kendo ui 网格未从 servlet 接收 json 数据

Question

我有一个名为 javaservlet 的 netbeans Web 应用程序。这个项目包有一个 servlet databaseconnection.java.here 我从一个数据库表 employee 中检索了 6 行，该表有 3 个列 eid,ename,esalary 并将其显示为 json 值 在“http://localhost:8084/javaservlet/databaseconnection”url 中。现在我想在 kendo 网格中显示所有 6 行数据。在 WEB-INF 文件夹中的 index.html 页面中，我试图从 url 读取 json 数据。但它不起作用。我在剑道 ui 网格和三个字符串字段中添加了三个标题 EmployeeSalary、EmployeeName、EmployeeId。当我运行文件时，仅在数据库表只有一行但表有多行剑道时才显示值没有显示任何数据..为什么会发生这种情况。请帮我解决问题。这是我的代码 数据库连接.java

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
 import java.sql.Statement;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.json.*;

@WebServlet(urlPatterns = {"/databaseconnection"})
public class databaseconnection extends HttpServlet {

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    response.setContentType("application/json");
    PrintWriter out = response.getWriter();
    Connection connection = null;
    Statement stmt = null;
    JSONArray jArray = new JSONArray();
    JSONObject jobj = new JSONObject();
    try {
        Class.forName("org.postgresql.Driver");
        connection = DriverManager.getConnection("jdbc:postgresql://localhost:5432/test", "postgres", "root");
        stmt = connection.createStatement();
     //  String sql = "INSERT INTO employee (eid,ename,esalary) " + "VALUES (7, 'Nadia', 35000)";
        //  stmt.executeUpdate(sql);
        ResultSet result = stmt.executeQuery("Select eid,ename,esalary from employee");
        while (result.next()) {
            String eid = result.getString("eid");
            String ename = result.getString("ename");
            String esalary = result.getString("esalary");
            jobj.put("eid", eid);
            jobj.put("ename", ename);
            jobj.put("esalary", esalary);
            out.print(jobj);
            out.flush();    

           // jArray.put(jobj);
            // System.out.print(jobj);
        }

    } catch (SQLException e) {

        System.out.println("Connection Failed! Check output console");
        e.printStackTrace();
        return;

    } catch (ClassNotFoundException ex) {
        Logger.getLogger(databaseconnection.class.getName()).log(Level.SEVERE, null, ex);
    }


}

Answer 1

请将 jsonobject 添加到 while loop.ex 内的 jsonarray 中：

 while (result.next()) {
            String type_json = result.getString("eid");
            String name_json = result.getString("ename");
            String id_json = result.getString("esalary");
            jobj.put("eid", type_json);
            jobj.put("ename", name_json);
            jobj.put("esalary", id_json);
            **jArray.add(jobj);**

        }

Answer 2

Sara5，我认为你应该像下面这样声明 Json 类的数组对象

JSONArray allArray = new JSONArray();

然后

while (result.next()) {
        String type_json = result.getString("eid");
        String name_json = result.getString("ename");
        String id_json = result.getString("esalary");
        jobj.put("eid", type_json);
        jobj.put("ename", name_json);
        jobj.put("esalary", id_json);
        allArray.add(jobj);

    }

然后在此之后，我们创建一个默认的 JSON 对象来包含所有 JSON 对象的数组和数量，如下所示

JSONObject myObj = new JSONObject();
myObj.put("success", true);
myObj.put("data", allArray); // all JSON objects
myObj.put("total", total);// total number of JSON objects

response.setContentType("application/json");// don't forget this
PrintWriter writer = response.getWriter();
writer.println(myObj.toString());

Answer 3

请尝试使用以下库 json-lib-2.2.2-jdk15 公共语言 2.5 commons-beanutils 1.8.0 公共集合 3.2.1 公共日志记录 1.1.1 ezmorph 1.0.6

像这样更改您的代码.. response.setContentType("application/json");

while (result.next()) {
            String type_json = result.getString("eid");
            String name_json = result.getString("ename");
            String id_json = result.getString("esalary");
            jobj.put("eid", type_json);
            jobj.put("ename", name_json);
            jobj.put("esalary", id_json);
            **jArray.add(jobj);**

        }
String output = jArray.toString();
    PrintWriter writer = response.getWriter();
    writer.write(output);`enter code here`
    writer.close();
return "success";

上面的代码sn-p会将json输出写入到forward为“success”的相应jsp中。