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1 package example;
2
3 import java.io.PrintWriter  ;
4 import java.io.IOException ;
5
6 import javax.servlet.ServletException ;
7
8 import javax.servlet.http.HttpServlet ;
9 import javax.servlet.http.HttpServletRequest ;
10 import javax.servlet.http.HttpServletResponse ;
11
12 import javax.persistence.EntityManager;
13 import javax.persistence.PersistenceContext;
14
15
18 public class CourseServlet extends HttpServlet {
19 @PersistenceContext(name="example")
20 private EntityManager _manager;
21
22
25 public void init()
26 throws ServletException
27 {
28 CourseBean course = null;
29
30 try {
31 course = _manager.find(CourseBean.class, new Integer (1));
32 if (course != null)
33 return;
34 } catch (Exception e) {
35 }
36
37 _manager.getTransaction().begin();
38 try {
39 CourseBean potions = new CourseBean();
40 potions.setCourse("Potions");
41 potions.setTeacher("Severus Snape");
42
43 _manager.persist(potions);
44
45 CourseBean xfig = new CourseBean();
46 xfig.setCourse("Transfiguration");
47 xfig.setTeacher("Minerva McGonagall");
48
49 _manager.persist(xfig);
50 } finally {
51 _manager.getTransaction().commit();
52 }
53 }
54
55
58 public void service(HttpServletRequest req, HttpServletResponse res)
59 throws java.io.IOException , ServletException
60 {
61 PrintWriter out = res.getWriter();
62
63 res.setContentType("text/html");
64
65 CourseBean []course = new CourseBean[2];
66
67 course[0] = _manager.find(CourseBean.class, new Integer (1));
68 course[1] = _manager.find(CourseBean.class, new Integer (2));
69
70 out.println("<h3>Course Details</h3>");
71
72 for (int i = 0; i < course.length; i++) {
73 out.println("course: " + course[i].getCourse() + "<br>");
74 out.println("teacher: " + course[i].getTeacher() + "<br>");
75 out.println("<br>");
76 }
77 }
78 }
79 |
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Java API By Example, From Geeks To Geeks.