1、 3/3JAVA實(shí)現(xiàn)詞法分析器 package BYYL; import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; public class CFFX public int ch; public int code;/保留字狀態(tài)碼 public StringBuffer strToken = new StringBuffer();/存放構(gòu)成單詞符號的字符串 public String retainWord

2、= new Stringint,if,else,return,main,void,while,break;/保留字 /判斷是否是字母 public boolean IsLetter() if(ch=65 return false; /判斷是否是數(shù)字 public boolean IsDigit() if(ch=48 return false; /判斷是否是空格 public boolean IsBC(int ch) if(ch = 32) return true; return false; /連接字符 public void Concat(char ch) strToken.append(c

3、h); /判斷是否是保留字 public int Reserve() for(int i = 0;i =0 return 2; / public void Retract() code = Reserve(); if(code = 1) System.out.println(+1+,+strToken+); else if(code = 2) System.out.println(+2+,+strToken+); else if(code = 3) System.out.println(+3+,+strToken+); strToken.delete(0, strToken.length();

4、 /* * 讀取文件 */ public void scanner() BufferedReader br; try br = new BufferedReader(new FileReader(d:tests.txt); while(ch = br.read() != -1) /System.out.println(=+(char)ch); if(IsBC(ch) = false) if(IsLetter() if(IsLetter() = true | IsDigit() = true) Concat(char) ch); else if(IsDigit() = true) Concat(

5、char)ch); else if(IsDigit() Concat(char) ch); else if(ch = 61) if(strToken.length() != 0 ) System.out.println(+4+,+strToken+); strToken.delete(0, strToken.length(); else strToken.append(char)ch); else if(ch = 43) Retract(); System.out.println(+4+,+(char) ch+); else if(ch = 45) Retract(); System.out.

6、println(+4+,+(char) ch+); else if(ch = 42) Retract(); System.out.println(+4+,+(char) ch+); else if(ch = 47) Retract(); System.out.println(+4+,+(char) ch+); else if(char) ch = ;) Retract(); System.out.println(+5+,+(char) ch+); else if(char) ch = () Retract(); System.out.println(+5+,+(char) ch+); else

7、 if(char) ch = ) Retract(); System.out.println(+5+,+(char) ch+); else if(char) ch = ) Retract(); System.out.println(+5+,+(char) ch+); else if(char) ch = ) Retract(); System.out.println(+5+,+(char) ch+); else if(char) ch = ,) Retract(); System.out.println(+5+,+(char) ch+); else Retract(); catch (FileNotFoundException e1) / TODO Auto-generated catch block e1.printStackTrace(); catch (IOException e) / TODO Auto-generated c