initializingbean接口的用途

左手的ㄟ右手 2022-12-28 14:14 168阅读 0赞

initializingbean接口只有一个afterPropertiesSet方法，实现了这个接口的类在初始化Bean时会执行这个方法。**所以这个接口的用途就是用来实现初始化数据用的。**

public interface InitializingBean {
        void afterPropertiesSet() throws Exception;
    }

> **那么就有一个疑问。static块不好用么干嘛还要多实现一个接口呢？**
> 
> **static只能对当前类中的静态成员进行操作，加入类成员变量不能是静态的呢？initializingbean接口的afterPropertiesSet方法就可以对非静态成员进行操作。**

**下面的****AbstractRoutingDataSource **类就是使用**initializingbean接口来初始化数据的。因为targetDataSources 成员是非静态的，所以并不能使用static静态块的方式实现**

public abstract class AbstractRoutingDataSource extends AbstractDataSource implements InitializingBean {
    
    	@Nullable
    	private Map<Object, Object> targetDataSources;
    
    	@Nullable
    	private Object defaultTargetDataSource;
    
    	private boolean lenientFallback = true;
    
    	private DataSourceLookup dataSourceLookup = new JndiDataSourceLookup();
    
    	@Nullable
    	private Map<Object, DataSource> resolvedDataSources;
    
    	@Nullable
    	private DataSource resolvedDefaultDataSource;
    	
    
    	@Override
    	public void afterPropertiesSet() {
    		if (this.targetDataSources == null) {
    			throw new IllegalArgumentException("Property 'targetDataSources' is required");
    		}
    		this.resolvedDataSources = new HashMap<>(this.targetDataSources.size());
    		this.targetDataSources.forEach((key, value) -> {
    			Object lookupKey = resolveSpecifiedLookupKey(key);
    			DataSource dataSource = resolveSpecifiedDataSource(value);
    			this.resolvedDataSources.put(lookupKey, dataSource);
    		});
    		if (this.defaultTargetDataSource != null) {
    			this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
    		}
    	}
    
    }