Main代码：
package com.zzu.client; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Scanner; import com.zzu.tool.db.DBLink; import com.zzu.tool.db.IRowMapper; public class Main { public static void main(String[] args) { System.out.println("*********************************"); System.out.println("*\t\t\t\t*"); System.out.println("*\t欢迎使用学生信息管理系统\t*"); System.out.println("*\t\t\t\t*"); System.out.println("*********************************"); while (true) { menu(); } } static void menu() { System.out.println("1、添加学生信息"); System.out.println("2、删除学生信息");// 学号 System.out.println("3、修改学生信息");// 地址传递 System.out.println("4、查询学生信息");// name System.out.println("请输入操作，以Enter键结束:"); Scanner scanner = new Scanner(System.in); int option = scanner.nextInt(); DBLink db = new DBLink(); switch (option) { case 1:{ System.out.println("请输入学号"); String id =scanner.next(); String sql = "select id from user_info1 where id = ?"; if(db.exist(sql, id)) { System.out.println("该学号已存在,操作中止！"); return; } System.out.println("请输入姓名"); String name = scanner.next(); System.out.println("请输入电话号码"); String mobile = scanner.next(); System.out.println("请输入家庭住址"); String address = scanner.next(); sql = "insert into user_info1 (id,name,mobile,address) value (?,?,?,?)"; if(db.update(sql, id,name,mobile,address)) { System.out.println("添加学生信息成功"); return; } break; } case 2:{ System.out.println("请输入学号"); String id =scanner.next(); String sql = "select id from user_info1 where id = ?"; if(!db.exist(sql, id)) { System.out.println("该学号不存在，操作中止"); return; } sql = "delete from user_info1 where id = ?"; if(db.update(sql, id)) { System.out.println("删除成功"); return; } System.out.println("删除失败"); break; } case 3:{ System.out.println("请输入学号"); String id =scanner.next(); String sql = "select id from user_info1 where id = ?"; if(!db.exist(sql, id)) { System.out.println("该学号不存在，操作中止"); return; } System.out.println("请输入性名"); String name = scanner.next(); System.out.println("请输入电话号码"); String mobile = scanner.next(); System.out.println("请输入家庭住址"); String address = scanner.next(); sql = "update user_info1 set name = ?,mobile = ?,address = ? where id = ?"; if(db.update(sql, name,mobile,address,id)) { System.out.println("修改成功"); return; } } break; case 4:{ System.out.println("请输入学号"); String id =scanner.next(); String sql = "select id,name,mobile,address from user_info1 where id = ?"; /*class RowMapper implements IRowMapper{ public void rowMapper(ResultSet rs) { try { if(rs.next()) { String id = rs.getString("id"); String name = rs.getString("name"); String mobile = rs.getString("mobile"); String address = rs.getString("address"); System.out.println("id:"+id+","+"name:" +name+","+"mobile" +mobile+","+"address"+address+"."); } System.out.println("没有找到信息"); } catch (SQLException e) { e.printStackTrace(); } } };*/ /* IRowMapper rowMapper = (rs)->{ try { if(rs.next()) { String name = rs.getString("name"); String mobile = rs.getString("mobile"); String address = rs.getString("address"); System.out.println("id:"+id+","+"name:" +name+","+"mobile" +mobile+","+"address"+address+"."); } System.out.println("没有找到信息"); } catch (SQLException e) { e.printStackTrace(); } }; db.select(sql, rowMapper, id);*/ db.select(sql,(rs)->{//逐步简化 try { if(rs.next()) { String name = rs.getString("name"); String mobile = rs.getString("mobile"); String address = rs.getString("address"); System.out.println("id:"+id+","+"name:" +name+","+"mobile" +mobile+","+"address"+address+"."); } System.out.println("没有找到信息"); } catch (SQLException e) { e.printStackTrace(); } } , id); break; } default: System.out.println("I'm Sorry,there is not the " + option + " option,please try again."); } } }PrepertiesTool 代码：
package com.zzu.tool; import java.io.IOException; import java.io.InputStream; import java.util.Properties; public class PropertiesTool { private static Properties properties = new Properties(); static { InputStream inputStream = PropertiesTool.class.getClassLoader().getResourceAsStream("db.properties");//将db.properties变为javaIO流对象 try { properties.load(inputStream); } catch (IOException e) { e.printStackTrace(); } } public static String getValue(String key) { return properties.getProperty(key); } }DBLink代码：
package com.zzu.tool.db; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; import org.apache.log4j.Logger; import com.zzu.tool.PropertiesTool; /** * 数据库管理工具类 * * @author GaoHuanjie */ public class DBLink { private Logger logger = Logger.getLogger(DBLink.class); /** * 获取数据库连接 * * @author GaoHuanjie */ private Connection getConnection() { try { Class.forName("com.mysql.jdbc.Driver");//加载驱动 String userName = PropertiesTool.getValue("db.username"); String password = PropertiesTool.getValue("db.password"); String url = PropertiesTool.getValue("db.url"); return DriverManager.getConnection(url, userName, password);//获取连接 } catch (Exception e) { logger.debug(e.getMessage(), e); } return null; } /** * 判断SQL语句是否能查出数据 * * @author GaoHuanjie */ public boolean exist(String sql) { Connection connection = null; Statement statement =null; ResultSet resultSet=null; try { connection = getConnection();//获取连接 statement = connection.createStatement(); resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中 return resultSet.next(); } catch (Exception e) { logger.debug(e.getMessage(), e); }finally { close(resultSet,statement,connection); } return false; } /** * 判断SQL语句是否能查出数据 * * @author GaoHuanjie */ public boolean exist(String sql, Object ...params) { Connection connection = null; PreparedStatement preparedStatement =null; ResultSet resultSet=null; try { connection = getConnection();//获取连接 preparedStatement = connection.prepareStatement(sql); for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i+1, params[i]); } resultSet= preparedStatement.executeQuery();//执行sql,将查询的数据存到ResultSet类型的变量中 return resultSet.next(); } catch (Exception e) { logger.debug(e.getMessage(), e); }finally { close(resultSet,preparedStatement,connection); } return false; } /** * 查询数据 * * @author GaoHuanjie */ public void select(String sql,IRowMapper rowMapper) {//接口无法创建对象，所以rowMapper参数一定指向IRowMapper接口实现类对象 Connection connection = null; Statement statement =null; ResultSet resultSet=null; try { connection = getConnection();//获取连接 statement = connection.createStatement(); resultSet= statement.executeQuery(sql);//执行sql,将查询的数据存到ResultSet类型的变量中 rowMapper.rowMapper(resultSet);//因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法 多态 } catch (Exception e) { logger.debug(e.getMessage(), e); }finally {//释放资源 close(resultSet,statement,connection); } } /** * 查询数据 * * @author GaoHuanjie */ public void select(String sql,IRowMapper rowMapper,Object ...params) { Connection connection = null; PreparedStatement preparedStatement =null; ResultSet resultSet=null; try { connection = getConnection();//获取连接 preparedStatement= connection.prepareStatement(sql);//含有？号占位符的sql for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i+1, params[i]);//为？号赋值 } resultSet= preparedStatement.executeQuery();//执行sql rowMapper.rowMapper(resultSet);//因为rowMapper参数指向IRowMapper接口实现类对象，所以此处将调用接口实现类中所实现的rowMapper方法 多态 } catch (Exception e) { logger.debug(e.getMessage(), e); }finally {//释放资源 close(resultSet,preparedStatement,connection); } } /** * 修改（insert、update和delete）数据 * * @author GaoHuanjie */ public boolean update(String sql) { Connection connection = null; Statement statement = null; try { connection = getConnection();//获取数据库连接对象，一个对象表示一次数据库连接 statement = connection.createStatement();//获取Statement对象 int result = statement.executeUpdate(sql);//执行sql语句，返回受影响的行数，仅限于数据insert、update和delete return result>0;//处理结果 } catch (Exception e) { logger.debug(e.getMessage(), e); }finally {//即便有异常也会执行代码 close(statement,connection); } return false; } /** * 修改（insert、update和delete）数据 * * @author GaoHuanjie */ public boolean update(String sql,Object ...params) { Connection connection= null; PreparedStatement preparedStatement= null; try { connection= getConnection(); preparedStatement= connection.prepareStatement(sql);//含有？号占位符的sql for (int i = 0; i < params.length; i++) { preparedStatement.setObject(i+1, params[i]);//为？号赋值 } return preparedStatement.executeUpdate()>0; } catch (Exception e) { logger.debug(e.getMessage(), e); }finally { close(preparedStatement,connection); } return false; } /** * 释放资源 * * @author GaoHuanjie */ private void close(Statement statement,Connection connection) { try { if(statement!=null) {//有可能由于异常导致statement没有赋值，比如url出错 statement.close(); } } catch (SQLException e) { logger.debug(e.getMessage(), e); } try { if(connection!=null) { connection.close(); } } catch (SQLException e) { logger.debug(e.getMessage(), e); } } /** * 释放资源 * * @author GaoHuanjie */ private void close(ResultSet resultSet,Statement statement,Connection connection) {//重载 try { if(resultSet!=null) { resultSet.close(); } } catch (SQLException e) { logger.debug(e.getMessage(), e); } close(statement,connection); } }IRowMapper :
package com.zzu.tool.db; import java.sql.ResultSet; public interface IRowMapper { void rowMapper(ResultSet rs); }
