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java - 使用 Jersey 在正文请求中发布 JSON

转载 作者：行者123 更新时间：2023-11-30 06:51:50 25 4
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我有一个 Java 动态 Web 项目(部署在本地应用程序服务器 Tomcat 7 上)，它使用 Jersey 创建 REST API。

我不使用任何构建自动化工具(所以我的库被添加到构建路径并且 servlet 被插入到 web.xml 文件中)。

我使用的库是:

asm-3.1.jar
gson-2.2.1.jar
jersey-client-1.0.3.jar
jersey-core-1.0.3.jar
jersey-json-1.18.jar
jersey-server-1.0.3.jar
jettison-1.1.jar
jsr311-api-1.0.jar
mysql-connector-java-5.0.8-bin.jar

我的 web.xml 如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>UserAccount</display-name>
    <servlet>
        <servlet-name>ServletAdaptor</servlet-name>
        <servlet-class>com.sun.jersey.server.impl.container.servlet.ServletAdaptor</servlet-class>
        <init-param>
            <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
            <param-value>true</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>ServletAdaptor</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>
</web-app>

应用程序正在与 MySQL 数据库交互。场景如下:数据库包含一个名为 users 的用户帐户表。这些列是 id、名称、用户名和密码。

我有一个 POST 方法来验证帐户(用户名 + 密码)是否有效。 (用户名和密码作为 header 参数传递) http://localhost:8080/UserAccount/rest/login/doLogin和标题:用户名:x密码:1234

@POST
@Path("/doLogin")
@Produces(MediaType.APPLICATION_JSON) 
public String doLogin(@HeaderParam("username") String uname, @HeaderParam("password") String pwd){
    String response = "";
    if(checkCredentials(uname, pwd)){
        response = Utility.constructJSON("login",true);
    }else{
        response = Utility.constructJSON("login", false, "Incorrect Email or Password");
    }
return response;        
}

如您所见，响应将根据用户帐户是否有效生成一个 true 或 false 的 JSON。到目前为止它工作正常。它也可以很好地执行 GET 并将参数作为查询参数传递(但这不是重点)。

现在我正在尝试执行 POST，但这次在 JSON 正文中传递用户名和密码:

{
    "username":"x",
    "password":"1234"
}

为此我创建了一个名为 User.java 的类:

@XmlRootElement()
@XmlAccessorType(XmlAccessType.FIELD)
public class User implements Serializable {
    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @XmlElement(name="username")
    private String username;

    @XmlElement(name="password")
    private String password;

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        // TODO Auto-generated method stub
        return "username: " + username;
    }
}

我创建了一个方法:

    //pass the arguments as JSON body
@POST
// Path: http://localhost:8080/UserAccount/rest/login/asklogin
@Path("/askLogin")
// Produces JSON as response
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public Response askLogin(User user) {
    System.out.println("Inside POST askLogin");
    if(checkCredentials(user.getUsername(), user.getPassword())) {
        return Response.ok().build();
    } else {
        return Response.serverError().build();
    }
}

我正在使用来自 Google Chrome 的 Advanced Rest Client 和来自 Firefox 的 REST Easy 来测试 API。

我还创建了一个实现 MessageBodyReader 的类，如下所示:

@Provider
public class UserBeanMessageBodyReader implements MessageBodyReader<User> {

    //used for MessageBodyReader
    @Override
    public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations,
            MediaType mediaType) {
        return type == User.class;
    }

    @Override
    public User readFrom(Class<User> type, Type genericType, Annotation[] annotations,
            MediaType mediaType, MultivaluedMap<String, String> httpHeaders,
            InputStream entityStream) throws IOException, WebApplicationException {
        try {
            JAXBContext jaxbContext = JAXBContext.newInstance(User.class);
            User user = (User) jaxbContext.createUnmarshaller().unmarshal(entityStream);
            return user;
        } catch (JAXBException jaxbException) {
            jaxbException.printStackTrace();
            System.out.println("Error deserializing a User" + jaxbException);
        }
        return null;
    }
}

经过调试，问题来了:

User user = (User) jaxbContext.createUnmarshaller().unmarshal(entityStream);

它继续执行 catch 语句。

堆栈跟踪如下:

    INFO: Server startup in 1239 ms
javax.xml.bind.UnmarshalException
 - with linked exception:
[org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is 

    not allowed in prolog.]
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.createUnmarshalException(AbstractUnmarshallerImpl.java:335)
        at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.createUnmarshalException(UnmarshallerImpl.java:563)
        at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:249)
        at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(UnmarshallerImpl.java:214)
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:157)
        at javax.xml.bind.helpers.AbstractUnmarshallerImpl.unmarshal(AbstractUnmarshallerImpl.java:204)
        at ro.useraccount.jersey.UserBeanMessageBodyReader.readFrom(UserBeanMessageBodyReader.java:36)
        at ro.useraccount.jersey.UserBeanMessageBodyReader.readFrom(UserBeanMessageBodyReader.java:1)
        at com.sun.jersey.spi.container.ContainerRequest.getEntity(ContainerRequest.java:393)
        at com.sun.jersey.server.impl.model.method.dispatch.EntityParamDispatchProvider$EntityInjectable.getValue(EntityParamDispatchProvider.java:139)
        at com.sun.jersey.server.impl.inject.InjectableValuesProvider.getInjectableValues(InjectableValuesProvider.java:43)
        at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$EntityParamInInvoker.getParams(AbstractResourceMethodDispatchProvider.java:126)
        at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:173)
        at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67)
        at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:163)
        at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111)
        at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:71)
        at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111)
        at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:63)
        at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:654)
        at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:612)
        at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:603)
        at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:309)
        at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:425)
        at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:590)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:612)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:503)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.
        at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(ErrorHandlerWrapper.java:203)
        at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.fatalError(ErrorHandlerWrapper.java:177)
        at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:400)
        at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(XMLErrorReporter.java:327)
        at com.sun.org.apache.xerces.internal.impl.XMLScanner.reportFatalError(XMLScanner.java:1437)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl$PrologDriver.next(XMLDocumentScannerImpl.java:999)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
        at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:118)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
        at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
        at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:643)
        at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(UnmarshallerImpl.java:243)
        ... 35 more
    Error deserializing a Userjavax.xml.bind.UnmarshalException
     - with linked exception:
    [org.xml.sax.SAXParseException; lineNumber: 1; columnNumber: 1; Content is not allowed in prolog.]
    Inside POST askLogin
    Oct 06, 2016 8:57:27 AM org.apache.catalina.core.StandardWrapperValve invoke
    SEVERE: Servlet.service() for servlet ServletAdaptor threw exception
    java.lang.NullPointerException
        at ro.useraccount.jersey.Login.askLogin(Login.java:67)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:175)
        at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67)
        at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:163)
        at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111)
        at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:71)
        at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:111)
        at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:63)
        at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:654)
        at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:612)
        at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:603)
        at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:309)
        at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:425)
        at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:590)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:723)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:861)
        at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:612)
        at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:503)
        at java.lang.Thread.run(Thread.java:745)

你怎么看？

最佳答案

您应该告诉 Jersey 使用 Gson 进行 JSON 处理。您可以实现 Jersey 提供的 MessageBodyReader 和 MessageBodyWriter 接口(interface)。在这个stackoverflow question你可以找到一个例子(见接受的答案)。如果您想为其添加一些上下文，请查看 the JSON section of the Jersey 1.x manual

编辑:我可能不理解你的代码，但是你的 Gson 调用在哪里UserBeanMessageBodyReader?尝试使用类似

的方式更改 reaedFrom 方法 
String result = new BufferedReader(new InputStreamReader(entityStream))
                 .lines().collect(Collectors.joining("\n"));
Gson gson = new GSon();
User myUser = gson.fromJson(result, User.class);

而不是使用 JAXBContext(它只理解 XML 输入)。

关于java - 使用 Jersey 在正文请求中发布 JSON，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/39846250/

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