Spring MVC中的JSONObject-严重上下文初始化失败错误

Question

当我尝试实例化JSONObject时出现错误：

SEVERE: Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'budgetController' defined in file [C:\Users\yqb18196\eclipse-workspace\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\wtpwebapps\Budget\WEB-INF\classes\biz\martyn\budget\controller\BudgetController.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [biz.martyn.budget.controller.BudgetController]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/json/JSONException
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1155)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1099)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
...

在这里发生错误：

public class ApiClient {

    ...

    public void requestData() {

        String str = "{}";
        JSONObject obj = new JSONObject(str); // <-- error
        // ...
    }
}

如果重要的话，可以从Spring MVC控制器中调用它：

@Controller
public class BudgetController {

    public BudgetController() {
        ApiClient apiClient = new ApiClient();
        apiClient.requestData();

    }
...

我看了无数有关如何使用JSONObject的教程，但我无法确切地知道我是如何错误地使用它的，但是后来我还是Java的新手，所以可能还有别的东西。