找不到 MessageBodyWriter 类型的响应对象:媒体类型的 java.util.ArrayList:text/html - 在 Resteasy

2022-01-19 00:00:00 java jaxb resteasy

我正在开发 RESTEasy 示例.在此示例中，我使用所有最新的依赖项并部署 om tomcat 8.x 版本.我可以成功部署应用程序，但是当我启动 url 时:http://localhost:8080/RESTfulExample/rest/restwebservice/list，我看到以下错误即将到来.请指导这里出了什么问题.

I am developing RESTEasy Example. In this example I am using all latest dependencies and deploying om tomcat 8.x version. I can successfully deploy the application but when I am launching the url: http://localhost:8080/RESTfulExample/rest/restwebservice/list, I see following errors are coming. Please guide what is going wrong here.

org.jboss.resteasy.core.NoMessageBodyWriterFoundFailure: Could not find MessageBodyWriter for response object of type: java.util.ArrayList of media type: text/html
    at org.jboss.resteasy.core.ServerResponseWriter.writeNomapResponse(ServerResponseWriter.java:66)
    at org.jboss.resteasy.core.SynchronousDispatcher.writeResponse(SynchronousDispatcher.java:466)
    at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:415)
    at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:202)
    at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:221)
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:56)
    at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:51)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

到目前为止我开发的代码供参考:pom.xml

The code I developed so far for reference: pom.xml

<repositories>
        <repository>
            <id>JBoss repository</id>
            <url>https://repository.jboss.org/nexus/content/groups/public-jboss/</url>
        </repository>
    </repositories>

    <properties>
        <java.version>1.8</java.version>
        <resteasy-jaxrs-version>3.0.16.Final</resteasy-jaxrs-version>
        <junit.version>4.12</junit.version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-jaxrs</artifactId>
            <version>${resteasy-jaxrs-version}</version>
        </dependency>

        <dependency>
            <groupId>org.jboss.resteasy</groupId>
            <artifactId>resteasy-servlet-initializer</artifactId>
            <version>${resteasy-jaxrs-version}</version>
        </dependency>

        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.2.11</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>${junit.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <!-- Project Build -->
    <build>
        <finalName>RESTfulExample</finalName>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>${java.version}</source>
                    <target>${java.version}</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

学生.java

@XmlRootElement
public class Student {

    private int student_id;
    private String student_name;
    private String student_rollnumber;
    // setters and getters
}

RESTEasyService.java

RESTEasyService.java

@ApplicationPath("/rest")
public class RESTEasyService extends Application{

}

RESTWebServiceJavaExample.java

RESTWebServiceJavaExample.java

@Path("/restwebservice")
public class RESTWebServiceJavaExample {
    private TreeMap<Integer, Student> webserviceMap= new TreeMap<>();

    public RESTWebServiceJavaExample(){

        Student student = new Student();
        student.setStudent_name("Ricky");
        student.setStudent_rollnumber("AOHP451");

        addStudent(student);

        student = new Student();
        student.setStudent_name("Mayer");
        student.setStudent_rollnumber("DKLP987");
        addStudent(student);

    }

    @GET
    @Path("list")
    public List<Student> getStudents() {
        List<Student> students = new ArrayList<Student>();
        students.addAll(webserviceMap.values());
        return students;
    }

    @POST
    @Path("add")
    @Produces("text/plain")
    @Consumes("application/xml")
    public void addStudent(Student student_param) {
        int id = webserviceMap.size();
        student_param.setStudent_id(id);
        webserviceMap.put(id, student_param);
    }
}

web.xml:

<web-app id="WebApp_ID" version="2.4"
    xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
    <display-name>Restful Web Application</display-name>

</web-app>

推荐答案

现在我可以解决这个问题了.我需要在 pom.xml 中添加以下依赖项:

Now I am able to solve this issue. I need to add following dependency in pom.xml:

<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jaxb-provider</artifactId>
    <version>3.0.16.Final</version>
</dependency>

并且 1) 我应该在方法签名上使用 @Produces(MediaType.APPLICATION_XML) 以获得以下响应.

And 1) I should be using @Produces(MediaType.APPLICATION_XML) on method signature to get following response.

<collection>
    <student>
        <student_id>0</student_id>
        <student_name>Ricky</student_name>
        <student_rollnumber>AOHP451</student_rollnumber>
    </student>
    <student>
        <student_id>1</student_id>
        <student_name>Mayer</student_name>
        <student_rollnumber>DKLP987</student_rollnumber>
    </student>
</collection>

  1. 如果你想使用 @Produces(MediaType.TEXT_PLAIN) 那么代码会给你以下看起来没什么用的输出.

  1. If you want to use @Produces(MediaType.TEXT_PLAIN) then code will gives you following output which doesn't looks useful.

[com.mkyong.rest.Student@4d5fd75e, com.mkyong.rest.Student@7715574d]

[com.mkyong.rest.Student@4d5fd75e, com.mkyong.rest.Student@7715574d]

所以使用 1) 解决方案.

So use 1) solution.

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