为什么这些列表不起作用？ （春天 - mvc）

Question

我被要求学习java和spring mvc的工作，但似乎我并不擅长它:( 无论如何，我试图动态创建两个列表，第一个工作，第二个没有（我没有真正理解我担心的get和post方法）你能告诉我为什么吗？

@Controller

@RequestMapping（value =＆＃34; /＆＃34;） 公共类ConfigController {

@RequestMapping(value = "home", method = RequestMethod.GET)
public String saveNum(Model model) {
    model.addAttribute("configuration", new Config());
    return "home";
}

@RequestMapping(value = "home", method = RequestMethod.POST)
public String saveNumPost(@ModelAttribute(value = "configuration") Config config, Model model) {
    List<Driver> drivers = new ArrayList<Driver>();
    for (int i = 0; i < config.getDriversNum(); i++) {
        drivers.add(new Driver());
    }
    Championship championship = new Championship();
    championship.setDrivers(drivers);
    model.addAttribute("championship", championship);
    return "configDrivers";
}

@RequestMapping(value = "configDrivers", method = RequestMethod.GET)
public String saveDriverList() {
    return "configDrivers";
}

@RequestMapping(value = "configDrivers", method = RequestMethod.POST)
public String createCars(@ModelAttribute Championship championship, Config config, Model model) {
    List<Car> cars = new ArrayList<Car>();
    for (int i = 0; i < championship.getDrivers().size(); i++) {
        cars.add(new Car());
    }
    championship.setCars(cars);
    model.addAttribute("championship", championship);

    return "configCars";
}

@RequestMapping(value = "configCars", method = RequestMethod.GET)
public String saveTrackNum(@ModelAttribute Config config, Model model) {
    model.addAttribute("configuration", config);
    return "trackNum";
}

@RequestMapping(value = "trackNum", method = RequestMethod.POST)
public String saveTracks(@ModelAttribute(value = "configuration") Config config, Championship championship,
        Model model) {
    List<Track> tracks = new ArrayList<Track>();
    for (int i = 0; i < config.getTracksNum(); i++) {
        tracks.add(new Track());
    }
    championship.setTracks(tracks);
    model.addAttribute("championship", championship);

    return "configTracks";
}

}

主页视图

    <c:url var="url" value="/home"/>
    <form:form action="${url}" method="POST" modelAttribute="configuration">
        <label>Insert number of drivers:</label> <br> 
        <form:input path="driversNum" placeholder="Type drivers number"/>
        <br>
        <input type="submit" />
        <!--number races-->
    </form:form>

configDrivers视图

  <c:url var="url" value="/configDrivers"/>

    <form:form action="${url}" method="POST" modelAttribute="championship">

        <label>Insert drivers:</label> 

        <c:forEach items="${championship.drivers}" var="driver" varStatus="i">
            <h3>Insert driver's name and surname of driver ${i.index} </h3>
            <form:input path="drivers[${i.index}].name" value="${driver.name}" placeholder="Type name here" />
            <br>
            <form:input path="drivers[${i.index}].surname" value="${driver.surname}" placeholder="Type surname here" />
            <br>
        </c:forEach>    
            <input type="submit" />
            <!--number races-->
    </form:form>

configCars视图

    <c:url var="url" value="/configCars"/>

    <form:form action="${url}" method="POST" modelAttribute="championship">

        <label>Insert cars:</label> 

        <c:forEach items="${championship.cars}" var="car" varStatus="i">
            <h3>Insert driver's team ${i.index} </h3>
            <form:input path="cars[${i.index}].team" value="${car.team}" placeholder="Type team here" />
            <br>
        </c:forEach>    



            <input type="submit" />
            <!--number races-->
    </form:form>

    <select>
          <c:forEach items="${championship.drivers}" var="car" varStatus="i">
              <option value="${i.index}">${driver.name}</option>
          </c:forEach>
        </select>

Car class

public class Car {

private String team;
private Driver driver;

public String getTeam() {
    return team;
}

public void setTeam(String team) {
    this.team = team;
}

public Driver getDriver() {
    return driver;
}

public void setDriver(Driver driver) {
    this.driver = driver;
}

}

冠军级别（带名单的那个）

public class Championship {

private List<Driver> drivers;
private List<Car> cars;
private List<Track> tracks;

public List<Driver> getDrivers() {
    return drivers;
}

public void setDrivers(List<Driver> drivers) {
    this.drivers = drivers;
}

public List<Car> getCars() {
    return cars;
}

public void setCars(List<Car> cars) {
    this.cars = cars;
}

public List<Track> getTracks() {
    return tracks;
}

public void setTracks(List<Track> tracks) {
    this.tracks = tracks;
}

}

Answer 1

可以粘贴此代码：

List<Car> cars = new ArrayList<Car>(); 
      for (int i= 0; i < config.getDriversNum(); i++) { 
          cars.add(new Car()); 
      }
  Championship championship = new Championship();
  championship.setCars(cars); 
  model.addAttribute("championship",championship);

在printDrivers（）方法中并检查。

我认为应该这样做。