Jersey 无法将 json 请求映射到类

我能够使用 Json 输出运行 Jersey，并且能够使用 Json 映射获取“GET”请求，没有任何问题。

我还有一些 JSON 方法，它们是“POST”方法，它们映射到 Java 类，就像这个方法一样 -

@POST
@Consumes({MediaType.APPLICATION_JSON})
@Produces({MediaType.TEXT_PLAIN})
@Path("/post")
public String postPerson(Person pers) 

供您参考，我正在遵循指南here https://www.nabisoft.com/tutorials/java-ee/producing-and-consuming-json-or-xml-in-java-rest-services-with-jersey-and-jackson or here https://www.mkyong.com/webservices/jax-rs/json-example-with-jersey-jackson/

在对这些发出有效的发布请求后，他们都开始抛出以下错误 -

我的 Maven 依赖项 pom.xml 是问题末尾的文件 -

exception

javax.servlet.ServletException: java.lang.NullPointerException
org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:489)
org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

root cause

java.lang.NullPointerException
newa.PersonResource.postPerson(PersonResource.java:31)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:498)
org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$TypeOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:205)
org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
org.glassfish.jersey.internal.Errors.process(Errors.java:315)
org.glassfish.jersey.internal.Errors.process(Errors.java:297)
org.glassfish.jersey.internal.Errors.process(Errors.java:267)
org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)

人类 -

  @JsonInclude(Include.NON_EMPTY)
public class Person {    
private String firstName;
private String lastName;
public void setLastName(String lastName) {
    this.lastName = lastName;
}
public String getLastName() {
    return lastName;
}
public String getFirstName() {
    return firstName;
}
public void setFirstName(String firstName) {
    this.firstName = firstName;
}
}

我使用邮递员（Chrome 扩展）发送的数据类似于 -

我的 pom.xml 文件 -

 <dependencies>


    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>



    <dependency>
        <groupId>org.glassfish.jersey.containers</groupId>
        <artifactId>jersey-container-servlet</artifactId>
        <version>2.24</version>
    </dependency>

    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-jackson</artifactId>
        <version>2.24</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-json-processing</artifactId>
        <version>2.24</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-multipart</artifactId>
        <version>2.24</version>
    </dependency>
    <dependency>
        <groupId>org.glassfish.jersey.media</groupId>
        <artifactId>jersey-media-sse</artifactId>
        <version>2.24</version>
    </dependency>

    <dependency>
        <groupId>com.sun.jersey</groupId>
        <artifactId>jersey-core</artifactId>
        <version>1.8</version>
        <type>jar</type>
    </dependency>
</dependencies>

从邮递员屏幕截图的外观来看，当您实际上想要 json 时，看起来您正在发送表单数据（除非这是您可以将发布数据输入到 POSTMAN 中的新方法。我刚刚尝试过，只能输入表单数据这边走）。

前往邮递员，点击body选项卡，单击raw单选按钮，然后选择application/json从右侧的下拉菜单中。从那里，将您的正文输入为 json，如下所示：

{"firstName": "Bill", "lastName": "Loney"}