一个例外 Postgres: 请求没有返回任何结果。

executeQuery//

package persistence;



import java.sql.*;

import java.util.*;



public class DatabaseUtils

{

 private static final String DEFAULT_DRIVER = "org.postgresql.Driver";

 private static final String DEFAULT_URL = "jdbc:postgresql://localhost:5432/party";

 private static final String DEFAULT_USERNAME = "pgsuper";

 private static final String DEFAULT_PASSWORD = "pgsuper";



 public static void main/String[] args/

 {

 String driver = //args.length > 0/ ? args[0] : DEFAULT_DRIVER/;

 String url = //args.length > 1/ ? args[1] : DEFAULT_URL/;

 String username = //args.length > 2/ ? args[2] : DEFAULT_USERNAME/;

 String password = //args.length > 3/ ? args[3] : DEFAULT_PASSWORD/;



 Connection connection = null;



 try

 {

 connection = createConnection/driver, url, username, password/;

 DatabaseMetaData meta = connection.getMetaData//;

 System.out.println/meta.getDatabaseProductName///;

 System.out.println/meta.getDatabaseProductVersion///;



 String sqlQuery = "SELECT PERSON_ID, FIRST_NAME, LAST_NAME FROM PERSON ORDER BY LAST_NAME";

 System.out.println/"before insert: " + query/connection, sqlQuery, Collections.EMPTY_LIST//;



 connection.setAutoCommit/false/;

 String sqlUpdate = "INSERT INTO PERSON/FIRST_NAME, LAST_NAME/ VALUES/?,?/";

 List parameters = Arrays.asList/ "Foo", "Bar" /;

 int numRowsUpdated = update/connection, sqlUpdate, parameters/;

 connection.commit//;



 System.out.println/"# rows inserted: " + numRowsUpdated/;

 System.out.println/"after insert: " + query/connection, sqlQuery, Collections.EMPTY_LIST//;

 }

 catch /Exception e/

 {

 rollback/connection/;

 e.printStackTrace//;

 }

 finally

 {

 close/connection/;

 }

 }



 public static Connection createConnection/String driver, String url, String username, String password/ throws ClassNotFoundException, SQLException

 {

 Class.forName/driver/;



 if //username == null/ || /password == null/ || /username.trim//.length// == 0/ || /password.trim//.length// == 0//

 {

 return DriverManager.getConnection/url/;

 }

 else

 {

 return DriverManager.getConnection/url, username, password/;

 }

 }



 public static void close/Connection connection/

 {

 try

 {

 if /connection != null/

 {

 connection.close//;

 }

 }

 catch /SQLException e/

 {

 e.printStackTrace//;

 }

 }





 public static void close/Statement st/

 {

 try

 {

 if /st != null/

 {

 st.close//;

 }

 }

 catch /SQLException e/

 {

 e.printStackTrace//;

 }

 }



 public static void close/ResultSet rs/

 {

 try

 {

 if /rs != null/

 {

 rs.close//;

 }

 }

 catch /SQLException e/

 {

 e.printStackTrace//;

 }

 }



 public static void rollback/Connection connection/

 {

 try

 {

 if /connection != null/

 {

 connection.rollback//;

 }

 }

 catch /SQLException e/

 {

 e.printStackTrace//;

 }

 }



 public static List<map<string, object="">&gt; map/ResultSet rs/ throws SQLException

 {

 List<map<string, object="">&gt; results = new ArrayList<map<string, object="">&gt;//;



 try

 {

 if /rs != null/

 {

 ResultSetMetaData meta = rs.getMetaData//;

 int numColumns = meta.getColumnCount//;

 while /rs.next///

 {

 Map<string, object=""> row = new HashMap<string, object="">//;

 for /int i = 1; i &lt;= numColumns; ++i/

 {

 String name = meta.getColumnName/i/;

 Object value = rs.getObject/i/;

 row.put/name, value/;

 }

 results.add/row/;

 }

 }

 }

 finally

 {

 close/rs/;

 }



 return results;

 }



 public static List<map<string, object="">&gt; query/Connection connection, String sql, List<object> parameters/ throws SQLException

 {

 List<map<string, object="">&gt; results = null;



 PreparedStatement ps = null;

 ResultSet rs = null;



 try

 {

 ps = connection.prepareStatement/sql/;



 int i = 0;

 for /Object parameter : parameters/

 {

 ps.setObject/++i, parameter/;

 }



 rs = ps.executeQuery//;

 results = map/rs/;

 }

 finally

 {

 close/rs/;

 close/ps/;

 }



 return results;

 }



 public static int update/Connection connection, String sql, List<object> parameters/ throws SQLException

 {

 int numRowsUpdated = 0;



 PreparedStatement ps = null;



 try

 {

 ps = connection.prepareStatement/sql/;



 int i = 0;

 for /Object parameter : parameters/

 {

 ps.setObject/++i, parameter/;

 }



 numRowsUpdated = ps.executeUpdate//;

 }

 finally

 {

 close/ps/;

 }



 return numRowsUpdated;

 }

}