csv 解析

csv 文件中，如果值中有分隔符，分隔符需要转义，否则会被解析掉．比如：你好\,世界,你是谁?,张三．你好,世界　需要作为一个整体解析．写了一个小方法，记录一下.

public static List<String> parseCSV(String s, char seprator) {
		char[] cs = s.toCharArray();
		List<String> list = new ArrayList<String>(); 
		StringBuilder sb = new StringBuilder();
		int pi = -1;
		for(int i = 0; i < cs.length; i++) {
			char c = cs[i];
			if (c == '\\') {
				sb.append(c);
				pi = i;
				continue;
			}
			if (c != seprator) {
				sb.append(c);
				continue;
			}
			if (pi + 1 == i) { // 是转义符
				sb.deleteCharAt(sb.length() - 1);
				sb.append(c);
				pi = -1;
			} else { // 是分隔符
				list.add(sb.toString());
				sb.delete(0, sb.length());
			}
		}
		list.add(sb.toString());
		return list;
	}

string.split(",")是正则分割，并且不能检索"\"．上面的方法是字符检索，经过测试，上面的方法比split要快一些 (3-4倍)．

int i = 0;
		long start = System.currentTimeMillis();
		do {
			parseCSV(content, ',');
		} while (i++ < 10000);
		long end = System.currentTimeMillis();
		System.out.println("" + (end - start));
		
		long start2 = System.currentTimeMillis();
		i = 0;
		do {
			content.split(",");
		} while (i++ < 10000);
		long end2 = System.currentTimeMillis();
		System.out.println("" + (end2 - start2));

另外一个小工具方法，http query string 解析：

public static Map<String, String> parseQueryString(String queryString) {
		Map<String, String> result = new HashMap<String, String>();
		String[] eles = queryString.split(",|&");
		for (String ele : eles) {
			String[] kv = ele.split(":|=", 2);
			result.put(kv[0], kv[1]);
		}
		return result;
	}