Question

我得到一个加密的String作为Spring参数的参数给Spring休息控制器方法。

我希望在字符串到达方法之前根据一些注释（比如@Decrypt）解密字符串，如下所示

@RequestMapping(value = "/customer", method = RequestMethod.GET)
public String getAppointmentsForDay(@RequestParam("secret") @Decrypt String customerSecret) {
    System.out.println(customerSecret);  // Needs to be a decrypted value.
   ...
}

这个用例中的自定义Formatter是正确的方法吗？

或者我应该使用自定义HandlerMethodArgumentResolver？

Answer 1

org.springframework.format.Formatter的自定义实现是此用例的有效方法。这就是Spring本身如何为日期，货币，数字样式等实现格式化程序。

步骤：

声明注释：Decrypt：

import java.lang.annotation.*;

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.FIELD, ElementType.PARAMETER, ElementType.ANNOTATION_TYPE})
public @interface Decrypt {

}

声明使用新注释的AnnotationFormatterFactory：

import org.springframework.context.support.EmbeddedValueResolutionSupport;
import org.springframework.format.AnnotationFormatterFactory;
import org.springframework.format.Formatter;
import org.springframework.format.Parser;
import org.springframework.format.Printer;

import java.text.ParseException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Locale;
import java.util.Set;

public class DecryptAnnotationFormatterFactory extends EmbeddedValueResolutionSupport
        implements AnnotationFormatterFactory<Decrypt> {

    @Override
    public Set<Class<?>> getFieldTypes() {
        Set<Class<?>> fieldTypes = new HashSet<>();
        fieldTypes.add(String.class);
        return Collections.unmodifiableSet(fieldTypes);
    }

    @Override
    public Printer<String> getPrinter(Decrypt annotation, Class<?> fieldType) {
        return configureFormatterFrom(annotation);
    }

    @Override
    public Parser<String> getParser(Decrypt annotation, Class<?> fieldType) {
        return configureFormatterFrom(annotation);
    }

    private Formatter<String> configureFormatterFrom(Decrypt annotation) {
        // you could model something on the Decrypt annotation for use in the decryption call
        // in this example the 'decryption' call is stubbed, it just reverses the given String
        // presumaby you implementaion of this Formatter will be different e.g. it will invoke your encryption routine
        return new Formatter<String>() {
            @Override
            public String print(String object, Locale locale) {
                return object;
            }

            @Override
            public String parse(String text, Locale locale) throws ParseException {
                return new StringBuilder(text).reverse().toString();
            }
        };
    }
}

使用您的网络背景注册此格式化工厂：

import org.springframework.context.annotation.Configuration;
import org.springframework.format.FormatterRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfigurer extends WebMvcConfigurerAdapter {
    @Override
    public void addFormatters(FormatterRegistry registry) {
        super.addFormatters(registry);
        registry.addFormatterForFieldAnnotation(new DecryptAnnotationFormatterFactory());
    }
}

就是这样。

完成上述操作后，@RequestParam符合@Decrypt条件的所有用法都将通过parse()中声明的DecryptAnnotationFormatterFactory方法传递，以便您实施解密就在那里打电话。

为证明这一点，以下测试通过：

@RunWith(SpringRunner.class)
@WebMvcTest(controllers = YourController.class)
public class YourControllerTest {
    @Autowired
    private MockMvc mockMvc;

    @Test
    public void theSecretRequestParameterWillBeConverted() throws Exception {
        MvcResult mvcResult = mockMvc.perform(get("/customer?secret=abcdef")).andExpect(status().isOk()).andReturn();

        // the current implementation of the 'custom' endpoint returns the value if the secret request parameter and
        // the current decrypt implementation just reverses the given value ...
        assertThat(mvcResult.getResponse().getContentAsString(), is("fedcba"));
    }
}

Answer 2

HandlerMethodArgumentResolver在这方面是最好的。

创建注释：

from numpy import *

foo= dtype(object, [])
x = array([[2., 3.], [3.]], dtype=foo)

创建自定义HandlerMethodArgumentResolver：

@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Decrypt {
    String value();
}

注册解析器：

public class DecryptResolver implements HandlerMethodArgumentResolver {

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        return parameter.getParameterAnnotation(Decrypt.class) != null;
    }

    @Override
    public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest,
            WebDataBinderFactory binderFactory) throws Exception {
        Decrypt attr = parameter.getParameterAnnotation(Decrypt.class);
        String encrypted = webRequest.getParameter(attr.value());
        String decrypted = decrypt(encrypted);

        return decrypted;
    }

    private String decrypt(String encryptedString) {
        // Your decryption logic here

        return "decrypted - "+encryptedString;
    }
}

瞧，你有解密的参数。请注意，您不再需要使用@RequestParam。

@Configuration
@EnableMvc // If you're not using Spring boot
public class WebConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addArgumentResolvers(List<HandlerMethodArgumentResolver> argumentResolvers) {
          argumentResolvers.add(new DecryptResolver());
    }
}

Answer 3

您可以尝试在CharacterEncodingFilter文件中添加init-param encoding UTF-8 web.xml。查看this example。

但是，如果它仍然不起作用，您可以通过添加以下参数以及init-param来强制编码。

<init-param>
        <param-name>forceEncoding</param-name>
        <param-value>true</param-value>
</init-param>

让我知道它是否适合你。

Spring MVC中@RequestParam的自定义转换器

3 个答案: