java 简单的词法分析

package com.seakt.example;
import java.io.*;
import java.lang.String;

public class J_Scanner {

	public String infile;
	public String outfile;
	public String []key = new String[33];
	FileOutputStream out =  null;

	public J_Scanner(String infile,String outfile){

		J_Scanner.this.infile = infile;
		J_Scanner.this.outfile = outfile;
		String[] key_temp = {"","auto","double","int","struct","break","else","long","switch",
				"case", "enum","register","typedef","char","extern","return","union","const",
				"float","short","unsigned","continue","for","signed","void","default","goto",
				"sizeof","volatile","do","if","while","static"};
		key = key_temp;

		try {
		out = new FileOutputStream(new File(outfile));
		}
		catch(IOException e){
			e.printStackTrace();
		}
	}

	//输出关键字
	public void print_key(){
		for(int i=0;i<J_Scanner.this.key.length;i++){
				System.out.printf("%s\r\n",J_Scanner.this.key[i]);
		}
	}

	//读文件
	 public void readFile() {

	        File file = new File(J_Scanner.this.infile);
	        BufferedReader reader = null;
	        try {

	            reader = new BufferedReader(new FileReader(file));
	            String tempString = null;

	            while ((tempString = reader.readLine()) != null) {
	                System.out.println(tempString.length());
	            	getToken(tempString);

	            }
	            reader.close();
	        } catch (IOException e) {
	            e.printStackTrace();
	        } finally {
	            if (reader != null) {
	                try {
	                    reader.close();
	                } catch (IOException e1) {
	                }
	            }
	        }
	    }

	 //判断是否字符
	 private boolean isLetter(char ch){
			if((ch>=65&&ch<=90)||(ch>=97&&ch<=122)||ch==35||ch==46)
				return true;
				else
				return false;
	 }

	 //判断是否数字
	 private boolean isDigit(char ch){
		 		if(ch>=48&&ch<=57)
				return true;
				else
				return false;
	 }

	//查找关键字
	 private int reserve(String s){
	 	for(int i=1;i<33;i++)
	 	if(s==key[i])
	 	   return i;
	 	return 0;
	 }

	 private void getToken(String s) throws IOException{

         String str_write=null;

			int i=0,code;
			char ch=' ';
			String temp="";
			if(s.length()!=0){
				ch=s.charAt(i);
			}
			while(i<s.length()){
			//如果是空跳过
			while(i<s.length()&&ch==' '){
			   i++;
			   ch=s.charAt(i);
			}
			//是字母
			if(isLetter(ch)){
				while((isLetter(ch)||isDigit(ch))&&i<s.length()){
				   temp+=ch;
				   i++;
				   if(i<s.length()-1){
					   ch=s.charAt(i);
				   }else{
					   ch=' ';
				   }
				}
				i--;
				code=reserve(temp);
					if(code==0){
						str_write = temp+"\t"+"标识符"+"\r\n";
						out.write(str_write.getBytes());
					   temp="";str_write="";
					}else{
						  str_write = temp+"\t"+"关键字"+"\r\n";
						  out.write(str_write.getBytes());
						   temp="";str_write="";
					}
			}else if(isDigit(ch)){
				while(isDigit(ch)){
				   temp+=ch;
				   i++;
				   if(i<s.length()-1){
					   ch=s.charAt(i);
				   }else{
					   ch=' ';
				   }
				}
				i--;

				str_write = temp+"\t"+"常数"+"\r\n";
				out.write(str_write.getBytes());
				temp="";str_write="";
			}else if(ch=='='){
				i++;
				 ch=s.charAt(i);
				if(ch== '=' ){
				 str_write = "=="+"\t"+"判断相等"+"\r\n";
				  out.write(str_write.getBytes());
				   temp="";str_write="";
				}
				else{
				   i--;
					  str_write = "="+"\t"+"赋值"+"\r\n";
					  out.write(str_write.getBytes());
					   temp="";str_write="";
				}
			}
			else if(ch=='+'){
			   i++;
			   ch=s.charAt(i);
			   if(ch=='+')
				    out.write(("++"+'\t'+"加1"+"\r\n").getBytes());
			   else{
				i--;
					out.write(("++"+'\t'+"加号"+"\r\n").getBytes());
			   }
			}
			else if(ch=='&'){
			   i++;
			   ch=s.charAt(i);
			   if(ch=='&')
				   out.write(("&&"+'\t'+"与"+"\r\n").getBytes());
			   else{
				i--;
				 out.write(("&"+'\t'+"按位与"+"\r\n").getBytes());
			   }
			}
			else if(ch=='|'){
			   i++;
			   ch=s.charAt(i);
			   if(ch=='|')
				   out.write(("||"+'\t'+"或"+"\r\n").getBytes());
			   else{
				i--;
				 out.write(("|"+'\t'+"按位或"+"\r\n").getBytes());
			   }
			}
			else if(ch=='-')
			 out.write(( (char)ch+'\t'+"减号"+"\r\n").getBytes());
			else if(ch==';')
			 out.write(( (char)ch+'\t'+"分号"+"\r\n").getBytes());
			else if(ch=='(')
			out.write(( (char)ch+'\t'+"左括号"+"\r\n").getBytes());
			else if(ch==')')
			out.write(( (char)ch+'\t'+"右括号"+"\r\n").getBytes());
			else if(ch=='{')
			 out.write(( (char)ch+'\t'+"左花括号"+"\r\n").getBytes());
			else if(ch=='}')
			out.write(( (char)ch+'\t'+"右花括号"+"\r\n").getBytes());
			else if(ch=='*'){
			i++;
			  ch=s.charAt(i);
			if(ch=='*')
				out.write(("**"+'\t'+"运算符"+"\r\n").getBytes());
			else{
			   i--;
				 out.write(("*"+'\t'+"乘号"+"\r\n").getBytes());
			}

			}
			else if(ch=='<'){
			i++;
			  ch=s.charAt(i);
			if(ch=='=')
			    out.write(("<="+'\t'+"小于等于"+"\r\n").getBytes());
			else{
			    i--;
				 out.write(("<"+'\t'+"小于"+"\r\n").getBytes());
			}
			}
			else if(ch=='>'){
				i++;
					if(i<s.length()-1){
					   ch=s.charAt(i);
				   }else{
					   ch=' ';
				   }
				if(ch=='=')
				    out.write((">="+'\t'+"大于等于"+"\r\n").getBytes());
				else{
				    i--;
					 out.write(("<"+'\t'+"大于"+"\r\n").getBytes());
				}
			}
			else
				return;

				i++;
				if(i<s.length()){
					ch=s.charAt(i);
				}
			}

	 }

	 	//关闭输出流
	 	public void close_outStream() throws IOException{
			J_Scanner.this.out.close();
		}

}