java运行时异常:在构建uberjar和zip包时“无法找到内容类型的编写器”

时间:2013-08-30 17:53:15

标签: java eclipse maven uberjar

使用maven程序集插件构建uberjar然后将其打包成zip文件时,遇到运行时故障:

java.lang.RuntimeException: could not find writer for content-type text/xml type: java.lang.String

当我在eclipse中运行我的项目时,或者当我使用eclipse Export创建和执行.jar时,不会发生这种失败 - > Runnable Jar File所以我怀疑我使用maven创建uberjar的方式有问题。

如何解决此问题?

1 个答案:

答案 0 :(得分:4)

事实证明,我的问题的根源是与maven程序集插件创建jar时发生的javax.ws.rs.ext.Providers文件冲突。 (此文件可在META-INF中的uberjar中找到 - > services - > javax.ws.rs.ext.Providers)

Providers文件包含可用提供程序类的列表。在我的项目的依赖项中,此文件存在于多个位置,并且不同的副本包含不同的提供程序列表。 maven程序集插件只是选择一个版本包含在jar中,因此在运行时无法找到所需的“writer”类:此类未在jar中的Providers文件中列出。

我使用了maven shade插件来克服这个问题。 shade插件包含有选择地合并依赖关系树中包含的重复文件的工具。在pom.xml中:

  <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
      <resource>META-INF/services/javax.ws.rs.ext.Providers</resource>
  </transformer>

通过附加任何重复的javax.ws.rs.ext.Providers告诉maven合并。

此外,通过将maven shade插件设置为在构建的package阶段执行,然后在install阶段执行maven程序集插件,我能够创建可执行的uberjar ,然后将该uberjar封装在.zip文件中,所有这些都使用简单的mvn clean install调用。

这是我的pom.xml的样子:

<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/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>

   <parent>
      ...
   </parent>

   <groupId>com.foo.bar</groupId>
   <artifactId>my-app</artifactId>
   <packaging>jar</packaging>
   <version>2.1.0.0-SNAPSHOT</version>
   <name>My App</name>

   <url>http://maven.apache.org</url>

   <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <issues-product>MyApp</issues-product>
      <issues-component>MY-APP</issues-component>
   </properties>

   <dependencies>
      ...
   </dependencies>

   <build>
   <finalName>${project.artifactId}</finalName>
   <plugins>
    <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>2.3.2</version>
        <configuration>
            <source>1.6</source>
            <target>1.6</target>
        </configuration>
    </plugin>
     <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>2.1</version>
        <executions>
            <execution>
                <phase>package</phase>
                <goals>
                    <goal>shade</goal>
                </goals>
            <configuration>
            <createDependencyReducedPom>false</createDependencyReducedPom>
                <transformers>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                        <mainClass>com.foo.bar.MyMainClass</mainClass>
                    </transformer>
                    <transformer implementation="org.apache.maven.plugins.shade.resource.AppendingTransformer">
                        <resource>META-INF/services/javax.ws.rs.ext.Providers</resource>
                    </transformer>
                </transformers>
                <filters>
                    <filter>
                        <artifact>*:*</artifact>
                    </filter>
                </filters>
                </configuration>
            </execution>
        </executions>
    </plugin>

    <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.2.2</version>
        <configuration>
            <finalName>${project.artifactId}</finalName>
            <appendAssemblyId>false</appendAssemblyId>
            <descriptors>
                <descriptor>src/assembly/my-app-assembly.xml</descriptor>
            </descriptors>
         </configuration>
         <executions>
            <execution>
                <phase>install</phase>
                <goals>
                    <goal>single</goal>
                </goals>
            </execution>
        </executions>
    </plugin>
   </plugins>
</project>

这是my-app-assembly.xml:

<assembly xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/2.2.2" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/2.2.2 http://maven.apache.org/xsd/assembly-2.2.2.xsd">
  <id>bin</id>
  <formats>
    <format>zip</format>
  </formats>
  <includeBaseDirectory>false</includeBaseDirectory>
  <fileSets>
    <fileSet>
      <directory>${project.basedir}</directory>
      <outputDirectory/>
      <includes>
        <include>Readme.pdf</include>
        <include>config\</include>
        <include>input\</include>
        <include>output\</include>
      </includes>
    </fileSet>
    <fileSet>
      <directory>${project.build.directory}</directory>
      <outputDirectory>bin\java\</outputDirectory>
      <includes>
        <include>my-app.jar</include>
      </includes>
    </fileSet>
  </fileSets>
</assembly>