使用jdbc连接本地postgreSQL的一个例子

package postgresql;
import java.sql.Clob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
public class PostgreSQLJDBC {
  private Connection connection = null;
  @SuppressWarnings("unused")
  private void select() {
    try {
      int index = 0;
      Class.forName("org.postgresql.Driver");
      connection = DriverManager.getConnection(
          "jdbc:postgresql://localhost:9812/zproduct", "postgres", "Saptest1");
      Statement stmt = connection.createStatement();
      String query = "SELECT * FROM public.comm_product;";
      ResultSet rs = stmt.executeQuery(query);
           while ( rs.next() ) {
            System.out.println("Row index: " + index++);
            String  client = rs.getString("client");
              System.out.println("Client: " + client);
              String  guid = rs.getString("product_guid");
              System.out.println("Product guid: " + guid);
              Timestamp validFrom = rs.getTimestamp("valid_from");
              System.out.println("Valid from: " + validFrom);
           }
           rs.close();
           stmt.close();
           connection.close();
    } catch (Exception e) {
      e.printStackTrace();
    } 
  }
  public static void main(String args[]) {
    PostgreSQLJDBC jdbcTest = new PostgreSQLJDBC();
    //jdbcTest.select();
    jdbcTest.clobTest();
  }
  @SuppressWarnings("unused")
  private void clobTest(){
    String description = null;
      Clob myClob = null;
      PreparedStatement pstmt = null;
      try {
        connection = DriverManager.getConnection(
          "jdbc:postgresql://localhost:9812/zproduct", "postgres", "Saptest1");
          String sql =
              "select text " +
              "from public.ztest2 " +
              "where key1 = ?";
          pstmt = this.connection.prepareStatement(sql);
          pstmt.setString(1, "1");
          ResultSet rs = pstmt.executeQuery();
          if (rs.next()) {
            System.out.println(rs.getString(1));
              //myClob = rs.getClob(1);
              //System.out.println("Length of retrieved Clob: " +
              //    myClob.length());
          }
          // description = myClob.getSubString(1, 10);
      } catch (SQLException sqlex) {
          sqlex.printStackTrace();
      } catch (Exception ex) {
          System.out.println("Unexpected exception: " + ex.toString());
      } finally {
          if (pstmt != null)
        try {
          pstmt.close();
        } catch (SQLException e) {
          e.printStackTrace();
        }
      }
      // System.out.println("Description: " + description);
  }
}