使用Spring容器最简单的代码姿势

﹏ヽ暗。殇╰゛Y 2023-06-03 12:53 7阅读 0赞

如果仅仅是为了测试简单使用一下Spring的IOC容器，或者研究一下Spring的容器的源码实现，那么在搭建Spring工程的时候，不需要复杂的xml配置。Spring3.0之后提供了Java注解配置的方式来启动Spring容器。下面是最简单的启动Spring容器的方式：

1.依赖包只需要spring-context即可：

<?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>
    
        <groupId>com.springexample</groupId>
        <artifactId>spring-ioc</artifactId>
        <version>1.0-SNAPSHOT</version>
    
        <dependencies>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-context</artifactId>
                <version>5.1.8.RELEASE</version>
            </dependency>
        </dependencies>
    
    </project>

2.一个启动测试类：

import com.spring.ioc.SpringConfig;
    import com.spring.ioc.UserService;
    import org.springframework.context.annotation.AnnotationConfigApplicationContext;
    
    public class Application {
    
        public static void main(String[] args) {
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
            UserService userService = context.getBean(UserService.class);
            System.out.println(userService.getSysUser());
        }
    }

3.一个配置类（@Configuration注解的类相当于一个xml文件），用于扫描和注册Bean，@ComponentScan注解用于要扫描哪个包下的Bean（即扫描@Service、@Repository等注解的Bean）：

import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    
    @ComponentScan("com.spring")
    @Configuration
    public class SpringConfig {
    
    }

4.模拟一个业务类，类上加上@Service注解：

import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    @Service
    public class UserService {
    
        @Autowired
        private UserDao userDao;
    
        public SysUser getSysUser() {
            return userDao.getSysUser();
        }
    }

5.模拟Dao服务，类上加上@Repository注解，提供数据访问服务：

import org.springframework.stereotype.Repository;
    
    @Repository
    public class UserDao {
        public SysUser getSysUser() {
            SysUser sysUser = new SysUser();
            sysUser.setUserId(2);
            sysUser.setUserName("Tom");
            return sysUser;
        }
    }

6.一个实体类，用于封装业务数据：

public class SysUser {
    
        private Integer userId;
        private String userName;
    
        public Integer getUserId() {
            return userId;
        }
    
        public void setUserId(Integer userId) {
            this.userId = userId;
        }
    
        public String getUserName() {
            return userName;
        }
    
        public void setUserName(String userName) {
            this.userName = userName;
        }
    
        @Override
        public String toString() {
            return "SysUser{" +
                    "userId=" + userId +
                    ", userName='" + userName + '\'' +
                    '}';
        }
    }

6.执行测试类Application中的main方法，查看输出结果：

SysUser{userId=2, userName='Tom'}

转载于:https://www.cnblogs.com/jun1019/p/11404346.html