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Spring-JDBC extension library. Provides IterableJdbcTemplate and IterableNamedParameterJdbcTemplate
that can return query result in lazy mode as iterators
package com.alexkasko.springjdbc.iterable;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.dao.DataAccessException;
import org.springframework.jdbc.core.*;
import org.springframework.jdbc.datasource.DataSourceUtils;
import org.springframework.jdbc.support.JdbcUtils;
import org.springframework.jdbc.support.nativejdbc.NativeJdbcExtractor;
import org.springframework.util.Assert;
import javax.sql.DataSource;
import java.sql.*;
import java.util.Map;
/**
* {@code JdbcTemplate} extension. All methods, that return {@code List}
* mirrored with {@code queryForIter} methods that return {@link CloseableIterator}.
*
* @author alexkasko
* Date: 11/7/12
*/
public class IterableJdbcTemplate extends JdbcTemplate implements IterableJdbcOperations {
private static final Log logger = LogFactory.getLog(IterableJdbcTemplate.class);
/**
* Constructor
*
* @param dataSource data source
*/
public IterableJdbcTemplate(DataSource dataSource) {
super(dataSource);
}
/**
* Static method to use in finally methods for closing
* {@link CloseableIterator}s. Writes warning into log on exception.
*
* @param iter iterator to close
*/
public static void closeQuetly(CloseableIterator iter) {
try {
if (iter != null) {
iter.close();
}
} catch (Exception e) {
logger.warn("Error on closing iterator: [" + iter + "]", e);
}
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(PreparedStatementCreator psc, RowMapper rowMapper) throws DataAccessException {
return queryForIter(psc, null, rowMapper);
}
/**
* {@inheritDoc}
*/
@Override
// see {@code JdbcTemplate#query(org.springframework.jdbc.core.PreparedStatementCreator, org.springframework.jdbc.core.PreparedStatementSetter, org.springframework.jdbc.core.ResultSetExtractor)}
// see {@code JdbcTemplate#execute(org.springframework.jdbc.core.PreparedStatementCreator, org.springframework.jdbc.core.PreparedStatementCallback)}
// see {@code JdbcTemplate#query(org.springframework.jdbc.core.PreparedStatementCreator, org.springframework.jdbc.core.PreparedStatementSetter, org.springframework.jdbc.core.ResultSetExtractor)}
public CloseableIterator queryForIter(PreparedStatementCreator psc, PreparedStatementSetter pss,
RowMapper rowMapper) throws DataAccessException {
Assert.notNull(psc, "PreparedStatementCreator must not be null");
Assert.notNull(rowMapper, "RowMapper must not be null");
if(logger.isDebugEnabled()) {
String sql = getSql(psc);
logger.debug("Executing prepared SQL statement" + (sql != null ? " [" + sql + "]" : ""));
}
DataSource ds = getDataSource();
Connection con = DataSourceUtils.getConnection(ds);
PreparedStatement ps = null;
ResultSet rs = null;
try {
Connection conToUse = con;
NativeJdbcExtractor nje = getNativeJdbcExtractor();
if(nje != null && nje.isNativeConnectionNecessaryForNativePreparedStatements()) {
conToUse = nje.getNativeConnection(con);
}
ps = psc.createPreparedStatement(conToUse);
applyStatementSettings(ps);
PreparedStatement psToUse = ps;
if(nje != null) {
psToUse = nje.getNativePreparedStatement(ps);
}
if(pss != null) {
pss.setValues(psToUse);
}
rs = psToUse.executeQuery();
ResultSet rsToUse = rs;
if(nje != null) {
rsToUse = nje.getNativeResultSet(rs);
}
// warnings are handled after query execution but before data access
handleWarnings(ps);
return new PreparedStatementCloseableIterator(ds, con, psc, pss, ps, rs, rsToUse, rowMapper);
} catch(SQLException ex) {
// Release Connection early, to avoid potential connection pool deadlock
// in the case when the exception translator hasn't been initialized yet.
if(psc instanceof ParameterDisposer) {
((ParameterDisposer) psc).cleanupParameters();
}
String sql = getSql(psc);
psc = null;
JdbcUtils.closeResultSet(rs);
rs = null;
JdbcUtils.closeStatement(ps);
ps = null;
DataSourceUtils.releaseConnection(con, getDataSource());
con = null;
throw getExceptionTranslator().translate("PreparedStatementCallback", sql, ex);
}
// resources will be closed in iterator
// finally {
// if(psc instanceof ParameterDisposer) {
// ((ParameterDisposer) psc).cleanupParameters();
// }
// JdbcUtils.closeStatement(ps);
// DataSourceUtils.releaseConnection(con, getDataSource());
// }
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, RowMapper rowMapper) throws DataAccessException {
Assert.hasText(sql, "Provided sql query is blank");
Assert.notNull(rowMapper, "RowMapper must not be null");
DataSource ds = getDataSource();
Connection con = DataSourceUtils.getConnection(ds);
Statement stmt = null;
ResultSet rs = null;
try {
Connection conToUse = con;
NativeJdbcExtractor nje = getNativeJdbcExtractor();
if(nje != null && nje.isNativeConnectionNecessaryForNativeStatements()) {
conToUse = nje.getNativeConnection(con);
}
stmt = conToUse.createStatement();
applyStatementSettings(stmt);
Statement stmtToUse = stmt;
if(nje != null) {
stmtToUse = nje.getNativeStatement(stmt);
}
rs = stmtToUse.executeQuery(sql);
ResultSet rsToUse = rs;
if(nje != null) {
rsToUse = nje.getNativeResultSet(rs);
}
// warnings are handled after query execution but before data access
handleWarnings(stmt);
return new StatementCloseableIterator(ds, con, stmt, rs, rsToUse, rowMapper);
} catch(SQLException ex) {
JdbcUtils.closeResultSet(rs);
rs = null;
// Release Connection early, to avoid potential connection pool deadlock
// in the case when the exception translator hasn't been initialized yet.
JdbcUtils.closeStatement(stmt);
stmt = null;
DataSourceUtils.releaseConnection(con, getDataSource());
con = null;
throw getExceptionTranslator().translate("StatementCallback", getSql(sql), ex);
}
// resources will be closed in iterator
// finally {
// JdbcUtils.closeStatement(stmt);
// DataSourceUtils.releaseConnection(con, getDataSource());
// }
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, Class elementType) throws DataAccessException {
return queryForIter(sql, getSingleColumnRowMapper(elementType));
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator> queryForIter(String sql) throws DataAccessException {
return queryForIter(sql, getColumnMapRowMapper());
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, PreparedStatementSetter pss, RowMapper rowMapper) throws DataAccessException {
return queryForIter(new SimplePreparedStatementCreator(sql), pss, rowMapper);
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, Object[] args, int[] argTypes, RowMapper rowMapper) throws DataAccessException {
return queryForIter(sql, newArgTypePreparedStatementSetter(args, argTypes), rowMapper);
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, Object[] args, RowMapper rowMapper) throws DataAccessException {
return queryForIter(sql, newArgPreparedStatementSetter(args), rowMapper);
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, RowMapper rowMapper, Object... args) throws DataAccessException {
return queryForIter(sql, newArgPreparedStatementSetter(args), rowMapper);
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, Object[] args, int[] argTypes, Class elementType) throws DataAccessException {
return queryForIter(sql, args, argTypes, getSingleColumnRowMapper(elementType));
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, Object[] args, Class elementType) throws DataAccessException {
return queryForIter(sql, args, getSingleColumnRowMapper(elementType));
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator queryForIter(String sql, Class elementType, Object... args) throws DataAccessException {
return queryForIter(sql, args, getSingleColumnRowMapper(elementType));
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator> queryForIter(String sql, Object[] args, int[] argTypes) throws DataAccessException {
return queryForIter(sql, args, argTypes, getColumnMapRowMapper());
}
/**
* {@inheritDoc}
*/
@Override
public CloseableIterator> queryForIter(String sql, Object... args) throws DataAccessException {
return queryForIter(sql, args, getColumnMapRowMapper());
}
/**
* Determine SQL from potential provider object.
* Borrowed from {@code JdbcTemplate}
*
* @param sqlProvider object that's potentially a SqlProvider
* @return the SQL string, or null
* @see SqlProvider
*/
private static String getSql(Object sqlProvider) {
if(sqlProvider instanceof SqlProvider) {
return ((SqlProvider) sqlProvider).getSql();
} else {
return null;
}
}
/**
* Simple adapter for PreparedStatementCreator, allowing to use a plain SQL statement.
* Borrowed from {@code JdbcTemplate}
*/
private static class SimplePreparedStatementCreator implements PreparedStatementCreator, SqlProvider {
private final String sql;
public SimplePreparedStatementCreator(String sql) {
Assert.notNull(sql, "SQL must not be null");
this.sql = sql;
}
public PreparedStatement createPreparedStatement(Connection con) throws SQLException {
return con.prepareStatement(this.sql);
}
public String getSql() {
return this.sql;
}
}
}
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