今天编译maven的时候出现问题了
mvn clean compile
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.3:compile (default-compile) on project iot_push_server: Compilation failure: Co
mpilation failure:
[ERROR] /D:/iot_push-master/iot_push_server/src/main/java/com/lxr/iot/bootstrap/BaseApi.java:[3,31] 程序包com.sun.istack.internal不存在
[ERROR] /D:/iot_push-master/iot_push_server/src/main/java/com/lxr/iot/bootstrap/BaseApi.java:[74,35] 找不到符号
[ERROR] 符号: 类 NotNull
[ERROR] 位置: 接口 com.lxr.iot.bootstrap.BaseApi
[ERROR] /D:/iot_push-master/iot_push_server/src/main/java/com/lxr/iot/bootstrap/BaseApi.java:[74,49] 找不到符号
[ERROR] 符号: 类 NotNull
[ERROR] 位置: 接口 com.lxr.iot.bootstrap.BaseApi
[ERROR] /D:/iot_push-master/iot_push_server/src/main/java/com/lxr/iot/bootstrap/BaseApi.java:[74,81] 找不到符号
[ERROR] 符号: 类 NotNull
[ERROR] 位置: 接口 com.lxr.iot.bootstrap.BaseApi
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn <goals> -rf :iot_push_server
这里最关键的提示是:
程序包 com.sun.istack.internal 不存在
我看了下ide，没有报错，可以点到com.sun.istack.internal这个包里面！
这就有点麻烦了。
首先，大概猜下为啥这个包不存在
我们是在编译java文件的时候需要依赖这个包中的class，也就是mvn compile调用的编译程序的classpath中没有包含 com.sun.istack.internal这个包，而ide中却包含了这个包。而通过ide，我们观察到 com.sun.istack.internal这个包在 ${MAVEN_HOME}/jre/lib/rt.jar这个jar中，所以我们可以得出一个大致的结论：
mvn compile调用的编译程序的classpath中缺少${MAVEN_HOME}/jre/lib/rt.jar 这个jar包
那么下一步，我们应该通过日志，去观察 mvn compile的编译程序所依赖的classpath
通过maven 命令，执行以下命令debug。
mvn compile -X -e
控制台日志
[INFO] --- maven-compiler-plugin:3.3:compile (default-compile) @ iot_push_server ---
[DEBUG] Configuring mojo org.apache.maven.plugins:maven-compiler-plugin:3.3:compile from plugin realm ClassRealm[plugin>org.apache.maven.plugins:maven-compiler
-plugin:3.3, parent: sun.misc.Launcher$AppClassLoader@33909752]
[DEBUG] Configuring mojo 'org.apache.maven.plugins:maven-compiler-plugin:3.3:compile' with basic configurator -->
[DEBUG] (f) basedir = D:\iot_push-master\iot_push_server
[DEBUG] (f) buildDirectory = D:\iot_push-master\iot_push_server\target
[DEBUG] (f) classpathElements = [XXXXXXXX some jar XXXXXXXX]
[DEBUG] (f) compileSourceRoots = [D:\iot_push-master\iot_push_server\src\main\java]
[DEBUG] (f) compilerId = javac
[DEBUG] (f) debug = true
[DEBUG] (f) encoding = UTF-8
[DEBUG] (f) failOnError = true
[DEBUG] (f) forceJavacCompilerUse = false
[DEBUG] (f) fork = false
[DEBUG] (f) generatedSourcesDirectory = D:\iot_push-master\iot_push_server\target\generated-sources\annotations
[DEBUG] (f) mojoExecution = org.apache.maven.plugins:maven-compiler-plugin:3.3:compile {execution: default-compile}
[DEBUG] (f) optimize = false
[DEBUG] (f) outputDirectory = D:\iot_push-master\iot_push_server\target\classes
[DEBUG] (f) project = MavenProject: com.lxr.iot:iot_push_server:1.0-SNAPSHOT @ D:\iot_push-master\iot_push_server\pom.xml
[DEBUG] (f) projectArtifact = com.lxr.iot:iot_push_server:jar:1.0-SNAPSHOT
[DEBUG] (f) session = org.apache.maven.execution.MavenSession@610db97e
[DEBUG] (f) showDeprecation = false
[DEBUG] (f) showWarnings = false
[DEBUG] (f) skipMultiThreadWarning = false
[DEBUG] (f) source = 1.8
[DEBUG] (f) staleMillis = 0
[DEBUG] (f) target = 1.8
[DEBUG] (f) useIncrementalCompilation = true
[DEBUG] (f) verbose = false
[DEBUG] -- end configuration --
[DEBUG] Using compiler 'javac'. （=======重要========）
[DEBUG] Source directories: [D:\iot_push-master\iot_push_server\src\main\java]
[DEBUG] Classpath: [D:\iot_push-master\iot_push_server\target\classes
D:\iot_push-master\iot_push_common\target\classes , XXXXXXXX some jar XXXXXXXX]
[DEBUG] Output directory: D:\iot_push-master\iot_push_server\target\classes
[DEBUG] Adding D:\iot_push-master\iot_push_server\target\generated-sources\annotations to compile source roots:
D:\iot_push-master\iot_push_server\src\main\java
[DEBUG] New compile source roots:
D:\iot_push-master\iot_push_server\src\main\java
D:\iot_push-master\iot_push_server\target\generated-sources\annotations
...
[DEBUG] Source roots:
[DEBUG] D:\iot_push-master\iot_push_server\src\main\java
[DEBUG] D:\iot_push-master\iot_push_server\target\generated-sources\annotations
[DEBUG] Command line options:（=======重要========）
[DEBUG] -d D:\iot_push-master\iot_push_server\target\classes -classpath XXXXXXXX some jar XXXXXXXX -sourcepath D:\iot_push-master\iot_push_server\src\main\java;D:\iot_push-master\iot_push_server\target\generated
-sources\annotations; -s D:\iot_push-master\iot_push_server\target\generated-sources\annotations -g -nowarn -target 1.8 -source 1.8 -encoding UTF-8
[DEBUG] incrementalBuildHelper#beforeRebuildExecution
[INFO] Compiling 31 source files to D:\iot_push-master\iot_push_server\target\classes
[DEBUG] incrementalBuildHelper#afterRebuildExecution
我们通过日志，发现两个很关键的内容
- 使用javac编译程序
[DEBUG] Using compiler 'javac'.
- javac的classpath参数不包含 jdk的lib文件中所包含的jar包
[DEBUG] Command line options:
[DEBUG] -d D:\iot_push-master\iot_push_server\target\classes
-classpath ... -sourcepath
通过classpath,我们知道 javac会找两个的classpath，一个是系统环境变量 CLASSPATH,一个是参数 -classpath ，这里参数不包含classpath，那么必须在环境变量CLASSPATH 中寻找。
验证：
我们在window中查找classpath
C:\Users\ezlhq> echo %classpath%
.;D:\java\jdk1.8.0_152\lib\dt.jar;D:\java\jdk1.8.0_152\lib\tools.jar;
对比 ide中的classpath
同时我们手动用javac 去编译类
C:\Users\ezlhq>javac -verbose D:\iot_push-master\iot_push_server\src\main\java\com\lxr\iot\bootstrap\BaseApi.java
[解析开始时间 RegularFileObject[D:\iot_push-master\iot_push_server\src\main\java\com\lxr\iot\bootstrap\BaseApi.java]]
[解析已完成, 用时 24 毫秒]
[源文件的搜索路径: .,D:\java\jdk1.8.0_152\lib\dt.jar,D:\java\jdk1.8.0_152\lib\tools.jar]
[类文件的搜索路径: xxxx
果然验证了我们之前的答案。mvn调用javac去编译我们应用程序的时候，并没有带上 rt.jar这个jar包
那么如何解决这个问题了?
- window修改全局变量后还得重启才能生效，考虑到还有其他开发人员，不可能人人都重启电脑，故弃之
- javac -classpath的时候加上
rt.jar
通过maven-compiler-plugin 插件使用
修改pom：bootclasspath 参考
<pluginManagement>
<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>
<encoding>UTF-8</encoding>
<!-- 过期的方法的警告
<compilerArgs>
<arg>-Xlint:deprecation</arg>
</compilerArgs> -->
<compilerArguments>
<!-- 是否输出所有的编译信息（包括类的加载等）-->
<!--<verbose />-->
<!-- 解决maven命令编译报错，因为rt.jar 和jce.jar在jre的lib下面，不在jdk的lib下面，
导致maven找不到（java7以后会出现这个问题），将这2个jar包拷贝到jdk的lib下面估计也好使-->
<bootclasspath>${java.home}\lib\rt.jar;${java.home}\lib\jce.jar</bootclasspath>
</compilerArguments>
</configuration>
</plugin>
</plugins>
</pluginManagement>
