Spring JDBC and Java 8 - JDBCTemplate: retrieving SQL statement and parameters for debugging - sql

Question

I am using Spring JDBC and some nice Java 8 lambda-syntax to execute queries with the JDBCTemplate.
The reason for choosing Springs JDBCTemplate, is the implicit resource-handling that Spring-jdbc offers (I do NOT want a ORM framework for my simple usecase's).
My problem is that I want to debug the whole SQL statements with their parameters. Spring prints the SQL by default but not the parameters. Therefor I have subclassed the JDBCTemplate and overridden a query-method.
An example usage of the JDBCTemplate:
public List<Product> getProductsByModel(String modelName) {
List<Product> productList = jdbcTemplate.query(
"select * from product p, productmodel m " +
"where p.modelId = m.id " +
"and m.name = ?",
(rs, rowNum) -> new Product(
rs.getInt("id"),
rs.getString("stc_number"),
rs.getString("version"),
getModelById(rs.getInt("modelId")), // method not shown
rs.getString("displayName"),
rs.getString("imageUrl")
),
modelName);
return productList;
}
To get hold of the parameters I have, as mentioned, overridden the JDBCTemplate class. By doing a cast and using reflection I get the Object[] field with the parameters from an instance of ArgumentPreparedStatementSetter.
I suspect this implementation could potentially be dangerous, as the actual implementation of the PreparedStatementSetter may not always be ArgumentPreparedStatementSetter (Yes I should do an instanceOf check). Also, the reflection code may not be as elegant, but that is besides the point now though :).
Here's my custom implementation:
public class CustomJdbcTemplate extends JdbcTemplate {
private static final Logger log = LoggerFactory.getLogger(CustomJdbcTemplate.class);
public CustomJdbcTemplate(DataSource dataSource) {
super(dataSource);
}
public <T> T query(PreparedStatementCreator psc, final PreparedStatementSetter pss, final ResultSetExtractor<T> rse)
throws DataAccessException {
if(log.isDebugEnabled()) {
ArgumentPreparedStatementSetter aps = (ArgumentPreparedStatementSetter) pss;
try {
Field args = aps.getClass().getDeclaredField("args");
args.setAccessible(true);
Object[] parameters = (Object[]) args.get(aps);
log.debug("Parameters for SQL query: " + Arrays.toString(parameters));
} catch (NoSuchFieldException | IllegalAccessException e) {
throw new GenericException(e.toString(), e);
}
}
return super.query(psc, pss, rse);
}
}
So, when I execute the log.debug(...) statement I would also like to have the original SQL query logged (same line). Has anyone done something similar or are there any better suggestions as to how this can be achieved?
I do quite a few queries using this CustomJDBCTemplate and all my tests run, so I think it may be an acceptable solution of for most debug purposes.
Kind regards,
Thomas

Answer 1

I found a way to get the SQL-statement, so I will answer my own question :)
The PreparedStatementCreator has the following implementation:
private static class SimplePreparedStatementCreator implements PreparedStatementCreator, SqlProvider
So the SqlProvider has a getSql() method which does exactly what I need.
Posting the "improved" CustomJdbcTemplate class if anyone ever should need to do the same :)
public class CustomJdbcTemplate extends JdbcTemplate {
private static final Logger log = LoggerFactory.getLogger(CustomJdbcTemplate.class);
public CustomJdbcTemplate(DataSource dataSource) {
super(dataSource);
}
public <T> T query(PreparedStatementCreator psc, final PreparedStatementSetter pss, final ResultSetExtractor<T> rse)
throws DataAccessException {
if(log.isDebugEnabled()) {
if(pss instanceof ArgumentPreparedStatementSetter) {
ArgumentPreparedStatementSetter aps = (ArgumentPreparedStatementSetter) pss;
try {
Field args = aps.getClass().getDeclaredField("args");
args.setAccessible(true);
Object[] parameters = (Object[]) args.get(aps);
log.debug("SQL query: [{}]\tParams: {} ", getSql(psc), Arrays.toString(parameters));
} catch (NoSuchFieldException | IllegalAccessException e) {
throw new GenericException(e.toString(), e);
}
}
}
return super.query(psc, pss, rse);
}
private static String getSql(Object sqlProvider) { // this code is also found in the JDBCTemplate class
if (sqlProvider instanceof SqlProvider) {
return ((SqlProvider) sqlProvider).getSql();
}
else {
return null;
}
}
}