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Java > Open Source Codes > example > cmp > create > CreateServlet


1 package example.cmp.create;
2
3 import javax.servlet.*;
4 import javax.servlet.http.*;
5
6 import javax.naming.*;
7 import javax.ejb.*;
8
9 import java.util.*;
10 import java.io.PrintWriter;
11
12 /**
13  * A client to illustrate the services of the CourseBean CMP bean.
14  */
15 public class CreateServlet extends HttpServlet {
16
17   private CourseHome _home = null;
18
19   /**
20    * Bean setter to configure the course home.
21    */
22   public void setCourseHome(CourseHome home)
23   {
24     _home = home;
25   }
26
27   /**
28    * gets a reference to the CourseBean home interface
29    */
30   public void init()
31     throws ServletException
32   {
33     if (_home == null) {
34       try {
35         Context ic = new InitialContext();
36
37         // get the house stub
38 _home = (CourseHome) ic.lookup("java:comp/env/cmp/create_CourseBean");
39       } catch (NamingException e) {
40         throw new ServletException(e);
41       }
42     }
43   }
44
45   public void service(HttpServletRequest req, HttpServletResponse res)
46     throws java.io.IOException, ServletException
47   {
48     PrintWriter out = res.getWriter();
49
50     res.setContentType("text/html");
51
52     out.println("<h3>Original classes</h3>");
53
54     try {
55       Collection c = _home.findAll();
56       Iterator iter = c.iterator();
57
58       while (iter.hasNext()) {
59         Course course = (Course) iter.next();
60
61         out.println(course.getCourseId() + " is taught by " +
62                     course.getInstructor() + "<br>");
63       }
64     } catch (FinderException e) {
65       throw new ServletException(e);
66     }
67
68     //
69 // Use the home interface to create 3 new Course entities.
70 //
71 // Because we employ CMP, each of the Courses will be automatically
72 // stored to a database table as we defined in cmp-create.ejb
73 //
74 Course divination = null;
75     Course creatures = null;
76
77     try {
78       out.println("<h3>Adding some classes</h3>");
79
80       //
81 // We can use any one of the create(...) methods defined in the local
82 // interface, Course.java. Each create(...) method needs matching
83 // ejbCreate(...) and ejbPostCreate(...) methods defined in the
84 // implementation class, CourseBean.java, with the same
85 // parameters.
86 //
87 // create(...) returns a new persistant entity, which means it also
88 // creates a new database column for the entity.
89
90       divination = _home.create("Divination", "Sybil Trelawney");
91       creatures = _home.create("Care of Magical Creatures", "Rubeus Hagrid");
92
93       Collection c = _home.findAll();
94       Iterator iter = c.iterator();
95
96       while (iter.hasNext()) {
97         Course course = (Course) iter.next();
98
99         out.println(course.getCourseId() + " is taught by " +
100                     course.getInstructor() + "<br>");
101       }
102     }
103     catch (Exception e) {
104       throw new ServletException(e);
105     }
106
107     out.println("<h3>Removing the new classes</h3>");
108
109     try {
110       if (divination != null)
111         divination.remove();
112       if (creatures != null)
113         creatures.remove();
114
115       Collection c = _home.findAll();
116       Iterator iter = c.iterator();
117
118       while (iter.hasNext()) {
119         Course course = (Course) iter.next();
120
121         out.println(course.getCourseId() + " is taught by " +
122                     course.getInstructor() + "<br>");
123       }
124     } catch (Exception e) {
125       throw new ServletException(e);
126     }
127   }
128 }
129
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