性能优化小记（1）

之前做系统优化，通过线程执行堆栈的检测，找到一个模板类的瓶颈，场景是一个2级下拉菜单，当时为了支持下拉菜单 键盘输入按拼音自动选择，在下拉菜单的属性里有一个值表示当前选择的中文词语的首字母串。如：

<option cls="ZHRMGHG">中华人民共和国</options>

....

由于这个菜单的option比较多，

有个工具类用来解析中文转拼音的工作，这个工具类存在性能瓶颈，主要原因是进行大量的中文encode

private final static int compare(String str1, String str2) {
		int result = 0;
		String s1 = EMPTY_STRING;
		String s2 = EMPTY_STRING;

		try {
			s1 = new String(str1.getBytes(_FromEncode_), _ToEncode_);
			s2 = new String(str2.getBytes(_FromEncode_), _ToEncode_);
		} catch (Exception e) {
			return str1.compareTo(str2);
		}

		result = chineseCompareTo(s1, s2);

		return result;
	}

	public final static int chineseCompareTo(String s1, String s2) {
		int len1 = s1.length();
		int len2 = s2.length();
		int n = Math.min(len1, len2);

		for (int i = 0; i < n; i++) {
			int s1Code = getCharCode(Character.toString(s1.charAt(i)));
			int s2Code = getCharCode(Character.toString(s2.charAt(i)));

			if ((s1Code * s2Code) < 0) {
				return Math.min(s1Code, s2Code);
			}

			if (s1Code != s2Code) {
				return s1Code - s2Code;
			}
		}

		return len1 - len2;
	}
	
	private final static int getCharCode(String s) {
		if ((s == null) || s.equals("")) {
			return -1;
		}

		byte[] b = s.getBytes();
		int value = 0;

		for (int i = 0; (i < b.length) && (i <= 2); i++)
			value = (value * 100) + b[i];

		return value;
	}

	public final static String getBeginCharacter(String res) {
		String a = res;
		String result = EMPTY_STRING;

		for (int i = 0; i < a.length(); i++) {
			String current = a.substring(i, i + 1);
			if (compare(current, "\u554A") < 0) {
				result = result + current;
			} else if ((compare(current, "\u554A") >= 0)
					&& (compare(current, "\u5EA7") <= 0)) {
				if (compare(current, "\u531D") >= 0) {
					result = result + "z";
				} else if (compare(current, "\u538B") >= 0) {
					result = result + "y";
				} else if (compare(current, "\u6614") >= 0) {
					result = result + "x";
				} else if (compare(current, "\u6316") >= 0) {
					result = result + "w";
				} else if (compare(current, "\u584C") >= 0) {
					result = result + "t";
				} else if (compare(current, "\u6492") >= 0) {
					result = result + "s";
				} else if (compare(current, "\u7136") >= 0) {
					result = result + "r";
				} else if (compare(current, "\u671F") >= 0) {
					result = result + "q";
				} else if (compare(current, "\u556A") >= 0) {
					result = result + "p";
				} else if (compare(current, "\u54E6") >= 0) {
					result = result + "o";
				} else if (compare(current, "\u62FF") >= 0) {
					result = result + "n";
				} else if (compare(current, "\u5988") >= 0) {
					result = result + "m";
				} else if (compare(current, "\u5783") >= 0) {
					result = result + "l";
				} else if (compare(current, "\u5580") >= 0) {
					result = result + "k";
				} else if (compare(current, "\u51FB") > 0) {
					result = result + "j";
				} else if (compare(current, "\u54C8") >= 0) {
					result = result + "h";
				} else if (compare(current, "\u5676") >= 0) {
					result = result + "g";
				} else if (compare(current, "\u53D1") >= 0) {
					result = result + "f";
				} else if (compare(current, "\u86FE") >= 0) {
					result = result + "e";
				} else if (compare(current, "\u642D") >= 0) {
					result = result + "d";
				} else if (compare(current, "\u64E6") >= 0) {
					result = result + "c";
				} else if (compare(current, "\u82AD") >= 0) {
					result = result + "b";
				} else if (compare(current, "\u554A") >= 0) {
					result = result + "a";
				}
			}
		}
		
		if (result.length() <=0)
			result = OTHER_TYPE;
		
		return result;
	}

	/**
	 * 得到字符串首字符的拼音首字母	 */
	public final static String getFirstSpell(String str) {
		String result = null;
		
		if (null != str && str.length() > 0) {
			char a = str.charAt(0);
			
			if (Character.isDigit(a)) {
				result = OTHER_TYPE;
			} else if (((a >= 'a') && (a <= 'z')) || ((a >= 'A') && (a <= 'Z'))) {
				result = Character.toString(a).toLowerCase();
			} else {
				result = getBeginCharacter(Character.toString(a));
			}
		}
		
		return result;
	}

 

大家看到这个问题之后第一想法就是优化这段代码

其实解决这个性能问题也有另外一种思路，由于option里的中文词语是有限的，可以枚举的，所以完全可以进行cache

做一个词语对应字母的map，通过这个可以有效的提升代码性能