Java 在jsp中以表格格式显示地图，其中对象为键，Arraylist为值

POJO类：

public class MapKey {
      private Integer id;
      private String name;
      private Integer status;

       public MapKey(Integer id, String name,Integer status) {
        this.id = id;
        this.name = name;
        this.status=status;
      }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }
 //All getters and setters

JSP代码：

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;      
    public int getrequestId() {
        return requestId;
    }
    public void setrequestId(int requestId) {
        requestId= requestId;
    }
     //All getters and setters

预期产出：

MapKey [reqid=123, name=A,status=1]:[Dashboard [reqid=123, NAME=A, PRICE=5,STATUS=2],Dashboard [reqid=123, NAME=A, PRICE=10,STATUS=3],...,..]
MapKey [reqid=456, name=B,status=2]:[Dashboard [reqid=456, NAME=B, PRICE=20,STATUS=3],Dashboard [reqid=456, NAME=B, PRICE=25,STATUS=2],...,..]

---

我有一个映射，其中key是一个对象，value是List。在映射中，键是我的表头，映射中的值是该表头的表数据。键取决于sql中的数据。它可以根据数据而变化。我想将每个键显示为表头，将其所有相关数据显示为表的行。我用jsp编写了代码来为每个键创建表。我是java开发的新手，这就是我能写的。我需要帮助来实现预期的输出。

下面给出的是一个最小的、可验证的示例：

Dashboard.java:

123  A   1   ///Table header 
123 A   5  2
123 A  10  3
//N no of rows 

456 B 2    ///Table header 
456 B  20  3
456 B  25  2
//N no of rows

package beans;

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;
    public Dashboard(int requestId, String loginUser, int price, int status) {
        this.requestId = requestId;
        this.loginUser = loginUser;
        this.price = price;
        this.status = status;
    }
    public int getRequestId() {
        return requestId;
    }
    public String getLoginUser() {
        return loginUser;
    }
    public int getPrice() {
        return price;
    }
    public int getStatus() {
        return status;
    } 
}

package beans;

public class MapKey {
    private Integer id;
    private String name;
    private Integer status;

    public MapKey(Integer id, String name, Integer status) {
        this.id = id;
        this.name = name;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public Integer getStatus() {
        return status;
    }
}

package servlets;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.RequestDispatcher;
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 beans.Dashboard;
import beans.MapKey;

@WebServlet("/Report")
public class AppController extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        populateData(request, response);
        RequestDispatcher view = request.getRequestDispatcher("my_page.jsp");
        view.forward(request, response);
    }

    public void populateData(HttpServletRequest request, HttpServletResponse response) {
        Map<MapKey, List<Dashboard>> map = new LinkedHashMap<>();
        map.put(new MapKey(123, "A", 1), List.of(new Dashboard(123, "A", 5, 2), new Dashboard(123, "A", 10, 3)));
        map.put(new MapKey(456, "B", 2), List.of(new Dashboard(456, "B", 20, 3), new Dashboard(456, "B", 25, 2)));
        request.setAttribute("reportMap", map);
    }
}

MapKey.java:

123  A   1   ///Table header 
123 A   5  2
123 A  10  3
//N no of rows 

456 B 2    ///Table header 
456 B  20  3
456 B  25  2
//N no of rows

package beans;

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;
    public Dashboard(int requestId, String loginUser, int price, int status) {
        this.requestId = requestId;
        this.loginUser = loginUser;
        this.price = price;
        this.status = status;
    }
    public int getRequestId() {
        return requestId;
    }
    public String getLoginUser() {
        return loginUser;
    }
    public int getPrice() {
        return price;
    }
    public int getStatus() {
        return status;
    } 
}

package beans;

public class MapKey {
    private Integer id;
    private String name;
    private Integer status;

    public MapKey(Integer id, String name, Integer status) {
        this.id = id;
        this.name = name;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public Integer getStatus() {
        return status;
    }
}

package servlets;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.RequestDispatcher;
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 beans.Dashboard;
import beans.MapKey;

@WebServlet("/Report")
public class AppController extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        populateData(request, response);
        RequestDispatcher view = request.getRequestDispatcher("my_page.jsp");
        view.forward(request, response);
    }

    public void populateData(HttpServletRequest request, HttpServletResponse response) {
        Map<MapKey, List<Dashboard>> map = new LinkedHashMap<>();
        map.put(new MapKey(123, "A", 1), List.of(new Dashboard(123, "A", 5, 2), new Dashboard(123, "A", 10, 3)));
        map.put(new MapKey(456, "B", 2), List.of(new Dashboard(456, "B", 20, 3), new Dashboard(456, "B", 25, 2)));
        request.setAttribute("reportMap", map);
    }
}

AppController.java:

123  A   1   ///Table header 
123 A   5  2
123 A  10  3
//N no of rows 

456 B 2    ///Table header 
456 B  20  3
456 B  25  2
//N no of rows

package beans;

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;
    public Dashboard(int requestId, String loginUser, int price, int status) {
        this.requestId = requestId;
        this.loginUser = loginUser;
        this.price = price;
        this.status = status;
    }
    public int getRequestId() {
        return requestId;
    }
    public String getLoginUser() {
        return loginUser;
    }
    public int getPrice() {
        return price;
    }
    public int getStatus() {
        return status;
    } 
}

package beans;

public class MapKey {
    private Integer id;
    private String name;
    private Integer status;

    public MapKey(Integer id, String name, Integer status) {
        this.id = id;
        this.name = name;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public Integer getStatus() {
        return status;
    }
}

package servlets;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.RequestDispatcher;
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 beans.Dashboard;
import beans.MapKey;

@WebServlet("/Report")
public class AppController extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        populateData(request, response);
        RequestDispatcher view = request.getRequestDispatcher("my_page.jsp");
        view.forward(request, response);
    }

    public void populateData(HttpServletRequest request, HttpServletResponse response) {
        Map<MapKey, List<Dashboard>> map = new LinkedHashMap<>();
        map.put(new MapKey(123, "A", 1), List.of(new Dashboard(123, "A", 5, 2), new Dashboard(123, "A", 10, 3)));
        map.put(new MapKey(456, "B", 2), List.of(new Dashboard(456, "B", 20, 3), new Dashboard(456, "B", 25, 2)));
        request.setAttribute("reportMap", map);
    }
}

包servlet；
导入java.io.IOException；
导入java.util.LinkedHashMap；
导入java.util.List；
导入java.util.Map；
导入javax.servlet.RequestDispatcher；
导入javax.servlet.ServletException；
导入javax.servlet.annotation.WebServlet；
导入javax.servlet.http.HttpServlet；
导入javax.servlet.http.HttpServletRequest；
导入javax.servlet.http.HttpServletResponse；
导入bean.Dashboard；
导入beans.MapKey；
@WebServlet（“/Report”）
公共类AppController扩展HttpServlet{
受保护的void doGet（HttpServletRequest请求、HttpServletResponse响应）
抛出ServletException、IOException{
doPost（请求、响应）；
}
受保护的void doPost（HttpServletRequest请求、HttpServletResponse响应）
抛出ServletException、IOException{
填充数据（请求、响应）；
RequestDispatcher视图=request.getRequestDispatcher（“my_page.jsp”）；
视图。转发（请求、响应）；
}
public void populateData（HttpServletRequest请求、HttpServletResponse响应）{
Map Map=newlinkedhashmap（）；
地图放置（新地图键（123，“A”，1），列表（新仪表板（123，“A”，5，2），新仪表板（123，“A”，10，3））；
地图放置（新地图键（456，“B”，2），列表（新仪表板（456，“B”，20，3），新仪表板（456，“B”，25，2））；
setAttribute（“reportMap”，map）；
}
}

my_page.jsp:

123  A   1   ///Table header 
123 A   5  2
123 A  10  3
//N no of rows 

456 B 2    ///Table header 
456 B  20  3
456 B  25  2
//N no of rows

package beans;

public class Dashboard {
    int requestId;
    String loginUser;                  
    int price;                                     
    int status;
    public Dashboard(int requestId, String loginUser, int price, int status) {
        this.requestId = requestId;
        this.loginUser = loginUser;
        this.price = price;
        this.status = status;
    }
    public int getRequestId() {
        return requestId;
    }
    public String getLoginUser() {
        return loginUser;
    }
    public int getPrice() {
        return price;
    }
    public int getStatus() {
        return status;
    } 
}

package beans;

public class MapKey {
    private Integer id;
    private String name;
    private Integer status;

    public MapKey(Integer id, String name, Integer status) {
        this.id = id;
        this.name = name;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public Integer getStatus() {
        return status;
    }
}

package servlets;

import java.io.IOException;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.RequestDispatcher;
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 beans.Dashboard;
import beans.MapKey;

@WebServlet("/Report")
public class AppController extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        populateData(request, response);
        RequestDispatcher view = request.getRequestDispatcher("my_page.jsp");
        view.forward(request, response);
    }

    public void populateData(HttpServletRequest request, HttpServletResponse response) {
        Map<MapKey, List<Dashboard>> map = new LinkedHashMap<>();
        map.put(new MapKey(123, "A", 1), List.of(new Dashboard(123, "A", 5, 2), new Dashboard(123, "A", 10, 3)));
        map.put(new MapKey(456, "B", 2), List.of(new Dashboard(456, "B", 20, 3), new Dashboard(456, "B", 25, 2)));
        request.setAttribute("reportMap", map);
    }
}

申请人资料
${map.key.id}${map.key.name}${map.key.status}
${item.requestId}${item.logiuser}${item.price}${item.status}

输出：

---

旁注：遵循例如

PRICE

应该是

PRICE

和

STATUS

应该是

STATUS

。我建议你阅读javadoc for interface@Abra我读了一些文档和教程，但这些都是非常基本的。它离我想做的事情不远了。@ArvindKumarAvinash更新了。请仔细看看。看起来更好，但是您仍然需要将

request\u id

更改为

requestId

，将

login\u user

更改为

loginUser

。说到您的问题，您需要创建

。非常感谢您给我这个想法。只需更新一下，映射是在jdbc类中定义的，我从sql db中获取数据。非常欢迎您。您需要在servlet中调用DAO（放置JDBC代码的类）。为了演示，我用示例数据填充了一个

Map

对象，在servlet.Ya中，我将检查一次..任何更新或更改我都会在此处发送消息。非常感谢您的帮助。我只运行了一次代码，就出现了此错误。HTTP状态500–内部服务器错误。键入异常报告。消息在[58]行处理[/Dashboard.jsp]时发生异常.Description:服务器遇到意外情况，无法完成请求。行为58 is${item.requestId}${item.loginUser}${item.price}${item.status}@初学者-建议您复制我的代码并运行它。然后，理解它并做出改变以更快地学习。