Java 为什么mvn compile从我的语法文件生成两行程序包？

为什么我的语法在使用

mvncile

编译后会产生两行包

我的文件夹结构如下所示：

src/main/antlr/eu/niehus/parser/Lexer.g4
src/main/antlr/eu/niehus/parser/Parser.g4

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

  <groupId>eu.niehus</groupId>
  <artifactId>parser</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

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

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <build>
    <plugins>
        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.7.0</version>
          <configuration>
            <source>1.9</source>
            <target>1.9</target>
          </configuration>
      </plugin>
      <plugin>
        <groupId>org.antlr</groupId>
        <artifactId>antlr4-maven-plugin</artifactId>
        <version>4.7</version>
        <configuration>
                <visitor>true</visitor>
                <treatWarningsAsErrors>true</treatWarningsAsErrors>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>antlr4</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
    <dependency>
       <groupId>org.antlr</groupId>
       <artifactId>antlr4-runtime</artifactId>
       <version>4.7</version>
    </dependency>
  </dependencies>
</project>

my Parser.g4的内容：

parser grammar Parser;

options {
    language = Java;
    tokenVocab = Lexer;
}

@header {
package eu.niehus.parser;
}
addition: NUMBER ('+' NUMBER)+;

现在，如果我使用mvn compile生成它，我将获得以下源代码：

// Generated from eu\niehus\parser\Lexer.g4 by ANTLR 4.7

package eu.niehus.parser;

package eu.niehus.parser;

import org.antlr.v4.runtime.Lexer;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.atn.*;
import org.antlr.v4.runtime.dfa.DFA;
import org.antlr.v4.runtime.misc.*;

它包含两条包装线。如何防止Maven生成两个包行

---

我已经尝试过在我的解析器/词法分析器中没有@header语句，它会删除一个包行。但是我不认为这是应该如何处理的

包语句之一是由于.g4文件（src/main/antlr/eu/niehus/parser/）的位置

---

另一个原因是由于.g4文件头部分中的package语句

您是否尝试对解析器部分使用

@parser:：header{…

而不是

@header{…

？

// Generated from eu\niehus\parser\Lexer.g4 by ANTLR 4.7

package eu.niehus.parser;

package eu.niehus.parser;

import org.antlr.v4.runtime.Lexer;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.*;
import org.antlr.v4.runtime.atn.*;
import org.antlr.v4.runtime.dfa.DFA;
import org.antlr.v4.runtime.misc.*;