去除java中的注释小工具开发心得

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问题需求：将一个java文件中的注释替换为空字符，即消除java文件中的注释。输入：一个目标文件绝对路径和输出文件的绝对路径

看似简单，实则需要花脑筋的一件事，最后决定用有限状态机来解决这个问题，参考了Tristan的表驱动方法，很巧妙，链接：http://my.oschina.net/Tristan/blog/34118

状态机如下表：

0：普通字符代码

1：出现一个/

2：//注释态

3：/*注释态

4：/*...*准备结束注释

5："双引号状态

6：有效转义字符态（双引号后遇到\）

7：'单引号状态

8：有效转义字符态2（单引号后遇到\）

9：注释结束状态，该状态时打印处理后的注释内容，并清空缓冲区

状态：

回车

其他字符

代码如下：

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileReader;

import java.io.FileWriter;

public class RemoveAnnotation2 {

static String inputFile = "E:\\test\\test1.java";

static String outputFile = "E:\\test\\test1_rep1.java ";

int[][] fsm = new int[10][128];

int state = 0;

public static void main(String[] args) {

// TODO Auto-generated method stub

if (args.length >= 2) {

inputFile = args[0];

outputFile = args[1];

}

RemoveAnnotation2 me = new RemoveAnnotation2();

me.initFSM();

File input = new File(inputFile);

File output = new File(outputFile);

try {

me.handleFile(input, output);

} catch (Exception ex) {

ex.printStackTrace();

}

public void initFSM() {

//初始化状态机

for (int i = 0; i < 128; i++) {

fsm[0][i] = 0;

fsm[1][i] = 0;

fsm[2][i] = 2;

fsm[3][i] = 3;

fsm[4][i] = 3;

fsm[5][i] = 5;

fsm[6][i] = 5;

fsm[7][i] = 7;

fsm[8][i] = 7;

fsm[9][i] = 0;

}

fsm[0]['/'] = 1;

fsm[0]['"'] = 5;

fsm[0]['\''] = 7;

fsm[1]['/'] = 2;

fsm[1]['*'] = 3;

fsm[1]['"'] = 5;

fsm[2]['\n'] = 9;

fsm[3]['*'] = 4;

fsm[4]['/'] = 9;

fsm[4]['*'] = 4;

fsm[5]['"'] = 0;

fsm[5]['\\'] = 6;

fsm[7]['\\'] = 8;

fsm[7]['\''] = 0;

fsm[9]['/'] = 1;

fsm[9]['"'] = 5;

fsm[9]['\''] = 7;

}

public int parseChar(char a) {

int result = a;

return result;

}

public char parseInt(int a) {

char result = (char) a;

return result;

}

public void handleFile(File in, File out) throws Exception {

int c;

String temp = "";

char[] cbuf = null;

BufferedReader br = new BufferedReader(new FileReader(in));

BufferedWriter bw = new BufferedWriter(new FileWriter(out));

while ((c = br.read()) != -1) {

state = fsm[state][c];

temp = temp + parseInt(c);

switch (state) {

case 0:

bw.write(temp);

temp = "";

break;

case 9:

//注释结束态，将除了换行的字符全部替换为“ ”输出。

cbuf = temp.toCharArray();

for (int i = 0; i < cbuf.length; i++)

if (cbuf[i] != '\n')

cbuf[i] = ' ';

bw.write(cbuf);

temp = "";

cbuf = null;

break;

}

br.close();

bw.close();

}

Reference：

原作者：http://www.programfan.com/blog/article.asp?id=34091

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