RestTemplate映射页面“页面大小不能小于一个" [英] RestTemplate mapping Page 'Page size must not be less than one'
问题描述
我有一个REST API端点,它将返回Page<User>
.我想为此端点提供一些测试,我发现了这个问题,我可以使用另一个答案具有另一个实现,即
I have a REST API endpoint that will return a Page<User>
. I want to provide some tests for this endpoint, and I found this question, of which I could use this answer (The accepted answer is outdated). When I tried to implement this, I noticed that another answer had another implementation, which was supposedly for spring 2.0.
但是,使用此代码时(下面的代码);我从映射器中得到一个例外.我注意到在Wireshark中,正确返回了Page
并将其填充.当我使用邮递员之类的工具手动发出请求时,我也正确地获得了Page
.
However, when using this (code below); I get an exception from the mapper. I noticed that in Wireshark the Page
is returned correctly, and filled. When I use a tool like Postman to manually make the request, I also correctly get the Page
.
控制器:
@GetMapping("/")
Page<User> findAll(@RequestParam("page") int page, @RequestParam("size") int size);
RestResponsePage(在此处找到):
RestResponsePage (as found here):
package org.company.product.userservice.helpers;
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;
import org.springframework.data.domain.Pageable;
import java.util.ArrayList;
import java.util.List;
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<>());
}
}
测试:
private OAuth2RestTemplate template;
/** template init code, retrieving token **/
UriComponentsBuilder uri = UriComponentsBuilder.fromHttpUrl(ZUUL_URI + "/api/users")
.queryParam("page", 0)
.queryParam("size", 10);
ResponseEntity<RestResponsePage<User>> user = template.exchange(uri.build().encode().toUri(), HttpMethod.GET, null, new ParameterizedTypeReference<RestResponsePage<User>>(){});
运行此命令会得到以下堆栈跟踪:
Running this gives the following stacktrace:
org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.company.project.userservice.helpers.RestResponsePage]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of 'org.company.project.userservice.helpers.RestResponsePage;', problem: Page size must not be less than one!
at [Source: (PushbackInputStream); line: 63, column: 1]
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.readJavaType(AbstractJackson2HttpMessageConverter.java:242)
at org.springframework.http.converter.json.AbstractJackson2HttpMessageConverter.read(AbstractJackson2HttpMessageConverter.java:227)
at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:102)
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:994)
at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:977)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:736)
at org.springframework.security.oauth2.client.OAuth2RestTemplate.doExecute(OAuth2RestTemplate.java:128)
at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:709)
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:627)
at org.company.project.userservice.api.OAuthMvcTest.testAddingAddressToUser(OAuthMvcTest.java:134)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:532)
at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:171)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:167)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:114)
at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:59)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$4(NodeTestTask.java:108)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:98)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:74)
at java.base/java.util.ArrayList.forEach(Unknown Source)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$4(NodeTestTask.java:112)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:98)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:74)
at java.base/java.util.ArrayList.forEach(Unknown Source)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$4(NodeTestTask.java:112)
at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:72)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:98)
at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:74)
at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57)
at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:220)
at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$6(DefaultLauncher.java:188)
at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:202)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:181)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:128)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:69)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of 'org.company.project.userservice.helpers.RestResponsePage', problem: Page size must not be less than one!
at [Source: (PushbackInputStream); line: 63, column: 1]
at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67)
at com.fasterxml.jackson.databind.DeserializationContext.instantiationException(DeserializationContext.java:1608)
at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.wrapAsJsonMappingException(StdValueInstantiator.java:484)
at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.rewrapCtorProblem(StdValueInstantiator.java:503)
at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromObjectWith(StdValueInstantiator.java:285)
at com.fasterxml.jackson.databind.deser.ValueInstantiator.createFromObjectWith(ValueInstantiator.java:229)
at com.fasterxml.jackson.databind.deser.impl.PropertyBasedCreator.build(PropertyBasedCreator.java:195)
at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeUsingPropertyBased(BeanDeserializer.java:488)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1287)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:326)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:159)
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:239)
... 48 more
Caused by: java.lang.IllegalArgumentException: Page size must not be less than one!
at org.springframework.data.domain.AbstractPageRequest.<init>(AbstractPageRequest.java:50)
at org.springframework.data.domain.PageRequest.<init>(PageRequest.java:71)
at org.springframework.data.domain.PageRequest.of(PageRequest.java:96)
at org.springframework.data.domain.PageRequest.of(PageRequest.java:84)
at org.company.project.userservice.helpers.RestResponsePage.<init>(RestResponsePage.java:28)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.base/java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.fasterxml.jackson.databind.introspect.AnnotatedConstructor.call(AnnotatedConstructor.java:124)
at com.fasterxml.jackson.databind.deser.std.StdValueInstantiator.createFromObjectWith(StdValueInstantiator.java:283)
... 57 more
我注意到杰克逊追溯使用的对象时,使用了空值和零值.但是,在BeanDeserializer._deserializeUsingPropertyBased()
函数中,我发现实际上存在正确的User对象:
I noticed that when tracing back the used objects by Jackson, that there are null values and zero values used. However, in the BeanDeserializer._deserializeUsingPropertyBased()
the function I found that the correct User objects are in fact present:
我应该在帮助器类中进行哪些更改以解决此问题,并将响应正确映射到Page<User>
?
What I should change in the helper class to fix this behaviour and correctly map the response to a Page<User>
?
推荐答案
解决方案:
下面是一个示例代码,在我的spring boot项目中可以正常工作.
Solution:
The below is a sample code that works fine in my spring boot project.
步骤(1):
创建一个扩展PageImpl<>
的自定义类.因为PageImpl<>
没有空的构造函数,因此不能在反序列化中使用.另外请注意,杰克逊将使用以下注释.
Step(1):
Create a custom class that extends the PageImpl<>
. because the PageImpl<>
does not have empty constructor and therefore can not be used in deserialization. Also note that the below annotations will be used by jackson.
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;
import org.springframework.data.domain.Pageable;
import java.util.ArrayList;
import java.util.List;
public class JacksonPageImpl<T> extends PageImpl<T> {
private static final long serialVersionUID = 1230183330548294567L;
@JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
public JacksonPageImpl(@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 JacksonPageImpl(List<T> content, Pageable pageable, long total) {
super(content, pageable, total);
}
public JacksonPageImpl(List<T> content) {
super(content);
}
public JacksonPageImpl() {
super(new ArrayList<>());
}
}
步骤(2):
现在调用如下所示的方法.
注意:您可以在exchange
方法的最后一个参数中直接使用WrapperRestResponse.class
.但是在这种情况下,JacksonPageImpl.getContent()
会为您提供List<LinkedHashMap>
而不是List<T>
,因为默认情况下,杰克逊将JSON对象反序列化为LinkedHashMap.因此在下面,我使用ParameterizedTypeReference
在结果中添加了List<T>
.
Step(2):
Now call a method like as the below.
Note: You can directly use WrapperRestResponse.class
in the last argument of the exchange
method. but in this case, the JacksonPageImpl.getContent()
gives you a List<LinkedHashMap>
instead of List<T>
, becuase Jackson by default deserializes a JSON object into a LinkedHashMap. So in the below I used the ParameterizedTypeReference
to have List<T>
in the result.
private String getPages(int pageNumber, int pageSize, ...){
String url = "https://example.com/your_endpoint?page=" + pageNumber + "&size="+pageSize;
//for example here: your_endpoint = endpoint1/endpoint2
HttpHeaders headers = new HttpHeaders();
headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON));
//if you have authorization (basic,oauth,...) in server side:
//headers.add("Authorization", ...);
HttpEntity<String> request = new HttpEntity<>(headers);
RestTemplate restTemplate = new RestTemplate();
ParameterizedTypeReference<WrapperRestResponse<T>> typeRef = new ParameterizedTypeReference<WrapperRestResponse<T>>(){};
ResponseEntity<WrapperRestResponse> rsp = restTemplate.exchange(url, HttpMethod.GET, request, typeRef);
if(rsp.getStatusCodeValue() == 200){
WrapperRestResponse<T> pojoAnswer = rsp.getBody();
JacksonPageImpl<T> page = pojoAnswer.getPage();
List<T> contents = page.getContent();
//continue your logic...
}
//...
}
步骤(3):我使用了WrapperRestResponse
如下所示,以便您可以简单地传递Page<>
之外的其他属性:
step(3): I used a WrapperRestResponse
as the below, so that you can pass other properties simply in addition to Page<>
:
public class WrapperRestResponse<T> {
private JacksonPageImpl<T> page;
//you can have other fields too
public WrapperRestResponse() {
}
public WrapperRestResponse(JacksonPageImpl<T> page, ...) {
this.page = page;
//other fields...
}
public JacksonPageImpl<T> getPage() {
return page;
}
//other fileds getter & setters
}
步骤(4):这是我的端点:
@RestController
@RequestMapping(value = "/endpoint1", produces = "application/json")
public class ResourceController {
//...
@GetMapping("/endpoint2")
public ResponseEntity getPages(Pageable pageable, ...){
Page<T> pages = ...;//get it by your logic
//...
return ResponseEntity.ok(new WrapperRestResponse(pages, ...));
}
}
希望对您有帮助.
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