• Spring注解开发(十)

    文章目录

    文章目录

    一、注解开发定义Bean

    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...");
    }
}


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    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>

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    3.案例

    1.BookDao

    package com.test.dao;

public interface BookDao {
    void save();
}


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    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...");
    }
}


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    3.BookService

    package com.test.service;

public interface BookService {
    void save();
}


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    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...");
    }
}


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    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>

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    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
 */

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    二、纯注解开发

    1.@Configuration注解代替了Spring的核心配置文件

    @Configuration

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    2.@ComponentScan注解用于设定扫描路径

    @ComponentScan("com.test")

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    3.加载配置类的初始化容器

    AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);

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    4.案例

    1.BookDao

    package com.test.dao;

public interface BookDao {
    void save();
}


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    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...");
    }
}


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    3.BookService

    package com.test.service;

public interface BookService {
    void save();
}


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    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...");
    }
}


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    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 {

}


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    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
 */

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    三、Bean的作用范围和生命周期

    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...");
    }   
}


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    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...");
    }
}


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    四、自动装配

    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();
    }
}


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    注意：
    在这里插入图片描述

    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();
    }
}


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    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);
    }

}


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    4.使用@PropertySource注解加载properties文件

    @PropertySource("jdbc.properties")

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    5.案例

    jdbc.properties

    name=Jack

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    1.BookDao

    package com.test.dao;

public interface BookDao {
    void save();
}


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    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);
    }

}


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    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...");
    }

}


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    4.BookService

    package com.test.service;

public interface BookService {
    void save();
}


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    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();
    }
}


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    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 {

}


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    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

 */

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    五、第三方Bean管理

    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;
    }

}


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    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);
    }
}


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    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 {
}


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    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;
    }
}


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    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 {


}


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    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;
    }
}


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    六、第三方Bean依赖注入

    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;
    }

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    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;
    }

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    七、xml配置比对注解配置

    在这里插入图片描述

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  • 原文地址：https://blog.csdn.net/qq_43514330/article/details/125428688