Java字符串处理技巧

1. 鲜为人知的replaceAll技巧

1System.out.println("foo[0]".replaceAll("\\[(\\d+)\\]", ".$1"));
2//输出： foo.0

2. 构建一个重复的字符串

1System.out.println(new String(new char[3]).replace("\0", "osc"));
2//输出： oscoscosc

3. 按行读取字符串

1BufferedReader br = new BufferedReader(new StringReader("osc1\r\nosc2\r\nosc3"));
2System.out.println(br.readLine());
3System.out.println(br.readLine());
4//输出：
5//osc1
6//osc2

4. 以指定编码从文件读取

1BufferedReader reader =new BufferedReader(new InputStreamReader(new FileInputStream("/home/joymufeng/file.txt"),"UTF-8"));
2reader.readLine();

5. 以指定编码写入文件

1Writer writer = new OutputStreamWriter(new FileOutputStream("/home/joymufeng/file.txt"), "UTF-8")
2writer.write("我是字符串！");
3writer.flush();
4writer.close();

   也可以使用PrintWriter：

1PrintWriter out = new PrintWriter("/home/joymufeng/file.txt", "UTF-8");
2out.print(true);
3out.print(3.14);
4out.printf("%d + %d = %d".format(1, 1, 2));
5out.println("我是字符串");
6out.flush();
7out.close();

6. 输出汉字的特定字符集编码

1String code = new BigInteger(1, "你好".getBytes("utf-8")).toString(16);
2System.out.println(code);

输出：

e4bda0e5a5bd