星期一, 五月 04, 2009

google appengine for java初体验 - - Java - JavaEye论坛 - 使用 Google 工具栏发送

google appengine for java初体验 - - Java - JavaEye论坛

相信google推出支持java appengine的大好消息在java圈中早已“炸开”，我在javaeye上看到这则新闻，第一反应就是立即注册——下载sdk包——动手体验。

感觉很爽，这个感觉是一切进展得很顺带来的。

注册：http://appengine.google.com/promo/java_runtime

kickstart: http://code.google.com/appengine/docs/java/gettingstarted/installing.html

跟着这个kickstart主要下载了for java的sdk包，然后安装一个eclipse plugin.

下载完sdk包到bin目录下就可以运行自带的guestbook sample:

Java代码
  1. dev_appserver.cmd ../dmos/guestbook/war 
 dev_appserver.cmd ../dmos/guestbook/war

看到了吧，熟悉的server启动

Java代码
  1. The server is running at http://localhost:8080/ 
The server is running at http://localhost:8080/

哈哈，赶紧打开ff

这个程序很简单，就是一个简单信息输入，post,然后页面显示post内容，不过，有一点不同的是，这些post内容已经被guestbook写到数据库当中持久化了！（什么数据库？！）

打开eclipse，你会发现多了几个按钮：

没错，这是google appengile for eclipse给你加的，你可以创建一个新的googleapp项目：

创建完成后，你可以看到一个完整的工程文件，是不是很熟悉？没错，跟一个web app没什么两样

你不用改动任何文件，立即运行，看看你的第一个google app:

你一定猜到了，google appengine eclipse plugin给你生成的是一个gwt ajax应用，呵呵，你立即进入到web2.0时代了。

很简单，很easy，google appengine for java很令人心动。。。

简单小结一下：

1. appengine for java开发包相当友好

2. appengine for java对ide也相当友好

3. appengine for java的webapp就是一个war

4. appengine for java开发包使用了geronimo

5. appengine for java使用了jdo作为数据接口

6. appengine for java支持gwt

8. appengine for java可以写jsp和servlet

9. appengine for java开发包使用了jetty和javadb?

...

来看看一段代码吧，一切尽在代码中

Java代码
  1. <%@ page contentType="text/html;charset=UTF-8" language="java" %>
  2. <%@ page import="java.util.List" %>
  3. <%@ page import="javax.jdo.PersistenceManager" %>
  4. <%@ page import="com.google.appengine.api.users.User" %>
  5. <%@ page import="com.google.appengine.api.users.UserService" %>
  6. <%@ page import="com.google.appengine.api.users.UserServiceFactory" %>
  7. <%@ page import="guestbook.Greeting" %>
  8. <%@ page import="guestbook.PMF" %>
  10. <html>
  11. <head>
  12. <link type="text/css" rel="stylesheet" href="/stylesheets/main.css" />
  13. </head>
  15. <body>
  17. <%
  18. UserService userService = UserServiceFactory.getUserService();
  19. User user = userService.getCurrentUser();
  20. if (user != null) {
  21. %>
  22. <p>Hello, <%= user.getNickname() %>! (You can
  23. <a href="<%= userService.createLogoutURL(request.getRequestURI()) %>">sign out</a>.)</p>
  24. <%
  25. } else {
  26. %>
  27. <p>Hello!
  28. <a href="<%= userService.createLoginURL(request.getRequestURI()) %>">Sign in</a>
  29. to include your name with greetings you post.</p>
  30. <%
  31. }
  32. %>
  34. <%
  35. PersistenceManager pm = PMF.get().getPersistenceManager();
  36. String query = "select from " + Greeting.class.getName() + " order by date desc range 0,5";
  37. List<Greeting> greetings = (List<Greeting>) pm.newQuery(query).execute();
  38. if (greetings.isEmpty()) {
  39. %>
  40. <p>The guestbook has no messages.</p>
  41. <%
  42. } else {
  43. for (Greeting g : greetings) {
  44. if (g.getAuthor() == null) {
  45. %>
  46. <p>An anonymous person wrote:</p>
  47. <%
  48. } else {
  49. %>
  50. <p><b><%= g.getAuthor().getNickname() %></b> wrote:</p>
  51. <%
  52. }
  53. %>
  54. <blockquote><%= g.getContent() %></blockquote>
  55. <%
  56. }
  57. }
  58. pm.close();
  59. %>
  61. <form action="/sign" method="post">
  62. <div><textarea name="content" rows="3" cols="60"></textarea></div>
  63. <div><input type="submit" value="Post Greeting" /></div>
  64. </form>
  66. </body>
  67. </html> 
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ page import="java.util.List" %> <%@ page import="javax.jdo.PersistenceManager" %> <%@ page import="com.google.appengine.api.users.User" %> <%@ page import="com.google.appengine.api.users.UserService" %> <%@ page import="com.google.appengine.api.users.UserServiceFactory" %> <%@ page import="guestbook.Greeting" %> <%@ page import="guestbook.PMF" %>  <html>   <head>     <link type="text/css" rel="stylesheet" href="/stylesheets/main.css" />   </head>    <body>  <%     UserService userService = UserServiceFactory.getUserService();     User user = userService.getCurrentUser();     if (user != null) { %> <p>Hello, <%= user.getNickname() %>! (You can <a href="<%= userService.createLogoutURL(request.getRequestURI()) %>">sign out</a>.)</p> <%     } else { %> <p>Hello! <a href="<%= userService.createLoginURL(request.getRequestURI()) %>">Sign in</a> to include your name with greetings you post.</p> <%     } %>  <%     PersistenceManager pm = PMF.get().getPersistenceManager();     String query = "select from " + Greeting.class.getName() + " order by date desc range 0,5";     List<Greeting> greetings = (List<Greeting>) pm.newQuery(query).execute();     if (greetings.isEmpty()) { %> <p>The guestbook has no messages.</p> <%     } else {         for (Greeting g : greetings) {             if (g.getAuthor() == null) { %> <p>An anonymous person wrote:</p> <%             } else { %> <p><b><%= g.getAuthor().getNickname() %></b> wrote:</p> <%             } %> <blockquote><%= g.getContent() %></blockquote> <%         }     }     pm.close(); %>      <form action="/sign" method="post">       <div><textarea name="content" rows="3" cols="60"></textarea></div>       <div><input type="submit" value="Post Greeting" /></div>     </form>    </body> </html>

这是guestbook的jsp文件，麻雀虽小五脏俱全，尤其注意读数据那块！

数据库可以在\WEB-INF\appengine-generated\local_db.bin中找到。

再来看看web.xml文件：

Xml代码
  1. <?xml version="1.0" encoding="utf-8"?>
  2. <!DOCTYPE web-app PUBLIC
  3. "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
  4. "http://java.sun.com/dtd/web-app_2_3.dtd">
  6. <web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">
  7. <servlet>
  8. <servlet-name>guestbook</servlet-name>
  9. <servlet-class>guestbook.GuestbookServlet</servlet-class>
  10. </servlet>
  11. <servlet-mapping>
  12. <servlet-name>guestbook</servlet-name>
  13. <url-pattern>/guestbook</url-pattern>
  14. </servlet-mapping>
  16. <servlet>
  17. <servlet-name>sign</servlet-name>
  18. <servlet-class>guestbook.SignGuestbookServlet</servlet-class>
  19. </servlet>
  20. <servlet-mapping>
  21. <servlet-name>sign</servlet-name>
  22. <url-pattern>/sign</url-pattern>
  23. </servlet-mapping>
  25. <welcome-file-list>
  26. <welcome-file>guestbook.jsp</welcome-file>
  27. <welcome-file>index.html</welcome-file>
  28. </welcome-file-list>
  29. </web-app> 
<?xml version="1.0" encoding="utf-8"?> <!DOCTYPE web-app PUBLIC  "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"  "http://java.sun.com/dtd/web-app_2_3.dtd">  <web-app xmlns="http://java.sun.com/xml/ns/javaee" version="2.5">     <servlet>         <servlet-name>guestbook</servlet-name>         <servlet-class>guestbook.GuestbookServlet</servlet-class>     </servlet>     <servlet-mapping>         <servlet-name>guestbook</servlet-name>         <url-pattern>/guestbook</url-pattern>     </servlet-mapping>      <servlet>         <servlet-name>sign</servlet-name>         <servlet-class>guestbook.SignGuestbookServlet</servlet-class>     </servlet>     <servlet-mapping>         <servlet-name>sign</servlet-name>         <url-pattern>/sign</url-pattern>     </servlet-mapping>      <welcome-file-list>         <welcome-file>guestbook.jsp</welcome-file>         <welcome-file>index.html</welcome-file>     </welcome-file-list> </web-app>

除此之外,appengine还有一个配置appengine-web.xml

Xml代码
  1. <?xml version="1.0" encoding="utf-8"?>
  2. <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">
  3. <application></application>
  4. <version>1</version>
  6. <system-properties>
  7. <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>
  8. </system-properties>
  9. </appengine-web-app> 
<?xml version="1.0" encoding="utf-8"?> <appengine-web-app xmlns="http://appengine.google.com/ns/1.0">     <application></application>     <version>1</version>      <system-properties>         <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>     </system-properties> </appengine-web-app>

呵呵，明显是用了java的log机制，有了这个开发就省心了。

粗粗的一看，的确让人期待，google的东西的确不赖。

(补充：发布你的app,也很简单，点开google小飞机：

用过picassa会有种似曾相识的感觉

)

发帖者 ivivian 时间： 星期一, 五月 04, 2009

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