[英]Why do I get NoMessageBodyWriterFoundFailure error?
我實現了以下REST調用:
@Path("/widgets")
public class WidgetResource {
@GET
@Produces("application/x-protobuf")
public WidgetsProtoc.WidgetList getAllWidgets() {
Widget widget1 =
Widget.newBuilder().setId("1").setName("widget 1").build();
Widget widget2 =
Widget.newBuilder().setId("2").setName("widget 2").build();
WidgetsProtoc.WidgetList list = WidgetsProtoc.WidgetList.newBuilder().addWidget(widget1).addWidget(widget2).build();
return list;
}
}
也是提供和使用application / x-protobuf的提供者類:
@Provider
@Produces("application/x-protobuf")
@Consumes("application/x-protobuf")
public class ProtobufMessageWriter implements MessageBodyWriter<WidgetsProtoc.WidgetList>, MessageBodyReader<WidgetsProtoc.WidgetList> {
public boolean isWriteable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return WidgetsProtoc.WidgetList.class.isAssignableFrom(type);
}
@Override
public long getSize(WidgetsProtoc.WidgetList widgetList, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return widgetList.getSerializedSize();
}
@Override
public void writeTo(WidgetsProtoc.WidgetList widgetList, Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) throws IOException, WebApplicationException {
entityStream.write(widgetList.toByteArray());
}
@Override
public boolean isReadable(Class<?> type, Type genericType, Annotation[] annotations, MediaType mediaType) {
return type.isAssignableFrom((Class<?>) genericType);
}
@Override
public WidgetsProtoc.WidgetList readFrom(Class<WidgetsProtoc.WidgetList> type, Type genericType, Annotation[] annotations, MediaType mediaType, MultivaluedMap<String, String> httpHeaders, InputStream entityStream) throws IOException, WebApplicationException {
try {
Method newBuilder = type.getMethod("newBuilder");
GeneratedMessage.Builder<?> builder = (GeneratedMessage.Builder<?>) newBuilder.invoke(type);
return (WidgetsProtoc.WidgetList) builder.mergeFrom(entityStream).build();
} catch (Exception e) {
throw new WebApplicationException(e);
}
}
}
我的pom.xml看起來像:
<?xml version="1.0"?>
<project xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://maven.apache.org/POM/4.0.0">
<modelVersion>4.0.0</modelVersion>
<groupId>com.mkyong.common</groupId>
<artifactId>RESTfulExample</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>RESTfulExample Maven Webapp</name>
<url>http://maven.apache.org</url>
<repositories>
<repository>
<id>JBoss repository</id>
<url>https://repository.jboss.org/nexus/content/groups/public-jboss/</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.8.2</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxrs</artifactId>
<version>3.1.0.Final</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jackson-provider</artifactId>
<version>3.1.0.Final</version>
</dependency>
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.1.0</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jettison-provider</artifactId>
<version>3.0.11.Final</version>
</dependency>
<dependency>
<groupId>org.jboss.resteasy</groupId>
<artifactId>resteasy-jaxb-provider</artifactId>
<version>3.1.0.Final</version>
</dependency>
<dependency>
<groupId>com.sun.jersey</groupId>
<artifactId>jersey-spring</artifactId>
<version>1.0</version>
</dependency>
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>20.0</version>
</dependency>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet-core</artifactId>
<version>2.15</version>
</dependency>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.13</version>
</dependency>
<dependency>
<groupId>com.sun.jersey</groupId>
<artifactId>jersey-json</artifactId>
<version>1.19.3</version>
</dependency>
</dependencies>
<pluginRepositories>
<pluginRepository>
<id>protoc-plugin</id>
<url>https://github.com/xolstice/protobuf-maven-plugin</url>
</pluginRepository>
</pluginRepositories>
<build>
<finalName>RESTfulExample</finalName>
<plugins>
<plugin>
<groupId>org.xolstice.maven.plugins</groupId>
<artifactId>protobuf-maven-plugin</artifactId>
<version>0.5.0</version>
<configuration>
<protocExecutable>C:\Users\DevUser\Downloads\protoc-3.1.0-win32\bin\protoc</protocExecutable>
</configuration>
<executions>
<execution>
<goals>
<goal>compile</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.6</source>
<target>1.6</target>
</configuration>
</plugin>
</plugins>
</build>
我的小部件.proto:
option java_package =“example”; option java_outer_classname =“WidgetsProtoc”;
message Widget {
required string id = 1;
required string name = 2;
}
message WidgetList {
repeated Widget widget = 1;
}
對於http:// localhost:8080 / RESTfulExample / widgets,我收到以下錯誤消息:
無法找到類型為響應對象的MessageBodyWriter:hu.example.WidgetsProtoc $媒體類型的WidgetList:application / x-protobuf
我的結構:在src-main-java-example包中,src-main-proto-中的Java類是(提供者和REST類).proto類src-main-webapp-WEB-INF web.xml文件和我將war文件部署到WildFly。
我不知道為什么我收到這條消息,我試着為jsos編寫另一種方法,這是有效的。
看來你的帶注釋的Provider類對於JAX-RS impl。的上下文是未知的,這種情況對於這種情況是重復的。
由於reasteasy和其他JAX-RS實現已經嵌入了json序列化/反序列化支持,因此您的json測試肯定有效。
根據Jboss文檔;
JAX-RS規范允許您插入自己的請求/響應主體讀取器和編寫器。 為此,您使用@Provider注釋一個類,並為編寫器指定@Produces類型,為讀取器指定@Consumes類型。 您還必須分別實現MessageBodyReader / Writer接口。 這是一個例子。
Resteasy ServletContextLoader將自動掃描您的WEB-INF / lib和classes目錄以查找使用@Provider注釋的類,或者您可以在web.xml中手動配置它們。 請參閱安裝/配置
首先,向@Provider類添加必要的日志記錄,並仔細檢查是否存在導致類加載/啟動的嵌套底層異常。
還要為您的提供程序類的web.xml添加配置,作為繞過(如果有)自動掃描問題的解決方法。
<context-param>
<param-name>resteasy.providers</param-name>
<param-value>hu.example.ProtobufMessageWriter</param-value>
</context-param>
最后,如果您能提供,異常的堆棧跟蹤也可能有所幫助。
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