spring学习（二） —— 高级装配

缺乏、安全感 2021-12-19 01:59 181阅读 0赞

### 一、注解解释 ###

1.  **@Profile("")**：通过profile注解来指定环境，只有与运行环境相同的bean才会被注册到spring上下文中
2.  **@Primary**：spring上下文中有多个相同BeanID的时候，使用自动装配注入方式会引起程序异常，使用primary类指定spring在注入多bean的时候优先注入哪个
3.  **@Qualifier**：自定义BeanId可以与@Component和@Bean一起使用，同时可以和@Autowired一起使用，指定注入Bean的名称
4.  **@Scope**：spring容器中的一个作用域，在 Spring容器中具有以下几种作用域：常用作用域**singleton（单例）**、**prototype(多例）**

### 二、装配Bean ###

继续上一个测试demo，创建test2

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDA3OTE3_size_16_color_FFFFFF_t_70][]

*   创建接口

package com.test.spring.test2;
    
    public interface Dog {
        String wangWangWang();
    }

*  创建两个实现类，并注册到spring容器中

package com.test.spring.test2;
    
    import org.apache.catalina.core.ApplicationContext;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.beans.factory.config.ConfigurableBeanFactory;
    import org.springframework.context.annotation.Primary;
    import org.springframework.context.annotation.Profile;
    import org.springframework.context.annotation.Scope;
    import org.springframework.stereotype.Component;
    
    
    @Primary
    @Component
    public class DaLangGou implements Dog {
        @Override
        public String wangWangWang() {
            String str = "我是大狼狗";
            System.out.println(str);
            return str;
        }
    }

package com.test.spring.test2;
    
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.context.annotation.Profile;
    import org.springframework.stereotype.Component;
    
    
    @Component
    public class XiaoLangGou implements Dog {
    
        @Override
        public String wangWangWang() {
            String str = "我是小狼狗~";
            System.out.println(str);
            return str;
        }
    }

*  创建javaConfig

package com.test.spring.test2;
    
    import org.springframework.context.annotation.ComponentScan;
    import org.springframework.context.annotation.Configuration;
    
    @Configuration
    @ComponentScan
    public class JavaConfig {
    }

*  测试

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes = JavaConfig.class)
    public class Test2 {
    
        @Autowired
        private Dog dog;
    
        @Test
        public void contextLoads() {
            dog.wangWangWang();
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDA3OTE3_size_16_color_FFFFFF_t_70 1][]

由于DaLangGou类使用了@Primary所以会优先装配

### 三、使用自定义BeanID方式 ###

*  修改实现类

//@Primary
    @Component
    @Qualifier("daGou")
    public class DaLangGou implements Dog {
        @Override
        public String wangWangWang() {
            String str = "我是大狼狗";
            System.out.println(str);
            return str;
        }
    }

@Component
    @Qualifier("xiaoGou")
    public class XiaoLangGou implements Dog {
    
        @Override
        public String wangWangWang() {
            String str = "我是小狼狗~";
            System.out.println(str);
            return str;
        }
    }

*  测试

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes = JavaConfig.class)
    public class Test2 {
    
        @Autowired
        @Qualifier("xiaoGou")
        private Dog dog;
    
        @Test
        public void contextLoads() {
            dog.wangWangWang();
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDA3OTE3_size_16_color_FFFFFF_t_70 2][]

由于使用自定义beanID方式，在装配时需要指定BeanID的名称

### 四、设置运行环境 ###

*   修改实现类，设置运行环境

//@Primary
    @Component
    @Profile("pro")
    //@Qualifier("daGou")
    public class DaLangGou implements Dog {
        @Override
        public String wangWangWang() {
            String str = "我是大狼狗";
            System.out.println(str);
            return str;
        }
    }

@Component
    @Profile("dev")
    //@Qualifier("xiaoGou")
    public class XiaoLangGou implements Dog {
    
        @Override
        public String wangWangWang() {
            String str = "我是小狼狗~";
            System.out.println(str);
            return str;
        }
    }

*  测试

/**
     * @ActiveProfiles
     * 指定使用的那个环境来创建，只有pro或没有指定环境的bean会被创建
     */
    @RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes = JavaConfig.class)
    @ActiveProfiles("pro")
    public class Test2 {
    
        @Autowired
        //@Qualifier("daGou")
        private Dog dog;
    
        @Test
        public void contextLoads() {
            dog.wangWangWang();
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDA3OTE3_size_16_color_FFFFFF_t_70 3][]

### 五、读取配置文件 ###

*  application.yml

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDA3OTE3_size_16_color_FFFFFF_t_70 4][]

*  测试

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(classes = JavaConfig.class)
    @PropertySource("classpath:application.yml")
    public class Test2 {
    
        /**
         * 读取配置文件注解方式和使用Environment方式
         */
        @Autowired
        private Environment env;
    
        @Value("${kkkk}")
        private String str;
    
        @Test
        public void testEnv(){
            System.out.println(env.getProperty("kkkk"));
            System.out.println(str);
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDA3OTE3_size_16_color_FFFFFF_t_70 5][]

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