Fegin 第5-1 章：AnnotatedParameterProcessor

分享未结  0  1122

李延 LV6 2021-06-22

悬赏：20积分

# 作用
用于Fegin参数的解析，在Contract中我们看到了它的调用过程，这里我们主要看一下默认的几个是如何绑定数据的。

# AnnotatedParameterProcessor
顶级接口，定义两个接口

- getAnnotationType 用于判断当前对象可以解析的注解
- processArgument解析过程

## 部分实现类代码

```java
private static final Class<MatrixVariable> ANNOTATION = MatrixVariable.class;

@Override
	public Class<? extends Annotation> getAnnotationType() {
		return ANNOTATION;
	}

@Override
	public boolean processArgument(AnnotatedParameterContext context, Annotation annotation, Method method) {
		int parameterIndex = context.getParameterIndex();
		Class<?> parameterType = method.getParameterTypes()[parameterIndex];
		MethodMetadata data = context.getMethodMetadata();
		String name = ANNOTATION.cast(annotation).value();

checkState(emptyToNull(name) != null, "MatrixVariable annotation was empty on param %s.",
				context.getParameterIndex());

context.setParameterName(name);

if (Map.class.isAssignableFrom(parameterType)) {
			data.indexToExpander().put(parameterIndex, this::expandMap);
		}
		else {
			data.indexToExpander().put(parameterIndex, object -> ";" + name + "=" + object.toString());
		}

return true;
	}

```

```java
private static final Class<RequestParam> ANNOTATION = RequestParam.class;

@Override
	public Class<? extends Annotation> getAnnotationType() {
		return ANNOTATION;
	}

if (Map.class.isAssignableFrom(parameterType)) {
			checkState(data.queryMapIndex() == null, "Query map can only be present once.");
			data.queryMapIndex(parameterIndex);

return true;
		}

RequestParam requestParam = ANNOTATION.cast(annotation);
		String name = requestParam.value();
		checkState(emptyToNull(name) != null, "RequestParam.value() was empty on parameter %s", parameterIndex);
		context.setParameterName(name);

Collection<String> query = context.setTemplateParameter(name, data.template().queries().get(name));
		data.template().query(name, query);
		return true;
	}

```

# 总结

这里我们看到其实就是对于RequestTemplate的各种属性的设置，比如：query、header、indexToExpander等等。我们在使用时说明。

回帖

消灭零回复