spring - Spring MVC中@RequestParam的自定义转换器

我正在获取一个加密的String作为Spring rest Controller 方法的Query参数。

我想在字符串到达​​基于某种注释(例如@Decrypt)的方法之前解密，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.
   ...
}

在这种用例中，自定义Formatter是否正确？

还是应该使用自定义的HandlerMethodArgumentResolver？

最佳答案

对于此用例，定制的org.springframework.format.Formatter实现是一种有效的方法。这就是Spring本身如何实现日期，货币，数字样式等格式器的方式。

脚步:

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 {

}

声明一个使用新注释的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();
            }
        };
    }
}

在您的Web上下文中注册此格式化程序工厂:

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，所有符合@RequestParam的@Decrypt用法都将通过parse()中声明的DecryptAnnotationFormatterFactory方法传递，以便您可以在此处实现解密调用。

为了证明这一点，通过了以下测试:

@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"));
    }
}