在java中将字符串转换为long

Question

我正在使用一个春季启动项目，我试图在控制器中创建一个具有动态参数数量的路由。路由是这样的:

@RequestMapping(value = "/addItem", method = RequestMethod.POST)
public String addItem(ModelMap model, @RequestParam Map<String,String> allRequestParams) {
String stringId = allRequestParams.get("id");
System.out.println(stringId);
long id = Long.valueOf(stringId);
System.out.println(id);
...
}

我需要将id参数转换为Long，我已经尝试使用Long.valueOf(stringId)和Long.parseLong(stringId)这样做，但是当我使用参数id作为1调用路由时，我得到此错误:

Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NumberFormatException: For input string: "1
"] with root cause
java.lang.NumberFormatException: For input string: "1

我像这样从表单中调用路由:

<form method="POST" action="addItem">
<div class="form-group">
<table id="details" class="table table-responsive">
<tr id="type">
<th class="text-left select-title">Type* :</th>
<td>
<select name="id" id="input" class="form-control form-control-sm inv-select" required>
<option value="" disabled selected>Selected...</option>
<%@ include file = "common/dropdown.jsp" %>
</select>
</td>   
</tr>
<tr id="component1">
<th class="text-left select-title">Type of Component * :</th>
<td>
<select id="select" name="component1" class="form-control form-control-sm inv-select" required>
<option value="" disabled selected>Selected...</option>
<%@ include file = "common/dropdown.jsp" %>
</select>
</td>
<th class="text-left quant-title">Quantity * :</th>
<td class="quantity-field">
<input name="quantity1" type="number" step="any" placeholder="Quantity" class="quantity-input" required>
</td>
</tr>
<tr class="table-row">
<td>
<button onclick="addComponent()" id="add-component" class="btn btn-md btn-outline-success"> + Add Component</button><br>
</td>
<td>
<button onclick="removeComponent()" id="rem-component" class="btn btn-md btn-outline-danger"> - Remove Component</button><br>
</td>
</tr>
<tr>
<th>
<input type="submit" name="submit" id="submit">
</th>
</tr>
</table>
</div>
</form>

控制器路由中的print语句用于调试，并且只打印第一个print语句。我怎样才能正确地将字符串转换为长?

Answer 1

您说字符串是"1rn"。

但是，Long.valueOf()只适用于仅由数字组成的字符串。

为了解决这个问题，使用trim():

Long.valueOf(stringId.trim());

我建议你使用Long#parseLong代替Long#valueOf，因为它返回long而不是Long。这样就摆脱了无用的对象创建。

@RequestMapping(value = "/addItem", method = RequestMethod.POST)
public String addItem(ModelMap model, @RequestParam Map<String,String> allRequestParams) {
String stringId = allRequestParams.get("id");
System.out.println(stringId);
long id = Long.parseLong(stringId.trim());
System.out.println(id);
...
}