struts2或webwork嵌套会合类型转换

struts2或webwork嵌套集合类型转换
给出例子代码

   public class TestAction{           private List users;      //////  getter setter   }  ....  public class User{      private  String username;    ////getter setter  }

在以上代码中，假设users集合装的是User类实例，则在于TestAction同包下建立一个TestAction-conversion.properties文件：

  Element_users = com.xxxx.User(早期用Collection_)

页面上输入用户名如下脚本

  <input name="users[0].username"/>

假设User用户有属于多个组group，那User变为

 public class User{      private  String username;      private  List groups;    ////getter setter  }

groups中存放的是com.yyy.Group类实例

   public class Group{     private String gname;       ////getter setter }

在于User同包下，建立User-conversion.properties:
Element_groups= com.yyy.Group
页面上输入组名如下

    <input name=users[0][0].gname  />

struts2或webwork给我们提供了以上支持，若是想明确集合中的对象，就在变量所属的类的同包下建立对应的***-conversion.properties,在文件中指定Element_xxx即可

假设有需求是集合中的元素也是集合，那struts2或webwork是不支持的，为了解决这个问题，首先重写XworkListPropertyAccessor

public class XWorkListPropertyAccessor extends ListPropertyAccessor{    public XWorkListPropertyAccessor()    {        _sAcc = new XWorkCollectionPropertyAccessor();    }    public Object getProperty(Map context, Object target, Object name)        throws OgnlException    {        if(OgnlContextState.isGettingByKeyProperty(context) || name.equals("makeNew"))            return _sAcc.getProperty(context, target, name);        if(name instanceof String)            return super.getProperty(context, target, name);        OgnlContextState.updateCurrentPropertyPath(context, name);        Class lastClass = (Class)context.get("last.bean.accessed");        String lastProperty = (String)context.get("last.property.accessed");        if((name instanceof Number) && OgnlContextState.isCreatingNullObjects(context) && XWorkConverter.getInstance().getObjectTypeDeterminer().shouldCreateIfNew(lastClass, lastProperty, target, null, true))        {            List list = (List)target;            int index = ((Number)name).intValue();            int listSize = list.size();            if(lastClass == null || lastProperty == null)                return super.getProperty(context, target, name);            Class beanClass = XWorkConverter.getInstance().getObjectTypeDeterminer().getElementClass(lastClass, lastProperty, name);            if(listSize <= index)            {                Object result = null;                for(int i = listSize; i < index; i++)                    list.add(null);                try                {                    list.add(index, result = ObjectFactory.getObjectFactory().buildBean(beanClass, context));                }                catch(Exception exc)                {                    throw new XworkException(exc);                }                return result;            }            if(list.get(index) == null)            {                Object result = null;                try                {                    list.set(index, result = ObjectFactory.getObjectFactory().buildBean(beanClass, context));                }                catch(Exception exc)                {                    throw new XworkException(exc);                }                return result;            }        }        return super.getProperty(context, target, name);    }   //////////setProperty    private XWorkCollectionPropertyAccessor _sAcc;}

注意在getProperty返回result时，判断result是否List类型

public class MoreXWorkListPropertyAccessor extends XWorkListPropertyAccessor{    public Object getProperty(Map context, Object target, Object name)        throws OgnlException    {        if(OgnlContextState.isGettingByKeyProperty(context) || name.equals("makeNew"))            return _sAcc.getProperty(context, target, name);        if(name instanceof String)            return super.getProperty(context, target, name);        OgnlContextState.updateCurrentPropertyPath(context, name);        Class lastClass = (Class)context.get("last.bean.accessed");        String lastProperty = (String)context.get("last.property.accessed");        if((name instanceof Number) && OgnlContextState.isCreatingNullObjects(context) && XWorkConverter.getInstance().getObjectTypeDeterminer().shouldCreateIfNew(lastClass, lastProperty, target, null, true))        {            List list = (List)target;            int index = ((Number)name).intValue();            int listSize = list.size();            if(lastClass == null || lastProperty == null)                return super.getProperty(context, target, name);            Class beanClass = XWorkConverter.getInstance().getObjectTypeDeterminer().getElementClass(lastClass, lastProperty, name);            if(listSize <= index)            {                Object result = null;                for(int i = listSize; i < index; i++)                    list.add(null);                try                {                    list.add(index, result = ObjectFactory.getObjectFactory().buildBean(beanClass, context));                }                catch(Exception exc)                {                    throw new XworkException(exc);                }                if(result instanceof List){                  OgnlContextState.setLastBeanPropertyAccessed(context,lastProperty+"_i");                  }                return result;            }            if(list.get(index) == null)            {                Object result = null;                try                {                    list.set(index, result = ObjectFactory.getObjectFactory().buildBean(beanClass, context));                }                catch(Exception exc)                {                    throw new XworkException(exc);                }    if(result instanceof List){                  OgnlContextState.setLastBeanPropertyAccessed(context,lastProperty+"_i");                  }                return result;            }        }        return super.getProperty(context, target, name);   // 单例   instance = new MoreXWorkListPropertyAccessor();  private MoreXWorkListPropertyAccessor{}   public MoreXWorkListPropertyAccessor getInstance(){return instance;}    }  

编写拦截器，设置MoreXWorkListPropertyAccessor;拦截器一定要配置在static-params之前

  public class MoreDimensesSupportInterceptor extends AroundInterceptor{    public void before(ActionInvocation invocation)throws Exception{      OgnlRuntime.setPropertyAccessor(List.class,MoreXWorkListPropertyAccessor.getInstance()); }}

现在只需在TestAction.properties中指定
Element_users=java.util.ArrayList //二维集合配置
Element_users_i=com.xxx.User //二维集合配置

Element_users=java.util.ArrayList //三维集合配置
Element_users_i=java.util.ArrayList //三维集合配置
Element_users_i_i=com.xxx.User //三维集合配置

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