泛型类型的 Jersey ClientResponse.getEntity

Posted 2023-02-26

【中文标题】泛型类型的 Jersey ClientResponse.getEntity

【英文标题】：Jersey ClientResponse.getEntity of generic type

【发布时间】：2015-02-05 03:38:47

【问题描述】：

我在使用 jeresy ClientRespone.getEntity 进行反序列化时遇到问题

我尝试了一些教程和问题，包括： http://jersey.576304.n2.nabble.com/How-can-I-parse-a-java-util-List-lt-gt-Is-it-supported-by-the-Jersey-client-td2300852.html https://jersey.java.net/nonav/documentation/1.5/json.html http://www.programcreek.com/java-api-examples/index.php?api=com.sun.jersey.api.client.GenericType

我仍然一遍又一遍地遇到同样的异常..

我的目标是： 而不是：

response.getEntity(String.class); --> "name":"Ben","type":"The man","id":0

然后解析它（例如使用 Jackson），我想将实体放入我的 POJO 对象中。

这是我目前的尝试：

服务器端：

@POST
@Path("/account") // route to a specific method.re
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response saveDataIntoHash(Account account) 
    Account createdAccount = new Account(account.getName(), account.getType());
    accountHash.put(createdAccount.getID(), createdAccount);
    return Response.status(201).entity(new AccountResponse(createdAccount.getID())).build();

服务器端帐户类：

private String name;
private String type;
private int ID;

private static int classID = 0;

public Account(String name, String type) 
    this.name = name;
    this.type = type;
    this.ID = classID++;


public Account() 


public void setName(String name)  this.name = name; 

public String getName()  return name; 

public void setType(String type)  this.type = type; 

public String getType()  return type; 

public int getID() 
    return ID;


public void setID(int ID) 
    this.ID = ID;


public static int getClassID() 
    return classID;


public static void setClassID(int classID) 
    Account.classID = classID;

客户端

private static void getToRestPartner(Client client) 
    WebResource webResource = client.resource("http://localhost:8080/RESTfulExample/rest/account/0");
    ClientResponse response = webResource.type("application/json").get(ClientResponse.class);

    if (!(response.getStatus() == 201 || response.getStatus() == 200)) 
        throw new RuntimeException("Failed : HTTP error code : " + response.getStatus());
    

    System.out.println("Output from Server .... \n");

    List<Account> accountList =  response.getEntity(new GenericType<List<Account>>() 
    );

    System.out.println(accountList.size());

客户账户类：

@XmlRootElement
public class Account 
@XmlElement
private String name;
@XmlElement
private String type;
@XmlElement
private int id;

public Account(String name, String type, Integer id) 
    this.name = name;
    this.type = type;
    this.id = id;


public Account() 


public String getName() 
    return name;


public void setName(String name) 
    this.name = name;


public String getType() 
    return type;


public void setType(String type) 
    this.type = type;


public int getId() 
    return id;


public void setId(int id) 
    this.id = id;

它抛出这个异常：

Dec 7, 2014 12:15:58 PM com.sun.jersey.api.client.ClientResponse getEntity
SEVERE: A message body reader for Java class java.util.List, and Java type java.util.List<Account>, and MIME media type application/json was not found
Dec 7, 2014 12:15:58 PM com.sun.jersey.api.client.ClientResponse getEntity
SEVERE: The registered message body readers compatible with the MIME media type are:
*/* ->
  com.sun.jersey.core.impl.provider.entity.FormProvider
  com.sun.jersey.core.impl.provider.entity.StringProvider
  com.sun.jersey.core.impl.provider.entity.ByteArrayProvider
  com.sun.jersey.core.impl.provider.entity.FileProvider
  com.sun.jersey.core.impl.provider.entity.InputStreamProvider
  com.sun.jersey.core.impl.provider.entity.DataSourceProvider
  com.sun.jersey.core.impl.provider.entity.XMLJAXBElementProvider$General
  com.sun.jersey.core.impl.provider.entity.ReaderProvider
  com.sun.jersey.core.impl.provider.entity.DocumentProvider
  com.sun.jersey.core.impl.provider.entity.SourceProvider$StreamSourceReader
  com.sun.jersey.core.impl.provider.entity.SourceProvider$SAXSourceReader
  com.sun.jersey.core.impl.provider.entity.SourceProvider$DOMSourceReader
  com.sun.jersey.core.impl.provider.entity.XMLRootElementProvider$General
  com.sun.jersey.core.impl.provider.entity.XMLListElementProvider$General
  com.sun.jersey.core.impl.provider.entity.XMLRootObjectProvider$General
  com.sun.jersey.core.impl.provider.entity.EntityHolderReader

Exception in thread "main" com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class java.util.List, and Java type java.util.List<Account>, and MIME media type application/json was not found
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:549)
    at com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:523)
    at com.sample.Sample.getToRestPartner(Sample.java:59)
    at com.sample.Sample.main(Sample.java:22)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:134)

您的帮助将不胜感激！

【参考方案1】：

很少有东西需要修复或添加（在您的情况下不确定，因为某些部分丢失了）

资源：自己做的测试，因为你的缺少一些项目

@Path("/")
public class AccountResource 
    @GET
    @Path("/account") // route to a specific method.re
    @Produces(MediaType.APPLICATION_JSON)
    public Response saveDataIntoHash() 
        List<Account> accounts = new ArrayList<Account>();
        accounts.add(new Account("Stack", "Savings"));
        accounts.add(new Account("Overflow", "Checkings"));
        GenericEntity generic = new GenericEntity<List<Account>>(accounts);
        return Response.status(201).entity(generic).build();
    

假设你有这个依赖：

<dependency>
    <groupId>com.sun.jersey</groupId>
    <artifactId>jersey-json</artifactId>
    <version>$jersey-version</version>
</dependency>

测试用例：注意客户端配置。这是必需的。

public void testMyResource() 
    ClientConfig config = new DefaultClientConfig();
    config.getClasses().add(JacksonJaxbJsonProvider.class);
    config.getFeatures().put(JSONConfiguration.FEATURE_POJO_MAPPING, Boolean.TRUE);

    Client c = Client.create(config);

    WebResource resource = c.resource(Main.BASE_URI);
    ClientResponse response = resource.path("account")
            .accept("application/json").get(ClientResponse.class);

    List<Account> accounts
                = response.getEntity(new GenericType<List<Account>>());

    StringBuilder builder = new StringBuilder("=== Accounts ===\n");
    for (Account account: accounts) 
        builder.append("Name: ").append(account.getName()).append(", ")
                .append("Type: ").append(account.getType()).append("\n");          
    
    builder.append("==================");
    System.out.println(builder.toString());    

帐户（客户端） 类缺少一个注释。当您使用字段注释时，它是必需的。另一种选择是为id添加一个getter和setter

@XmlRootElement  
@XmlAccessorType(XmlAccessType.FIELD)  // <======= This Here
public class Account 
    // added toString for testing
    @Override
    public String toString() 
        return "Account" + "name=" + name 
                          + ", type=" + type 
                          + ", id=" + id + '';
    

结果来自测试：

=== Accounts ===
Name: Stack, Type: Savings
Name: Overflow, Type: Checkings
==================

注意：此测试基于您的服务器端没有任何问题的假设。