如何从 spring 中的 JSON 响应中过滤属性？

Question

我有一个如下所示的 controller，

@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 controller 像这样，

@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> {
}

这从结果 class 延伸而来：

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

    /*Constructors, getters and setters*/
}

现在我要设置到结果字段中的 model 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。 我怎样才能在 spring 中实现这一目标。非常感谢任何帮助！

Answer 1

您是否考虑过@JsonView ？

Spring MVC支持它，它允许您根据序列化的上下文来过滤字段。

首先定义您的观点：

public class View {     

    interface SampleView { }  
    interface SampleViewWithAge extends SampleView { }   
}

然后使用所需的视图注释字段：

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，在序列化响应时注释您的处理程序以使用视图：

@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 2

我认为最简单的方法是使用Jackson @JsonFilter如果您希望它动态的话。

例如，这里可能是Spring Boot的一个例子：

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，此筛选器将全部序列化。 此步骤是强制性的，如果不指定该步骤，则会出现一个异常，即将到来的时候他不知道myFilter ，此时您的控制器将尝试生成对象响应。

然后，在您的控制器中，这是您的常规端点，用于序列化所有字段（使用先前声明的过滤器）：

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

现在，端点具有相同的对象，并且只序列化了一些字段：

@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"

Answer 3

在模态类中使用必填字段覆盖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 4

公共类BeanFilterCustom {

public Object filterBean(Object object,String someBeanFilter)  {

    SimpleBeanPropertyFilter filter = SimpleBeanPropertyFilter.filterOutAllExcept("","");
    FilterProvider filters = new SimpleFilterProvider()
            .addFilter(someBeanFilter, filter);
    MappingJacksonValue mapping = new MappingJacksonValue(object);
    mapping.setFilters(filters);
    return mapping.getValue();
}

}

Answer 5

您可以在不想包含在JSON中的字段上使用@JsonIgnore 。

public class SampleImpl implements Sample {

    private Long id;
    private String name;

    @JsonIgnore
    private int age;

    /* Getters and Setters */

}