ServletParser.java

package lib;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.StringTokenizer;

public class ServletParser {
    /*this is a parse class aim to parse jsp file to servlet.java file
    *
    * https://github.com/XUranus
    *
    * */

    private String className;
    private String jspContent;

    public ServletParser(File file) {
        String content = "";
        try {
            BufferedReader in = new BufferedReader(new FileReader(file));
            String line = "";
            while ((line = in.readLine())!=null) {
                content = content + line +"\n";
            }
        }
        catch (IOException e) {
            System.out.println("Parser Construct Err");
        }

        String className = file.getName();// 可以加后缀
        className = className.replace(".", "_");
        System.out.println("this file name is "+className);
        String jspContent = content;
        this.className = className;
        this.jspContent = jspContent;
    }

    public ServletParser(String className,String jspContent) {
        this.className = className;
        this.jspContent = jspContent;
    }

    public String parse() throws Exception {
        String str = jspContent;

        String importPart = "";
        String doGetPartString = "";
        String definitionPartString = "";
        String servicePartString = "";
        int htmlContentBegin = 0;

        for(int i=0;i<str.length();i++) {
            if (str.charAt(i) == '<'){
                if(str.charAt(i+1)=='%') {
                    if(str.charAt(i+2)=='=') {
                        //jsp expression tag <%=  %>
                        int end = getStringIndex(i+3,str,"%>");
                        doGetPartString += htmlContentString(str,htmlContentBegin,i-1);
                        htmlContentBegin = end+2;
                        doGetPartString += expresstionsString(str,i+3,end-1);
                        i = end + 1;
                        continue;
                    }
                    else if(str.charAt(i+2)=='!'){
                        //jsp declaration tag <%!  %>
                        int end = getStringIndex(i+3,str,"%>");
                        doGetPartString += htmlContentString(str,htmlContentBegin,i-1);
                        htmlContentBegin = end+2;
                        definitionPartString += declarationsString(str,i+3,end-1);
                        i = end + 1;
                        continue;
                    }
                    else if(str.charAt(i+2)=='@'){
                        //jsp directive tag <%@  %>
                        int end = getStringIndex(i+3,str,"%>");
                        doGetPartString += htmlContentString(str,htmlContentBegin,i-1);
                        htmlContentBegin = end+2;
                        jspDirectiveString(str,i+3,end-1);
                        servicePartString += jspDirectiveString(str,i+3,end-1);
                        i = end + 1;
                        continue;
                    }
                    else if(str.charAt(i+2)=='-' && str.charAt(i+3)=='-'){
                        //jsp comment tag <%-- --%>
                        //do nothing
                        int end = getStringIndex(i+3,str,"%>");
                        doGetPartString += htmlContentString(str,htmlContentBegin,i-1);
                        htmlContentBegin = end+2;
                        i = end + 1;
                        continue;
                    }
                    else {
                        //scriptlets tag
                        int end = getStringIndex(i+2,str,"%>");
                        doGetPartString += htmlContentString(str,htmlContentBegin,i-1);
                        htmlContentBegin = end+2;
                        doGetPartString += scriptletsString(str,i+2,end-1);
                        i = end + 1;
                        continue;
                    }
                }
                else if(stringMatches(str,i,"<jsp:")) {
                    //JSP standard action like <jsp:usebean>
                    int end = getStringIndex(i+5,str,">");
                    doGetPartString += htmlContentString(str,htmlContentBegin,i-1);
                    htmlContentBegin = end+1;
                    System.out.println(scriptletsString(str,i+5,end-1));
                    i = end;
                    //temp debug solution !!!
                    continue;
                }
            }
        }

        return new ServletGenerator().generate(className,importPart,definitionPartString,"",servicePartString+"\n"+doGetPartString,servicePartString+"\n"+doGetPartString,"");
    }




    String scriptletsString(String str,int begin,int end) {
        //handle <jsp: ... >
        return removeSideBlanks(str.substring(begin,end+1))+"\n";
    }

    String jspDirectiveString(String str,int begin,int end) {
        //handle <%@ ... %>
        String content = removeSideBlanks(str.substring(begin,end+1));
        String directType = content.split(" ")[0];
        String parameter =  content.split(" ")[1];
        switch (directType) {
            case "page":
                if(parameter.startsWith("contentType")) {
                    return "response.setContentType(" + parameter.substring(12,parameter.length()) + ");";
                }
                break;
            case "import":
                break;
            case "include":
                break;
            case "taglib":
                break;
            default:
                break;
        }
        return "[jspDirectiveString Error:" + content + "]";
    }


/**************************************   codes and logical below is easy...   ******************************************************/

    String expresstionsString(String str,int begin,int end) {
        //handle <%! ... %>
        //example : "out.println(content);"
        return "out.println("+removeSideLineFeed(removeSideBlanks(str.substring(begin,end+1)))+");"+"\n";
    }

    String declarationsString(String str,int begin,int end) {
        //handle <%! ... %>
        //class globe definition of function and variables
        return removeSideBlanks(str.substring(begin,end+1))+"\n";
    }

    String htmlContentString(String str,int begin,int end) {
        //handle default ; unrecognized tags
        if(begin >= end) return "";
        String res = "";
        String html = removeSideBlanksAndLineFeeds(str.substring(begin,end+1));
        StringTokenizer st = new StringTokenizer(html,"\n");
        while (st.hasMoreTokens()) {
            String temp = st.nextToken();
            if(!temp.trim().isEmpty()) {
                res +=  "out.write(\""+temp+"\");"+"\n";
            }
        }
        return res;
    }

    String removeSideLineFeed(String str) {
        //this function is used to remove the blank in each side of the string
        int begin = 0;
        while (str.charAt(begin)=='\n') begin++;
        int end = str.length();
        while (str.charAt(end-1)=='\n') end--;
        return str.substring(begin,end);
    }

    String removeSideBlanks(String str) {
        //this function is used to remove the blank in each side of the string
        int begin = 0;
        while (str.charAt(begin)==' ') begin++;
        int end = str.length();
        while (str.charAt(end-1)==' ') end--;
        return str.substring(begin,end);
    }

    String removeSideBlanksAndLineFeeds(String str) {
        //转义
        str = str.replace("\"","\\\"");
        str = str.replace("    ","\\t");
        return str;
        //this function is used to remove the blank in each side of the string
        /*int begin = 0;
        while (str.charAt(begin)==' '||str.charAt(begin)=='\n') begin++;
        int end = str.length();
        while (str.charAt(end-1)==' '||str.charAt(end-1)=='\n') end--;
        return str.substring(begin,end);*/
    }

    private boolean stringMatches(String str,int index,String module) {
        //return whether a string starts at index has a prefix module
        if(module.length()+index>=str.length()) return false;
        for(int i=0;i<module.length();i++) {
            if(str.charAt(index+i)!=module.charAt(i)) return false;
        }
        return true;
    }

    private int getStringIndex(int start,String str,String subStr) {
        /*
        search str[start,str.length())
        return the index that sub_string appear in the string
        if found return the index of the first char
        if not found return -1
        */
        for(int i=start;i<str.length()-subStr.length()+1;i++) {
            boolean flag = true;
            for(int j=0;j<subStr.length();j++) {
                if (subStr.charAt(j) != str.charAt(i + j)) {
                    flag = false;
                    break;
                }
            }
            if(flag) return i;
        }
        return -1;
    }
}