maven-compiler-pluginはどのように異なるjdkで動作しますか？

Question

$ mvn --version 
Apache Maven 3.5.2 (138edd61fd100ec658bfa2d307c43b76940a5d7d; 2017-10-18T03:58:13-04:00) 
Maven home: /usr/local/apache-maven 
Java version: 1.8.0_151, vendor: Oracle Corporation 
Java home: /usr/lib/jvm/java-8-oracle/jre 
Default locale: en_CA, platform encoding: UTF-8 
OS name: "linux", version: "4.4.0-98-generic", arch: "amd64", family: "unix" 

マシンにインストールされているjvmバージョンのみです。 pom.xmlで

---

、1.4としてsource & targetバージョンの設定について、ここ

<build> 
    <plugins> 
     <plugin> 
     <groupId>org.apache.maven.plugins</groupId> 
     <artifactId>maven-compiler-plugin</artifactId> 
     <version>2.0.2</version> 
     <configuration> 
      <source>1.4</source> 
      <target>1.4</target> 
     </configuration> 
     </plugin> 
    </plugins> 
    </build> 

---

はmvn packageの出力であり、

$ mvn package 
[INFO] Scanning for projects... 
[INFO] 
[INFO] ------------------------------------------------------------------------ 
[INFO] Building mywebapp 1.0-SNAPSHOT 
[INFO] ------------------------------------------------------------------------ 
Downloading from central: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-compiler-plugin/2.0.2/maven-compiler-plugin-2.0.2.pom 
Downloaded from central: https://repo.maven.apache.org/maven2/org/apache/maven/plugins/maven-compiler-plugin/2.0.2/maven-compiler-plugin-2.0.2.pom (2.4 kB at 934 B/s) 
.... 
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ mywebapp --- 
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent! 
[INFO] skip non existing resourceDirectory /home/mohet01/git/Projects/myapp/mywebapp/src/main/resources 
[INFO] 
[INFO] --- maven-compiler-plugin:2.0.2:compile (default-compile) @ mywebapp --- 
... 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-api/1.5.3/plexus-compiler-api-1.5.3.pom 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-api/1.5.3/plexus-compiler-api-1.5.3.pom (624 B at 700 B/s) 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler/1.5.3/plexus-compiler-1.5.3.pom 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler/1.5.3/plexus-compiler-1.5.3.pom (1.5 kB at 1.8 kB/s) 
... 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-manager/1.5.3/plexus-compiler-manager-1.5.3.pom 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-manager/1.5.3/plexus-compiler-manager-1.5.3.pom (634 B at 732 B/s) 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-javac/1.5.3/plexus-compiler-javac-1.5.3.pom 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-javac/1.5.3/plexus-compiler-javac-1.5.3.pom (797 B at 871 B/s) 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compilers/1.5.3/plexus-compilers-1.5.3.pom 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compilers/1.5.3/plexus-compilers-1.5.3.pom (7.6 kB at 9.4 kB/s) 
... 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-api/1.5.3/plexus-compiler-api-1.5.3.jar 
... 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-manager/1.5.3/plexus-compiler-manager-1.5.3.jar 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-api/1.5.3/plexus-compiler-api-1.5.3.jar (20 kB at 20 kB/s) 
... 
Downloading from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-javac/1.5.3/plexus-compiler-javac-1.5.3.jar 
... 
Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-javac/1.5.3/plexus-compiler-javac-1.5.3.jar (14 kB at 8.2 kB/s) 
... 

Downloaded from central: https://repo.maven.apache.org/maven2/org/codehaus/plexus/plexus-compiler-manager/1.5.3/plexus-compiler-manager-1.5.3.jar (5.3 kB at 2.1 kB/s) 
..... 

[INFO] Packaging webapp 
[INFO] Assembling webapp [mywebapp] in [/home/mohet01/git/Projects/myapp/mywebapp/target/mywebapp-1.0-SNAPSHOT] 
[INFO] Processing war project 
[INFO] Copying webapp resources [/home/mohet01/git/Projects/myapp/mywebapp/src/main/webapp] 
[INFO] Webapp assembled in [79 msecs] 
[INFO] Building war: /home/mohet01/git/Projects/myapp/mywebapp/target/mywebapp-1.0-SNAPSHOT.war 
[INFO] WEB-INF/web.xml already added, skipping 
[INFO] ------------------------------------------------------------------------ 
[INFO] BUILD SUCCESS 
[INFO] ------------------------------------------------------------------------ 
[INFO] Total time: 36.643 s 
[INFO] Finished at: 2017-12-07T01:56:43-05:00 
[INFO] Final Memory: 14M/140M 
[INFO] ------------------------------------------------------------------------ 
$ 

---

javaソースコードをコンパイルする前に、mavenがjavacコンパイラの1.4版をオンラインのmavenレポからプルしますか？対応するjdkを指すには？

Answer 1

いいえ、javacは（わずかな例外を除いて）後方compalibileコードにコンパイルする能力無し