package jdbc;import java.io.InputStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import java.sql.Statement;import java.util.Properties;public class JdbcUtils { private static String url; private static String user; private static String password; static { try { //FileInputStream in = new FileInputStream(new File("./src/db.properties")); InputStream in = JdbcUtils.class.getResourceAsStream("/db.properties"); Properties properties = new Properties(); properties.load(in); Class.forName(properties.getProperty("driver")); url = properties.getProperty("url"); user = properties.getProperty("user"); password = properties.getProperty("password"); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } } /** * 获取连接 * @return */ public static Connection getConnection() { try { return DriverManager.getConnection(url, user, password); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } } /** * 关闭连接 */ public static void close(Statement stateMent, Connection connection) { if (stateMent != null) { try { stateMent.close(); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } } if (connection != null) { try { connection.close(); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } } } }

package jdbc.statement;import java.sql.Connection;import java.sql.ResultSet;import java.sql.Statement;import jdbc.JdbcUtils;import org.junit.Test;public class StateMentTest { @Test public void testInsert() { Connection conn = null; Statement stmt = null; try { conn = JdbcUtils.getConnection(); stmt = conn.createStatement(); String sql = "insert into test (name) values (‘test‘)"; int count = stmt.executeUpdate(sql); System.out.println(count); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } finally { JdbcUtils.close(stmt, conn); } } @Test public void testUpdate() { Connection conn = null; Statement stmt = null; try { conn = JdbcUtils.getConnection(); stmt = conn.createStatement(); String sql = "update test set name = ‘update‘ where id=4"; int count = stmt.executeUpdate(sql); System.out.println(count); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } finally { JdbcUtils.close(stmt, conn); } } @Test public void testDelete() { Connection conn = null; Statement stmt = null; try { conn = JdbcUtils.getConnection(); stmt = conn.createStatement(); String sql = "delete from test where id=4"; int count = stmt.executeUpdate(sql); System.out.println(count); } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } finally { JdbcUtils.close(stmt, conn); } } @Test public void testSelect() { Connection conn = null; Statement stmt = null; try { conn = JdbcUtils.getConnection(); stmt = conn.createStatement(); String sql = "select * from test"; ResultSet resultSet = stmt.executeQuery(sql); while(resultSet.next()) { System.out.println(resultSet.getString("name")); } } catch (Exception e) { e.printStackTrace(); throw new RuntimeException(e); } finally { JdbcUtils.close(stmt, conn); } }}

package jdbc.prepared;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import jdbc.JdbcUtils;import org.junit.Test;public class PreparedStateMent { @Test public void testInsert() { Connection conn = JdbcUtils.getConnection(); String sql = "insert into test (name) values (?)"; PreparedStatement pstmt = null; try { pstmt = conn.prepareStatement(sql, PreparedStatement.RETURN_GENERATED_KEYS); pstmt.setString(1, "prepared"); int count = pstmt.executeUpdate(); ResultSet resultSet = pstmt.getGeneratedKeys(); if (resultSet.next()) { System.out.println(resultSet.getString(1)); } System.out.println(count); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } finally{ JdbcUtils.close(pstmt, conn); } } @Test public void testUpdate() { Connection conn = JdbcUtils.getConnection(); String sql = "update test set name = ? where id = ?"; PreparedStatement pstmt = null; try { pstmt = conn.prepareStatement(sql); pstmt.setString(1, "prepareds"); pstmt.setInt(2, 6); int count = pstmt.executeUpdate(); System.out.println(count); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } finally{ JdbcUtils.close(pstmt, conn); } } @Test public void testDelete() { Connection conn = JdbcUtils.getConnection(); String sql = "delete from test where id = ?"; PreparedStatement pstmt = null; try { pstmt = conn.prepareStatement(sql); pstmt.setInt(1, 6); int count = pstmt.executeUpdate(); System.out.println(count); } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } finally{ JdbcUtils.close(pstmt, conn); } } @Test public void testSelect() { Connection conn = JdbcUtils.getConnection(); String sql = "select * from test"; PreparedStatement pstmt = null; try { pstmt = conn.prepareStatement(sql); ResultSet set = pstmt.executeQuery(); while(set.next()) { System.out.println(set.getString("name")); } } catch (SQLException e) { e.printStackTrace(); throw new RuntimeException(e); } finally{ JdbcUtils.close(pstmt, conn); } }}