springboot源码学习--设计模式及工具类

单例模式-ApplicationConversionService

private static volatile ApplicationConversionService sharedInstance;

public static ConversionService getSharedInstance() {
		ApplicationConversionService sharedInstance = ApplicationConversionService.sharedInstance;
		if (sharedInstance == null) {
			synchronized (ApplicationConversionService.class) {
				sharedInstance = ApplicationConversionService.sharedInstance;
				if (sharedInstance == null) {
					sharedInstance = new ApplicationConversionService();
					ApplicationConversionService.sharedInstance = sharedInstance;
				}
			}
		}
		return sharedInstance;
	}

StringUtils(org.springframework.util.StringUtils)

去除空格

public static String trimAllWhitespace(String str) {
		if (!hasLength(str)) {
			return str;
		}

		int len = str.length();
		StringBuilder sb = new StringBuilder(str.length());
		for (int i = 0; i < len; i++) {
			char c = str.charAt(i);
			if (!Character.isWhitespace(c)) {
				sb.append(c);
			}
		}
		return sb.toString();
	}
	
public static boolean hasLength(@Nullable String str) {
		return (str != null && !str.isEmpty());
	}

字符串转数组

public static String[] commaDelimitedListToStringArray(@Nullable String str) {
		return delimitedListToStringArray(str, ",");
	}
	
public static String[] delimitedListToStringArray(@Nullable String str, @Nullable String delimiter) {
		return delimitedListToStringArray(str, delimiter, null);
	}
	
public static String[] delimitedListToStringArray(
			@Nullable String str, @Nullable String delimiter, @Nullable String charsToDelete) {

		if (str == null) {
			return new String[0];
		}
		if (delimiter == null) {
			return new String[] {str};
		}

		List result = new ArrayList<>();
		if (delimiter.isEmpty()) {
			for (int i = 0; i < str.length(); i++) {
				result.add(deleteAny(str.substring(i, i + 1), charsToDelete));
			}
		}
		else {
			int pos = 0;
			int delPos;
			while ((delPos = str.indexOf(delimiter, pos)) != -1) {
				result.add(deleteAny(str.substring(pos, delPos), charsToDelete));
				pos = delPos + delimiter.length();
			}
			if (str.length() > 0 && pos <= str.length()) {
				// Add rest of String, but not in case of empty input.
				result.add(deleteAny(str.substring(pos), charsToDelete));
			}
		}
		return toStringArray(result);
}

双亲加载

java.lang public abstract class ClassLoader
protected Class loadClass(String name, boolean resolve)
        throws ClassNotFoundException
    {
        synchronized (getClassLoadingLock(name)) {
            // First, check if the class has already been loaded
            Class c = findLoadedClass(name);
            if (c == null) {
                long t0 = System.nanoTime();
                try {
                    if (parent != null) {
                        c = parent.loadClass(name, false);
                    } else {
                        c = findBootstrapClassOrNull(name);
                    }
                } catch (ClassNotFoundException e) {
                    // ClassNotFoundException thrown if class not found
                    // from the non-null parent class loader
                }

                if (c == null) {
                    // If still not found, then invoke findClass in order
                    // to find the class.
                    long t1 = System.nanoTime();
                    c = findClass(name);

                    // this is the defining class loader; record the stats
                    sun.misc.PerfCounter.getParentDelegationTime().addTime(t1 - t0);
                    sun.misc.PerfCounter.getFindClassTime().addElapsedTimeFrom(t1);
                    sun.misc.PerfCounter.getFindClasses().increment();
                }
            }
            if (resolve) {
                resolveClass(c);
            }
            return c;
        }
    }
 private Class findBootstrapClassOrNull(String name)
    {
        if (!checkName(name)) return null;

        return findBootstrapClass(name);
    }
 // return null if not found
private native Class findBootstrapClass(String name);