文件内容关键字检索与查找下一个(上一个)实现

骑猪看日落 2023-10-04 20:17 37阅读 0赞

private List returnList = new ArrayList();//在方法外定义一个存储的全局变量

public String logSearch(Long before,Long after,String findStr,String path) {
    //before为关键字前多少行,after为关键字后多少行,findstr为查找的关键字,path为查找的文件路径
    
        //参数校验
        if(before == null){
            before = 0L;
        }
        if(after == null){
            after = 0L;
        }
        if(StringUtils.isEmpty(findStr)){
            throw new BusinessException("查找的字段为空");
        }
        if(path == null){
            throw new BusinessException("文件的路径为空");
        }
    
        returnList.clear();//全局变量清空
    
        String result = "";
    
        StringBuilder strLink = new StringBuilder();
    
        BufferedReader readerLink = null;
        try {
            readerLink = new BufferedReader(new InputStreamReader(new FileInputStream(path), "GB2312"));
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
            throw new BusinessException("文件转码异常");
        } catch (FileNotFoundException e) {
            e.printStackTrace();
            throw new BusinessException("未找到指定文件");
    
        }
    
        int len = 0; //读取字符
        Long i = 0L; //定位要查询字符前一位起始位置
        Long k = 1L; //定位行数(总行数与查询字符出现的行数)
        Long count = 0L;
        int h = 1; //存储集合的索引key
    
        Map linkMap = new HashMap(); //存放关键行数
        Map countMap = new HashMap();//存放每行要跳过的字符数
        countMap.put(1L,0L); //初始化
        while (true) {
            try {
                if (!((len = readerLink.read()) != -1)){ break;};
            } catch (IOException e) {
                e.printStackTrace();
                throw new BusinessException("IO异常");
            }
            char lenChar = (char) len;
            strLink.append(lenChar);
            if (lenChar == 10) { //换行符
                if (strLink.toString().contains(findStr)) {
    
                    linkMap.put(h,k);//h为key索引,解析为第x个,k为关键行数
                    h++;
    
                }
                int charSize = strLink.length();
                count+=charSize;
                countMap.put(k+1,count);//第k+1行,需要跳过xx字符
                strLink = new StringBuilder();
                k++;
            }
    
            i++;
        }
    
        int size = linkMap.size();
    
        for (int n = 1; n < size+1; n++) {
            // 以跳过的字符数控制开头,以行数k控制结尾
            Long hang  = (Long) linkMap.get(1);
    
            if(hang == null){
                throw new BusinessException("未查询到结果");
            }
    
            Long total = 1L;
            Long chu = 0L;
            Long charSize = 0L;
    
            if(hang == 1L){ //指针与顶重合
    
                charSize = 0L;
                total = 1 + after;
    
            }else if(before >= hang || hang == before+1) {  //触顶或破顶,使用新的逻辑
    
                before = hang - 1;
                chu = hang - before;
                charSize = (Long) countMap.get(chu);
                total = before + 1 + after;
    
            }else {//无触顶,普通逻辑(包含before为0,after为0的特殊情况)
    
                chu = hang-before;
                charSize  = (Long) countMap.get(chu);
                total = before + 1 + after;
            }
    
            StringBuilder str = new StringBuilder();
            BufferedReader reader = null;
            try {
                reader = new BufferedReader(new InputStreamReader(new FileInputStream(path), "GB2312"));
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
                throw new BusinessException("文件转码异常");
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                throw new BusinessException("未找到指定文件");
            }
            len = 0;
            if(charSize != 0){
                try {
                    reader.skip(charSize);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            Long j = 1L;//内置计数器
            while (true) {
                try {
                    if (!((len = reader.read()) != -1)){ break;};
                } catch (IOException e) {
                    e.printStackTrace();
                    throw new BusinessException("IO异常");
                }
                boolean flag = false;//外置控制器->内循环控制外循环
                char lenChar = (char) len;
                str.append(lenChar);
                if (lenChar == 10) {//换行符
    
                    if(j.equals(total)){
                        flag =true;
                    }
                    j++;
                }
    
                if(flag){
                    break;
                }
    
            }
    
            if(n == 1){//默认返回查询到的第一个结果
    
                result = str.toString();
            }
    
            returnList.add(str.toString());
        }
    
    
        return result;
    
    }