BlogJava-开源俱乐部-随笔分类-Ajax技术相关

Dwr---example

HandSoft — Sun, 21 Jan 2007 15:35:00 GMT

1. 在web.xml文件中注册dwr

    dwr-invoker
    DWR Servlet
    Direct Web Remoter Servlet
    uk.ltd.getahead.dwr.DWRServlet

        debug
        true


    dwr-invoker
    /dwr/*

    search.jsp

2.dwr.xml










3.DB
CREATE TABLE APARTMENTS (id INTEGER, bedrooms INTEGER, bathrooms INTEGER, price INTEGER, address VARCHAR, city VARCHAR, province VARCHAR);
INSERT INTO APARTMENTS VALUES (16001, 1, 1, 850, '123 King St. East', 'Toronto', 'ON');
INSERT INTO APARTMENTS VALUES (16002, 2, 1, 1000, '1023 Yonge Ave.', 'Toronto', 'ON');
INSERT INTO APARTMENTS VALUES (16003, 2, 2, 1050, '27 Winchester St.', 'Toronto', 'ON');
4.Apertment.java
普通的javabean
5.DBUtils.java
   数据库链接类
   public class DBUtils {

/*
* Creates the sample data (table and records).
*/
public static void setupDatabase(BufferedReader reader) {
  Connection c = null;
  Statement stmt = null;
  try {
   c = openConnection();
   stmt = c.createStatement();
   // reads the file with the SQL statements
   String line;
   while ((line = reader.readLine()) != null) {
    stmt.execute(line);
   }
   stmt.close();
   c.close();
  } catch (IOException e) {
   e.printStackTrace();
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   try {
    stmt.close();
    c.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
}

/*
* Opens a database connection.
*/
public static Connection openConnection() throws SQLException {
  Connection c = DriverManager.getConnection("jdbc:hsqldb:mem:dwr-sample", "sa", "");
  return c;
}

}

6.ContextListener.java
   实现了ServletContextListerer接口的类
   public class ContextListener implements javax.servlet.ServletContextListener {

/**
* This method is invoked when the Web Application has been removed and is
* no longer able to accept requests.
* @param event
*/
public void contextDestroyed(ServletContextEvent event) {
}

/**
* This method is invoked when the Web Application is ready to service requests.
* @param event
*/
public void contextInitialized(ServletContextEvent event) {
  try {
   // load the driver
   Class.forName("org.hsqldb.jdbcDriver");
   // create the table and add sample data
   InputStreamReader in = new InputStreamReader(getClass().getClassLoader().getResourceAsStream("db.sql"));
   BufferedReader reader = new BufferedReader(in);
   DBUtils.setupDatabase(reader);
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  }

}

}
7.ApartmentDAO.java
   业务逻辑层
   public class ApartmentDAO {

/**
* Returns the available apartments based on the search criteria.
* @param bedrooms minimum number of bedrooms
* @param bathrooms minimum number of bathrooms
* @param price maximum price to be paid
* @return
*/
public Collection findApartments(int bedrooms, int bathrooms, int price) {
  Collection list = new Vector();
  String sql = "select * from APARTMENTS" +
    createSearchWhereClause(bedrooms, bathrooms, price) +
    "order by bedrooms, bathrooms, price";

  // define db variables
  Connection c = null;
  Statement stmt = null;
  try {
   c = DBUtils.openConnection();
   stmt = c.createStatement();
   // just run the sql statement
   ResultSet rs = stmt.executeQuery(sql);
   while(rs.next()) {
    Apartment apartment = this.getApartment(rs);
    list.add(apartment);
   }
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   try {
    stmt.close();
    c.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }

  return list;
}

/**
* Returns the number of available apartments based on the search criteria.
* @param bedrooms minimum number of bedrooms
* @param bathrooms minimum number of bathrooms
* @param price maximum price to be paid
* @return
*/
public int countApartments(int bedrooms, int bathrooms, int price) {
  String sql = "select count(*) as total from APARTMENTS" + createSearchWhereClause(bedrooms, bathrooms, price);
  int numberApartments = -1;
  // define db variables
  Connection c = null;
  Statement stmt = null;
  try {
   c = DBUtils.openConnection();
   stmt = c.createStatement();
   // just run the sql statement
   ResultSet rs = stmt.executeQuery(sql);
   if (rs.next()) {
    numberApartments = rs.getInt("total");
   }
  } catch (SQLException e) {
   e.printStackTrace();
  } finally {
   try {
    stmt.close();
    c.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }

  return numberApartments;
}

/**
* Creates a Unit object from the database.
* @param rs
* @return
* @throws SQLException
*/
private Apartment getApartment(ResultSet rs) throws SQLException {
  Apartment ap = new Apartment();
  ap.setId(rs.getInt("id"));
  ap.setAddress(rs.getString("address"));
  ap.setBedrooms(rs.getInt("bedrooms"));
  ap.setBathrooms(rs.getInt("bathrooms"));
  ap.setPrice(rs.getInt("price"));
  ap.setCity(rs.getString("city"));
  ap.setProvince(rs.getString("province"));
  return ap;
}

/**
* Creates the where clause for the search SQL statement.
* @param bedrooms
* @param bathrooms
* @param price
* @return
*/
private String createSearchWhereClause(int bedrooms, int bathrooms, int price) {
  String where = " where bedrooms >= " + bedrooms +
    " and bathrooms >= " + bathrooms +
    " and price < " + price;
  return where;
}

}
8. search.jsp

DWR Example

Find an apartment to rent

City	Toronto
Beds
Baths
Price
Available apartments:

Results

Id	Address	Beds	Baths	Price

由于项目需要,需在我们现有的struts、hibernate工程上集成ajax功能.项目组决定使用Dwr.
刚开始研究Dwr.觉得真的很不错, 只需很少量的代码,就能在现有的工程上集成ajax技术. 期待Dwr有更辉煌的明天！
喜欢Dwr技术的IT界朋友可以与本人联系！望提出好的意见与建议.

HandSoft 2007-01-21 23:35 发表评论

Dwr

HandSoft — Sun, 21 Jan 2007 07:59:00 GMT

Ajax，或者说是异步JavaScript和XML，描述了一种使用混合了HTML(或XHTML)和层叠样式表作为表达信息,来创建交互式的Web应用的开发技术;文档对象模型(DOM)，JavaScript,动态地显示和与表达信息进行交互;并且，XMLHttpRequest对象与Web服务器异步地交换和处理数据。

　　因特网上许多例子展示了在一个HTML文件内部使用XMLHttpRequest与服务器端进行交互的必要的步骤。当手工地编写和维护XMLHttpRequest代码时，开发者必须处理许多潜在的问题，特别是类似于跨浏览器的DOM实现的兼容性这样的问题。这将会导致在编码和调试Javascript代码上面花费数不清的时间，这显然对开发者来说很不友好。

　　DWR(直接Web远程控制)项目是在Apache许可下的一个开源的解决方案，它供给那些想要以一种简单的方式使用Ajax和XMLHttpRequest的开发者。它具有一套Javascript功能集，它们把从HTML页面调用应用服务器上的Java对象的方法简化了。它操控不同类型的参数，并同时保持了HTML代码的可读性。
一. Util.js
      util.js包含一系列的工具函数使用javascript返回的数据来帮助更新Web页面。
util.js中有四种基本的页面操作函数:
getValue[s];setValue[s]可以和除过tables、lists、images的大部分的html元素交互.
getText()可以和选择列表(select lists)交互.
编辑tables用addRows()和removeAllRows()方法.编辑列表(选择lists和ul,ol列表)用
addOptions()和removeAllOptions().
1.${}
${}函数是一个(javascript)全局变量.
$=document.getElementById
'$'可以通过给定的'ID'取得HTML文档元素.他也可返回一个包含返回元素的数组.
2.Generating Lists
DWRUtil.addOptions()描述了下拉列表的实现
var sel = DWRUtil.getValue(id);
DWRUtil.removeAllOptions(id);
DWRUtil.addOptions(id,...);
DWRUtil.setValue(id,sel);
如果想要添加"请选择..."项,可以添加以下项: DWRUtil.addOptions(id,["Please select ..."]);
DWRUtil.addOptions有四种使用模式:
Array:
       DWRUtil.addOptions(selectid,array)和用文本和值创建了选择列表.
Array of Objects(using option text = option value):
       DWRUtil.addOptions(selectid,data,prop)用数组元素创建了选择列表,选择列表中的值和文本设定为
       数组中的每个对象的属性.
Array of objects(with differing option text and value):
       DWRUtil.addOptions(selectid,array,valueprop,textprop)
Object:
       DWRUtil.addOptions(selectid,map,reverse)
Map of object:
       DWRUtil.addOptions(ulid,array)

HandSoft 2007-01-21 15:59 发表评论

科以人重科亦重，人以科传人可知

HandSoft — Wed, 27 Sep 2006 06:16:00 GMT

本人毕业于西安电子科技大学，本科。热爱软件开发，精通JAVA .熟悉Struts,Spring,Hibernate,Jboss,Eclipse等多种开源技术。
现主要从事于Oracle相关产品的开发。有着ERP,CRM,MES系统的开发经验，目前正着手于Struts与Ajax技术的集成系统的开发，
官方给出的AjaxTags也只是测试版，此技术正处于起步阶段。望对此技术有研究的朋友与我联系，给出指点。
真诚结交IT届同仁，共同学习，共同交流。构建和谐社会。
QQ: 541638655
MSN: jucracker@hotmail.com
Phone: 13817080595

HandSoft 2006-09-27 14:16 发表评论