四大门户网站是哪些,单位网站建设目的,北京网站设计公司hlh成都柚米科技15,成功网站运营案例1.MyBatis的CRUD 创建工程#xff1a; 1.1.查询 1.1.1.单个参数绑定 //单个参数传递public User findUserById(Integer id);!--parameterType:指定输入参数的类型resultType#xff1a;指定数据结果封装的数据类型#{id}#xff1a;它代表占位符#xff0c;相当于原来…1.MyBatis的CRUD 创建工程 1.1.查询 1.1.1.单个参数绑定 //单个参数传递public User findUserById(Integer id);!--parameterType:指定输入参数的类型resultType指定数据结果封装的数据类型#{id}它代表占位符相当于原来 jdbc 部分所学的?都是用于替换实际的数据。--select idfindUserById parameterTypejava.lang.Integer resultTypecom.wt.pojo.User select * from user where id#{id}!--只有一个参数时#{任意书写}--/selectTestpublic void testFindUserById(){UserDao userDao sqlSession.getMapper(UserDao.class);User user userDao.findUserById(41);System.out.println(user);}1.1.2.序号参数绑定 //传递多个参数public User findUserByIdAndName(Integer id, String username);select idfindUserByIdAndName resultTypecom.wt.pojo.User SELECT * FROM userWHERE id #{arg0} AND username #{arg1} !--arg0 arg1 arg2 ...--/selectselect idfindUserByIdAndName resultTypecom.wt.pojo.User SELECT * FROM userWHERE id #{param1} AND username #{param2} !--param1 param2 param3 ...--/selectTestpublic void testFindUserByIdAndName(){UserDao userDao sqlSession.getMapper(UserDao.class);User user userDao.findUserByIdAndName(41,张三丰);System.out.println(user);}1.1.3.注解参数绑定(推荐) //传递多个参数public User findUserByIdAndName2(Param(id) Integer id,Param(username)String username);select idfindUserByIdAndName2 resultTypecom.wt.pojo.User SELECT * FROM userWHERE id #{id} AND username #{username}/selectTestpublic void testFindUserByIdAndName2(){UserDao userDao sqlSession.getMapper(UserDao.class);User user userDao.findUserByIdAndName2(41,张三丰);System.out.println(user);}1.1.4.对象参数绑定(推荐) //使用对象属性进行参数绑定public User findUserByUserInfo(User user);select idfindUserByUserInfo parameterTypecom.wt.pojo.User resultTypecom.wt.pojo.UserSELECT * FROM userWHERE id #{id} AND username #{username}!--参数为对象时#{属性名}--/selectTestpublic void testFindUserByName(){UserDao userDao sqlSession.getMapper(UserDao.class);User userInfo new User();userInfo.setId(41);userInfo.setUsername(张三丰);User user userDao.findUserByUserInfo(userInfo);System.out.println(user);}1.1.5.Map参数绑定 //使用Map进行参数绑定public User findUserByMap(MapString, Object map);select idfindUserByMap parameterMapjava.util.Map resultTypecom.wt.pojo.UserSELECT * FROM userWHERE id #{id} AND username #{username}/selectTestpublic void testFindUserByMap(){UserDao userDao sqlSession.getMapper(UserDao.class);MapString, Object map new HashMapString, Object();map.put(id,41);map.put(username,张三丰);User user userDao.findUserByMap(map);System.out.println(user);}1.1.6.模糊查询(推荐使用${}) //模糊查询public ListUser findUserByName(String username);select idfindUserByName parameterTypestring resultTypecom.wt.pojo.User!-- select * from user where username like concat(%,#{username},%) --select * from user where username like %${value}%!--${}括号中只能是value--/selectTestpublic void testFindUserByName(){UserDao userDao sqlSession.getMapper(UserDao.class);ListUser userList userDao.findUserByName(张);for (User user : userList) {System.out.println(user);}}1.1.7.sql注入 //sql注入public User login(User user);select idlogin parameterTypecom.wt.pojo.User resultTypecom.wt.pojo.Userselect * from user where username ${username} and password ${password}/selectTestpublic void testLogin(){UserDao userDao sqlSession.getMapper(UserDao.class);User userInfo new User();// #会使sql语句后面的内容被注释掉此时无论密码输入什么都会成功userInfo.setUsername(张三丰 #);userInfo.setPassword(123);User user userDao.login(userInfo);System.out.println(user);}#{} 和${}的区别 #{}符 #{}表示一个占位符号 通过#{}可以实现 preparedStatement 向占位符中设置值自动进行 java 类型和 jdbc 类型转换#{}可以接收简单类型值或 pojo 属性值。 如果 parameterType 传输单个简单类 型值#{}括号中可以是 value 或其它名称。#{}可以有效防止 sql 注入。 ${}符 表示拼接 s q l 串通过 {}表示拼接 sql 串 通过 表示拼接sql串通过{}可以将 parameterType 传入的内容拼接在 sql 中且不进行 jdbc 类型转换 可以接收简单类型值或 p o j o 属性值如果 p a r a m e t e r T y p e 传输单个简单类型值 {}可以接收简单类型值或 pojo 属性值如果 parameterType 传输单个简单类型值 可以接收简单类型值或pojo属性值如果parameterType传输单个简单类型值{}括号中只能是 value 1.1.8.聚合函数查询 //聚合函数查询 public Integer getTotal();!--聚合函数查询-- select idgetTotal resultTypeintSELECT COUNT(id) FROM user /selectTest public void testGetTotal(){Integer total userDao.getTotal();System.out.println(total); }1.2.删除 //删除public void deleteUserById(Integer id);delete iddeleteUserById parameterTypeIntegerDELETE FROM userWHERE id #{id}/deleteTestpublic void testDeleteUserById(){UserDao userDao sqlSession.getMapper(UserDao.class);userDao.deleteUserById(41);sqlSession.commit();}1.3.修改 //修改public void updateUserById(User user);update idupdateUserById parameterTypecom.wt.pojo.Userupdate user set username#{username},password#{password},birthday#{birthday},sex#{sex},address#{address} where id#{id}/updateTestpublic void testUpdateUserById(){UserDao userDao sqlSession.getMapper(UserDao.class);User user new User();user.setUsername(马德华);user.setPassword(111);user.setBirthday(new Date());user.setSex(男);user.setAddress(高老庄);user.setId(42);userDao.updateUserById(user);sqlSession.commit();}1.4.添加 //添加public void insertUser(User user);insert idinsertUser parameterTypecom.wt.pojo.User!--主键回填新增之后获取新增记录的id值keyPropertyid主键对应实体类的属性orderAFTER先执行插入语句之后再执行查询语句resultTypejava.lang.Integer主键的数据类型--selectKey keyPropertyid orderAFTER resultTypejava.lang.Integer/*查询出刚刚插入的记录自增长id*/select last_insert_id();/selectKeyinsert into user(username,password,birthday,sex,address)values(#{username},#{password},#{birthday},#{sex},#{address}); /insert或者 !--useGeneratedKeys“true”获取数据库生成的主键keyProperty“id”主键对应实体类的属性--insert idinsertUser useGeneratedKeystrue keyPropertyid parameterTypecom.wt.pojo.User!--主键回填新增之后获取新增记录的id值keyPropertyid主键对应实体类的属性orderAFTER先执行插入语句之后再执行查询语句resultTypejava.lang.Integer主键的数据类型selectKey keyPropertyid orderAFTER resultTypejava.lang.Integer/*查询出刚刚插入的记录自增长id*/select last_insert_id();/selectKey--insert into user(username,password,birthday,sex,address)values(#{username},#{password},#{birthday},#{sex},#{address})/insertTestpublic void testInsertUser(){UserDao userDao sqlSession.getMapper(UserDao.class);User user new User();user.setUsername(刘德华);user.setPassword(111);user.setBirthday(new Date());user.setSex(男);user.setAddress(香港);userDao.insertUser(user);System.out.println(新增记录的id值user.getId());sqlSession.commit();}