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我正在開發一個Java EE Web應用程序。Apache httpclient 4.3.1 java.lang.NoSuchFieldError：INSTANCE
這裏是我的pom.xml：
<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>bitcoin</groupId>
<artifactId>bitcoin</artifactId>
<packaging>war</packaging>
<version>1.0-SNAPSHOT</version>
<name>Chens Bitcoin Webapp</name>
<url>http://maven.apache.org</url>
<properties>
<endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<!-- Define the version of the JBoss BOMs we want to import to specify tested stacks. -->
<version.jboss.bom>1.0.5.CR6</version.jboss.bom>
</properties>
<repositories>
<repository>
<id>prime-repo</id>
<name>Prime Repo</name>
<url>http://repository.primefaces.org</url>
</repository>
</repositories>
<dependencyManagement>
<dependencies>
<!-- Define the version of JBoss' Java EE 6 APIs we want to use -->
<!-- JBoss distributes a complete set of Java EE 6 APIs including
a Bill of Materials (BOM). A BOM specifies the versions of a "stack" (or
a collection) of artifacts. We use this here so that we always get the correct
versions of artifacts. Here we use the jboss-javaee-6.0-with-security stack
(you can read this as the JBoss stack of the Java EE 6 APIs with Security).
You can actually use this stack with any version of JBoss AS that implements
Java EE 6, not just JBoss AS 7! -->
<dependency>
<groupId>org.jboss.bom</groupId>
<artifactId>jboss-javaee-6.0-with-security</artifactId>
<version>${version.jboss.bom}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<dependency>
<groupId>javax</groupId>
<artifactId>javaee-web-api</artifactId>
<version>7.0</version>
<scope>provided</scope>
</dependency>
<!--<dependency>-->
<!--<groupId>org.jboss.spec.javax.faces</groupId>-->
<!--<artifactId>jboss-jsf-api_2.2_spec</artifactId>-->
<!--<version>2.2.0</version>-->
<!--</dependency>-->
<!--<dependency>-->
<!--<groupId>com.sun.faces</groupId>-->
<!--<artifactId>jsf-spi</artifactId>-->
<!--<version>1.0</version>-->
<!--</dependency>-->
<!-- Rewrite -->
<dependency>
<groupId>org.ocpsoft.rewrite</groupId>
<artifactId>rewrite-servlet</artifactId>
<version>2.0.8.Final</version>
</dependency>
<dependency>
<groupId>org.ocpsoft.rewrite</groupId>
<artifactId>rewrite-config-prettyfaces</artifactId>
<version>2.0.8.Final</version>
</dependency>
<dependency>
<groupId>org.omnifaces</groupId>
<artifactId>omnifaces</artifactId>
<version>1.6</version>
</dependency>
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3</version>
</dependency>
<dependency>
<groupId>org.primefaces</groupId>
<artifactId>primefaces</artifactId>
<version>3.5</version>
</dependency>
<!-- Data time management -->
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>2.2</version>
</dependency>
<dependency>
<groupId>commons-codec</groupId>
<artifactId>commons-codec</artifactId>
<version>1.9</version>
</dependency>
<dependency>
<groupId>org.apache.httpcomponents</groupId>
<artifactId>httpclient</artifactId>
<version>4.3.1</version>
</dependency>
<dependency>
<groupId>com.googlecode.json-simple</groupId>
<artifactId>json-simple</artifactId>
<version>1.1.1</version>
</dependency>
<!-- Import the PicketLink API, we deploy this as library with the application,
and can compile against it -->
<dependency>
<groupId>org.picketlink</groupId>
<artifactId>picketlink-core-api</artifactId>
</dependency>
<!-- Import the PicketLink implementation, we deploy this as library with the application,
but can't compile against it -->
<dependency>
<groupId>org.picketlink</groupId>
<artifactId>picketlink-core-impl</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<finalName>bitcoin</finalName>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<compilerArguments>
<endorseddirs>${endorsed.dir}</endorseddirs>
</compilerArguments>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<failOnMissingWebXml>false</failOnMissingWebXml>
</configuration>
</plugin>
<plugin>
<groupId>org.jboss.as.plugins</groupId>
<artifactId>jboss-as-maven-plugin</artifactId>
<version>7.4.Final</version>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.6</version>
<executions>
<execution>
<phase>validate</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<outputDirectory>${endorsed.dir}</outputDirectory>
<silent>true</silent>
<artifactItems>
<artifactItem>
<groupId>javax</groupId>
<artifactId>javaee-endorsed-api</artifactId>
<version>7.0</version>
<type>jar</type>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
我要創建HttpClient的一種方法，它單獨工作正常，但有問題的JSF頁面調用時：
public void doSth() {
......
HttpClient httpclient = HttpClientBuilder.create().build();
......
}
此方法在JSF頁面上通過commonbutton調用，當點擊按鈕時發生以下錯誤：
Caused by: java.lang.NoSuchFieldError: INSTANCE
at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:52) [httpcore-4.3.jar:4.3]
at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<init>(DefaultHttpRequestWriterFactory.java:56) [httpcore-4.3.jar:4.3]
at org.apache.http.impl.io.DefaultHttpRequestWriterFactory.<clinit>(DefaultHttpRequestWriterFactory.java:46) [httpcore-4.3.jar:4.3]
......
GOOGLE了它，似乎HttpClient的jar文件具有與其他一些階級衝突，但我實在想不出哪一個，並在POM所有的依賴關係是必要的。
順便說一句，我使用WildFly 8 CR作爲服務器。
在此先感謝。
聞起來很像你有兩個不同版本的httpclient在你的classpath中。你有沒有檢查過WildFly是否帶有一個httpclient？除此之外，也許你的一個依賴關係會自帶httpclient。嘗試使用mvn依賴關係：樹並檢查是否有兩個版本的httpclient –
另外，可能不相關，在依賴管理中使用「jboss-javaee-6.0-with-security」bom，但在依賴關係中，使用javaee-web- API-7.0 –