java - 使用 Struts2 和 hibernate 创建 Web 服务(SOAP 或 REST)

Question

我在使用 struts 2 和 hibernate 调用 Web 服务时遇到问题...

HTTP Status 500 - Unable to instantiate Action, actions.events.rest.EventController, defined for 'event' in namespace '/'Error creating bean with name 'actions.events.rest.EventController': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [actions.events.rest.EventController]: Constructor threw exception; nested exception is java.lang.NullPointerException

这是我的来源:

事件 Controller :

public class EventController extends BaseAction implements ModelDriven<Object> {
private static final long serialVersionUID = 1L;
private String id;
private Object model; 

private static Map<String, Event> map;
{ 
    List<Event> events = services.getEvents();
    for(Event event : events){
        map.put(event.getId() + "", event);
    } 
}

public HttpHeaders index() {
    model = map;
    return new DefaultHttpHeaders("index").disableCaching();
}

public String add(){ 
    services.createEvent("Event1");
    return "SUCCESS";
}

public String getId() {
    return id;
}
public void setId(String id) {
    Integer iid = Integer.parseInt(id);
    model = services.getEventById(iid);
    this.id = id;
}

public Object getModel() {
    return model;
} 

基础 Action :

public class BaseAction extends ActionSupport {
// So that spring can inject the business singleton
protected Services services;

public void setServices(Services value) {
    services=value;
}

// For redirect results
protected String redirectUrl;

public String getRedirectUrl() {
    return redirectUrl;
}

public String redirect(String to) {
    redirectUrl = to;
    return "redirect";
}

当我调试时，我在 List<Event> events = services.getEvents(); 中遇到错误在 EventController .它可以是什么？

Answer 1

• 异常是由于
  您从静态初始化 block 中引用注入(inject)的bean 服务 :

  { 
      List<Event> events = services.getEvents();
      for(Event event : events){
          map.put(event.getId() + "", event);
      } 
  }
  

  完全删除它，在 prepare() 方法或 @PostConstruct 方法或任何地方执行此类操作，但单独保留静态 block 。

也就是说，您正在遵循一些不良做法:

• 您正在返回 "SUCCESS"，而它应该是 "success" 或 SUCCESS(是 “成功”)

• 你正在将逻辑放在 setter 中，最好不要

• 我还建议放弃 ModelDriven，完全放弃 Spring 和 use CDI ，但这是我的拙见。顺便说一句，确保到take a look at what I'm talking about .