利用Jmesa处理List<Map>方法

<本篇文章是与从同事的博客上拿来学习,代码做一点我的.呵....>

Jmesa中处理Map的List对象
目前需求, 客户上传excel文件, 有列名, 列名不固定, 想预览数据, 使用Jmesa做table, 有两种实现方法. 第一种使用动态类, 封装map对象. 第二种是一种巧妙的方法. 下面先介绍第一种方法:
使用动态类:

package com.founder.cst.action;

import Java.util.ArrayList;
import Java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BasicDynaBean;
import org.apache.commons.beanutils.BasicDynaClass;
import org.apache.commons.beanutils.DynaBean;
import org.apache.commons.beanutils.DynaClass;
import org.apache.commons.beanutils.DynaProperty;
import org.jmesa.core.filter.MatcherKey;
import org.jmesa.facade.TableFacade;
import org.jmesa.facade.TableFacadeFactory;
import org.jmesa.view.html.component.HtmlTable;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.web.bind.annotation.RequestMapping;

import com.founder.cst.common.StringFilterMatcher;

@Controller
@RequestMapping
public class DynaController {

 @RequestMapping
 public String books(final HttpServletRequest request, HttpServletResponse response, ModelMap model){

  DynaClass  bookClass = createBasicDynaClass();
  try {
 //get parsed result
  List<Map<String,String>> sdfList = (List<Map<String, String>>)sdfMap.get("result");
  String[] keys = (String[]) sdfMap.get("fields");
  
  //set fields to dynamic class
   DynaClass  structureClass = createBasicDynaClass(keys);
		
  //set property to dynamic object.
   List<DynaBean> results = new ArrayList<DynaBean>();
   for (Map<String, String> structure : sdfList) {
       DynaBean stru = structureClass.newInstance();
       for (String key : keys) {
	stru.set(key, structure.get(key));
	}
	results.add(stru);
    }
   
   TableFacade tableFacade = TableFacadeFactory.createTableFacade("booksTable", request);
   
   tableFacade.setColumnProperties("id", "name", "price");
   tableFacade.setMaxRows(10);
   tableFacade.setMaxRowsIncrements(10, 20, 30);
   tableFacade.setItems(results);
   HtmlTable table = (HtmlTable) tableFacade.getTable();
   table.getTableRenderer().setWidth("558px");
   table.getRow().setUniqueProperty("id");
   String html = tableFacade.render();
   model.addAttribute("html", html);
  } catch (IllegalAccessException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  } catch (InstantiationException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }
  return "books";
 }
 
 private DynaClass createBasicDynaClass(String[] keys) {
		DynaClass dynaClass = null;
        //create basic field for dynaClass
		int columnSize = keys.length;
        DynaProperty[] dynaProps = new DynaProperty[columnSize];
        for (int i = 0; i < columnSize; i++) {
        	dynaProps[i] = new DynaProperty(keys[i], String.class); 
        }
       
        //create map filed for dynaClass
        dynaClass = new BasicDynaClass("Structures",    BasicDynaBean.class, dynaProps);
        return dynaClass;
    }


}

下面第二种:

@RequestMapping
 public String bookslist(final HttpServletRequest request, HttpServletResponse response, ModelMap model){
  List<Map<String, String>> books = new ArrayList<Map<String, String>>();
  Map<String, String> book1 = new HashMap<String, String>();
  book1.put("id", "1");
  book1.put("name", "Spring");
  book1.put("price", "18.29");
  books.add(book1);
  
  Map<String, String> book2 = new HashMap<String, String>();
  book2.put("id", "2");
  book2.put("name", "Hibernate");
  book2.put("price", "28.98");
  books.add(book2);
  
  Map<String, String> book3 = new HashMap<String, String>();
  book3.put("id", "3");
  book3.put("name", "Python");
  book3.put("price", "38.22");
  books.add(book3);
  
  model.addAttribute("books", books);
  return "booklist";
 }

页面为:

<jmesa:tableFacade 
     id="booksTable" 
     items="${books}"
     maxRows="10" 
     maxRowsIncrements="10,20,30" 
     var="book">
     <jmesa:htmlTable width="630px">
      <jmesa:htmlRow>
       <c:forEach items="${book}" var="b">
       <jmesa:htmlColumn property="${b.key}" title="${b.key}" filterable="false"/>
       </c:forEach>
      </jmesa:htmlRow>
     </jmesa:htmlTable>
    </jmesa:tableFacade>

这里注意property中的值.

今天查看源码, 和昨天想象一样,  jmesa在渲染单元格的时候, 分两种, 一种就是map类型, 使用get(key)来取值, 另一种就是普通的javabean对象, 使用getPropertyName()取值渲染.

/*
 * Copyright 2004 original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jmesa.util;

import Java.util.Collection;
import Java.util.Map;

import org.apache.commons.beanutils.PropertyUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * General utilities to process the Collecton of Beans or the Collection of
 * Maps. Most methods wrap or add value to the commons Beanutils.
 * 
 * @since 2.1
 * @author Jeff Johnston
 */
public class ItemUtils {

    private static final Logger logger = LoggerFactory.getLogger(ItemUtils.class);
    public static final String JMESA_ITEM = "jmesa-item";

    private ItemUtils() {
        // hide constructor
    }

    /**
     * Get the value from the Bean or Map by property.
     * 
     * @param item The Bean or Map.
     * @param property The Bean attribute or Map key.
     * @return The value from the Bean or Map.
     */
    public static Object getItemValue(Object item, String property) {
        Object itemValue = null;

        try {
            if (item instanceof Map) {
                itemValue = ((Map<?, ?>) item).get(property);
                if (itemValue != null) {
                    return itemValue;
                }

                // ports such as the tags will store the original bean
                Object bean = ((Map<?, ?>) item).get(JMESA_ITEM);                if (bean == null) {
                    logger.debug("the map does not have property " + property);
                    return null;
                }

                itemValue = getItemValue(bean, property);
            } else {
                itemValue = PropertyUtils.getProperty(item, property);
            }
        } catch (Exception e) {
            logger.debug("item class " + item.getClass().getName() + " does not have property " + property);
        }

        return itemValue;
    }

    /**
     * Get the Class for the property.
     * 
     * @param items The Collection of Beans or Maps.
     * @param property The Bean attribute or Map key.
     * @return The Class for the property.
     */
    public static Class<?> getPropertyClassType(Collection<?> items, String property)
        throws Exception {

        Object item = items.iterator().next();

        if (item instanceof Map) {
            for (Object object : items) {
                Map map = (Map) object;
                Object val = map.get(property);

                if (val == null) {
                    continue;
                }

                return val.getClass();
            }
        }

        return PropertyUtils.getPropertyType(item, property);
    }
}