关于Java：如何验证@RequestParams是否为空？

How do I validate that the @RequestParams are not empty?

我有一个计算器服务，可从用户那里获取操作类型num1和num2。我需要验证用户是否实际输入了这些值，而不仅仅是将其留为空白。

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@RequestMapping(value ="/calculate")
@ResponseBody
public CalculationResult calculate(@RequestParam(name ="op") String operation, @RequestParam(name ="num1") Double num1, @RequestParam(name ="num2") Double num2) {
System.out.print("Operation:" + operation);
Double calculate = calculatorService.calculate(operation, num1, num2);
return new CalculationResult(calculate);
}

我有一个集成测试，我需要通过该测试，因为它当前因错误而失败：

{\"timestamp\":1488875777084,\"status\":400,\"error\":\"Bad
Request\",\"exception\":\"org.springframework.web.method.annotation.MethodArgumentTypeMismatchException\",\"message\":\"Failed
to convert value of type 'java.lang.String' to required type
'java.lang.Double';

以下是我的测试用例：

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@Test
public void validates_all_parameters_are_set() throws Exception {
ResponseEntity<String> response = template.getForEntity("/calculate?op=&num1=&num2=",
String.class);
assertThat(response.getStatusCode(), equalTo(HttpStatus.BAD_REQUEST));
assertThat(response.getBody(), equalTo("{"error":"At least one parameter is invalid or not supplied"}"));
}

我不知道该如何验证。

相关讨论

我早在这里就回答了类似的问题，您也可以按照下面的步骤编写测试：

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@Validated
public class CalculationController {

@RequestMapping(value ="/calculate")
@ResponseBody
public CalculationResult calculate(
@Valid @NotBlank @RequestParam(name ="op") String operation,
@Valid @NotNull @RequestParam(name ="num1") Double num1,
@Valid @NotNull @RequestParam(name ="num2") Double num2) {
System.out.print("Operation:" + operation);
Double calculate = calculatorService.calculate(operation, num1, num2);
return new CalculationResult(calculate);
}
}

应该修改相应的@Test以测试"可能不为空"消息的数组，如下所示：

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您到目前为止不检查这些值；您可以将代码更改为：

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import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;

@RequestMapping(value ="/calculate")
@ResponseBody
public ResponseEntity<CalculationResult> calculate(@RequestParam(name ="op") String operation,
@RequestParam(name ="num1") Double num1,
@RequestParam(name ="num2") Double num2) {

if(null == op || null == num1 || null == num2) {
throw new IllegalArgumentException("{"error":"At least one parameter is invalid or not supplied"}")
}

System.out.print("Operation:" + operation);
Double calculate = calculatorService.calculate(operation, num1, num2);

return new ResponseEntity<>(new CalculationResult(calculate), HttpStatus.OK);
}

@ExceptionHandler(IllegalArgumentException.class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
public final String exceptionHandlerIllegalArgumentException(final IllegalArgumentException e) {
return '"' + e.getMessage() + '"';
}