MyBatis使用注解开发和无主配置文件开发的情况

MyBatis使用注解开发时就不在需要和接口对应的映射文件了

主要有以下几个注解

@Select() @Insert @Update() @Delete()

代码演示

项目结构：

数据库表设计

实体类

User

public class User implements Serializable {   private long userId ; private String userName ; private Date birthday ; private String sex ; private String address ;   getter setter toString

主配置文件mybatis-config.xml

<? xml version = "1.0" encoding = "UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">   <configuration> <properties resource = "db.properties" />   <!--开启驼峰命名--> <settings> <setting name = "mapUnderscoreToCamelCase" value = "true" /> </settings>   <!--起别名 typeAliases--> <typeAliases> <package name = "com.codeyancy.cn.entity" /> </typeAliases>   <environments default = "development" > <environment id = "development" > <transactionManager type = "JDBC" /> <dataSource type = "POOLED" > <property name = "driver" value = "${jdbc.driverClassName}" /> <property name = "url" value = "${jdbc.url}" /> <property name = "username" value = "${jdbc.username}" /> <property name = "password" value = "${jdbc.password}" /> </dataSource> </environment> </environments>   <mappers> <!--包扫描--> <package name = "com.codeyancy.cn.mapper" /> </mappers> </configuration>

db.properties

jdbc . driverClassName = com . mysql . jdbc . Driver jdbc . url = jdbc : mysql : //localhost:3306/web_test?characterEncoding=utf-8 jdbc . username = root jdbc . password = 666

mapper接口

public interface UserMapper {   /** * 查询所有用户信息 */ @Select ( "select * from user" ) List < User > findAll ();   /** * 根据id查询用户信息 */ @Select ( "select * from user where user_id=#{userId}" ) User findById ( Integer id );   /** * 新增 */ @Insert ( "insert into user (user_name,birthday,sex,address) values (#{userName},#{birthday},#{sex},#{address})" ) void insertUser ( User user );   /** * 修改 */ @Update ( "update user set user_name=#{userName},birthday=#{birthday},sex=#{sex},address=#{address} where user_id=#{userId}" ) void updateUser ( User user );   /** * 删除 */ @Delete ( "delete from user where user_id=#{userId}" ) void deleteUserById ( Integer id );   /** * 通过id或者名字模糊查询 * 多个参数查询方式二：@Param */ @Select ( "select * from user where user_id=#{id} or user_name like '%${name}%'" ) List < User > select ( @Param ( "id" ) Integer id , @Param ( "name" ) String name ); }

测试类
Demo

public class Demo {   public static void main ( String [] args ) { String path = "mybatis-config.xml" ; InputStream resourceAsStream = null ; try { resourceAsStream = Resources . getResourceAsStream ( path ); } catch ( IOException e ) { e . printStackTrace (); } SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder (). build ( resourceAsStream ); SqlSession sqlSession = sqlSessionFactory . openSession ( true ); UserMapper mapper = sqlSession . getMapper ( UserMapper . class );   //System.out.println(mapper.findAll()); //System.out.println(mapper.findById(1));   /*User user = new User(); user.setUserName("老皮"); user.setBirthday(new Date()); mapper.insertUser(user);*/   /*User user = new User(); user.setUserName("李立林"); user.setBirthday(new Date()); user.setUserId(27); mapper.updateUser(user);*/   //mapper.deleteUserById(27);   System . out . println ( mapper . select ( 1 , "麻" ));   sqlSession . close (); try { resourceAsStream . close (); } catch ( IOException e ) { e . printStackTrace (); } } }

使用注解开发的一些问题

如果数据库字段名和实体类的属性名不一致，也不遵循驼峰命名。这种情况下，如果是使用映射文件可以用resultMap来解决。

但是注解开发也是可以解决的：

* 如果数据库列名和实体类属性名不一致或者没有开启驼峰命名，可以使用 @Results 解决这个问题 * * @Select ( "sql语句" ) * @Results ({ * @Result ( column = "" , property = "" ), * @Result ( column = "" , property = "" ), * @Result ( column = "" , property = "" ), * }) * * 使用注解也可以一对一，一对多 * @Result ( column = "" , property = "" , one = @One ( "sql语句" )), 一对一 * @Result ( column = "" , property = "" , one = @Many ( "sql语句" )), 一对多

在mybatis的使用中，主配置文件mybatis-config.xml 是十分重要的，那么能不能不使用主配置文件进行mybatis开发呢？

可以！！！

在官网中清楚的指出了可以使用java代码来代替xml主配置文件----》如下

尝试使用java类来代替主配置文件

MyBatisDemo

/** *使用java类代替mybatis-config.xml主配置文件 */ public class MyBatisDemo { public static void main ( String [] args ) { //加载db.properties文件方式一 // InputStream resourceAsStream = MyBatisDemo.class.getClassLoader().getResourceAsStream("db.properties"); // Properties properties = new Properties(); // try { // properties.load(resourceAsStream); // } catch (IOException e) { // e.printStackTrace(); // } // String drive = properties.getProperty("jdbc.driverClassName"); // String url = properties.getProperty("jdbc.url"); // String name = properties.getProperty("jdbc.username"); // String pass = properties.getProperty("jdbc.password"); // DataSource dataSource = new PooledDataSource(drive,url,name,pass);   //加载db.properties文件方式二(推荐) ResourceBundle bundle = ResourceBundle . getBundle ( "db" ); String drive = bundle . getString ( "jdbc.driverClassName" ); String url = bundle . getString ( "jdbc.url" ); String name = bundle . getString ( "jdbc.username" ); String pass = bundle . getString ( "jdbc.password" );   DataSource dataSource = new PooledDataSource ( drive , url , name , pass ); TransactionFactory transactionFactory = new JdbcTransactionFactory (); Environment environment = new Environment ( "development" , transactionFactory , dataSource ); Configuration configuration = new Configuration ( environment ); //开启包扫描 configuration . addMappers ( "com.codeyancy.cn.mapper" ); //开启驼峰命名 configuration . setMapUnderscoreToCamelCase ( true ); //设置别名 //configuration.getTypeAliasRegistry().registerAliases("com.codeyancy.cn.entity"); SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder (). build ( configuration ); SqlSession sqlSession = sqlSessionFactory . openSession ( true ); UserMapper mapper = sqlSession . getMapper ( UserMapper . class );   //打印查询所有 System . out . println ( mapper . findAll ());   sqlSession . close (); } }

简单测试后，是可以使用的。

到此这篇关于MyBatis使用注解开发和无主配置文件开发的情况的文章就介绍到这了,更多相关MyBatis注解开发无主配置文件内容请搜索以前的文章或继续浏览下面的相关文章希望大家以后多多支持！

原文链接：https://blog.csdn.net/qq_45503643/article/details/114763577

查看更多关于MyBatis使用注解开发和无主配置文件开发的情况的详细内容...