Spring MVC不允许为特定控制器/控制器的方法设置字段

@Controller
public class MyController {

    @RequestMapping("/example")
    public String exampleMethod(@RequestParam String param, Model model) {
        model.addAttribute("result", process(param));
        return "viewName";
    }

    private String process(String param) {
        // 处理逻辑
        return "processed_" + param;
    }
}

@Controller
public class MyController {

    @Autowired
    private RequestScopedBean requestScopedBean;

    @RequestMapping("/example")
    public String exampleMethod(@RequestParam String param, Model model) {
        requestScopedBean.setData(param);
        model.addAttribute("result", requestScopedBean.getData());
        return "viewName";
    }
}

@RequestScope
@Component
public class RequestScopedBean {
    private String data;

    public String getData() {
        return data;
    }

    public void setData(String data) {
        this.data = data;
    }
}

@Controller
public class MyController {

    @Autowired
    private SessionScopedBean sessionScopedBean;

    @RequestMapping("/example")
    public String exampleMethod(@RequestParam String param, Model model) {
        sessionScopedBean.setData(param);
        model.addAttribute("result", sessionScopedBean.getData());
        return "viewName";
    }
}

@SessionScope
@Component
public class SessionScopedBean {
    private String data;

    public String getData() {
        return data;
    }

    public void setData(String data) {
        this.data = data;
    }
}