使用JSF时的等效Spring自定义集合属性编辑器

问题描述

我想知道如何在类似于Spring集合属性编辑器的Java Server Faces中使用转换器

假设下面的模型

  public class Group {
 
 private String name; 
 
 List< User> users = new ArrayList< User>（）; 
 
 // getter和setter的
} 
  

 < form ...> 
< h1>分组表单< / h1> 
< label for =name>输入名称< / label> 
< input type =textname =name/> 
 
< label for =users>选择用户< / label> 
<！ -  value属性存储userId  - > 
< input type =checkboxvalue =1name =users/> User 1 
< input type =checkboxvalue =2name =users/>用户2 
< input type =checkboxvalue =3name =users/>用户3 
< / form> 
  

如果我使用Spring绑定Group类中的用户属性，我调用

  binder.registerCustomEditor（List.class，new CustomCollectionEditor（）{
 protected Object convertElement（Object userId）{
 return new User （Integer）userId）; 
} 
}）; 
  

如何在使用Java Server Faces时获得相同的效果？

您可以实现。它的API是相当自解释：相应地写入 getAsString（）方法，它返回 String code> Object ，其可以在每个技术ID下，例如 userId 。然后，要在应用请求参数阶段期间让JSF设置正确的 Object ，您需要实现 getAsObject（）返回与给定的 String 值相关联的 Object 。

基本上：

  public class UserConverter implements Converter {
 
 private UserDAO userDAO = SomeDAOManager.getUserDAO（）; 
 
 public String getAsString（FacesContext context，UIComponent component，Object value）{
 return String.valueOf（（（User）value）.getId（））; 
} 
 
 public Object getAsObject（FacesContext context，UIComponent component，String value）{
 return userDAO.find（Long.valueOf（value））; 
} 
 
} 
  

在 faces-config.xml ，如下所示：

 < converter& 
< converter-for-class> com.example.model.User< / converter-for-class> 
< converter-class> com.example.converter.UserConverter< / converter-class> 
< / converter> 
  

这应该是。要了解更多信息，您可以或文章有用。

I would like to know how to use Converters in Java Server Faces similar to Spring collection property editor

Suppose the following model

public class Group {

    private String name;

    List<User> users = new ArrayList<User>();

    // getter's and setter's
}

And equivalent form

<form ...>
    <h1>Group form</h1>
    <label for="name">Enter name</label>
    <input type="text" name="name"/>

    <label for="users">Select users</label>
    <!--value attribute stores userId-->
    <input type="checkbox" value="1" name="users"/> User 1
    <input type="checkbox" value="2" name="users"/> User 2
    <input type="checkbox" value="3" name="users"/> User 3
</form>

If i use Spring to bind users property in Group class, i call

binder.registerCustomEditor(List.class, new CustomCollectionEditor() {
    protected Object convertElement(Object userId)  {
        return new User((Integer) userId);
    }
});

How do i get the same effect when using Java Server Faces ?

regards,

解决方案

For that you can implement javax.faces.convert.Converter. Its API is pretty self-explaining: write the getAsString() method accordingly that it returns the String representation of the Object, which can be under each the technical ID such as userId. Then, to get JSF set the right Object during apply request parameters phase, you need to implement getAsObject() that it returns the Object associated with the given String value.

Basically:

public class UserConverter implements Converter {

    private UserDAO userDAO = SomeDAOManager.getUserDAO();

    public String getAsString(FacesContext context, UIComponent component, Object value) {
        return String.valueOf(((User) value).getId());
    }

    public Object getAsObject(FacesContext context, UIComponent component, String value) {
        return userDAO.find(Long.valueOf(value));
    }

}

Register it in faces-config.xml as follows:

<converter>
    <converter-for-class>com.example.model.User</converter-for-class>
    <converter-class>com.example.converter.UserConverter</converter-class>
</converter>

That should be it. For more insights you may this or this article useful.

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