如何在spring中过滤JSON响应中的属性？

Question

我有一个如下的控制器，

@RequestMapping(value = "rest/v1/tester")
public class TestController {

    @RequestMapping(value = "/search", method = RequestMethod.GET)
    public ResponseEntity<SampleResults> search(@ModelAttribute("criteria")SampleCriteria criteria) throws Exception {
            SampleResults sampleResults = sampleService.search(criteria);
            return new ResponseEntity<>(sampleResults, OK);
    }

}

我有另一个这样的控制器，

@RequestMapping(value = "rest/v1/second")
public class SecondTestController {

@RequestMapping(value = "/search", method = RequestMethod.GET)
    public ResponseEntity<SampleResults> search(@ModelAttribute("criteria")SampleCriteria criteria) throws Exception {
            SampleResults sampleResults = secondsampleService.search(criteria);
            return new ResponseEntity<>(sampleResults, OK);
    }

}

我的结果结构如下：

public class SampleResults extends Results<SearchSummary, Sample> {
}

这扩展了结果类：

public class Results<SUMMARY,RESULTS> {
    private SUMMARY summary;
    private List<RESULTS> results;

    /*Constructors, getters and setters*/
}

现在，我将要设置到结果字段中的模型是，

@JsonDeserialize(as = SampleImpl.class)
public interface Sample {

    Long getId();
    void setId(Long id);

    String getName();
    void setName(String name);

    int getAge();
    void setAge(int age);

}

public class SampleImpl implements Sample {

    private Long id;
    private String name;
    private int age;

    /* Getters and Setters */

}

现在，对于上面提到的TestController，我想显示json响应中的所有字段，而在SecondTestController中，我想屏蔽(不显示)json响应中的age属性。在Spring我该如何实现这一点。非常感谢任何帮助！

Answer 1

使用必填字段重写模式类中的 toString 方法，并将其显式转换为 json，如下所示在第二个控制器方法中。

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
//get yourObject

ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
String json = ow.writeValueAsString(yourObject);

Answer 2

您是否考虑过@JsonView？

它受Spring MVC支持，允许您根据序列化的上下文过滤字段。

首先定义您的视图：

public class View {     

    interface SampleView { }  
    interface SampleViewWithAge extends SampleView { }   
}

然后使用所需视图注释字段：

public class SampleImpl implements Sample { 

    @JsonView(View.SampleView.class)
    private Long id; 

    @JsonView(View.SampleView.class)
    private String name; 

    @JsonView(View.SampleViewWithAge.class)
    private int age;

    // Getters and setters
 }

最后，注释您的处理程序以在序列化响应时使用视图：

@JsonView(View.SampleView.class) 
@RequestMapping(value = "/search", method = RequestMethod.GET)  
public ResponseEntity<SampleResults> search() {
    ... 
}

@JsonView(View.SampleViewWithAge.class)
@RequestMapping(value = "/search", method = RequestMethod.GET)  
public ResponseEntity<SampleResults> searchWithAge() {
    ... 
}

Answer 3

我认为最简单的方法是使用Jackson @JsonFilter，如果你想要它动态的话。

例如，这里有一个使用Spring Boot的示例：

您的文件 ：

@JsonFilter("myFilter")
class Document {
   private field1;
   private field2;
}

修改默认配置的HttpMessageConverter：

@Configuration
class WebMvcConfiguration extends WebMvcConfigurationSupport {
    @Override
    protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
        for(HttpMessageConverter<?> converter: converters) {
            if(converter instanceof MappingJackson2HttpMessageConverter) {
                ObjectMapper mapper = ((MappingJackson2HttpMessageConverter)converter).getObjectMapper();
                mapper.setFilterProvider(new SimpleFilterProvider().addFilter("myFilter", SimpleBeanPropertyFilter.serializeAll()));
            }
        }
    }
}

默认情况下，此过滤器将序列化所有内容。此步骤是强制性的，如果您不指定它，当您的控制器尝试生成对象响应时，您将出现他不知道myFilter的异常。

然后，在您的控制器中，这里是您序列化所有字段的常规endpoint(使用之前声明的过滤器):

@RequestMapping(value = "path/document", method = RequestMethod.GET)
public Document getDocumentWithAllFields() {
   return new Document("val1","val2");
} 
//result : {"field1":"val1","field2":"val2"}

现在，endpoint具有相同的对象，只有一些字段被序列化：

@RequestMapping(value = "path/document", method = RequestMethod.GET)
public MappingJacksonValue getDocumentWithSomeFields(@RequestParam String[] fields) {
    MappingJacksonValue wrapper = new MappingJacksonValue(new Document("val1","val2"));
    FilterProvider filterProvider = new SimpleFilterProvider().addFilter("myFilter", 
         SimpleBeanPropertyFilter.filterOutAllExcept(fields)); 
    wrapper.setFilters(filterProvider);
    return wrapper;
} 
//result : {"field1":"val1"} (with 'fields' being a coma separated list, containing here just "field1"