错误的服务配置文件,或在构造处理器对象时引发的异常

2022-09-02 20:47:52

我正在用Java编写一个简单的自定义注释,并遇到了一个问题。这是我的代码的主要部分。

LogMeCustomAnnotation.java

package fun.n.learn.annotation;

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

// We need this annotation only till before compilation.
@Retention(RetentionPolicy.SOURCE)
// This is a simple custom annotation.
public @interface LogMeCustomAnnotation {

}

LogMeCustomAnnotationProcessor.java

package fun.n.learn.annotation;

import java.util.Set;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.Messager;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.lang.model.element.TypeElement;
import javax.tools.Diagnostic;

// List the custom annotations that are supported.
@SupportedAnnotationTypes({ "fun.n.learn.annotation.LogMeCustomAnnotation" })
// Extend AbstractProcessor. This will let you process.
public class LogMeCustomAnnotationProcessor extends AbstractProcessor {

    @Override
    public boolean process(Set<? extends TypeElement> annotations,
            RoundEnvironment roundEnv) {

        Messager messager = processingEnv.getMessager();
        messager.printMessage(Diagnostic.Kind.NOTE, "I was here.");

        // TODO: Put some meaningful code here. Right now just get it to work.

        // return false;
        // We have already handled these annotations. No more. So return true.
        return true;
    }

}

/src/main/resources/META-INF/services/javax.annotation.processing.Processor

fun.n.learn.annotation.LogMeCustomAnnotationProcessor

啪.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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>fun.n.learn</groupId>
    <artifactId>javaCustomAnnotation</artifactId>
    <version>0.1.0</version>

    <build>
        <plugins>
            <plugin>
                <!-- Configure the project to use java 8 version. -->
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.5.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <!-- Disable annotation processing for ourselves. -->
                    <!-- <compilerArgument>-proc:none</compilerArgument> -->
                </configuration>
            </plugin>
        </plugins>
    </build>


</project>

现在当我运行时,我遇到以下问题mvn -e clean install

[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] Bad service configuration file, or exception thrown while constructing Processor object: javax.annotation.processing.Processor: Provider fun.n.learn.annotation.LogMeCustomAnnotationProcessor not found
[INFO] 1 error

我一定在这里错过了一个简单的技巧。有什么帮助吗?


答案 1

默认的 maven 生命周期使用 javax.annotation.processing.Processor 文件作为类路径的一部分运行 javac。这会导致编译器需要文件中列出的注释处理器的已编译实例。但当时没有编译,所以编译器会引发“糟糕的服务配置文件......”错误。请参阅错误报告

为了解决这个问题,maven编译阶段可以分开,首先编译注释处理器,然后编译整个项目。LogMeCustomAnnotationProcessor

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.5.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
            </configuration>
            <executions>
                <execution>
                    <id>default-compile</id>
                    <configuration>
                        <compilerArgument>-proc:none</compilerArgument>
                        <includes>
                            <include>fun/n/learn/annotation/LogMeCustomAnnotationProcessor.java</include>
                            <!--include dependencies required for LogMeCustomAnnotationProcessor -->
                        </includes>
                    </configuration>
                </execution>
                <execution>
                    <id>compile-project</id>
                    <phase>compile</phase>
                    <goals>
                        <goal>compile</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

default-compile执行编译禁用的注释处理,以便成功编译。
使用注释处理编译整个项目。LogMeCustomAnnotationProcessorcompile-project


答案 2

好的。发现问题。早些时候,我的pom.xml把这句话注释掉了。现在我已经把它重新付诸行动,它编译得很好。我需要弄清楚这条线到底是做什么的,但我问题的答案只是把游戏放回去。这就是我的pom.xml的构建部分现在的样子。proc:noneproc:none

<build>
    <plugins>
        <plugin>
            <!-- Configure the project to use java 8 version. -->
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>3.5.1</version>
            <configuration>
                <source>1.8</source>
                <target>1.8</target>
                <!-- Disable annotation processing for ourselves. -->
                <compilerArgument>-proc:none</compilerArgument>
            </configuration>
        </plugin>
    </plugins>
</build>

推荐