DBUtils的定义

1. 导入3个jar包
   
2. 代码实现

public class DBUtils {//1.配置数据库连接信息（MySQL）//数据库驱动private static final String DRIVER = "com.mysql.jdbc.Driver";//数据库名private static final String DATABASE = "test_db" ;//数据库用户名private static final String USER = "root";//数据库密码private static final String PWD = "root";//数据库URLprivate static final String URL = "jdbc:mysql://127.0.0.1:3306/"+DATABASE+"?useUnicode=true&characterEncoding=UTF-8";//使用QueryRunner类private static QueryRunner runner ;//2.连接池，获取DataSource对象static{DruidDataSource ds = new DruidDataSource();ds.setUrl(URL);ds.setUsername(USER);ds.setPassword(PWD);ds.setDriverClassName(DRIVER);runner = new QueryRunner(ds);}//3.使用QueryRunner类中的方法操作数据库//3.1修改数据public static int udpate(String sql ,Object... param ){try {return runner.update(sql, param);} catch (SQLException e) {e.printStackTrace();}return 0 ;}//3.2将查询结果的第一行数据，封装到Bean对象public static<T> T queryOneToBean(String sql, Class<T> clazz,Object... param  ){try {BasicRowProcessor brp = new BasicRowProcessor(new GenerousBeanProcessor());return runner.query(sql, new BeanHandler<T>(clazz,brp),param);} catch (SQLException e) {e.printStackTrace();}return null;}//3.3将查询结果的第一行数据封装到map集合public static Map<String,Object> queryOneToMap(String sql, Object... param  ){try {return  runner.query(sql,new MapHandler(),param);} catch (SQLException e) {e.printStackTrace();}return null;}//3.4将查询结果的每一行封装到Bean对象，然后再存入List集合public static<T> List<T> queryAllList(String sql, Class<T> clazz,Object... param ){try {BasicRowProcessor brp = new BasicRowProcessor(new GenerousBeanProcessor());return runner.query(sql, new BeanListHandler<T>(clazz,brp),param);} catch (SQLException e) {e.printStackTrace();}return null;}//3.5将查询结果的每一行封装到map集合（key=列名，value=列值），再将map集合存入List集合public static List<Map<String,Object>> queryAllMap(String sql, Object... param ){try {return runner.query(sql,new MapListHandler(),param );} catch (SQLException e) {e.printStackTrace();}return null;}
}

DBUtils的使用

    public boolean userLogin(User user) {String sql = "select * from user where name=? and pwd=?";User user = DBUtils.queryOneToBean(sql, User.class, user.getUserName(), user.getUserPwd());return user;}public boolean selectUser(String name) {String sql = "select * from user where name=?";User user = DBUtils.queryOneToBean(sql, User.class, name);return user;}