Question

目前，当我点击退款按钮时，$ {messages}和$ {changes}会显示在网址上，而不是显示在jsp内部。

网址看起来像这个localhost：8080 / name /？messages = Nice + Try％21＆amp; changes = Quarters％3A + 0 +％7C + Nickels％3A + 0％0ADimes％3A + 0 +％7C + Pennies ％3A + 0

根本没有任何东西出现在jsp体内。

我试过c：out value =＆＃34; $ {changes}＆＃34;，它没有用。我也尝试将requestMethod更改为POST，没有运气。

块引用

JSP
<div class='row text-center' id='change-display'>
    <div id="change">
        ${changes}    <---- should display the string, but nothing shows up here.
    </div>
</div>
<div class='row text-center' id='getChangeButtonDiv'>
    <a href="Money/refund">
        <button class='btn btn-purchase' type='button' id='refund-button'>
             <p>Refund</p>   <------- refund button
        </button>
    </a>
</div>

@RequestMapping(value="/refund", method=RequestMethod.GET)
public String refund(Model model) throws PersistenceException{
    BigDecimal zero = new BigDecimal(0);
    BigDecimal total = service.calculateInsertedTotal();
    int quarterInt=0, dimeInt=0, nickelInt=0, pennyInt=0;
    String message="Here is your refund!";

    if(total.compareTo(zero) != 1){
        message="Nice Try!";
    }else{
        while(total.compareTo(quarter)==0||total.compareTo(quarter)== 1){
            quarterInt ++;
            total = total.subtract(quarter);
        }
        while(total.compareTo(dime)==0||total.compareTo(dime)== 1){
            dimeInt ++;
            total = total.subtract(dime);
        }
        while(total.compareTo(nickel)==0||total.compareTo(nickel)== 1){
            nickelInt ++;
            total = total.subtract(nickel);
        }
        while(total.compareTo(nickel)==0||total.compareTo(nickel)== 1){
            nickelInt ++;
            total = total.subtract(nickel);
        }
    }
    String quarterString = "Quarters: "+ quarterInt;
    String dimeString = "Dimes: "+ dimeInt;
    String nickelString = "Nickels: "+ nickelInt;
    String pennyString = "Pennies: "+ pennyInt;
    String changes = quarterString + " | " + nickelString
            +"\n"+dimeString + " | " + pennyString;
    service.removeMoney();
    model.addAttribute("messages", message);
    model.addAttribute("changes", changes);
    return "redirect:/";
}

Answer 1

实际上，由于您使用attributes代替redirect:/，forward正在丢失，当您从一个请求重定向到另一个请求时，新的 http请求已创建，因此旧请求附加的model将丢失，这意味着您的属性消息和更改也将丢失，因此要解决此问题，您必须将您的属性保存在RedirectAttributes：

中

@RequestMapping(value="/refund", method=RequestMethod.GET)
public String refund(Model model, RedirectAttributes redirectModel) throws PersistenceException{

    //...

    redirectModel.addFlashAttribute("messages", message);
    redirectModel.addFlashAttribute("changes", changes);

    return "redirect:/";
}

如何在jsp体内显示控制器的值

1 个答案: