无法获取json的所有值

Question

我正在尝试使用 rest webservice 将从数据库获取的值返回到前端视图，但问题是它只返回 json 值的一行（第一行）

我有这样的json：

{"jobName":"NASA Scientist","jobPrimarySkill":null,"jobRole":"JOB_ROLE","jobDesignation":"JOB_EXP","jobDescription":"Sample 2","jobSalaryRange":"JOB_POSITIONS","jobExp":"JOB_SAL_RANGE","jobPositions":"JOB_POSTEDBY","jobPostedBy":null}
{"jobName":"NASA Scientist","jobPrimarySkill":null,"jobRole":"JOB_ROLE","jobDesignation":"JOB_EXP","jobDescription":"JOB_DESCRIPTION","jobSalaryRange":"JOB_POSITIONS","jobExp":"JOB_SAL_RANGE","jobPositions":"JOB_POSTEDBY","jobPostedBy":null}
{"jobName":"Web developer","jobPrimarySkill":null,"jobRole":"JOB_ROLE","jobDesignation":"JOB_EXP","jobDescription":"XYZ 123","jobSalaryRange":"JOB_POSITIONS","jobExp":"JOB_SAL_RANGE","jobPositions":"JOB_POSTEDBY","jobPostedBy":null}
{"jobName":"Web developer","jobPrimarySkill":null,"jobRole":"JOB_ROLE","jobDesignation":"JOB_EXP","jobDescription":"JOB_DESCRIPTION","jobSalaryRange":"JOB_POSITIONS","jobExp":"JOB_SAL_RANGE","jobPositions":"JOB_POSTEDBY","jobPostedBy":null}
{"jobName":"Programmer","jobPrimarySkill":null,"jobRole":"JOB_ROLE","jobDesignation":"JOB_EXP","jobDescription":"JOB_DESCRIPTION","jobSalaryRange":"JOB_POSITIONS","jobExp":"JOB_SAL_RANGE","jobPositions":"JOB_POSTEDBY","jobPostedBy":null}
{"jobName":"Programmer","jobPrimarySkill":null,"jobRole":"JOB_ROLE","jobDesignation":"JOB_EXP","jobDescription":"JOB_DESCRIPTION","jobSalaryRange":"JOB_POSITIONS","jobExp":"JOB_SAL_RANGE","jobPositions":"JOB_POSTEDBY","jobPostedBy":null}

它只将第一行 json 值返回到前端，而不是全部返回。我将从数据库中获取的值添加到 List 并像这样在 web 服务中公开它：

public class FetchJobSummaryDAO {

public List getJobSummaries() {

JobSummaries jobSummaries = new JobSummaries();
List<JobSummaries> jobSummaryList = new ArrayList<JobSummaries>();

try {
    Connection con = DBConnection.getConnection();

    String query = "select JOB_NAME,JOB_DESCRIPTION,JOB_ROLE,JOB_PRIMARY_SKILL,JOB_DESIGNATION,JOB_EXP,JOB_SAL_RANGE, JOB_POSTEDBY from TBL_JOBPOSTING";

    PreparedStatement pst = con.prepareStatement(query);
    ResultSet rs = pst.executeQuery();

    ResultSetMetaData rsmd = rs.getMetaData();
    int columnsNumber = rsmd.getColumnCount();
    while (rs.next()) {
        jobSummaries.setJobName(rs.getString("JOB_NAME"));
        jobSummaries.setJobDescription(rs.getString("JOB_DESCRIPTION"));
        jobSummaries.setJobRole(rs.getString("JOB_ROLE"));
        jobSummaries.setJobPrimarySkill(rs.getString("JOB_PRIMARY_SKILL"));
        jobSummaries.setJobDesignation(rs.getString("JOB_DESIGNATION"));
        jobSummaries.setJobExp(rs.getString("JOB_EXP"));
        jobSummaries.setJobSalaryRange(rs.getString("JOB_SAL_RANGE"));
        jobSummaries.setJobPostedBy(rs.getString("JOB_POSTEDBY"));
        jobSummaryList.add(jobSummaries);

        for (int i = 1; i <= columnsNumber; i++) {
            if (i > 1) {
                System.out.print(",  ");
            }
            String columnValue = rs.getString(i);
            System.out.print(rsmd.getColumnName(i) + " " + columnValue);
        }
        System.out.println("");
    }

} catch (SQLException ex) {
    Logger.getLogger(FetchJobSummaryDAO.class.getName()).log(Level.SEVERE, null, ex);
}
return jobSummaryList;
}

网络服务：

@Path("/FetchJobSummary")
public class FetchJobSummaryService {
FetchJobSummaryDAO dao = new FetchJobSummaryDAO();

@GET
@Produces(MediaType.APPLICATION_JSON)
public List<JobSummaries> fetch() {
    List js = dao.getJobSummaries();
    for(int i=0; i< js.size(); i++){
        System.out.println(js); //prints values with same hashcode
    }
    return dao.getJobSummaries();
    }
}

当我打印列表时，它会打印具有相同哈希码的值，所以我猜它只得到一个 json 值

[com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809]
[com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809]
[com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809]
[com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809]
[com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809]
[com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809, com.RTH.WebServices.JobSummaries@691c5809]

Answer 1

我认为有两个问题： 1）每次循环getJobSummaries时都需要创建一个新实例 2）您需要每次打印出每一行而不是列表

问题就在这里：

List js = dao.getJobSummaries();
    for(int i=0; i< js.size(); i++){
        System.out.println(js); //prints the whole list every time
    }

您每次都在打印列表。我认为您想获取列表中的项目-例如：

List js = dao.getJobSummaries();
for (Object j : js) {
        System.out.println(j); //prints each item in the list
}

Answer 2

这样改

public class FetchJobSummaryDAO {

     public List getJobSummaries() {

     JobSummaries jobSummaries = null;
     List<JobSummaries> jobSummaryList = new ArrayList<JobSummaries>();

  try {

    Connection con = DBConnection.getConnection();

String query = "select JOB_NAME,JOB_DESCRIPTION,JOB_ROLE,JOB_PRIMARY_SKILL,JOB_DESIGNATION,JOB_EXP,JOB_SAL_RANGE, JOB_POSTEDBY from TBL_JOBPOSTING";

PreparedStatement pst = con.prepareStatement(query);
ResultSet rs = pst.executeQuery();

ResultSetMetaData rsmd = rs.getMetaData();
int columnsNumber = rsmd.getColumnCount();
while (rs.next()) {
    jobSummaries =  new JobSummaries()
    jobSummaries.setJobName(rs.getString("JOB_NAME"));
    jobSummaries.setJobDescription(rs.getString("JOB_DESCRIPTION"));
    jobSummaries.setJobRole(rs.getString("JOB_ROLE"));
   jobSummaries.setJobPrimarySkill(rs.getString("JOB_PRIMARY_SKILL"));
    jobSummaries.setJobDesignation(rs.getString("JOB_DESIGNATION"));
    jobSummaries.setJobExp(rs.getString("JOB_EXP"));
    jobSummaries.setJobSalaryRange(rs.getString("JOB_SAL_RANGE"));
    jobSummaries.setJobPostedBy(rs.getString("JOB_POSTEDBY"));
    jobSummaryList.add(jobSummaries);

    for (int i = 1; i <= columnsNumber; i++) {
        if (i > 1) {
            System.out.print(",  ");
        }
        String columnValue = rs.getString(i);
        System.out.print(rsmd.getColumnName(i) + " " + columnValue);
    }
    System.out.println("");
}

 } catch (SQLException ex) {
Logger.getLogger(FetchJobSummaryDAO.class.getName()).log(Level.SEVERE,               null, ex);
   }
  return jobSummaryList;

}