Spring注解驱动开发--自动装配

一、使用@Autowired

• 默认优先按照类型去容器中找对应的组件，需要使用时自动注入(applicationContext.getBean(BookService.class);)

  package org.hao.service;
  
  import org.hao.dao.BookDao;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.stereotype.Service;
  
  @Service
  public class BookService {
        
        
      @Autowired
      private BookDao bookDao;
  
      public void print(){
        
        
          System.out.println(bookDao);
      }
  
      @Override
      public String toString() {
        
        
          return "BookService{" +
                  "bookDao=" + bookDao +
                  '}';
      }
  }
  

  

二、@Resource和@Inject

• 功能与@Autowired基本一样，都能实现自动注入
• @Autowired是Spring定义的，@Resource和@Inject都是Java规范

三、Aware注入Spring底层组件

• 自定义组件实现xxxAware：在创建对象时，会调用接口规定的方法注入相关组件

  package org.hao.bean;
  
  import org.springframework.beans.BeansException;
  import org.springframework.beans.factory.BeanNameAware;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.ApplicationContextAware;
  import org.springframework.context.EmbeddedValueResolverAware;
  import org.springframework.stereotype.Component;
  import org.springframework.util.StringValueResolver;
  
  @Component
  public class Red implements ApplicationContextAware, BeanNameAware, EmbeddedValueResolverAware {
        
        
      private ApplicationContext applicationContext;
  
      public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        
        
          System.out.println("传入的IOC：" + applicationContext);
          this.applicationContext = applicationContext;
      }
  
      public void setBeanName(String s) {
        
        
          System.out.println("当前Bean的名字：" + s);
      }
  
      public void setEmbeddedValueResolver(StringValueResolver stringValueResolver) {
        
        
          String resolveStringValue = stringValueResolver.resolveStringValue("你好${os.name}");
          System.out.println("解析的字符串：" + resolveStringValue);
      }
  }
  

  

四、@Profile

• Spring为我们提供的可以根据当前环境，动态的激活和切换一系列组件的功能
• @Profile环境搭建

  /**
  *	有三个数据源：测试、开发、生产
  */
  package org.hao.config;
  
  import com.mchange.v2.c3p0.ComboPooledDataSource;
  import org.springframework.beans.factory.annotation.Value;
  import org.springframework.context.EmbeddedValueResolverAware;
  import org.springframework.context.annotation.Bean;
  import org.springframework.context.annotation.Configuration;
  import org.springframework.context.annotation.PropertySource;
  import org.springframework.util.StringValueResolver;
  
  import javax.sql.DataSource;
  import java.beans.PropertyVetoException;
  
  @PropertySource("classpath:/dbconfig.properties")
  @Configuration
  public class MainConfigOfProfile implements EmbeddedValueResolverAware {
        
        
  
      @Value("${db.user}")
      private String user;
  
      private StringValueResolver valueResolver;
  
      private String driverClass;
  
      @Bean("testDataSource")
      public DataSource dataSourceTest(@Value("${db.password}") String pwd) throws PropertyVetoException {
        
        
          ComboPooledDataSource dataSource = new ComboPooledDataSource();
          dataSource.setUser(user);
          dataSource.setPassword(pwd);
          dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/chapter05");
          dataSource.setDriverClass(driverClass);
          return dataSource;
      }
  
      @Bean("devDataSource")
      public DataSource dataSourceDev(@Value("${db.password}") String pwd) throws PropertyVetoException {
        
        
          ComboPooledDataSource dataSource = new ComboPooledDataSource();
          dataSource.setUser(user);
          dataSource.setPassword(pwd);
          dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/hao");
          dataSource.setDriverClass(driverClass);
          return dataSource;
      }
  
      @Bean("prodDataSource")
      public DataSource dataSourceProd(@Value("${db.password}") String pwd) throws PropertyVetoException {
        
        
          ComboPooledDataSource dataSource = new ComboPooledDataSource();
          dataSource.setUser(user);
          dataSource.setPassword(pwd);
          dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/crashcourse");
          driverClass = valueResolver.resolveStringValue("${db.driverClass}");
          dataSource.setDriverClass(driverClass);
          return dataSource;
      }
  
      public void setEmbeddedValueResolver(StringValueResolver stringValueResolver) {
        
        
          this.valueResolver = stringValueResolver;
      }
  }
  

• @Profile：指定组件在哪个环境下能被注册到容器中；若不指定，任何环境下都能注册这个组件
• 加了环境标识的Bean，只有在激活时才能被注册。默认是default环境。
  
• 激活环境的方法：

1. 使用命令行动态参数：在Edit Configurations...处加载-Dspring.profiles.active = test
2. 代码方式激活