java获取json格式中的值

import org.json.JSONArray;
import org.json.JSONException;
 
public class test2 {
    public static void main(String[] args) throws JSONException {
        String str = "[{'columnId':5,'columnName':'人文历史'},{'columnId':2,'columnName':'商业视野'}]}";
        JSONArray jsonArray = null;
        jsonArray = new JSONArray(str);
        System.out.println(jsonArray.getJSONObject(0).get("columnName"));
    }
}

/**
  * 项目变更详情
  * @param request
  * @param response
  * @throws Exception
  */
  @RequestMapping("detail")
  @Action(description="编辑项目变更表")
  public ModelAndView detail(HttpServletRequest request) throws Exception{
	Long recordId=RequestUtil.getLong(request,"recordId",0L);
	FundRecords fundRecord = fundRecordsService.getById(recordId);
	FundModify fundModify = fundModifyService.getByRecordId(recordId);
	String fileName = fundModify.getModifyFile();//failName = [{"id":"10000058240001","name":"附件.xls"}]
	net.sf.json.JSONArray jsonArray = net.sf.json.JSONArray.fromObject(fileName);
	String fileNames = "";
	for (int i = 0; i < jsonArray.size(); i++) {
	　　fileNames += jsonArray.getJSONObject(i).get("name")+",";
	}
	fileNames = fileNames.substring(0, fileNames.lastIndexOf(","));
	return getAutoView().addObject("recordId", recordId).addObject("fundRecords", fundRecord)
	.addObject("fundModify", fundModify).addObject("fileNames", fileNames);
}