详解PropertyPlaceholderConfigurer、PropertyOverrideConfigurer等对属性配置文件Properties的加载和使用【享学Spring】(下)

@Configuration
public class RootConfig {
    @Bean
    public PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        PropertySourcesPlaceholderConfigurer configurer = new PropertySourcesPlaceholderConfigurer();
        configurer.setOrder(Ordered.HIGHEST_PRECEDENCE);
        configurer.setLocation(new ClassPathResource("beaninfo.properties"));
        return configurer;
    }
    @Scope("${bean.scope}") // 这里是能够使用占位符的
    @Bean
    public Person person() {
        Person person = new Person();
        return person;
    }
}
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {RootConfig.class})
public class TestSpringBean {
    @Autowired
    private ApplicationContext applicationContext;
    @Autowired
    private ConfigurableBeanFactory beanFactory;
    // 通过它，可以把生效的配置都拿到
    @Autowired
    private PropertySourcesPlaceholderConfigurer configurer;
    @Test
    public void test1() {
        Environment environment = applicationContext.getEnvironment();
        BeanExpressionResolver beanExpressionResolver = beanFactory.getBeanExpressionResolver();
        PropertySources appliedPropertySources = configurer.getAppliedPropertySources();
        System.out.println(environment.containsProperty("bean.scope")); //false  注意环境里是没有这个key的
        System.out.println(beanExpressionResolver);
        System.out.println(appliedPropertySources);
        // 获取环境的和我们自己导入的
        PropertySource<?> envProperties = appliedPropertySources.get(PropertySourcesPlaceholderConfigurer.ENVIRONMENT_PROPERTIES_PROPERTY_SOURCE_NAME);
        PropertySource<?> localProperties = appliedPropertySources.get(PropertySourcesPlaceholderConfigurer.LOCAL_PROPERTIES_PROPERTY_SOURCE_NAME);
        System.out.println(envProperties.getSource() == environment); //true  可以看到这个envProperties的source和环境里的是同一个
        System.out.println(localProperties.containsProperty("bean.scope"));//true 本地配置里是包含这个属性的
    }
}

// @since 12.03.2003
public class PropertyOverrideConfigurer extends PropertyResourceConfigurer {
  // The default bean name separator.  
  public static final String DEFAULT_BEAN_NAME_SEPARATOR = ".";
  // 下面提供了set方法可以修改
  private String beanNameSeparator = DEFAULT_BEAN_NAME_SEPARATOR;
  private boolean ignoreInvalidKeys = false; // 默认是不忽略非法的key
  private final Set<String> beanNames = Collections.newSetFromMap(new ConcurrentHashMap<>(16));
  // 实现了父类的抽象方法：给每个bean进行覆盖处理   注意：这里不是处理占位符~~~~
  @Override
  protected void processProperties(ConfigurableListableBeanFactory beanFactory, Properties props)
      throws BeansException {
    // 按照props有的这些属性值们进行覆盖~~~~
    for (Enumeration<?> names = props.propertyNames(); names.hasMoreElements();) {
      String key = (String) names.nextElement();
      try {
        // 1、拿到beanName 这样拿出来String beanName = key.substring(0, separatorIndex);
        // 2、根据beanName拿到bean定义信息BeanDefinition
        // 3、bdToUse.getPropertyValues().addPropertyValue(pv);  显然这样子存在的key就覆盖  否则保持原样
        processKey(beanFactory, key, props.getProperty(key));
      }
    }
  }
}

beanName.property=value  //第一个.前面一定是beanName

# 故意把它放在第一位 最顶部
app.full=${app.key} + ${app.myname}
app.myname=fsx
app.key=${user.home}

@Slf4j
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {RootConfig.class, JdbcConfig.class})
public class TestSpringBean {
    @Value("${app.full}")
    private String key;
    @Test
    public void test1() throws SQLException {
        System.out.println(key); //C:\Users\fangshixiang + fsx
    }
}