Java/Servlets/Error Exceptions
Содержание
Error code
<source lang="java">
import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class Sender extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
/*
* if the servlet tries to access a resource and finds out that the
* client is not authorized to access it - "401 Unauthorized"
*/
//response.sendError(401,"You are not authorized to view the requested
// component");
/*
* if the servlet tries to access a resource that is forbidden for this
* client and there is no further information on it - "403 Forbidden"
*/
response.sendError(403);
/*
* if the servlet tries to access a resource that is not found given the
* client"s provided URL - "404 Not Found"
*/
//response.sendError(404);
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
doPost(request, response);
}
}
</source>
Generate errors
<source lang="java">
import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ErrorGen extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
//check the servlet exception
Throwable throwable = (Throwable) request
.getAttribute("javax.servlet.error.exception");
String servletName = (String) request
.getAttribute("javax.servlet.error.servlet_name");
if (servletName == null)
servletName = "Unknown";
String requestUri = (String) request
.getAttribute("javax.servlet.error.request_uri");
if (requestUri == null)
requestUri = "Unknown";
response.setContentType("text/html");
java.io.PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Error page</title>");
out.println("</head>");
out.println("<body>");
if (throwable == null) {
out.println("The error information is not available
"); out.println("Please return to the ");
} else {
out.println("Here is the error information
"); out
.println("The servlet name associated with throwing the exception: "
+ servletName + "
");
out.println("The type of exception: "
+ throwable.getClass().getName() + "
");
out.println("The request URI: " + requestUri + "
");
out.println("The exception message: " + throwable.getMessage());
}
out.println("</body>");
out.println("</html>");
out.close();
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
doPost(request, response);
}
}
</source>
Servlet throws Exceptions
<source lang="java">
import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class Thrower extends HttpServlet {
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
throw new java.io.IOException("IO thrown");
//response.sendError(403);
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
doPost(request, response);
}
}
</source>
