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Java > Open Source Codes > example > cmp > ejbql > FindServlet


1 package example.cmp.ejbql;
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
11 import java.io.PrintWriter;
12
13 /**
14  * A client to illustrate entity bean finder methods
15  */
16 public class FindServlet extends HttpServlet {
17   private CourseHome _courseHome = null;
18   private TeacherHome _teacherHome = null;
19   private StudentHome _studentHome = null;
20   private HouseHome _houseHome = null;
21
22   /**
23    * Sets the local CourseHome
24    */
25   public void setCourseHome(CourseHome home)
26   {
27     _courseHome = home;
28   }
29
30   /**
31    * Sets the local TeacherHome
32    */
33   public void setTeacherHome(TeacherHome home)
34   {
35     _teacherHome = home;
36   }
37
38   /**
39    * Sets the local StudentHome
40    */
41   public void setStudentHome(StudentHome home)
42   {
43     _studentHome = home;
44   }
45
46   /**
47    * Sets the local HouseHome
48    */
49   public void setHouseHome(HouseHome home)
50   {
51     _houseHome = home;
52   }
53
54   public void init()
55     throws ServletException
56   {
57     try {
58       Context ic = new InitialContext();
59       // The JNDI context containing EJBs
60 Context cmp = (Context) ic.lookup("java:comp/env/cmp");
61
62       // get the bean stubs
63 if (_courseHome == null)
64         _courseHome = (CourseHome) cmp.lookup("ejbql_course");
65       if (_teacherHome == null)
66         _teacherHome = (TeacherHome) cmp.lookup("ejbql_teacher");
67       if (_studentHome == null)
68         _studentHome = (StudentHome) cmp.lookup("ejbql_student");
69       if (_houseHome == null)
70         _houseHome = (HouseHome) cmp.lookup("ejbql_house");
71
72     } catch (NamingException e) {
73       throw new ServletException(e);
74     }
75   }
76
77   public void service(HttpServletRequest req, HttpServletResponse res)
78     throws java.io.IOException, ServletException
79   {
80     PrintWriter out = res.getWriter();
81     res.setContentType("text/html");
82
83     try {
84       out.println("<H3>Students enrolled at Hogwarts</H3>");
85       Collection allStudents = _studentHome.findAll();
86       Iterator studentIter = allStudents.iterator();
87       
88       while (studentIter.hasNext()) {
89         out.println(((Student)studentIter.next()).getName() + "<BR>");
90       }
91
92       // Find out for all Students who their teachers are
93 out.println("<h3>Students are taking classes from these teachers:</h3>");
94       studentIter = allStudents.iterator();
95       
96       while (studentIter.hasNext()) {
97         Student student = (Student)studentIter.next();
98         String studentName = student.getName();
99         Iterator teacherIter =
100           _teacherHome.findByStudent(studentName).iterator();
101         out.println("<b>"+studentName+"'s teachers</b><BR>");
102         
103         if (! teacherIter.hasNext())
104           out.println(studentName + " is not taking any classes<BR>");
105         
106         while (teacherIter.hasNext())
107           out.println(((Teacher)teacherIter.next()).getName()+"<BR>");
108
109         out.println("<BR>");
110       }
111       
112       // Find out what classes are taken by Students in Gryffindor
113 String houseName = "Gryffindor";
114       out.println("<h3>Students in " + houseName +
115                   " are taking these classes:</h3>");
116       Collection courses = _courseHome.findByHouse("Gryffindor");
117       Iterator courseIter = courses.iterator();
118       
119       if (! courseIter.hasNext())
120         out.println("Students in " + houseName + " are lazy. " +
121                     "Nobody is taking any courses.<BR>");
122       
123       while (courseIter.hasNext()) {
124         Course course = (Course)courseIter.next();
125         out.println(course.getName() + " (taught by Professor " +
126                     course.getTeacher().getName() + ")<BR>");
127       }
128       
129       out.println("<BR>");
130     } catch (FinderException e) {
131       throw new ServletException(e);
132     }
133   }
134 }
135
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