/[projects]/miscJava/CircuitBreaker/src/main/java/dk/thoerup/circuitbreaker/web/CircuitBreakerServletBase.java
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CircuitBreaker/src/dk/thoerup/curcuitbreaker/web/CircuitBreakerServletHelper.java revision 411 by torben, Wed Oct 7 15:56:01 2009 UTC CircuitBreaker/src/dk/thoerup/circuitbreaker/web/CircuitBreakerServletBase.java revision 1307 by torben, Tue Apr 19 15:45:26 2011 UTC
# Line 1  Line 1 
1  package dk.thoerup.curcuitbreaker.web;  package dk.thoerup.circuitbreaker.web;
2    
3  import java.io.IOException;  import java.io.IOException;
4    
5  import javax.servlet.ServletException;  import javax.servlet.ServletException;
6    import javax.servlet.ServletRegistration;
7  import javax.servlet.http.*;  import javax.servlet.http.*;
8    
9  /**  /**
10   * This is a web interface for viewing and controlling the CircuitBreakers currently registered in CircuitBreakerManager   * This is a web interface for viewing and controlling the CircuitBreakers currently registered in CircuitBreakerManager
11   * <p>   * <p>
12   * To use this servlet in you .war module just create a simple servlet where doGet just delegates to this class' doGet method   * To use this servlet in you .war module just create a simple servlet that extends this class (instead of HttpServlet)
13   *   * The new custom servlet doesn't need to implement any of the standard servlet methods - its all done in this implementation.
14     *  
15     * <p>
16   * Example:   * Example:
17   * <pre>   * <pre>
18   * public class CircuitBreakerServlet extends HttpServlet {   * public class CircuitBreakerServlet extends CircuitBreakerServletBase {
19   *   private static final long serialVersionUID = 1L;   *   private static final long serialVersionUID = 1L;
  *    
  *   CircuitBreakerServletHelper helper = new CircuitBreakerServletHelper();  
  *   protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {  
  *     helper.doGet(req, resp);  
  *   }  
20   * }   * }
21   * </pre>   * </pre>
22     *
23     * If you add a servlet init pameter to your deployment descriptor with the name 'readonly' and a integer value > 0,  you can disable the
24     * control buttons:
25     * <p>
26     *   &lt;init-param>&lt;param-name>readonly&lt;/param-name>&lt;param-value>1&lt;/param-value>&lt;/init-param>
27     *   <!-- <init-param><param-name>readonly</param-name><param-value>1</param-value></init-param> -->
28     *  
29     *  You could also configure it dynamically from a ContextListener:
30     *  ServletRegistration.Dynamic dynconf = sce.getServletContext().addServlet("circuitbreaker", dk.thoerup.circuitbreaker.web.CircuitBreakerServletBase.class );
31     *  dynconf.addMapping("/CircuitBreakerServlet");
32     *  dynconf.setInitParameter("readonly", "1");
33     *
34   */   */
35    
36  public class CircuitBreakerServletHelper{  public class CircuitBreakerServletBase  extends javax.servlet.http.HttpServlet  {
37            
38            private static final long serialVersionUID = 1L;
39            
40            private boolean readOnly = false;
41            
42            
43                    
44            @Override
45            public void init() throws ServletException {
46                    super.init();
47                    
48                    String readOnlyStr = getInitParameter("readonly");
49                    if (readOnlyStr != null && readOnlyStr.trim().length() >0) {
50                            int readOnlyInt = Integer.parseInt(readOnlyStr.trim());
51                            readOnly = (readOnlyInt > 0);
52                    }
53            }
54    
55            private Command getCommand(String command) throws ServletException {
56                    if (command == null || command.equals("list"))
57                            return new ListCircuitBreakers();
58                    
59                    if (command.equals("view"))
60                            return new ViewCircuitBreaker(readOnly);
61                    if (command.equals("action"))
62                            return new ActionCommand(readOnly);
63                    if (command.equals("log"))
64                            return new LogViewCommand();
65                    
66                    throw new ServletException("No such command:" + command);
67            }
68    
69            @Override
70          public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {          public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
71                  ListCircuitBreakers cmd = new ListCircuitBreakers();                  Command cmd = getCommand( req.getParameter("command"));
72                                    
73                  String response = cmd.doCommand(req);                  String response = cmd.execute(req,resp);
74                                    
75                  resp.setDateHeader("Expires", 0);                  resp.setDateHeader("Expires", 0);
76                  resp.setHeader("Pragma", "no-cache");                  resp.setHeader("Pragma", "no-cache");
77                  resp.setHeader("Cache-Control", "no-cache");                  resp.setHeader("Cache-Control", "no-cache");
78                    resp.setContentType("text/html");
79                                    
80                  resp.getWriter().print(response);                  resp.getWriter().print(response);
81          }          }
82    
83            @Override
84            protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
85                    doGet(req, resp);
86            }
87    
88  }  }
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