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Spring Boot页面反序列化 - PageImpl没有构造函数

javaspringspring-bootpaginationdeserialization
27

尝试对从Spring Boot接收的页面进行单元测试。如果与JavaScript一起使用，则可以轻松地反序列化页面，但在Java中失败。已为Spring添加了默认构造函数（这是另一个stackoverflow帖子中被接受的答案），但在此处不起作用。

单元测试

@Test
public void test_read_pagination_happy(@Autowired ObservationSet set) {

    repository.save(set);

    final HttpEntity<String> authHeaders = authentication.convert("", authSuccess);
    final ParameterizedTypeReference<RestResponsePage<ObservationSet>> responseType = new ParameterizedTypeReference<RestResponsePage<ObservationSet>>() {
    };
    // final ResponseEntity<String> result = restTemplate.exchange(base + "/api/v1/observationset", HttpMethod.GET, authHeaders, String.class);
    final ResponseEntity<RestResponsePage<ObservationSet>> result = restTemplate.exchange(base + "/api/v1/observationset", HttpMethod.GET, authHeaders,
                    responseType);
    System.out.println(result.getBody());
    assertSame(HttpStatus.OK, result.getStatusCode(), "incorrect status code");
}

RestRespongePage 类

class RestResponsePage<T> extends PageImpl<T> {

    private static final long serialVersionUID = 3248189030448292002L;

    public RestResponsePage(List<T> content, Pageable pageable, long total) {
        super(content, pageable, total);
    }

    public RestResponsePage(List<T> content) {
        super(content);
    }

    public RestResponsePage() {
        super(new ArrayList<T>());
    }

}

代码可在Github上找到-->https://github.com/OpenPCM/openpcm-server/blob/integration-test/src/test/java/org/openpcm/controller/ObservationSetControllerIntTest.java

反序列化会产生这个错误：

org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.springframework.data.domain.Pageable]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.springframework.data.domain.Pageable` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
 at [Source: (PushbackInputStream); line: 1, column: 294] (through reference chain: org.openpcm.controller.RestResponsePage["pageable"])
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:240)
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:225)
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:100)
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:959)
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:942)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:689)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:644)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:593)
    at org.springframework.boot.test.web.client.TestRestTemplate.exchange(TestRestTemplate.java:843)
    at org.openpcm.controller.ObservationSetControllerIntTest.test_read_pagination_happy(ObservationSetControllerIntTest.java:85)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:436)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:170)
    at org.junit.jupiter.engine.execution.ThrowableCollector.execute(ThrowableCollector.java:40)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:166)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:113)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:58)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$3(HierarchicalTestExecutor.java:112)
    at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.executeRecursively(HierarchicalTestExecutor.java:108)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.execute(HierarchicalTestExecutor.java:79)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$2(HierarchicalTestExecutor.java:120)
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
    at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
    at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
    at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:430)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$3(HierarchicalTestExecutor.java:120)
    at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.executeRecursively(HierarchicalTestExecutor.java:108)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.execute(HierarchicalTestExecutor.java:79)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$2(HierarchicalTestExecutor.java:120)
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
    at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177)
    at java.base/java.util.Iterator.forEachRemaining(Iterator.java:133)
    at java.base/java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
    at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
    at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
    at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
    at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
    at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:430)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$3(HierarchicalTestExecutor.java:120)
    at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.executeRecursively(HierarchicalTestExecutor.java:108)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.execute(HierarchicalTestExecutor.java:79)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:55)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:43)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:170)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:154)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:90)
    at org.eclipse.jdt.internal.junit5.runner.JUnit5TestReference.run(JUnit5TestReference.java:89)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)
Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.springframework.data.domain.Pageable` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information
 at [Source: (PushbackInputStream); line: 1, column: 294] (through reference chain: org.openpcm.controller.RestResponsePage["pageable"])
    at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
    at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1451)
    at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1027)
    at com.fasterxml.jackson.databind.deser.AbstractDeserializer.deserialize(AbstractDeserializer.java:265)
    at com.fasterxml.jackson.databind.deser.impl.FieldProperty.deserializeAndSet(FieldProperty.java:136)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:288)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:151)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4013)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3084)
    at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:237)
    ... 65 more
1
请提供异常的文本。（请参考：http://idownvotedbecau.se/imageofanexception/） - Prashant
一个解决方法是在控制器端点中不将Page作为响应类型暴露出来，而是返回一个List<YourEntity>。Page有一个方法getContent()，你可以调用它将Page转换为List<YourEntity>。就像我说的，这不是一个修复方法，而是一个变通方法。 - user10367961
@alexrolea 我实际上想要返回整个页面而不仅仅是列表，这样如果你在Web客户端中，就可以通过页面进行标签切换。 - GSUgambit
如果客户端在其端跟踪类似于“pageIndex”和“pageSize”的内容，并使用请求发送这两个参数，则您实际上不需要向客户端公开“Page”。但是，正如我所说，这更像是一种解决方法而不是修复方法 :) - user10367961
1
是的，但如果您从响应中隐藏页面对象“numberOfPages”等，则UI将不知道可能有多少页。您可以硬编码每页要显示的元素数量，但您无法知道总页数，这将不允许您显示page1...page127等，基本上只有在进行调用并返回不同数量的元素后才会知道存在的页码。我已经找到了如何使此工作的答案。 - GSUgambit
显示剩余5条评论
11个回答
52

在这里的另一篇帖子中找到了答案，但它不应该是被接受的答案。

Spring RestTemplate和分页API

@rvheddeg的答案是正确的。您只需放置@JsonCreator并提供带有所有属性的构造函数，这是我的RestResponsePage类，可以解决此问题。

class RestResponsePage<T> extends PageImpl<T> {

    private static final long serialVersionUID = 3248189030448292002L;

    @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
    public RestResponsePage(@JsonProperty("content") List<T> content, @JsonProperty("number") int number, @JsonProperty("size") int size,
                    @JsonProperty("totalElements") Long totalElements, @JsonProperty("pageable") JsonNode pageable, @JsonProperty("last") boolean last,
                    @JsonProperty("totalPages") int totalPages, @JsonProperty("sort") JsonNode sort, @JsonProperty("first") boolean first,
                    @JsonProperty("numberOfElements") int numberOfElements) {
        super(content, PageRequest.of(number, size), totalElements);
    }

    public RestResponsePage(List<T> content, Pageable pageable, long total) {
        super(content, pageable, total);
    }

    public RestResponsePage(List<T> content) {
        super(content);
    }

    public RestResponsePage() {
        super(new ArrayList<T>());
    }

}
1
对于Spring 2.3.3，我遇到了编译错误：new PageRequest(page, size)访问受保护。您可以使用PageRequest.of(page, size)。 - Praytic
很糟糕，但是能用。我在mockMvc测试中使用这种方法。 - Дима Годиков
14

有一个更简单的方法可以实现它 - 创建并注册Page接口的自定义反序列化器。这样使用起来就很简单：

//Catalog is the paged entity
Page<Catalog> page = objectMapper.readValue(content, new TypeReference<Page<Catalog>>() {});

ObjectMapper 配置：

ObjectMapper objectMapper= new ObjectMapper();
objectMapper.registerModule(new PageModule());

页面模块：

public class PageModule extends SimpleModule {
    private static final long serialVersionUID = 1L;

    public PageModule() {
        addDeserializer(Page.class, new PageDeserializer());
    }
}

页面反序列化器：

public class PageDeserializer extends JsonDeserializer<Page<?>> implements ContextualDeserializer {
    private static final String CONTENT = "content";
    private static final String NUMBER = "number";
    private static final String SIZE = "size";
    private static final String TOTAL_ELEMENTS = "totalElements";
    private JavaType valueType;

    @Override
    public Page<?> deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {
        final CollectionType valuesListType = ctxt.getTypeFactory().constructCollectionType(List.class, valueType);

        List<?> list = new ArrayList<>();
        int pageNumber = 0;
        int pageSize = 0;
        long total = 0;
        if (p.isExpectedStartObjectToken()) {
            p.nextToken();
            if (p.hasTokenId(JsonTokenId.ID_FIELD_NAME)) {
                String propName = p.getCurrentName();
                do {
                    p.nextToken();
                    switch (propName) {
                        case CONTENT:
                            list = ctxt.readValue(p, valuesListType);
                            break;
                        case NUMBER:
                            pageNumber = ctxt.readValue(p, Integer.class);
                            break;
                        case SIZE:
                            pageSize = ctxt.readValue(p, Integer.class);
                            break;
                        case TOTAL_ELEMENTS:
                            total = ctxt.readValue(p, Long.class);
                            break;
                        default:
                            p.skipChildren();
                            break;
                    }
                } while (((propName = p.nextFieldName())) != null);
            } else {
                ctxt.handleUnexpectedToken(handledType(), p);
            }
        } else {
            ctxt.handleUnexpectedToken(handledType(), p);
        }

        //Note that Sort field of Page is ignored here.
        //Feel free to add more switch cases above to deserialize it as well.  
        return new PageImpl<>(list, PageRequest.of(pageNumber, pageSize), total);
    }

    /**
     * This is the main point here.
     * The PageDeserializer is created for each specific deserialization with concrete generic parameter type of Page.
     */
    @Override
    public JsonDeserializer<?> createContextual(DeserializationContext ctxt, BeanProperty property) {
        //This is the Page actually
        final JavaType wrapperType = ctxt.getContextualType();
        final PageDeserializer deserializer = new PageDeserializer();
        //This is the parameter of Page
        deserializer.valueType = wrapperType.containedType(0);
        return deserializer;
    }
}
2
这个答案和被接受的答案一样好，但其他一些替代方案在反序列化页面时可能会导致Blockhound报告阻塞调用。我正在使用Spring WebFlux。 - LeoFuso
14

这个有效了（org.springframework.cloud:spring-cloud-openfeign-core:2.2.5.RELEASE）：

@Configuration
public class FeignConfigurationFactory {

    @Bean
    public Module pageJacksonModule() {
        return new PageJacksonModule();
    }

    @Bean
    public Module sortJacksonModule() {
        return new SortJacksonModule();
    }
}
2
当我以jar形式运行时，使用org.springframework.cloud:spring-cloud-openfeign-core出现了java.lang.ClassNotFoundException: feign.codec.EncodeException的错误。需要改用org.springframework.cloud:spring-cloud-starter-openfeign。 - min
8

我必须对代码进行小改动，忽略空属性的未知属性：

package ...helper;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.JsonNode;
import org.springframework.data.domain.PageImpl;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;

import java.util.ArrayList;
import java.util.List;

@JsonIgnoreProperties(ignoreUnknown = true)
public class RestResponsePage<T> extends PageImpl<T> {
    @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
    public RestResponsePage(@JsonProperty("content") List<T> content,
                            @JsonProperty("number") int number,
                            @JsonProperty("size") int size,
                            @JsonProperty("totalElements") Long totalElements,
                            @JsonProperty("pageable") JsonNode pageable,
                            @JsonProperty("last") boolean last,
                            @JsonProperty("totalPages") int totalPages,
                            @JsonProperty("sort") JsonNode sort,
                            @JsonProperty("first") boolean first,
                            @JsonProperty("numberOfElements") int numberOfElements) {

        super(content, PageRequest.of(number, size), totalElements);
    }

    public RestResponsePage(List<T> content, Pageable pageable, long total) {
        super(content, pageable, total);
    }

    public RestResponsePage(List<T> content) {
        super(content);
    }

    public RestResponsePage() {
        super(new ArrayList<>());
    }
}
我也不得不这样做。谢谢，现在它可以工作了。 - berturion
4

如果您在测试环境中使用响应并序列化它，这些解决方案将不起作用。我不得不自己将内容序列化为List :)
在这种情况下，我使用了RestAssured响应。

protected static <T> List<T> getResponsePageDTO(Response response, Class<T> clazz) throws IOException {
    Map<String, Object> objectMap = objectMapper.readValue(response.getBody().print(), Map.class);
    List<Object> content = (List<Object>) objectMap.get("content");
    List<T> result = new ArrayList<>();
    for (Object o : content) {
        result.add(objectMapper.convertValue(o, clazz));
    }
    return result;
}
3
与@GSUgambit的答案类似，但更加紧凑，因为您不必指定未使用的构造函数参数。技巧是使用@JsonIgnoreProperties标注。
@JsonIgnoreProperties(ignoreUnknown = true, value = {"pageable"})
public class RestPage<T> extends PageImpl<T> {
    @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
    public RestPage(@JsonProperty("content") List<T> content,
                    @JsonProperty("number") int page,
                    @JsonProperty("size") int size,
                    @JsonProperty("totalElements") long total) {
        super(content, PageRequest.of(page, size), total);
    }

    public RestPage(Page<T> page) {
        super(page.getContent(), page.getPageable(), page.getTotalElements());
    }
}
1

有一个PageJacksonModule和一个SortJacksonModule。

Kotlin：

private val mapper = jacksonObjectMapper().registerModules(
    PageJacksonModule(),
    SortJacksonModule()
)
1
实际上，Spring MVC使用Jackson序列化对象，因此注入一个PageImp序列化器应该可以解决问题。 步骤1：PageSerializer类：
   public class PageSerializer extends StdSerializer<PageImpl> {

    public PageSerializer() {
        super(PageImpl.class);
    }

    @Override
    public void serialize(PageImpl value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();
        gen.writeNumberField("number", value.getNumber());
        gen.writeNumberField("numberOfElements", value.getNumberOfElements());
        gen.writeNumberField("totalElements", value.getTotalElements());
        gen.writeNumberField("totalPages", value.getTotalPages());
        gen.writeNumberField("size", value.getSize());
        gen.writeFieldName("content");
        provider.defaultSerializeValue(value.getContent(), gen);
        gen.writeEndObject();
    }
 }

步骤2: 注入Jackson模块：

@Bean
public Module jacksonPageWithJsonViewModule() {
    SimpleModule module = new SimpleModule("jackson-page-with-jsonview",
        unknownVersion());
    module.addSerializer(PageImpl.class, new PageSerializer());
    return module;
}

好的，结束。

0
你可以这样做
final PageImplDeserializer<YOUR_CLASS> response = objectMapper.readValue(jsonResponse, new TypeReference<>() {});


public class PageImplDeserializer<T> {
    private List<T> content;
    private int number;
    private int size;
    private Long totalElements;
    private JsonNode pageable;
    private boolean last;
    private int totalPages;
    private JsonNode sort;
    private boolean first;
    private int numberOfElements;

... HERE GETTERS AND SETTERS...

}
0

我在Kotlin上遇到了这个问题，并以以下方式解决：

import com.fasterxml.jackson.annotation.JsonCreator
import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.databind.JsonNode
import org.springframework.data.domain.PageImpl
import org.springframework.data.domain.PageRequest

class RestResponsePage<T> @JsonCreator(mode = JsonCreator.Mode.PROPERTIES) constructor(
    @JsonProperty("content") content: List<T>?,
    @JsonProperty("number") number: Int,
    @JsonProperty("size") size: Int,
    @JsonProperty("totalElements") totalElements: Long?,
    @JsonProperty("pageable") pageable: JsonNode?,
    @JsonProperty("last") last: Boolean,
    @JsonProperty("totalPages") totalPages: Int,
    @JsonProperty("sort") sort: JsonNode?,
    @JsonProperty("first") first: Boolean,
    @JsonProperty("numberOfElements") numberOfElements: Int
) : PageImpl<T>(
    content!!, PageRequest.of(number, size),
    totalElements!!
)

使用方法如下：

private fun getPersonsRequest(
        page: Int,
        size: Int,
    ): RestResponsePage<PersonsResponse> {}
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