = String.format("SELECT [%s], [%s] FROM [%s] %s", nameColumn, valueColumn, tableName, whereClause);
logger.info("Reading configuration properties from database. Query=" + sql);
try {
jdbcTemplate.query(sql, new RowCallbackHandler() {
#Override
public void processRow(ResultSet rs) throws SQLException {
String name = rs.getString(nameColumn);
String value = rs.getString(valueColumn);
if (null == name || null == value) {
throw new SQLException("Configuration database contains empty data. Name='" + (name == null ? "" : name)
+ "', Value='" + (value == null ? "" : value) + "'.");
}
props.setProperty(name, value);
}
});
} catch (Exception e) {
logger.fatal("There is an error in either 'application.properties' or the configuration database.");
throw new IOException(e);
}
if (props.size() == 0) {
logger.fatal("The configuration database could not be reached or does not contain any properties in '" + tableName
+ "'.");
} else {
logger.info("Application config info loaded from configuration database.");
}
}
#Override
protected String convertPropertyValue(String originalValue) {
if (originalValue.startsWith("!!")) {
// TODO ex: return EncryptUtil.decrypt(originalValue); see org.owasp.esapi.reference.crypto.EncryptedPropertiesUtils
return originalValue;
}
return originalValue;
}
public void setJdbcTemplate(JdbcTemplate newJdbcTemplate) {
this.jdbcTemplate = newJdbcTemplate;
}
public void setNameColumn(String newNameColumn) {
this.nameColumn = newNameColumn;
}
public void setValueColumn(String newValueColumn) {
this.valueColumn = newValueColumn;
}
public void setTableName(String newTableName) {
this.tableName = newTableName;
}
public void setWhereClause(String newWhereClause) {
if (newWhereClause == null || newWhereClause.trim().length() == 0) {
this.whereClause = "";
} else {
if (newWhereClause.trim().toUpperCase().startsWith("WHERE ")) {
this.whereClause = newWhereClause;
} else {
this.whereClause = "WHERE " + newWhereClause;
}
}
}
}
Doing it this way works as expected and I have variable ${PATH.ICON_FILES} properly resolved.
However, I don't want to have my dataSource bean with username, password and all stuff hard coded on the XML file. I would like to load it from another property file, preferentially encrypted.
How do I get this done?
I already tried to add another PropertyPlaceholderConfigurer with jdbc configuration (plain text at this time) by adding the code below into context-beans.xml:
<bean id="jdbcConfigurer" name="jdbcConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:jdbc.properties</value>
</list>
</property>
</bean>
Then I changed dataSource bean to read from there:
<bean id="dataSource" name="dataSource" class="org.apache.tomcat.dbcp.dbcp.BasicDataSource" p:driverClassName="${jdbc.driver_class}"
p:url="${jdbc.url}" p:username="${jdbc.username}" p:password="${jdbc.password}" destroy-method="close" />
When I try to run I get the following error:
[2012-10-10 11:33:48,744] WARN (SQLErrorCodesFactory.java:227) - Error while extracting database product name - falling back to empty error codes
org.springframework.jdbc.support.MetaDataAccessException: Could not get Connection for extracting meta data; nested exception is org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot load JDBC driver class '${jdbc.driver_class}'
Any idea what I'm doing wrong here? Looks like it is instantiating MyAppPropertyPlaceholderConfigurer prior to getting the values from the regular PropertyPlaceholderConfigurer...
Thanks.