java（JDBC连接数据库）[对PreparedStatement进行封装]
package com.iflytec.ex01; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; public class ConnectionDB { /** * 数据库驱动类名称 */ private static final String DRIVER = "com.microsoft.sqlserver.jdbc.SQLServerDriver"; /** * 连接字符串 */ private static final String URLSTR = "jdbc:sqlserver://localhost:1433; databaseName=Northwind"; /** * 用户名 */ private static final String USERNAME = "sa"; /** * 密码 */ private static final String USERPASSWORD = "111111"; /** * 创建数据库连接类 */ private Connection connnection = null; private PreparedStatement preparedStatement = null; /** * 创建结果集对象 */ private ResultSet resultSet = null; static { try { // 加载数据库驱动程序 Class.forName(DRIVER); } catch (ClassNotFoundException e) { System.out.println("加载驱动错误"); System.out.println(e.getMessage()); } } /** * 建立数据库连接 * * @return */ public Connection getConnection() { try { // 获取连接 connnection = DriverManager.getConnection(URLSTR, USERNAME, USERPASSWORD); } catch (SQLException e) { System.out.println(e.getMessage()); } return connnection; } public int executeUpdate(String sql, Object[] params) { int affectedLine = 0; try { connnection = this.getConnection(); preparedStatement = connnection.prepareStatement(sql); for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i + 1, params[i]); } affectedLine = preparedStatement.executeUpdate(); } catch (SQLException e) { System.out.println(e.getMessage()); } finally { closeAll(); } return affectedLine; } private ResultSet executeQueryRS(String sql, Object[] params) { try { connnection = this.getConnection(); preparedStatement = connnection.prepareStatement(sql); for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i + 1, params[i]); } resultSet = preparedStatement.executeQuery(); } catch (SQLException e) { System.out.println(e.getMessage()); } return resultSet; } /** * 获取结果集，并将结果放在List中 * @param sql SQL语句 * @return List结果集 */ public List<Object> excuteQuery(String sql, Object[] params) { ResultSet rs = executeQueryRS(sql,params); ResultSetMetaData rsmd = null; int columnCount = 0; try { rsmd = rs.getMetaData(); columnCount = rsmd.getColumnCount(); } catch (SQLException e1) { System.out.println(e1.getMessage()); } List<Object> list = new ArrayList<Object>(); try { while(rs.next()) { Map<String, Object> map = new HashMap<String, Object>(); for(int i = 1; i <= columnCount; i++) { map.put(rsmd.getColumnLabel(i), rs.getObject(i)); } list.add(map); } } catch (SQLException e) { System.out.println(e.getMessage()); } finally { closeAll(); } return list; } private void closeAll() { if (resultSet != null) { try { resultSet.close(); } catch (SQLException e) { System.out.println(e.getMessage()); } } if (preparedStatement != null) { try { preparedStatement.close(); } catch (SQLException e) { System.out.println(e.getMessage()); } } if (connnection != null) { try { connnection.close(); } catch (SQLException e) { System