public static FactoryMethodConnectionSource createConnectionSource()

in log4j-core/src/main/java/org/apache/logging/log4j/core/appender/db/jdbc/FactoryMethodConnectionSource.java [71:157]
76 lines of code
8 McCabe index (conditional complexity)

    public static FactoryMethodConnectionSource createConnectionSource(
            @PluginAttribute("class") final String className, @PluginAttribute("method") final String methodName) {
        if (Strings.isEmpty(className) || Strings.isEmpty(methodName)) {
            LOGGER.error("No class name or method name specified for the connection factory method.");
            return null;
        }

        final Method method;
        try {
            final Class<?> factoryClass = Loader.loadClass(className);
            method = factoryClass.getMethod(methodName);
        } catch (final Exception e) {
            LOGGER.error(e.toString(), e);
            return null;
        }

        final Class<?> returnType = method.getReturnType();
        String returnTypeString = returnType.getName();
        DataSource dataSource;
        if (returnType == DataSource.class) {
            try {
                dataSource = (DataSource) method.invoke(null);
                returnTypeString += "[" + dataSource + ']';
            } catch (final Exception e) {
                LOGGER.error(e.toString(), e);
                return null;
            }
        } else if (returnType == Connection.class) {
            dataSource = new DataSource() {
                @Override
                public Connection getConnection() throws SQLException {
                    try {
                        return (Connection) method.invoke(null);
                    } catch (final Exception e) {
                        throw new SQLException("Failed to obtain connection from factory method.", e);
                    }
                }

                @Override
                public Connection getConnection(final String username, final String password) throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public int getLoginTimeout() throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public PrintWriter getLogWriter() throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                @SuppressWarnings("unused")
                public java.util.logging.Logger getParentLogger() {
                    throw new UnsupportedOperationException();
                }

                @Override
                public boolean isWrapperFor(final Class<?> iface) throws SQLException {
                    return false;
                }

                @Override
                public void setLoginTimeout(final int seconds) throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public void setLogWriter(final PrintWriter out) throws SQLException {
                    throw new UnsupportedOperationException();
                }

                @Override
                public <T> T unwrap(final Class<T> iface) throws SQLException {
                    return null;
                }
            };
        } else {
            LOGGER.error(
                    "Method [{}.{}()] returns unsupported type [{}].", className, methodName, returnType.getName());
            return null;
        }

        return new FactoryMethodConnectionSource(dataSource, className, methodName, returnTypeString);
    }