自动装配在Spring 4中不起作用

Question

我有以下源代码示例，它在Spring 3.2.6中有效但在4.0.1中不起作用

public interface RunTest<T extends Number> {
void run(T number);

}

public class BasicRunTest implements RunTest<Integer>{

@Override
public void run(Integer number) {
}

}

@Component
public class BeanTest  {
@Autowired
private RunTest<Number> runTest; 
}

如果我运行应用程序，我会得到例外：

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [org.test.RunTest] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Answer 1

这是一个新的Spring Feature: Spring now treats generic types as a form of qualifier when injecting Beans - 换句话说：autowire注意泛型类型！

你有BasicRunTest implements RunTest<Integer>（整数）并问春天@Autowire prive RunTest<Number> runTest;（数字） - 这是不兼容的！

尝试

private RunTest<? extends Number> runTest;

（它适用于Spring 3.x，或多或少是一个bug，因为你的代码破坏了通用约束）