Подключение к PostgreSQL с помощью драйвера JDBC

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class JDBCExample {

    public static void main(String[] args) {

		// https://docs.oracle.com/javase/8/docs/api/java/sql/package-summary.html#package.description
        // auto java.sql.Driver discovery -- no longer need to load a java.sql.Driver class via Class.forName

        // register JDBC driver, optional, since java 1.6
        /*try {
            Class.forName("org.postgresql.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }*/
		
        // auto close connection
        try (Connection conn = DriverManager.getConnection(
                "jdbc:postgresql://127.0.0.1:5432/test", "postgres", "password")) {

            if (conn != null) {
                System.out.println("Connected to the database!");
            } else {
                System.out.println("Failed to make connection!");
            }

        } catch (SQLException e) {
            System.err.format("SQL State: %s\n%s", e.getSQLState(), e.getMessage());
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
}

> javac JDBCExample.java

> java JDBCExample
SQL State: 08001
No suitable driver found for jdbc:postgresql://127.0.0.1:5432/test

> java -cp "c:\db\postgresql-42.2.5.jar;c:\db" JDBCExample
Connected to the database!

	
		org.postgresql
		postgresql
		42.2.5
	

package com.mkyong.jdbc;

import com.mkyong.jdbc.model.Employee;

import java.math.BigDecimal;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class JDBCExample2 {

    public static void main(String[] args) {

        List result = new ArrayList<>();

        String SQL_SELECT = "Select * from EMPLOYEE";

        // auto close connection and preparedStatement
        try (Connection conn = DriverManager.getConnection(
                "jdbc:postgresql://127.0.0.1:5432/test", "postgres", "password");
             PreparedStatement preparedStatement = conn.prepareStatement(SQL_SELECT)) {

            ResultSet resultSet = preparedStatement.executeQuery();

            while (resultSet.next()) {

                long id = resultSet.getLong("ID");
                String name = resultSet.getString("NAME");
                BigDecimal salary = resultSet.getBigDecimal("SALARY");
                Timestamp createdDate = resultSet.getTimestamp("CREATED_DATE");

                Employee obj = new Employee();
                obj.setId(id);
                obj.setName(name);
                obj.setSalary(salary);
                // Timestamp -> LocalDateTime
                obj.setCreatedDate(createdDate.toLocalDateTime());

                result.add(obj);

            }
            result.forEach(x -> System.out.println(x));

        } catch (SQLException e) {
            System.err.format("SQL State: %s\n%s", e.getSQLState(), e.getMessage());
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

package com.mkyong.jdbc.model;

import java.math.BigDecimal;
import java.time.LocalDateTime;

public class Employee {

    private Long id;
    private String name;
    private BigDecimal salary;
    private LocalDateTime createdDate;

    //...
}

CREATE TABLE EMPLOYEE
(
    ID serial,
    NAME varchar(100) NOT NULL,
    SALARY numeric(15, 2) NOT NULL,
    CREATED_DATE timestamp with time zone NOT NULL DEFAULT CURRENT_TIMESTAMP
    PRIMARY KEY (ID)
);