Spring框架纯注解开发

编写三个测试类

package com.itheima.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.PropertySource;

/**
 * @Configuration
 * 表示该类是一个Spring的配置类，用来存放spring的配置信息
 * @ComponentScan
 * 用于指定 Spring 在初始化容器时要扫描的包,相当于xml配置时的<context:component-scan base-package="com.itheima"/>
 * @PropertySource
 * 用于加载配置文件,相当于xml配置时的<context:property-placeholder location="classpath:jdbc.properties"/>
 * @Import
 * 用于导入其他的配置类,相当于xml配置时的<import resource="classpath:applicationContext-dao.xml"/>
 */
@Configuration
@ComponentScan("com.itheima")
@PropertySource("classpath:jdbc.properties")    //
@Import({JDBCConfig.class, MybatisConfig.class})    //用于导入其他配置类
public class SpringConfig {
}

package com.itheima.config;

import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;

import javax.sql.DataSource;

public class MybatisConfig {

    @Bean
    public SqlSessionFactoryBean getSqlSessionFactoryBean(@Autowired DataSource dataSource) {
        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
        sqlSessionFactoryBean.setDataSource(dataSource);
        sqlSessionFactoryBean.setTypeAliasesPackage("com.itheima.domain");
        return sqlSessionFactoryBean;
    }

    @Bean
    public MapperScannerConfigurer getMapperScannerConfigurer() {
        MapperScannerConfigurer mapperScannerConfigurer = new MapperScannerConfigurer();
        mapperScannerConfigurer.setBasePackage("com.itheima.dao");
        return mapperScannerConfigurer;
    }
}

package com.itheima.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;

import javax.sql.DataSource;

public class JDBCConfig {

    @Value("${jdbc.driver}")
    private String driver;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String username;
    @Value("${jdbc.password}")
    private String password;

    @Bean("dataSource")
    public DataSource getDataSource(){
        DruidDataSource dataSource = new DruidDataSource();
        dataSource.setDriverClassName(driver);
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }
}

数据访问层接口

package com.itheima.dao;

import com.itheima.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import java.util.List;

public interface UserDao {

    @Insert("INSERT INTO user VALUES (#{id},#{user_id},#{username},#{age},#{sex},#{phone});")
    int save(User user);

    @Update("UPDATE user SET username=#{username}, age=#{age}, sex=#{sex}, phone=#{phone} WHERE user_id=#{user_id}")
    int update(User user);

    @Delete("DELETE FROM user WHERE user_id=#{user_id}")
    int delete(String user_id);

    @Select("SELECT * FROM user WHERE user_id = #{user_id}")
    User findById(String user_id);

    @Select("SELECT * FROM user")
    List<User> findAll();
}

业务逻辑层接口及实现类

package com.itheima.service;

import com.itheima.domain.User;

import java.util.List;

public interface UserService {

    int save(User user);

    int update(User user);

    int delete(String user_id);

    User findById(String user_id);

    List<User> findAll();
}

//==========实现类分割线==================

package com.itheima.service.impl;

import com.itheima.dao.UserDao;
import com.itheima.domain.User;
import com.itheima.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.List;

@Component("userService")
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    @Override
    public int save(User user) {
        return userDao.save(user);
    }

    @Override
    public int update(User user) {
        return userDao.update(user);
    }

    @Override
    public int delete(String user_id) {
        return userDao.delete(user_id);
    }

    @Override
    public User findById(String user_id) {
        return userDao.findById(user_id);
    }

    @Override
    public List<User> findAll() {
        return userDao.findAll();
    }
}

编写测试类有两种办法：
一：
需要导入包

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
</dependency>

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-test</artifactId>
    <version>5.1.9.RELEASE</version>
</dependency>

package com.itheima;

import com.itheima.config.SpringConfig;
import com.itheima.domain.User;
import com.itheima.service.UserService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpringConfig.class)
public class App {

    @Autowired
    private UserService userService;

    @Test
    public void test(){
        User user = userService.findById("1001");
        System.out.println(user);
    }
}

二：
原始方法

package com.itheima;

import com.itheima.config.SpringConfig;
import com.itheima.domain.User;
import com.itheima.service.UserService;
import com.itheima.service.impl.UserServiceImpl;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class App {

    @Test
    public void test(){
        ApplicationContext applicationContext = new AnnotationConfigApplicationContext(SpringConfig.class);
        UserService userService = (UserService) applicationContext.getBean(UserServiceImpl.class);
        User user = userService.findById("1001");
        System.out.println(user);
    }
}