Revize 092ba8cb

#24 throws exceptions early, catch them late

- throw own exception and handle it with error page

sources/imiger-core/src/main/java/cz/zcu/kiv/offscreen/servlets/DataAccessError.java

@@ +1 @@
+package cz.zcu.kiv.offscreen.servlets;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+public class DataAccessError extends HttpServlet {
+
+    @Override
+    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        handleRequest(req, resp);
+    }
+
+    @Override
+    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        handleRequest(req, resp);
+    }
+
+
+    private void handleRequest(HttpServletRequest request, HttpServletResponse response) throws IOException {
+        Throwable throwable = (Throwable) request.getAttribute("javax.servlet.error.exception");
+        response.setContentType("application/json");
+        PrintWriter out = response.getWriter();
+
+        JsonObject json = new JsonObject();
+        json.addProperty("exception", throwable.getMessage());
+
+        out.println(new Gson().toJson(json));
+    }
+}

sources/imiger-core/src/main/java/cz/zcu/kiv/offscreen/user/DB.java

@@ -34 +34 @@
 			connection.setAutoCommit(true);
 		} catch (ClassNotFoundException | SQLException e) {
 			logger.error("Can not open database connection: ", e);
+			throw new DataAccessException(e);
 		}
 	}
 
@@ -43 +44 @@
 	 * @param query query with ? on values.
 	 * @param returnGeneratedKeys true - RETURN_GENERATED_KEYS flag is set, false - no flag is set
 	 */
-	PreparedStatement getPreparedStatement(String query, boolean returnGeneratedKeys) throws SQLException {
-		if (returnGeneratedKeys) {
-			return connection.prepareStatement(query, PreparedStatement.RETURN_GENERATED_KEYS);
-		} else {
-			return connection.prepareStatement(query);
+	PreparedStatement getPreparedStatement(String query, boolean returnGeneratedKeys) {
+		try {
+			if (returnGeneratedKeys) {
+				return connection.prepareStatement(query, PreparedStatement.RETURN_GENERATED_KEYS);
+			} else {
+				return connection.prepareStatement(query);
+			}
+		}catch (SQLException e){
+			logger.error("Can not execute query: " + query);
+			throw new DataAccessException(e);
 		}
 	}
 
@@ -63 +69 @@
 			return preparedStatement.getResultSet();
 		} catch (SQLException e) {
 			logger.error("Can not execute database query: ", e);
+			throw new DataAccessException(e);
 		}
-		return null;
 	}
 
 	/**
@@ -78 +84 @@
 			return preparedStatement.getGeneratedKeys();
 		} catch (SQLException e) {
 			logger.error("Can not execute database query: ", e);
+			throw new DataAccessException(e);
 		}
-		return null;
 	}
 
 	/**
@@ -95 +101 @@
 
 		} catch(SQLException | NullPointerException e) {
 			logger.error("Can not execute database query: ", e);
+			throw new DataAccessException(e);
 		}
-		return null;
 	}
 
 	/**
@@ -107 +113 @@
 	int executeStatement(PreparedStatement preparedStatement) {
 		try {
 			return preparedStatement.executeUpdate();
-		} catch(SQLException e) {
-			logger.error("Can not execute database query: ", e);
-			return -1;
-		} catch (NullPointerException e) {
+		} catch(NullPointerException | SQLException e) {
 			logger.error("Can not execute database query: ", e);
-			return -2;
+			throw new DataAccessException(e);
 		}
 	}
 

sources/imiger-core/src/main/java/cz/zcu/kiv/offscreen/user/DataAccessException.java

@@ +1 @@
+package cz.zcu.kiv.offscreen.user;
+
+public class DataAccessException extends RuntimeException {
+
+    public DataAccessException(Throwable cause) {
+        super(cause);
+    }
+}

sources/imiger-core/src/main/java/cz/zcu/kiv/offscreen/user/Diagram.java

@@ -58 +58 @@
             }
         }  catch (SQLException e){
             logger.error("Can not get owner id: ", e);
+            throw new DataAccessException(e);
         }
         return -1;
     }
@@ -78 +79 @@
             }
         }  catch (SQLException e){
             logger.error("Can not check if diagram is public: ", e);
+            throw new DataAccessException(e);
         }
         return false;
     }
@@ -97 +99 @@
             }
         }  catch (SQLException e){
             logger.error("Can not get json of diagram: ", e);
+            throw new DataAccessException(e);
         }
         return "";
     }
@@ -120 +123 @@
 
         } catch (SQLException e) {
             logger.error("Can not get diagram: ", e);
+            throw new DataAccessException(e);
         }
 
         return Collections.emptyMap();
@@ -172 +176 @@
             }
         } catch (SQLException e) {
             logger.error("Can not update diagram: ", e);
+            throw new DataAccessException(e);
         }
     }
 
@@ -190 +195 @@
 
         } catch (SQLException e) {
             logger.error("Can not delete diagram: ", e);
+            throw new DataAccessException(e);
         }
     }
 
@@ -235 +241 @@
 
         } catch (SQLException e){
             logger.error("Can not create map from input result set: ", e);
+            throw new DataAccessException(e);
         }
-
-        return new ArrayList<>();
     }
 
     /**

sources/imiger-core/src/main/java/cz/zcu/kiv/offscreen/user/User.java

@@ -62 +62 @@
 			}
 		} catch (SQLException | IllegalArgumentException e) {
 			logger.error("Can not login user: ", e);
+			throw new DataAccessException(e);
 		}
 
 		return false;
@@ -98 +99 @@
 
 		} catch (SQLException e) {
 			logger.error("Can not register user: ", e);
+			throw new DataAccessException(e);
 		}
 	}
 
@@ -130 +132 @@
 			}
 		} catch (SQLException e) {
 			logger.error("Can not get user: ", e);
+			throw new DataAccessException(e);
 		}
 
 		return Collections.emptyMap();
@@ -159 +162 @@
 
 			} catch (SQLException e) {
 				logger.error("Can not get user session: ", e);
+				throw new DataAccessException(e);
 			}
 		}
 	}
@@ -181 +185 @@
 				db.executeStatement(pst);
 			} catch (SQLException e) {
 				logger.error("Can not update user: ", e);
+				throw new DataAccessException(e);
 			}
 		}
 	}
@@ -199 +204 @@
 				}
 			}  catch (SQLException e){
 				logger.error("Can not get users nick name: ", e);
+				throw new DataAccessException(e);
 			}
 		}
 
@@ -241 +247 @@
 			}
 		} catch (SQLException e) {
 			logger.error("Can not check if user exits: ", e);
+			throw new DataAccessException(e);
 		}
 
 		return false;

sources/imiger-core/src/main/webapp/WEB-INF/web.xml

@@ -80 +80 @@
 		<servlet-name>RestRawInput</servlet-name>
 		<servlet-class>cz.zcu.kiv.offscreen.servlets.rest.RawInput</servlet-class>
 	</servlet>
+	<servlet>
+		<servlet-name>DataAccessError</servlet-name>
+		<servlet-class>cz.zcu.kiv.offscreen.servlets.DataAccessError</servlet-class>
+	</servlet>
 
 	<!--
 	URL-to-servlet mappings
@@ -132 +136 @@
 		<servlet-name>RestRawInput</servlet-name>
 		<url-pattern>/rest/raw-input</url-pattern>
 	</servlet-mapping>
+	<servlet-mapping>
+		<servlet-name>DataAccessError</servlet-name>
+		<url-pattern>/data-access-error</url-pattern>
+	</servlet-mapping>
+
+	<error-page>
+		<exception-type>cz.zcu.kiv.offscreen.user.DataAccessException</exception-type>
+		<location>/data-access-error</location>
+	</error-page>
 
 	<session-config>
 		<session-timeout>120</session-timeout>