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Spring|基础|第一个spring项目

Spring

发布于：2024年3月25日

使用场景

hello Spring

结合上面的使用场景，设计一个查询用户的案例的两个需求，来看Spring框架帮我们简化了什么开发工作:

  1. 查询用户数据 - 来看DAO+POJO-> Service 的初始化和装载。
  2. 给所有Service的查询方法记录日志

  1. 创建maven项目

  2. 添加pom依赖

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    <properties>
            <maven.compiler.source>8</maven.compiler.source>
            <maven.compiler.target>8</maven.compiler.target>
            <spring.version>5.3.9</spring.version>
            <aspectjweaver.version>1.9.6</aspectjweaver.version>
        </properties>

        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-core</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-beans</artifactId>
                <version>${spring.version}</version>
            </dependency>
            <dependency>
                <groupId>org.aspectj</groupId>
                <artifactId>aspectjweaver</artifactId>
                <version>${aspectjweaver.version}</version>
            </dependency>
        </dependencies>

  3. 创建用户实例 - User

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    public class User {
        private String userName;
        private Integer age;

        public User() {
        }

        public User(String userName, Integer age) {
            this.userName = userName;
            this.age = age;
        }

        public String getUserName() {
            return userName;
        }

        public void setUserName(String userName) {
            this.userName = userName;
        }

        public Integer getAge() {
            return age;
        }

        public void setAge(Integer age) {
            this.age = age;
        }
    }

  4. 配置dao层

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    public class UserDaoImpl {
        public UserDaoImpl() {
        }

        /**
         *  forged a query instance of the findUserList method
         */
        public List<User> findUserList(){
            return Collections.singletonList(new User("wey",18));
        }
    }

  5. 配置daos.xml

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    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
     http://www.springframework.org/schema/beans/spring-beans.xsd">
        <bean id="userDao" class="x.dao.UserDaoImpl">
            <!-- additional collaborators and configuration for this bean go here -->
        </bean>
        <!-- more bean definitions for data access objects go here -->
    </beans>

  6. 配置服务层

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    public class UserServiceImpl {
        private UserDaoImpl userDao;

        public UserServiceImpl() {
        }

        // get the result of the forged a query instance of the findUserList method
        public List<User> findUserList(){
            return this.userDao.findUserList();
        }

        public void setUserDao(UserDaoImpl userDao){
            this.userDao = userDao;
        }
    }

  7. 配置services.xml

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    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
     http://www.springframework.org/schema/beans/spring-beans.xsd">
        <!-- services -->
        <bean id="userService" class="x.service.UserServiceImpl">
            <!-- ps:The ref attribute of the property may be marked red in IDEA,
                    but this does not affect the execution result  -->
            <property name="userDao" ref="userDao"/>
            <!-- additional collaborators and configuration for this bean go here -->
        </bean>
    <!--  ps:If you don't want to see this red mark, add the following line of code  -->
    <!--    <bean id="userDao" class="x.dao.UserDaoImpl"/>-->

        <!-- more bean definitions for services go here -->
    </beans>

  8. 配置aspect

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    @Aspect
    public class LogAspect {
        /**
         * set aspect to get the name of the service method being done
         * @param pjp
         * @return
         * @throws Throwable
         */
        @Around("execution(* x.service.*.*(..))")
        public Object businessService(ProceedingJoinPoint pjp) throws Throwable{
            Method method = ((MethodSignature) pjp.getSignature()).getMethod();
            System.out.println("execute method:"+method.getName());
            return pjp.proceed();
        }
    }

  9. 配置axpects.xml

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    <?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:aop="http://www.springframework.org/schema/aop"
           xmlns:context="http://www.springframework.org/schema/context"
           xsi:schemaLocation="http://www.springframework.org/schema/beans
     http://www.springframework.org/schema/beans/spring-beans.xsd
     http://www.springframework.org/schema/aop
     http://www.springframework.org/schema/aop/spring-aop.xsd
     http://www.springframework.org/schema/context
     http://www.springframework.org/schema/context/spring-context.xsd
    ">

        <context:component-scan base-package="x" />

        <aop:aspectj-autoproxy/>

        <bean id="logAspect" class="x.aspect.LogAspect">
            <!-- configure properties of x.aspect here as normal -->
        </bean>
        <!-- more bean definitions for data access objects go here -->
    </beans>

  10. 实现App

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    public class App {
        public static void main(String[] args) {
            // create and configure beans
            ApplicationContext context =
                    new ClassPathXmlApplicationContext("aspects.xml", "daos.xml", "services.xml");

            // retrieve configured instance
            UserServiceImpl service = context.getBean("userService", UserServiceImpl.class);

            // use configured instance
            List<User> userList = service.findUserList();

            // print info from beans
            userList.forEach(a -> System.out.println(a.getUserName() + "," + a.getAge()));
        }
    }

  11. 项目结构

简化上述项目的配置

通过config简化配置

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@EnableAspectJAutoProxy
@Configuration
public class BeanConfig {

    /**
     * @return userDao
     */
    @Bean("userDao")
    public UserDaoImpl userDao(){
        return new UserDaoImpl();
    }

    /**
     * @return user service
     */
    @Bean("userService")
    public UserServiceImpl userService() {
        UserServiceImpl userService = new UserServiceImpl();
        userService.setUserDao(userDao());
        return userService;
    }

    /**
     * @return log aspect
     */
    @Bean("logAspect")
    public LogAspect logAspect() {
        return new LogAspect();
    }
}

public class App {
    public static void main(String[] args) {
        // create and configure beans
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(BeanConfig.class);

        // retrieve configured instance
        UserServiceImpl service = context.getBean("userService", UserServiceImpl.class);

        // use configured instance
        List<User> userList = service.findUserList();

        // print info from beans
        userList.forEach(a -> System.out.println(a.getUserName() + "," + a.getAge()));
    }
}

这种简化方式，没创建一个Bean都需要在config文件中去添加相应的映射。

⭐注解简化配置

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@Configuration
@EnableAspectJAutoProxy
public class BeanConfig {

}

// UserDaoImpl 添加@Repository注解
@Repository
public class UserDaoImpl {
    /**
     *  forged a query instance of the findUserList method
     */
    public List<User> findUserList(){
        return Collections.singletonList(new User("wey",18));
    }
}

// UserServiceImpl添加了@Service注解，并通过@Autowired注解注入userDao
@Service
public class UserServiceImpl {

    /**
     * user dao impl.
     */
    @Autowired
    private UserDaoImpl userDao;

    /**
     * find user list.
     * @return user list
     */
    public List<User> findUserList() {
        return userDao.findUserList();
    }
}

// app
public class App {
    public static void main(String[] args) {
        // create and configure beans
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
                "x");

        // retrieve configured instance
        UserServiceImpl service = context.getBean(UserServiceImpl.class);

        // use configured instance
        List<User> userList = service.findUserList();

        // print info from beans
        userList.forEach(a -> System.out.println(a.getUserName() + "," + a.getAge()));
    }
}

🌟SpringBoot托管

SpringBoot实际上通过约定大于配置的方式，使用xx-starter统一的对Bean进行默认初始化，用户只需要很少的配置就可以进行开发了。

博客内容遵循 署名-非商业性使用-相同方式共享 4.0 国际 (CC BY-NC-SA 4.0) 协议

本文永久链接是：https://solitaire-12.github.io/2024/03/25/spring/spring项目/

更新于：2024年3月25日

spring

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