1、将接口返回信息写入文件中

//从用户注册接口的返回结果中获取userid、username、token，缺省值为“NULL”
if(vars.get("userid").equals("NULL") == false&&vars.get("username").equals("NULL") == false&&vars.get("token").equals("NULL") == false){
　　FileWriter fstream = new FileWriter(".\\usersinfo.csv",true); 
　　BufferedWriter out = new BufferedWriter(fstream); 
　　out.write(vars.get("userid")+","+vars.get("username")+","+vars.get("token")+"\n"); 
　　out.close(); 
　　fstream.close(); 
}

2、读取文件中数据的行数（通过文件行数可以控制循环控制器的循环次数）

import org.apache.jmeter.services.FileServer;
import com.bzj.utils.*;
import java.io.BufferedReader;
import java.io.FileReader;

String fname = vars.get("filename");
String baseDir=FileServer.getFileServer().getBaseDir(); //获取到脚本所在的目录
String filePath = baseDir+"\\data\\"+fname; //拼接成要读取文件的路径

BufferedReader br = new BufferedReader(new FileReader(filePath));
String tmpStr = "";
int rowNum = 0;
while(tmeStr = br.readLine()!=null){
    rowNum++;
}
rowNum = rowNum - 1;
vars.put("cycleNum",rowNum.toString());