java - REST 处理错误参数

Question

在 RESTful 服务中处理错误参数的正确方法是什么？如果发送了错误的数据类型，我现在有一个端点返回 400。

@ResponseBody
@RequestMapping(produces = "application/json", method = RequestMethod.GET, value="/v1/test")
public MyResponse getSomething(@RequestParam BigDecimal bd) {
    MyResponse r = new MyResponse();
    r.setBd(bd);
    return r;
}

如果最终用户传递一个字符串而不是 BigDecimal，那将非常好，响应将返回一个 json，其中包含响应代码、状态以及我希望它包含的任何其他内容，而不仅仅是 400。有没有办法做到这一点？

更新:我最初的想法是包装每个参数，然后检查它是否是该包装类中的正确类型。这似乎有点傻。难道没有一个我可以添加到类路径中的 validator 来识别这样的东西吗？

另外，有一种方法可以很容易地使用我可以自己创建的 Bean 类型来处理这个问题，但是像 BigDecimal 这样的标准类型呢？

UPDATE-2:此更新解决了使用 @ExceptionHandler 的答案。

TestController.java

import java.math.BigDecimal;
import javax.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.ServletRequestBindingException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping("/")
public class TestController {

    //this is where correct input from user is passed, no binding errors
    @RequestMapping(produces = "application/json", method = RequestMethod.GET, value="/v1/test")
    public
    @ResponseBody
    MyResponse getSomething(@RequestParam BigDecimal bd) {
        MyResponse r = new MyResponse();
        r.setBd(bd);
        return r;
    }

    //this will handle situation when you except number and user passess string (A123.00 for example)
    @ExceptionHandler(ServletRequestBindingException.class)
    public @ResponseBody MyErrorResponse handleMyException(Exception exception, HttpServletRequest request) {

        MyErrorResponse r = new MyErrorResponse();
        r.setEexception(exception);

        return r;
    }


}

TestUnitTest.java

public class TestUnitTest {

protected MockMvc mockMvc;

@Autowired
protected WebApplicationContext wac;

@Before
public void setup() {
    this.mockMvc = MockMvcBuilders.webAppContextSetup(this.wac).build();
}


@Test
public void test() throws Exception {
    String url =  "/v1/test?bd=a123.00";

    log.info("Testing Endpoint::: " + url);

    MvcResult result =  mockMvc.perform(get(url))
                        .andExpect(status().isOk())
                        .andReturn();

    log.info("RESPONSE::: " + result.getResponse().getContentAsString());
}

}

MyResponse.java

import java.math.BigDecimal;

public class MyResponse {

    private BigDecimal bd;

    public BigDecimal getBd() {
        return bd;
    }

    public void setBd(BigDecimal bd) {
        this.bd = bd;
    }

}

MyErrorResponse.java

public class MyErrorResponse {

    private Exception exception;

    public Exception getException() {
        return exception;
    }

    public void setEexception(Exception e) {
        this.exception = e;
    }

}

Answer 1

像这样使用 Spring @ExceptionHandler 和标准的 @RequestMapping 注解:

//this is where correct input from user is passed, no binding errors
@RequestMapping(produces = "application/json", method = RequestMethod.GET, value="/v1/test")
public
@ResponseBody
MyResponse getSomething(@RequestParam BigDecimal bd) {
    MyResponse r = new MyResponse();
    r.setBd(bd);
    return r;
}

//this will handle situation when there's exception during binding, for example you except number and user passess string (A123.00 for example)
@ExceptionHandler(TypeMismatchException.class)
public 
@ResponseBody
MyErrorResponse handleMyException(Exception exception, HttpServletRequest request) {
    //....
}

TypeMismatchException 是在尝试设置 bean 属性时抛出的一般异常。您可以进一步概括代码并使用几种方法捕获每个绑定(bind)异常，例如:

@ExceptionHandler(TypeMismatchException.class)
public
@ResponseBody
String typeMismatchExpcetionHandler(Exception exception, HttpServletRequest request) {
    return "type mismatch";
}

@ExceptionHandler(MissingServletRequestParameterException.class)
public
@ResponseBody
String missingParameterExceptionHandler(Exception exception, HttpServletRequest request) {
    return "missing param";
}

@ExceptionHandler(Exception.class)
public
@ResponseBody
String generalExceptionHandler(Exception exception, HttpServletRequest request) {
    return "general exception";
}

非常灵活，允许在签名和返回对象中使用很多参数Annotation Type ExceptionHandler

使用@ResponseBody，您可以返回任何对象，可以序列化为JSON。它只需要在你的类路径中有 jackson 库，但我假设你已经知道了这一点