Java TwelveMonkeys 3.1.1 | | 3.1.2不使用maven依赖插件

我试图在我的应用程序中使用来处理缩略图生成。另外，我正在使用

maven依赖插件

解包所有依赖项并创建一个胖jar。虽然，该插件在正常情况下工作得很好，但在与maven依赖插件一起使用时根本不起作用。以下是我的POM XML：

<?xml version="1.0" encoding="UTF-8"?>
<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>

    <groupId>com.prakhar</groupId>
    <artifactId>demo</artifactId>
    <name>demo</name>

    <packaging>jar</packaging>
    <version>0.0.1-SNAPSHOT</version>

    <organization>
        <!-- Used as the 'Vendor' for JNLP generation -->
        <name>Your Organisation</name>
    </organization>

    <properties>
        <slf4j.version>1.6.1</slf4j.version>
    </properties>

    <build>
        <plugins>

            <plugin>
                <!-- Get the dependencies jar files to a common place, for jar signing -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-dependency-plugin</artifactId>
                <executions>
                    <execution>
                        <id>unpack-dependencies</id>
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>unpack-dependencies</goal>
                        </goals>
                        <configuration>
                            <!-- <includeArtifactIds>commons-net,imageio-bmp,imageio-jpeg,imageio-tiff,imageio-pnm,imageio-psd,imageio-iff,imageio-pcx,imageio-pict,imageio-sgi,imageio-tga,imageio-icns,imageio-thumbsdb,imageio-core,imageio-metadata,common-lang,common-io,common-image</includeArtifactIds> -->
                            <outputDirectory>${project.build.directory}/classes</outputDirectory>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

        </plugins>
    </build>


    <dependencies>

        <!-- MigLayout -->



        <!-- Apache Commons -->

        <dependency>
            <groupId>commons-lang</groupId>
            <artifactId>commons-lang</artifactId>
            <version>2.6</version>
        </dependency>

        <!-- Logging  -->

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>jcl-over-slf4j</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.16</version>
        </dependency>

        <!-- Twelve Monkeys dependencies -->
        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-bmp</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-jpeg</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-tiff</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-pnm</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-psd</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-iff</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-pcx</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-pict</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-sgi</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-tga</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-icns</artifactId>
            <version>3.1.1</version>
        </dependency>

        <dependency>
            <groupId>com.twelvemonkeys.imageio</groupId>
            <artifactId>imageio-thumbsdb</artifactId>
            <version>3.1.1</version>
        </dependency>

    </dependencies>

</project>

以下是我得到的一个例外：

java.lang.NullPointerException: Input == null
    at com.twelvemonkeys.image.ResampleOp.filter(Unknown Source)

---

如果有人知道如何解决，请说明。

总之，对于未来的读者，问题是每个ImageIO插件JAR包含多个

META-INF/services

下的资源。自动发现ImageIO插件需要这些资源。它们是：

META-INF/services/javax.imageio.spi.ImageReaderSpi
META-INF/services/javax.imageio.spi.ImageWriterSpi
META-INF/services/javax.imageio.spi.ImageInpuStreamSpi
META-INF/services/javax.imageio.spi.ImageOutputStreamSpi

可能还有更多，但十二只猴子不使用这些

对于感兴趣的学生，您可以阅读更多关于机制的内容，尤其是类

当您将所有JAR文件解压到一个文件夹中时，每个JAR都会覆盖这些文件。相反，需要将具有相同名称的资源合并到新的单个资源中

---

提供了一个解决方案，请参见资源转换器，特别是

你想读什么样的文件？错误消息表明您没有该文件格式的读卡器插件。我不知道fat jar插件是如何工作的，但我知道每个

imageio xxx.jar

插件都包含同名的

META-INF/services/

下的图像。这些需要以某种方式合并。如果它们被覆盖，插件将不会被注册。@我自己：上面的评论中有一个输入错误。；-）它应该说“每个

imageio xxx.jar

插件包含

META-INF/services/

下同名的资源”。也就是说，有多个

META-INF/services/javax.imageio.spi.ImageReaderSpi

（和其他）资源需要合并到单个资源中。我不确定Maven插件是如何处理的。Maven Shade插件似乎提供了一个解决方案，请参阅资源转换器，尤其是。@haraldK，非常感谢您将我指向

META-INF/services/

文件夹。阴影插件确实击中了要害。我用遗留的

maven依赖插件

替换了它，我的快速临时解决方案是将这一行

com.twevelmonkeys.imageio.plugins.pnm.pnmimagerspi

添加到

/META-INF/services/javax.imageio.spi.ImageReaderSpi

，因为我只需要读取pnm/PGM文件。提交我的作业效果很好！

META-INF/services/javax.imageio.spi.ImageReaderSpi
META-INF/services/javax.imageio.spi.ImageWriterSpi
META-INF/services/javax.imageio.spi.ImageInpuStreamSpi
META-INF/services/javax.imageio.spi.ImageOutputStreamSpi