注入实例上的Guice nullpointer异常 [英] Guice nullpointer exception on injected instance
本文介绍了注入实例上的Guice nullpointer异常的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在使用Jersey2中的Guice进行DI(我想使用它，以便可以使用Google App Engine->不适用于HK2).
I'm using Guice in Jersey2 for DI (i want to use it so i can use Google App Engine -> not working with HK2).
我的ApplicationResource:
My ApplicationResource:
public class ApplicationResource extends ResourceConfig {
private static final Logger LOGGER = null;
public ApplicationResource() {
System.out.println("Application startup");
// Register resources and providers using package-scanning.
packages("com.crawler.c_api");
// Register my custom provider - not needed if it's in my.package.
register(ResponseCorsFilter.class);
Injector createInjector = Guice.createInjector(new AbstractModule(){
@Override
protected void configure() {
bind(NLPProvider.class).toInstance(new NLPProvider());
}
});
// Register an instance of LoggingFilter.
register(new LoggingFilter(LOGGER, true));
// Enable Tracing support.
property(ServerProperties.TRACING, "ALL");
EncodingFilter.enableFor(this, GZipEncoder.class);
}
}
NLPProvider加载了一堆文件-并且文件已正确加载. 但是当我尝试注入NLPProvider的实例时，它保持为空.
NLPProvider loads a bunch of files - and the files are loaded correctly. But when i try to inject the Instance of NLPProvider it stay null.
Crwaler资源:
CrwalerResource:
@Path("/crawler")
public class CrawlerResource {
@Inject
NLPProvider pipeline;
@GET
@Produces(MediaType.APPLICATION_JSON + ";charset=utf-8")
public Response crawlUrl(@BeanParam CrawlerQueryParam queryParameters) {
CrawlerService crawl = new CrawlerService();
return Response.status(200).entity(crawl.extractFromUrl(queryParameters, pipeline)).build();
}
}
考虑到我以前使用过HK2，我在做什么?
What am i doing wrong considering that i used HK2 before?
我的pom.xml-也许问题出在这里:
My pom.xml - maybe the issue comes from here:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.crawler</groupId>
<artifactId>C_API</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>C_API</name>
<build>
<finalName>C_API</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.2</version>
<inherited>true</inherited>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
</plugins>
</build>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.glassfish.jersey</groupId>
<artifactId>jersey-bom</artifactId>
<version>${jersey.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependencies>
<dependency>
<groupId>org.glassfish.jersey.containers</groupId>
<artifactId>jersey-container-servlet</artifactId>
<!-- use the following artifactId if you don't need servlet 2.x compatibility -->
<!-- artifactId>jersey-container-servlet</artifactId -->
</dependency>
<dependency>
<groupId>org.glassfish.jersey.media</groupId>
<artifactId>jersey-media-moxy</artifactId>
</dependency>
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP-java6</artifactId>
<version>2.2.5</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.36</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.9</version>
</dependency>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.9.13</version>
</dependency>
<dependency>
<groupId>org.mindrot</groupId>
<artifactId>jbcrypt</artifactId>
<version>0.3m</version>
</dependency>
<dependency>
<groupId>net.sf.json-lib</groupId>
<artifactId>json-lib</artifactId>
<version>2.4</version>
<classifier>jdk15</classifier>
</dependency>
<dependency>
<groupId>com.syncthemall</groupId>
<artifactId>boilerpipe</artifactId>
<version>1.2.1</version>
</dependency>
<dependency>
<groupId>xerces</groupId>
<artifactId>xercesImpl</artifactId>
<version>2.11.0</version>
</dependency>
<dependency>
<groupId>net.sourceforge.nekohtml</groupId>
<artifactId>nekohtml</artifactId>
<version>1.9.22</version>
</dependency>
<dependency>
<groupId>org.apache.opennlp</groupId>
<artifactId>opennlp-tools</artifactId>
<version>1.6.0</version>
</dependency>
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>14.0.1</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
<dependency>
<groupId>com.github.mpkorstanje</groupId>
<artifactId>simmetrics</artifactId>
<version>3.2.1</version>
</dependency>
<dependency>
<groupId>com.cybozu.labs</groupId>
<artifactId>langdetect</artifactId>
<version>1.1-20120112</version>
</dependency>
<dependency>
<!-- jsoup HTML parser library @ http://jsoup.org/ -->
<groupId>org.jsoup</groupId>
<artifactId>jsoup</artifactId>
<version>1.8.3</version>
</dependency>
<dependency>
<groupId>com.google.inject</groupId>
<artifactId>guice</artifactId>
<version>3.0</version>
</dependency>
</dependencies>
<properties>
<jersey.version>2.21</jersey.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
</project>
推荐答案
您需要将guice与HK2桥接，如此处.
You will need to bridge guice with HK2, as mentioned here.
@Inject
public ApplicationResource(ServiceLocator locator) {
GuiceBridge.getGuiceBridge().initializeGuiceBridge(locator);
// add your Guice modules.
Injector injector = Guice.createInjector(new GuiceModule());
GuiceIntoHK2Bridge guiceBridge = locator.getService(GuiceIntoHK2Bridge.class);
guiceBridge.bridgeGuiceInjector(injector);
}
您还需要HK2 guice-bridge依赖项
You'll also need the HK2 guice-bridge dependency
<dependency>
<groupId>org.glassfish.hk2</groupId>
<artifactId>guice-bridge</artifactId>
<version>2.4.0-b31</version>
</dependency>
这篇关于注入实例上的Guice nullpointer异常的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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