没有序列化程序在java restfull Web服务上发现错误

Question

我已经像这样创建了一个json数组

[
  {
    "proj_bugcount":"20",
    "pro_id":"1",
    "proj_status":"bugs",
    "pro_name":"Driver MAnagement System"
  },
  {
    "proj_bugcount":"0",
    "pro_id":"3",
    "proj_status":"released",
    "pro_name":"Hotel MAnagement System"
  }
]

使用以下代码

package com.test.databaseservice;

import com.test.entity.DashBoard;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import org.json.JSONException;
import org.json.JSONObject;

public class DashboardService {

    public static List<JSONObject> findRelatedData(int userId) throws JSONException {

        String setBugCount = null;
        String proId = null;
        String setProject = null;
        String setStatus = null;

        DashBoard dashboard = new DashBoard();
        List<JSONObject> resList = new ArrayList<JSONObject>();

        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            System.out.println(e);
        }

        try {

            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/project_management_system", "root", "");

            PreparedStatement ps = con.prepareStatement("SELECT project.proj_status,project.Pro_Name,project.proj_bugcount,project.Pro_Id FROM project_details INNER JOIN project ON project_details.Pro_Id = project.Pro_Id WHERE emp_id = ?");

            ps.setInt(1, userId);
            ResultSet rs = ps.executeQuery();


            ResultSetMetaData rsMeta = rs.getMetaData();
            int columnCnt = rsMeta.getColumnCount();

            ArrayList<String> columnNames = new ArrayList<String>();
            for (int i = 1; i < columnCnt + 1; i++) {

                columnNames.add(rsMeta.getColumnName(i).toLowerCase());

            }
            while (rs.next()) {
                JSONObject obj = new JSONObject();

                for (int a = 1; a < columnCnt + 1; a++) {

                    String key = columnNames.get(a - 1);
                    String value = rs.getString(a);
                    obj.put(key, value);

                }
                resList.add(obj);
            }
            con.close();

        } catch (SQLException e) {
            System.out.println(e);
        }


        return resList;
    }
}

然后我将它传递给下面的网络服务

package com.test.rest;

import com.test.databaseservice.DashboardService;
import java.util.ArrayList;
import java.util.List;
import javax.ws.rs.Consumes;
import javax.ws.rs.Produces;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.core.MediaType;
import org.json.JSONException;
import org.json.JSONObject;

@Path("dashboard")
public class DashBoardRestServices {

    @Path("find/{userName}")
    @GET
    @Consumes({MediaType.APPLICATION_JSON})
    @Produces(MediaType.APPLICATION_JSON)
    public List<JSONObject> find(@PathParam("userName") int userName) throws JSONException{
        //Find Employee from the database with give Id
        //DashBoard dashboard = new DashBoard();
        DashboardService Dashboardservice = new DashboardService();

        List<JSONObject> resList = Dashboardservice.findRelatedData(userName);
        System.out.println(resList);

        return resList;

    }

}

system.out.println正确输出创建的数组。

但是当我导航到网络服务Url时，它显示在Error

下面

    No serializer found for class org.json.JSONObject and no properties discovered to create BeanSerializer (to avoid exception,
disable SerializationFeature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.ArrayList[0])

那里有什么问题？