Matrix42：今天做了一下午才做完 用到了JDBC和反射,虽然以前学过,但是没真正用过所以做的挺费劲 首先是表设计: id为用户id promo_code为优惠码 value为面值(可以是具体价值或折扣) condition为使用条件 expire_data为优惠码过期时间 思路:把优惠码信息封装成一个javaBean,然后读取和写入都用bean对象,字段和赋值都是用反射完成的 下面是代码: package nowcoder; import java.lang.reflect.Field; import java.lang.reflect.Method; 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.List; /** * 用来连接数据库,查询以及执行SQL语句 * @author Matrix42 * */ public class JDBCConnector { private Connection conn; private String JDBCUrl; private String driverUrl; public JDBCConnector(String JDBCUrl,String driverUrl,String username,String password) { this.JDBCUrl = JDBCUrl; this.driverUrl = driverUrl; conn = getConnection(JDBCUrl,driverUrl,username,password); } /** * 与数据库建立连接 * @param JDBCUrl * @param driverUrl * @param username * @param password * @return */ private Connection getConnection(String JDBCUrl,String driverUrl,String username,String password){ try { //加载驱动 Class.forName(JDBCUrl); } catch (ClassNotFoundException e) { System.out.println("驱动加载失败!"); e.printStackTrace(); } Connection connection = null; try { //建立连接 connection = DriverManager.getConnection(driverUrl,username,password); } catch (SQLException e) { System.out.println("建立连接失败!"); e.printStackTrace(); } return connection; } /** * 插入一条数据 * @param object * @param table * @return */ public int insert(Object object,String table){ int rows = 0; String sql = "insert into "+table + " values" +getValue(object); System.out.println(sql); PreparedStatement statement = null; try { statement = conn.prepareStatement(sql); } catch (SQLException e) { e.printStackTrace(); } try { rows = statement.executeUpdate(); } catch (SQLException e) { e.printStackTrace(); } return rows; } /** * 所有结果封装到List里 * @param primaryKey * @param table * @return */ public List queryAll(Class<?> clazz,String table){ List<Object> resultList = new ArrayList<Object>(); PreparedStatement statement = null; String sql = "select * from "+table; try { statement = conn.prepareStatement(sql); } catch (SQLException e) { e.printStackTrace(); } ResultSet resultSet = null; try { resultSet = statement.executeQuery(); } catch (SQLException e) { e.printStackTrace(); } ResultSetMetaData metaData = null; int colCount = 0; try { metaData = resultSet.getMetaData(); colCount = metaData.getColumnCount(); } catch (SQLException e1) { e1.printStackTrace(); } //获取字段的个数 Field[] fields = clazz.getDeclaredFields(); try{ while (resultSet.next()) { //构造实例 Object object = clazz.newInstance(); for(int i=1;i<=colCount;i++){ //获取单个结果 Object value = resultSet.getObject(i); //遍历字段,如果相同则赋值 for(int j=0;j<fields.length;j++){ Field f = fields[j]; if(f.getName().equalsIgnoreCase(metaData.getColumnName(i))){ f.setAccessible(true); f.set(object, value); } } } //存入list resultList.add(object); } }catch(Exception e){ e.printStackTrace(); } return resultList; } /** * 获取列 * @param object * @return */ public static String getColomns(Object object){ String colomns = "("; Class<?> clazz = object.getClass(); Field[] fields = clazz.getDeclaredFields(); for(int i=0;i<fields.length;i++){ if(i<fields.length-1){ colomns+=fields[i].getName()+","; }else { colomns+=fields[i].getName(); } } colomns+=") "; return colomns; } /** * 获取值 * @param object * @return */ public static String getValue(Object object){ String colomns = "("; Class<?> clazz = object.getClass(); Field[] fields = clazz.getDeclaredFields(); try { for(int i=0;i<fields.length;i++){ fields[i].setAccessible(true); if(i<fields.length-1){ colomns+="'"+fields[i].get(object)+"'"+","; }else { colomns+="'"+fields[i].get(object)+"'"; } } } catch (IllegalArgumentException | IllegalAccessException e) { e.printStackTrace(); } colomns+=")"; return colomns; } /** * 获取方法 * @param clazz * @return */ public static Method[] getSetFunc(Class<?> clazz){ Method[] methods = clazz.getDeclaredMethods(); for(int i=0;i<methods.length;i++){ methods[i].setAccessible(true); } return methods; } } javaBean package nowcoder; import java.sql.Timestamp; public class CodeBean { private int id; private String promo_code; private double value; private double condition; private Timestamp expire_data; public CodeBean() { super(); } public CodeBean(int id, String promo_code, double value, double condition, Timestamp expire_data) { super(); this.id = id; this.promo_code = promo_code; this.value = value; this.condition = condition; this.expire_data = expire_data; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getPromo_code() { return promo_code; } public void setPromo_code(String promo_code) { this.promo_code = promo_code; } public double getValue() { return value; } public void setValue(double value) { this.value = value; } public double getCondition() { return condition; } public void setCondition(double condition) { this.condition = condition; } public Timestamp getExpire_data() { return expire_data; } public void setExpire_data(Timestamp expire_data) { this.expire_data = expire_data; } @Override public String toString() { return "CodeBean [id=" + id + ", promo_code=" + promo_code + ", value=" + value + ", condition=" + condition + ", expire_data=" + expire_data + "]"; } } package nowcoder; import java.sql.Timestamp; public class Client { public static void main(String[] args) { JDBCConnector connector = new JDBCConnector("com.mysql.jdbc.Driver", "jdbc:mysql://localhost:3306/nowcoder","root","123456"); //插入操作 CodeBean bean = new CodeBean(); bean.setCondition(12); bean.setExpire_data(new Timestamp(System.currentTimeMillis())); bean.setId(4); bean.setPromo_code("121"); bean.setValue(2333); connector.insert(bean, "code"); //查询所有数据 for (Object object : connector.queryAll(CodeBean.class, "code")) { System.out.println(object); } } } 下面是输出结果,就几条数据查看图片

牛妹：东北-----锅包肉

牛客4859027号：牛妹

牛妹前男友：我读书少，你别骗我-------李小龙

牛妹前男友：这代码也注释？ 轮到看别人代码的时候，这没有注释的代码怎么看？！

牛油：同样详细的一个校招总结帖子:非CS水硕的2016研发岗位校招总结 = = 互联网求职失败的经验教训

无务：我举报你

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我不懂了：自己在北京的房子，自己装饰的很有爱，不舍的删查看图片

恭喜您又涨工资了：2017上半年要找到好实习，下半年要签好工作，加油

向宇同桌：少看片，多玩球