Java使用JDBC连接postgresql数据库示例

package tool;import java.sql.Connection;import java.sql.DriverManager;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;public class PsqlConnectionTool { private String url = "jdbc:postgresql://xxx.xxx.xxx.xxx:5432/testdb"; private String username = "postgres"; private String password = "postgres"; private Connection connection = null; public Connection getConn() {  try {   Class.forName("org.postgresql.Driver").newInstance();   connection = DriverManager.getConnection(url, username, password);  } catch (InstantiationException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } catch (IllegalAccessException e) {   // TODO Auto-generated catch block   e.printStackTrace();  } catch (ClassNotFoundException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }catch (SQLException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }  return connection; } public ResultSet query(Connection conn, String sql) {  PreparedStatement pStatement = null;  ResultSet rs = null;  try {   pStatement = conn.prepareStatement(sql);   rs = pStatement.executeQuery();  } catch (SQLException e) {   e.printStackTrace();  }  return rs; } public boolean queryUpdate(Connection conn, String sql) {  PreparedStatement pStatement = null;  int rs = 0;  try {   pStatement = conn.prepareStatement(sql);   rs = pStatement.executeUpdate();  } catch (SQLException e) {   // TODO Auto-generated catch block   e.printStackTrace();  }  if (rs > 0) {   return true;  }  return false; } public static void main(String[] args) throws SQLException {  PsqlConnectionTool pgtool = new PsqlConnectionTool();  Connection myconn = pgtool.getConn();  pgtool.queryUpdate(myconn, "insert into test values (1,'smoon','man')");  ResultSet rs = pgtool.query(myconn, "select * from test");  while(rs.next()){   int id = rs.getInt("id");   String name = rs.getString("name");   String gender = rs.getString("gender");   System.out.println("id:"+id+" 姓名："+name+" 性别："+gender);   myconn.close();  } }}