Spring-注解开发

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1.使用@component定义Bean

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.stereotype.Component;


@Component("dao")
public class BookDaoImpl implements BookDao { 
    public void save() { 
        System.out.println("BookDaoImpl...");
    }
}

2.核心配置文件通过组件扫描加载Bean

<?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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
            https://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            https://www.springframework.org/schema/context/spring-context.xsd">
   <context:component-scan base-package="com.test.dao.impl"></context:component-scan>
 
</beans>

3.案例

1.BookDao

package com.test.dao;

public interface BookDao { 
    void save();
}

2.BookDaoImpl

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.stereotype.Component;


@Component("dao")
public class BookDaoImpl implements BookDao { 
    public void save() { 
        System.out.println("BookDaoImpl...");
    }
}

3.BookService

package com.test.service;

public interface BookService { 
    void save();
}

4.BookServiceImpl

package com.test.service.impl;

import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.stereotype.Component;

@Component
public class BookServiceImpl implements BookService { 
    private BookDao bookDao;
    public void setBookDao(BookDao bookDao) { 
        this.bookDao = bookDao;
    }

    public void save() { 
        System.out.println("BookServiceImpl...");
    }
}

5.applicationContext.xml

<?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:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
            https://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            https://www.springframework.org/schema/context/spring-context.xsd">
   <context:component-scan base-package="com.test.dao.impl"></context:component-scan>
   <context:component-scan base-package="com.test.service"></context:component-scan>


</beans>

6.Test

import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test { 
    public static void main(String[] args) { 
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        BookDao bookDao = context.getBean("dao",BookDao.class);
        System.out.println(bookDao);
        BookService bean = context.getBean(BookService.class);
        System.out.println(bean);
    }
}
/* com.test.dao.impl.BookDaoImpl@5427c60c com.test.service.impl.BookServiceImpl@6366ebe0 */

1.@Configuration注解代替了Spring的核心配置文件

@Configuration

2.@ComponentScan注解用于设定扫描路径

@ComponentScan("com.test")

3.加载配置类的初始化容器

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);

4.案例

1.BookDao

package com.test.dao;

public interface BookDao { 
    void save();
}

2.BookDaoImpl

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.stereotype.Component;


@Component("dao")
public class BookDaoImpl implements BookDao { 
    public void save() { 
        System.out.println("BookDaoImpl...");
    }
}

3.BookService

package com.test.service;

public interface BookService { 
    void save();
}

4.BookServiceImpl

package com.test.service.impl;

import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.stereotype.Component;

@Component
public class BookServiceImpl implements BookService { 
    private BookDao bookDao;
    public void setBookDao(BookDao bookDao) { 
        this.bookDao = bookDao;
    }

    public void save() { 
        System.out.println("BookServiceImpl...");
    }
}

5.SpringConfig

package com.test.config;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan("com.test")
public class SpringConfig { 

}

6.Test

import com.test.config.SpringConfig;
import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test { 
    public static void main(String[] args) { 
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        BookDao bookDao = context.getBean("dao",BookDao.class);
        System.out.println(bookDao);
        BookService bean = context.getBean(BookService.class);
        System.out.println(bean);
    }
}
/* com.test.dao.impl.BookDaoImpl@77e4c80f com.test.service.impl.BookServiceImpl@255b53dc */

1.@Scope()定义Bean的作用范围

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

@Scope("singleton")
@Component("dao")
public class BookDaoImpl implements BookDao { 
    public void save() { 
        System.out.println("BookDaoImpl...");
    }   
}

2.@PostConstruct和@PreDestroy定义Bean的生命周期

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

@Scope("singleton")
@Component("dao")
public class BookDaoImpl implements BookDao { 
    public void save() { 
        System.out.println("BookDaoImpl...");
    }
    @PostConstruct
    public void init(){ 
        System.out.println("init...");
    }
    @PreDestroy
    public void destroy(){ 
        System.out.println("destroy...");
    }
}

1.使用@Autowired开启自动装配模式

package com.test.service.impl;

import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
@Component
public class BookServiceImpl implements BookService { 
    @Autowired
    private BookDao bookDao;
    /*set可以省略*/
    /*public void setBookDao(BookDao bookDao) { this.bookDao = bookDao; }*/

    public void save() { 
        System.out.println("BookServiceImpl...");
        bookDao.save();
    }
}

注意︰自动装配基于反射设计创建对象并暴力反射对应属性为私有属性初始化数据，因此无需提供setter方法
注意∶自动装配建议使用无参构造方法创建对象（默认），如果不提供对应构造方法，请提供唯一的构造方法

2.使用@Qualifier注解开启指定名称装配Bean

package com.test.service.impl;

import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
@Component
public class BookServiceImpl implements BookService { 
    @Autowired
    @Qualifier("dao2")
    private BookDao bookDao;
    /*set可以省略*/
    /*public void setBookDao(BookDao bookDao) { this.bookDao = bookDao; }*/

    public void save() { 
        System.out.println("BookServiceImpl...");
        bookDao.save();
    }
}

3.使用@Value进行简单的注入

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;


@Component("dao1")
public class BookDaoImpl implements BookDao { 
    @Value("小马哥")
    private String name;
    public void save() { 
        System.out.println("BookDaoImpl..."+name);
    }

}

4.使用@PropertySource注解加载properties文件

@PropertySource("jdbc.properties")

5.案例 jdbc.properties

name=Jack

1.BookDao

package com.test.dao;

public interface BookDao { 
    void save();
}

2.BookDaoImpl

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;


@Component("dao1")
public class BookDaoImpl implements BookDao { 
    /*@Value("小马哥")*/
    @Value("${name}")
    private String name;
    public void save() { 
        System.out.println("BookDaoImpl..."+name);
    }

}

3.BookDaoImpl2

package com.test.dao.impl;
import com.test.dao.BookDao;
import org.springframework.stereotype.Component;


@Component("dao2")
public class BookDaoImpl2 implements BookDao { 
    public void save() { 
        System.out.println("BookDaoImpl2...");
    }

}

4.BookService

package com.test.service;

public interface BookService { 
    void save();
}

5.BookServiceImpl

package com.test.service.impl;

import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
@Component
public class BookServiceImpl implements BookService { 
    @Autowired
    @Qualifier("dao1")
    private BookDao bookDao;
    /*set可以省略*/
    /*public void setBookDao(BookDao bookDao) { this.bookDao = bookDao; }*/

    public void save() { 
        System.out.println("BookServiceImpl...");
        bookDao.save();
    }
}

6.SpringConfig

package com.test.config;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;

@Configuration
@ComponentScan("com.test")
@PropertySource("jdbc.properties")
public class SpringConfig { 

}

7.Test

import com.test.config.SpringConfig;
import com.test.dao.BookDao;
import com.test.service.BookService;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test { 
    public static void main(String[] args) { 
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        BookService dao = context.getBean(BookService.class);
        dao.save();
    }
}
/* BookServiceImpl... BookDaoImpl...Jack */

1.使用@Bean配置第三方bean

SpringConfig:

package com.jkj.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;

@Configuration
public class SpringConfig { 
    //2.添加@Bean，表示当前方法的返回值是一个bean
    @Bean
    //1.定义一个方法获得要管理的对象
    public DataSource dataSource(){ 
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/spring");
        ds.setUsername("root");
        ds.setPassword("root");
        return ds;
    }

}

Test:

import com.jkj.config.SpringConfig;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import javax.sql.DataSource;

public class Test { 
    public static void main(String[] args) { 
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        DataSource bean = context.getBean(DataSource.class);
        System.out.println(bean);
    }
}

2.将独立的配置类加入核心配置

1.导入式使用@Import注解手动加入配置类到核心配置，此注解只能添加一次，多个数据使用数组格式。

案例： SpringConfig:

package com.jkj.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;

import javax.sql.DataSource;

@Configuration
@Import(JdbcConfig.class)
public class SpringConfig { 
}

JdbcConfig:

package com.jkj.config;

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

import javax.sql.DataSource;

public class JdbcConfig { 
    //2.添加@Bean，表示当前方法的返回值是一个bean
    @Bean
    //1.定义一个方法获得要管理的对象
    public DataSource dataSource(){ 
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/spring");
        ds.setUsername("root");
        ds.setPassword("root");
        return ds;
    }
}

2.扫描式(不推荐使用）使用@ComponentScan注解扫描配置类所在的包，加载对应的配置类信息

案例： SpringConfig:

package com.jkj.config;

        import com.alibaba.druid.pool.DruidDataSource;
        import org.springframework.context.annotation.Bean;
        import org.springframework.context.annotation.ComponentScan;
        import org.springframework.context.annotation.Configuration;
        import org.springframework.context.annotation.Import;

        import javax.sql.DataSource;

@Configuration
@ComponentScan("com.jkj.config")
public class SpringConfig { 


}

JdbcConfig:

package com.jkj.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.sql.DataSource;
@Configuration
public class JdbcConfig { 
    //2.添加@Bean，表示当前方法的返回值是一个bean
    @Bean
    //1.定义一个方法获得要管理的对象
    public DataSource dataSource(){ 
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/spring");
        ds.setUsername("root");
        ds.setPassword("root");
        return ds;
    }
}

1.简单依赖注入

public class JdbcConfig { 
    @Value("com.mysql.jdbc.Driver")
    private String driver;
    @Value("jdbc:mysql://localhost:3306/spring")
    private String url;
    @Value("root")
    private String username;
    @Value("root")
    private String password;
    
    //2.添加@Bean，表示当前方法的返回值是一个bean
    @Bean
    //1.定义一个方法获得要管理的对象
    public DataSource dataSource(){ 
        System.out.println(bookDao);
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName(driver);
        ds.setUrl(url);
        ds.setUsername(username);
        ds.setPassword(password);
        return ds;
    }

2.引用类型注入

引用类型注入只需要bean定义方法设置形参即可，容器会根据类型自动装配对象。

//2.添加@Bean，表示当前方法的返回值是一个bean
    @Bean
    //1.定义一个方法获得要管理的对象
    public DataSource dataSource(BookDao bookDao){ 
        System.out.println(bookDao);
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName(driver);
        ds.setUrl(url);
        ds.setUsername(username);
        ds.setPassword(password);
        return ds;
    }

定义bean

- xml配置：bean标签：id属性，class属性 - 注解：@Component，@controller，@Service，@Repository，@ComponentScan

设置依赖注入

- xml配置：setter注入(set方法)，构造器注入(构造方法)，引用/简单，自动装配 - 注解：@Autowired，@Qualifier，@Value

配置第三方bean

- xml配置：bean标签：静态工厂、实例工厂、FactoryBean - 注解：@Bean

作用范围

- xml配置：scope属性 - 注解：@scope

生命周期

- xml配置：标准接口，init-method，destroy-method - 注解：@PostConstructor，@PreDestroy

本文为互联网自动采集或经作者授权后发布，本文观点不代表立场，若侵权下架请联系我们删帖处理！文章出自：https://blog.csdn.net/qq_43514330/article/details/125428688

Spring-注解开发

1.使用@component定义Bean

2.核心配置文件通过组件扫描加载Bean

3.案例

1.@Configuration注解代替了Spring的核心配置文件

2.@ComponentScan注解用于设定扫描路径

4.案例

1.@Scope()定义Bean的作用范围

2.@PostConstruct和@PreDestroy定义Bean的生命周期

1.使用@Autowired开启自动装配模式

2.使用@Qualifier注解开启指定名称装配Bean

3.使用@Value进行简单的注入

4.使用@PropertySource注解加载properties文件

1.使用@Bean配置第三方bean

2.将独立的配置类加入核心配置

1.简单依赖注入

2.引用类型注入

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