webwork与orm结合时，参数绑定的方法

问题1.从客户端传来的id,需要转化成持久化对象,webwork默认会为我们创建出空对象,但不满足,希望webwork能按照id值绑定持久化对象.
解决办法:创建自己的转化器
    1.创建xwork-conversion.properties,内容如下
            

com.abest.common.domain.CommonEntity=com.abest.common.EntityWebworkConverter

其中CommonEntity为所有持久化实体类的超类，更详细的资料见:
http://wiki.opensymphony.com/display/XW/XWork+Conversion

    2.实现自定义转换器

public class EntityWebworkConverter extends WebWorkTypeConverter {

    public static EntityWebworkConverterDelegate delegate = null;

    public EntityWebworkConverter() {
    }

    public Object convertFromString(Map map, String[] strings, Class toClass) {
        return delegate.convertFromString(map,strings,toClass);
    }

    public String convertToString(Map map, Object o) {
        return delegate.convertToString(map,o);
    }
}

public class EntityWebworkConverterDelegate extends WebWorkTypeConverter {

    private QueryService queryService = null;

    public EntityWebworkConverterDelegate(QueryService queryService) {
        this.queryService = queryService;
    }


    public Object convertFromString(Map map, String[] strings, Class toClass) {
        if(strings.length > 0)
        {
            int id = 0;
            try {
                id = Integer.parseInt(strings[0]);
            } catch (NumberFormatException e) {
            }
            if(id > 0)
            {
                return queryService.find(toClass,id);
            }
        }

        try {
            return toClass.newInstance();
        } catch (InstantiationException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }
    }

    public void setQueryService(QueryService queryService) {
        this.queryService = queryService;
    }


    public String convertToString(Map map, Object o) {
        return null;
    }
}

在这里，因为不了解webwork有什么合适的机制对converter的创建进行控制，因此，converter使用静态属性delegate，该属性由ServletContextListener来注入

这样便可完成参数的绑定了，页面传的参数形式，譬如 foo.bar=1即可

问题2:如何绑定到列表
1.使用java5泛型,xwork..-tiger.jar
2.客户端参数形式changedList[0].id=1,changedList[0].name=name,changedList[1].id=2,changedList[1].name=name2
3.预load对象,以使得其它属性能正确的绑定到对象中.处理逻辑为"先过滤出id,对起进行参数绑定,之后，再交由webwork自带的参数拦截器去绑定其它的参数",拦截器代码如下(保留使用原有的params拦截器):

public class AnotherGridEditDataBindInterceptor extends AroundInterceptor {
    protected void after(ActionInvocation actionInvocation, String s) throws Exception {

    }

    protected void before(ActionInvocation actionInvocation) throws Exception {
        Object action = actionInvocation.getAction();
        Map map = actionInvocation.getInvocationContext().getParameters();
        Map entityIdMap = new HashMap();
        for(int i = 0;i < 200;i++)
        {
            String key = "changedList[" + i + "].id";
            String[] ids = (String[]) map.get(key);
            if(ids != null && ids.length > 0)
            {
                entityIdMap.put("changedList["+i+"]",ids);
                map.remove(key);
            }
        }
        for(int i = 0;i < 200;i++)
        {
            String key = "newList[" + i + "].id";
            String[] ids = (String[]) map.get(key);
            if(ids != null && ids.length > 0)
            {
                entityIdMap.put("newList["+i+"]",ids);
                map.remove(key);
            }
        }
        bindParametersToTarget(entityIdMap,action);

    }



    private void bindParametersToTarget(Map propertiesValue, Object target) {
        ActionContext invocationContext = ActionContext.getContext();
        OgnlValueStack stack = null;
        Object preRoot = null;
        try {
            invocationContext.put(InstantiatingNullHandler.CREATE_NULL_OBJECTS, Boolean.TRUE);
            invocationContext.put(XWorkMethodAccessor.DENY_METHOD_EXECUTION, Boolean.TRUE);
            invocationContext.put(XWorkConverter.REPORT_CONVERSION_ERRORS, Boolean.TRUE);

            if (propertiesValue != null) {
                stack = ActionContext.getContext().getValueStack();
                preRoot = stack.pop();
                stack.push(target);

                for (Iterator iterator = propertiesValue.entrySet().iterator();
                     iterator.hasNext();) {
                    Map.Entry entry = (Map.Entry) iterator.next();
                    stack.setValue(entry.getKey().toString(), entry.getValue());
                }
            }
        } finally {
            invocationContext.put(InstantiatingNullHandler.CREATE_NULL_OBJECTS, Boolean.FALSE);
            invocationContext.put(XWorkMethodAccessor.DENY_METHOD_EXECUTION, Boolean.FALSE);
            invocationContext.put(XWorkConverter.REPORT_CONVERSION_ERRORS, Boolean.FALSE);
            if (preRoot != null) {
                stack.pop();
                stack.push(preRoot);
            }
        }
    }


}

其中，changedList表示的是修改过的对象，newList表示的是新增的对象

总结:需要建立Xwork的Converter,Interceptor。servlet的ServletContextListener为converter注入orm的持久对象查找方法;orm提供find(class,id)这样的方法