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visionary_2006
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doubleselect:如何数据从数据库里提取

JSPStrutsDAOfreemarkerC 
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今天在做PetStore时要用到doubleselect,但数据需要从数据库里提取.说说简单,做做难啊,下面,给大家看下代码:

sql1:
引用

DROP TABLE IF EXISTS `petstore`.`category`;
CREATE TABLE  `petstore`.`category` (
  `category_id` int(10) unsigned NOT NULL auto_increment COMMENT '类别ID',
  `category_name` varchar(45) character set utf8 NOT NULL COMMENT '类别名',
  `category_desc` varchar(500) character set utf8 default NULL COMMENT '详细描述',
  `category_url` varchar(100) character set utf8 default NULL COMMENT '图片URL',
  PRIMARY KEY  (`category_id`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk;


sql2:
引用

DROP TABLE IF EXISTS `petstore`.`product`;
CREATE TABLE  `petstore`.`product` (
  `product _id` int(10) unsigned NOT NULL auto_increment COMMENT '子类别ID',
  `product _name` varchar(45) NOT NULL COMMENT '子类别名',
  `product _desc` varchar(500) default NULL COMMENT '子类别图片URL',
  `product _url` varchar(100) default NULL COMMENT '详细描述',
  `category_id` int(10) unsigned NOT NULL COMMENT '类别ID',
  PRIMARY KEY  (`product _id`),
  KEY `FK_product_1` (`category_id`),
  CONSTRAINT `FK_product_1` FOREIGN KEY (`category_id`) REFERENCES `category` (`category_id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=gbk;


action: 
package petstore.action.redirect;

import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

import petstore.dao.CategoryDao;
import petstore.dao.ProductDao;
import petstore.model.Category;
import petstore.model.Product;

public class ItemAddRedirectAction extends ActionSupport {

    private static final long serialVersionUID = 1L;

    public static final String GLOBAL_CATEGORY = "global_category_list"; // 宠物大类列表
    public static final String GLOBAL_DOUBLE_LIST = "global_double_list"; // 宠物类列表

    private ProductDao productDao;
    private CategoryDao categoryDao;

    private List<Category> categorys;

    @SuppressWarnings("unchecked")
    private Map doubleMap = new HashMap();

    public List<Category> getCategorys() {
	return categorys;
    }

    public void setCategorys(List<Category> categorys) {
	this.categorys = categorys;
    }

    @SuppressWarnings("unchecked")
    public Map getDoubleMap() {
	return doubleMap;
    }

    @SuppressWarnings("unchecked")
    public void setDoubleMap(Map doubleMap) {
	this.doubleMap = doubleMap;
    }

    public void setProductDao(ProductDao productDao) {
	this.productDao = productDao;
    }

    public void setCategoryDao(CategoryDao categoryDao) {
	this.categoryDao = categoryDao;
    }

    @SuppressWarnings("unchecked")
    public String execute() throws Exception {
	
	//优化数据库性能
	categorys = (List) ActionContext.getContext().getSession().get(
		GLOBAL_CATEGORY);

	if (categorys == null) {
	    categorys = categoryDao.findAll();
	    ActionContext.getContext().getSession().put(GLOBAL_CATEGORY,
		    categorys);

	}

	for (int i = 0; i < categorys.size(); i++) {

	    List<Product> products = productDao
		    .findProductByCategoryId(categorys.get(i).getCategoryId());

	    List c = new LinkedList();
	    for (int j = 0; j < products.size(); j++) {

		c.add(products.get(j));
	    }
	    doubleMap.put(categorys.get(i), c);
	}
	return SUCCESS;
    }
}


jsp page:
引用

<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title><s:text name="additem_page" /></title>
</head>
<body>
<s:actionerror />
<p id="title">
增加宠物
</p>
<s:form action="itemAddAction" enctype="multipart/form-data" name="itemAdd" id="itemAdd">
<s:doubleselect name="category" list="a" doubleName="product"
doubleList="b.get(top)"></s:doubleselect>
<s:submit key="submit"></s:submit><s:reset key="reset"></s:reset>
</s:form>
</body>
</html>


struts.xml:
引用

<action name="directItemAdd" class="petstore.action.redrect.ItemAddRedirectAction">
<result>/jsp/itemAdd.jsp</result>
</action>


值得注意的是jsp这里,必须在form里加上name属性,名字随意
不加上的话会出现错误:
引用

FreeMarker template error!

Expression parameters.formName is undefined on line 98, column 43 in template/simple/doubleselect.ftl.
The problematic instruction:
----------
==> ${parameters.formName} [on line 98, column 41 in template/simple/doubleselect.ftl]
in include "/${parameters.templateDir}/simple/doubleselect.ftl" [on line 25, column 1 in template/xhtml/doubleselect.ftl]
----------


第二,还必须加上id,否则当第一次打加页面时会报错,联级菜单不会正常显示,须刷新后才能正常!
分享到：
| 在struts2.0和hibernate3.2开发中解决中文 ...
评论
3 楼 visionary_2006 2008-05-22  
值得注意的是jsp这里,必须在form里加上name属性,名字随意
不加上的话会出现错误:
2 楼 xiaomogui 2008-05-22  
我也遇到了相同的问题@@。没有解决啊。。。lz知道怎么解决了没有。。
1 楼 visionary_2006 2008-04-17  
doubleMap这里我不知道怎么放到actionContext里面去,我按上面做的话提示出错,不加的话就正确,有朋友会的指教一下,谢谢
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