取得系统属性，如果因为Java安全的限制而失败，则将错误打在Log中，然后返回 <code>null</code>。

@param name 属性名
@param quiet 安静模式，不将出错信息打在<code>System.err</code>中

@return 属性值或<code>null</code>
327624
public static String get(String name, boolean quiet) {
		try {
			return System.getProperty(name);
		} catch (SecurityException e) {
			if (false == quiet) {
				Console.error("Caught a SecurityException reading the system property '{}'; the SystemUtil property value will default to null.", name);
			}
			return null;
		}
	}
653318
public static Logger getConsoleLogger(final String name) {
        return new Logger() {
            @Override
            public void log(String description, Object... params) {
                System.out.print("[" + name + "]: " + description + "\t");
                for (Object param: params)
                    System.out.print(param + "\t");
                System.out.println();
            }
        };
    }
999041
static String checkStringArgument(String s, String name) {
    checkNotNull(s, name);
    checkArgument(!s.trim().isEmpty(), "'" + name + "' must not be blank. Was: '" + s + "'");
    return s;
  }
725573
private static String checkNotEmpty(String v, String name) {
    Preconditions.checkNotNull(v, name);
    Preconditions.checkArgument(!v.isEmpty(), "%s cannot be empty", name);
    return v;
  }
1298406
public String param(final String name) {
        try {
            return request.getParameter(name);
        } catch (final Exception e) {
            LOGGER.log(Level.ERROR, "Can't parse request parameter [uri=" + request.getRequestURI() + ", method=" + request.getMethod() + ", parameterName=" + name + "]: " + e.getMessage());

            return null;
        }
    }
954549
private static String getStringProperty(String name) {
        String prop = null;
        try {
            prop = System.getProperty(name);
        } catch (SecurityException e) {
            // Ignore
        }
        return prop == null ? simpleLogProps.getProperty(name) : prop;
    }
972410
public static String sanitizeName(String name) {

        if (name  == null)
            throw new NullPointerException("Parameter name cannot be null");

        name = name.trim();

        if (name.length() == 0)
            throw new IllegalArgumentException("Parameter name cannot be empty");

        StringBuilder ret = new StringBuilder("");

        for (int i = 0; i < name.length(); i++) {
            char ch = name.charAt(i);
            if (Character.isLetter(ch) || Character.isDigit(ch)) {
                ret.append(ch);
            } else {
                ret.append("_");
            }

        }

        return ret.toString();
    }
129609
public static void notEmpty(final Object[] arg, final String name) {
        if(arg == null) {
            throw new NullPointerException(String.format("%s should not be null.", name));
        }
        
        if(arg.length == 0) {
            throw new IllegalArgumentException(String.format("%s should has length ararys.", name));
        }
    }
295663
public static String checkNotEmpty(final String name,
                                       final String parameter) {
        if (parameter == null || parameter.trim().length() == 0) {
            throw new IllegalArgumentException("Parameter named '" + name + "' should be filled!");
        }
        return parameter;
    }
1172066
public static SerializationFormat getInputFormat(String name) {
        for (SerializationFormat ft : Instance.serializationFormats) {
            if (ft.isAcceptedAsInput(name)) {
                return ft;
            }
        }
        return null;
    }
948307
public static <T> T requireNonNull(String name, T value) {
        Objects.requireNonNull(value, "Argument [" + name + "] cannot be null");
        return value;
    }
955601
public void addLog(final String name) {
        ErrorLogger log = new ErrorLogger(name);
        logs.put(name, log);
        log.setVerboseDebug(debugLevel);
    }
1133813
private <T> T getBeanOrNull(String name, Class<T> requiredType) {
		if (name == null || !applicationContext.containsBean(name)) {
			return null;
		} else {
			try {
				return applicationContext.getBean(name, requiredType);
			} catch (BeansException be) {
				log.error("Error during getBeanOrNull, not rethrown, " + be.getMessage(), be);
				return null;
			}
		}
	}
172947
protected String getReqPar(final HttpServletRequest req, final String name) throws Throwable {
    return Util.checkNull(req.getParameter(name));
  }
141362
public Log getLog(String name) {
		Log log = logCache.get(name);
		if (null == log) {
			log = createLog(name);
			logCache.put(name, log);
		}
		return log;
	}
536582
public boolean isNull(String name) {
        JsonElement value = nameValuePairs.get(name);
        return value.isNull();
    }
598007
public static Logger getLogger(String name) {
        Logger logger = Logger.getLogger(name);
        logger.setUseParentHandlers(false);
        for (Handler handler : logger.getHandlers()) {
            logger.removeHandler(handler);
        }
        // TODO when output log to the standard error
        Formatter formatter = new Formatter() {
            @Override
            public String format(LogRecord record) {
                long millis = record.getMillis();
                return String.format("[%tF %<tT.%<tL]%s%n", millis, record.getMessage());
            }
        };
        ConsoleHandler handler = new ConsoleHandler();
        handler.setFormatter(formatter);
        logger.addHandler(handler);
        if (loggerEnabled) {
            logger.setLevel(Level.INFO);
        } else {
            logger.setLevel(Level.OFF);
        }
        return logger;
    }