有时压测时，需要从日志文件中提取每行指定字段的值(S_KEYWORD_COMPLETE_NEW字段)，如下：

?S_KEYWORD_COMPLETE_NEW=%E7%94%9F%E4%BA%A7&NewId=60773611

截取策略：以 "S_KEYWORD_COMPLETE_NEW="为开头标识，以"S_KEYWORD_COMPLETE_NEW="字段值后第一个"&"为结束。

以下为具体java代码

import java.io.*;

/**
 * @Author: jiajun.du
 * @Date: 2021/8/3 18:00
 */
public class ExtractFieldValues {


    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream("D:\\50.130\\onlyuri.log"), "GB2312"));//源日志文件
            BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("D:\\50.130\\onlyuri.txt"), "GB2312"));//存放截取值的新文件
            StringBuffer sb = new StringBuffer();
            String b = "";
            int num =0;//读取行数控制
            try {
                while ((b = br.readLine()) != null && num <80000) {
                    sb.append(b);
                    String s = sb.toString();
                    String strNew = s.substring(s.indexOf("S_KEYWORD_COMPLETE_NEW=") + 23, s.length());//每行截取起始标识
                    String key = strNew.substring(0, strNew.indexOf("&"));//每行截取结束标识
                    //String keyNew = unicodeToString(key);
                    bw.write(key+"\n");//写入文件并换行
                    num++;
                    sb.delete(0,sb.length());//清空数据
                }
                bw.flush();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                br.close();
                bw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        } catch (UnsupportedEncodingException | FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}