Spring MVC数据绑定-基本类型

Question

I'm currently revising a web application, and I have questions about data binding. I have a method that has been mapped with @RequestMapping, and in one of it's arguments I have a primitive integer type, something like this (the following code is basically a summary of my problem, not the actual code):

@RequestMapping(value = "/processSomething" , method = RequestMethod.GET)
public String processSomething(@ModelAttribute("myValue") int myValue)
{
   // Do something with "myValue".
}

When I run the web application, i get the following:

HTTP Status 500 - Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [int]: No default constructor found; nested exception is java.lang.NoSuchMethodException: int.()

It makes me realize that data binding works only with objects. I tried to change int with Integer, but I ended up getting something very similar:

HTTP Status 500 - Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [java.lang.Integer]: No default constructor found; nested exception is java.lang.NoSuchMethodException: java.lang.Integer.()

I know @ModelAttribute allows us to make data binding with the Spring MVC model, and if a model is not in there, it is created automatically by Spring and then it's returned. What am I doing wrong? What I forgot to do? Do I need to create a PropertyEditor for primitive types?

The funny thing is that it works perfectly with @RequestParam, but I would not want the user to see the value of my property in the URL.

NOTE : I'm currently using Spring Web MVC 4.1.1.RELEASE (with MAVEN)

---

UPDATE

I did what was suggested by tofindabhishek user. I created a class with the name Inteiro (translated as Integer), and I am using it as @ModelAttribute, just like this:

@RequestMapping(value = "/usuarios" , method = RequestMethod.GET)
public String getUsuarios(
        Model model , 
        @RequestParam("pag")            int pagina ,                    
        @ModelAttribute("total")        Inteiro registros ,             
        @ModelAttribute("pesquisa")     CriterioBuilder criterio ,      
        @ModelAttribute("id_sexo_f")    Inteiro idSexF ,                
        @ModelAttribute("id_grupo_adm") Inteiro idGrpAdm )              
{
    // ...
}

The Inteiro class has basically just a single int primitive field with a public and empty constructor, and a set, get, equals and hashCode method. The previous problem appears to have been resolved, but when running my application, I came across this:

HTTP Status 500 - javax.el.ELException: Cannot convert com.regra7.minhaapp.controle.wrap.Inteiro@3b of type class com.regra7.minhaapp.controle.wrap.Inteiro to class java.lang.Long

Here's the Inteiro source code:

public class Inteiro
{
    // #############################################################################################
    //                                                                                    INSTÂNCIAS
    // #############################################################################################

    private int valor;

    // #############################################################################################
    //                                                                                  CONSTRUTORES
    // #############################################################################################

    public Inteiro()
    {
        this.valor = 0;
    }

    // #############################################################################################
    //                                                                                 MODIFICADORES
    // #############################################################################################

    public void set(int valor) { this.valor = valor; }

    // #############################################################################################
    //                                                                                        ACESSO
    // #############################################################################################

    public int get() { return this.valor; }

    // #############################################################################################
    //                                                                             EQUALS E HASHCODE
    // #############################################################################################

    @Override
    public boolean equals(Object o) 
    {
        if (o == null) 
        {
            return false;
        }
        else if (o == this) 
        {
            return true;
        }
        else if (o.getClass() != this.getClass()) 
        {
            return false;
        }

        Inteiro inteiro = (Inteiro) o;

        return inteiro.get() == valor;
    }

    @Override
    public int hashCode() 
    {
        return valor;
    }
}

For what reason Spring is complaining that can not convert Inteiro to java.lang.Long? I'm not working with Long. Moreover... EL? That would mean "Expression Language", right? Does this have something to do with some of my JSP pages? I am trying to develop a JSP page that displays search results, and on this page I use EL. Is there any possibility to be a problem in my JSP page?

Thank you for your help.

Answer 1

public class ViewModel {
   private Integer myValue;
}

Use Wrapper object(ViewModel) to capture your value and Bind ViewModel class as model attribute in this case you can handle null values by using Wrapper(Integer).if you don't want to handle null values you can use int.

public class ViewModel {
   private int myValue;
}