新的Java访问mysql数据库工具类的操作代码新的Java访问mysql数据库工具类

【新的Java访问mysql数据库工具类的操作代码】这是之前软工课设我写的java访问mysql工具类，它经过了多轮的测试，应该能够适应大多数的操作需求。比之前大二写的更鲁棒，更易用。

package util; import java.lang.reflect.Field; import java.sql.*; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import javax.swing.JOptionPane; public class JdbcUtilV2 {/*** 定义需要的变量*/private static Connection connection = null; /*** 在大多情况下，我们使用的是PrepardStatement 来代替Statement* 这样可以防止sql注入*/private static PreparedStatement preparedStatement = null; private static ResultSet resultSet = null; /*** 连接数据库参数*/private static String username = ""; private static String password = ""; private static String driver = ""; private static String url = ""; /*** 加载驱动，只需一次*/public JdbcUtilV2(String dr, String ur,String user, String passwd) {try {username = user; password = passwd; driver = dr; url = ur; Class.forName(driver); } catch (Exception e) {System.err.println("连接失败，请检查连接参数"); e.printStackTrace(); }}/*** 获取数据库连接** @return 返回Connection*/private static Connection getConnection() {try {connection = DriverManager.getConnection(url, username, password); } catch (Exception e) {JOptionPane.showConfirmDialog(null , "获取连接失败,请检查网络是否连通", "系统消息", JOptionPane.CLOSED_OPTION); e.printStackTrace(); }return connection; }/***查询表*@return 返回查询结果的List*/public ArrayList query(String sql, Object ...params){try {connection = getConnection(); preparedStatement = connection.prepareStatement(sql); setPreparedStatement(params); resultSet = preparedStatement.executeQuery(); ResultSetMetaData metaData = https://www.it610.com/article/resultSet.getMetaData(); // key nameint columnCount = metaData.getColumnCount(); // column countArrayList list = new ArrayList(); while(resultSet.next()) {HashMap rowData = new HashMap(); for(int i = 1; i <= columnCount; ++i) {rowData.put(metaData.getColumnName(i), resultSet.getObject(i)); }list.add(rowData); }return list; }catch (Exception e){System.err.println("查询失败！"); e.printStackTrace(); } finally {close(); }return null; }public boolean exists(String sql, Object ...params) {try {connection = getConnection(); preparedStatement = connection.prepareStatement(sql); setPreparedStatement(params); resultSet = preparedStatement.executeQuery(); return resultSet.next(); }catch (Exception e){System.err.println("查询失败！"); e.printStackTrace(); } finally {close(); }return false; }/*** 可处理insert/delete/update语句* @param sql sql语句* @param params 占位符参数数组* @return 返回bool值，表示是否成功*/public boolean execute(String sql, Object ...params){try {//获取连接connection = getConnection(); preparedStatement = connection.prepareStatement(sql); //对占位符进行赋值setPreparedStatement(params); //提交sqlpreparedStatement.executeUpdate(); return true; } catch (Exception e){System.err.println("表更新失败!"); e.printStackTrace(); } finally {close(); }return false; }public void executeVoidProc(String sql, Object ...params){try {//获取连接connection = getConnection(); preparedStatement = connection.prepareStatement(sql); //对sql中的占位符进行赋值setPreparedStatement(params); preparedStatement.execute(); }catch (Exception e){System.err.println("查询失败！"); e.printStackTrace(); } finally {close(); }}/*** 对sql语句中的占位符进行赋值* @param params 参数值* @throws SQLException sql异常*/private void setPreparedStatement(Object ... params) throws SQLException {if(params != null && params.length > 0){for(int i = 0; i < params.length; i++){if("null".equals(params[i])){preparedStatement.setNull(i + 1, Types.NULL); }else{preparedStatement.setObject(i + 1, params[i]); }}}} /*** 关闭资源的函数*/private void close() {if(resultSet != null) {try {resultSet.close(); } catch (Exception e) {e.printStackTrace(); }resultSet = null; }if(preparedStatement != null) {try {preparedStatement.close(); } catch (Exception e) {e.printStackTrace(); }preparedStatement = null; }if(connection != null) {try {connection.close(); } catch (Exception e) {e.printStackTrace(); }connection = null; }}}

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