1. 在web.xml文件中注冊dwr
?? <servlet>
??? <servlet-name>dwr-invoker</servlet-name>
??? <display-name>DWR Servlet</display-name>
??? <description>Direct Web Remoter Servlet</description>
??? <servlet-class>uk.ltd.getahead.dwr.DWRServlet</servlet-class>
??? <init-param>
??????? <param-name>debug</param-name>
??????? <param-value>true</param-value>
??? </init-param>
?</servlet>
?<servlet-mapping>
??? <servlet-name>dwr-invoker</servlet-name>
??? <url-pattern>/dwr/*</url-pattern>
?</servlet-mapping>
?<welcome-file-list>
??? <welcome-file>search.jsp</welcome-file>
?</welcome-file-list>
2.dwr.xml
?<dwr>
??? <allow><convert convert="bean"? match="dwr.sample.Apartment"/>
??? <create>
?????????? <creator="new" javascript="ApartmentDAO" class="dwr.sample.ApartmentDAO">
????????????????? <include method="findApartments"/>
????????????????? <include method="countApartments"/>
?????????? </creator>
??? </create>
??? </allow>
</dwr>
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
???數據庫鏈接類
?? 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
?? 實現了ServletContextListerer接口的類
?? 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
?? 業務邏輯層
?? 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
? <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
? <title>DWR Example</title>
?? <style type="text/css" media="screen">
?????? @import url( style.css );
?? </style>?
?
? <script src='dwr/interface/ApartmentDAO.js'></script>
? <script src='dwr/engine.js'></script>
? <script src='dwr/util.js'></script>
? <script>
?
? function updateTotal() {
??? $("resultTable").style.display = 'none';
??? var bedrooms = document.getElementById("bedrooms").value;
??? var bathrooms = document.getElementById("bathrooms").value;
??? var price = document.getElementById("price").value;
??? ApartmentDAO.countApartments(loadTotal, bedrooms, bathrooms, price);
? }
? function updateResults() {
??? DWRUtil.removeAllRows("apartmentsbody");
??? var bedrooms = document.getElementById("bedrooms").value;
??? var bathrooms = document.getElementById("bathrooms").value;
??? var price = document.getElementById("price").value;
??? ApartmentDAO.findApartments(fillTable, bedrooms, bathrooms, price);
??? $("resultTable").style.display = '';
? }
?
? var getId = function(unit) { return unit.id };
? var getAddress = function(unit) { return unit.address };
? var getBedrooms = function(unit) { return unit.bedrooms };
? var getBathrooms = function(unit) { return unit.bathrooms };
? var getPrice = function(unit) { return unit.price };
???
? function loadTotal(data) {
??? document.getElementById("totalRecords").innerHTML = data;
? }
?
? function fillTable(apartment) {
??? DWRUtil.addRows("apartmentsbody", apartment, [ getId, getAddress, getBedrooms, getBathrooms, getPrice ]);
? }
?
</script>
</head>
<body onload="updateTotal();">
<h2>Find an apartment to rent</h2>
<table border="0">
<form name="rentalForm">
? <tr width="400">
?? <td width="100">City</td>
?? <td width="300">Toronto</td>
? </tr>
? <tr>
?? <td>Beds</td>
?? <td>
??? <select id="bedrooms" onchange="updateTotal()">
???? <option value="1">1 or more</option>
???? <option value="2">2 or more</option>
???? <option value="3">3 or more</option>
???? <option value="4">4 or more</option>
??? </select>
?? </td>
? </tr>
? <tr>
?? <td>Baths</td>
?? <td>
??? <select id="bathrooms" onchange="updateTotal()">
???? <option value="1">1 or more</option>
???? <option value="2">2 or more</option>
???? <option value="3">3 or more</option>
???? <option value="4">4 or more</option>
??? </select>
?? </td>
? </tr>
? <tr>
?? <td>Price</td>
?? <td>
??? <select id="price" onchange="updateTotal()">
???? <option value="800">under $800</option>
???? <option value="1000">under $1,000</option>
???? <option value="1250">under $1,250</option>
???? <option value="1500" selected="selected">under $1,500</option>
???? <option value="1800">under $1,800</option>
???? <option value="2000">under $2,000</option>
??? </select>
?? </td>
? </tr>
? <tr>
?? <td colspan="2">
??? <blockquote>
???? Available apartments: <span id="totalRecords" style="font-weight:bold;"></span>
??? </blockquote>
?? </td>
? </tr>
</form>
</table>
<p><input type="button" value="Show results!" onClick="updateResults();"></p>
<div id="resultTable">
<h2>Results</h2>
?<table border="1">
? <thead>
??? <tr>
????? <th width="40">Id</th>
????? <th width="180">Address</th>
????? <th width="60">Beds</th>
????? <th width="60">Baths</th>
????? <th width="60">Price</th>
??? </tr>
? </thead>
? <tbody id="apartmentsbody">
? </tbody>
?</table>
</div>
</body>
</html>
由于項目需要,需在我們現有的struts、hibernate工程上集成ajax功能.項目組決定使用Dwr.
剛開始研究Dwr.覺得真的很不錯, 只需很少量的代碼,就能在現有的工程上集成ajax技術. 期待Dwr有更輝煌的明天！
喜歡Dwr技術的IT界朋友可以與本人聯系！望提出好的意見與建議.