本文共 7477 字，大约阅读时间需要 24 分钟。

环境

服务器：centos6

疑惑

[yutao@master01 elasticsearch-6.0.0]$ bin/elasticsearch-plugin install file:///home/yutao/download/x-pack-6.0.0.zip -> Downloading file:///home/yutao/download/x-pack-6.0.0.zipException in thread "main" java.nio.file.AccessDeniedException: /tmp/2089611009639660923.zip        at sun.nio.fs.UnixException.translateToIOException(UnixException.java:84)        at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)        at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)        at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)        at java.nio.file.Files.newByteChannel(Files.java:361)        at java.nio.file.Files.createFile(Files.java:632)        at java.nio.file.TempFileHelper.create(TempFileHelper.java:138)        at java.nio.file.TempFileHelper.createTempFile(TempFileHelper.java:161)        at java.nio.file.Files.createTempFile(Files.java:852)        at org.elasticsearch.plugins.InstallPluginCommand.downloadZip(InstallPluginCommand.java:322)        at org.elasticsearch.plugins.InstallPluginCommand.download(InstallPluginCommand.java:245)        at org.elasticsearch.plugins.InstallPluginCommand.execute(InstallPluginCommand.java:213)        at org.elasticsearch.plugins.InstallPluginCommand.execute(InstallPluginCommand.java:204)        at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:69)        at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:134)        at org.elasticsearch.cli.MultiCommand.execute(MultiCommand.java:69)        at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:134)        at org.elasticsearch.cli.Command.main(Command.java:90)        at org.elasticsearch.plugins.PluginCli.main(PluginCli.java:47)

这个错误，在上一篇博客中也提到过，就是因为我使用yutao用户安装时，没有目录tmp的权限。而我想这个目录它为什么要用到？我能不能通过配置文件来进行配置？

查看源码

带着这样的疑惑，我开始查看源码：

// 从这句看出，其调用的是org.elasticsearch.plugins包下的PluginCli类的main方法org.elasticsearch.plugins.PluginCli.main(PluginCli.java:47)// 和上面同理 org.elasticsearch.plugins.InstallPluginCommand.download(InstallPluginCommand.java:245)

其InstallPluginCommand类路径elasticsearch-6.0.0.zip\elasticsearch-6.0.0\lib\plugin-cli-6.0.0.jar\org\elasticsearch\plugins\InstallPluginCommand.class

protected void execute(final Terminal terminal, final OptionSet options, final Environment env) throws Exception {        final String pluginId = (String)this.arguments.value(options);        final boolean isBatch = options.has((OptionSpec)this.batchOption) || System.console() == null;        this.execute(terminal, pluginId, isBatch, env);    }    void execute(final Terminal terminal, final String pluginId, final boolean isBatch, final Environment env) throws Exception {        if (pluginId == null) {            throw new UserException(64, "plugin id is required");        }        final Path pluginZip = this.download(terminal, pluginId, env.tmpFile());        final Path extractedZip = this.unzip(pluginZip, env.pluginsFile());        this.install(terminal, isBatch, extractedZip, env);    }

再看到其中的download方法，其有个参数env.tmpFile()；而这个方法是这个Environment类中的。

路径：elasticsearch-6.0.0.jar\org\elasticsearch\env\Environment.class

public Environment(final Settings settings, final Path configPath) {       // 重点就是这句        this.tmpFile = PathUtils.get(System.getProperty("java.io.tmpdir"), new String[0]);        if (Environment.PATH_HOME_SETTING.exists(settings)) {            final Path homeFile = PathUtils.get((String)Environment.PATH_HOME_SETTING.get(settings), new String[0]).normalize();            if (configPath != null) {                this.configFile = configPath.normalize();            }            else {                this.configFile = homeFile.resolve("config");            }            this.pluginsFile = homeFile.resolve("plugins");            final List
   
     dataPaths = (List
    
     )Environment.PATH_DATA_SETTING.get(settings);            final ClusterName clusterName = (ClusterName)ClusterName.CLUSTER_NAME_SETTING.get(settings);            if (!dataPaths.isEmpty()) {                this.dataFiles = new Path[dataPaths.size()];                this.dataWithClusterFiles = new Path[dataPaths.size()];                for (int i = 0; i < dataPaths.size(); ++i) {                    this.dataFiles[i] = PathUtils.get((String)dataPaths.get(i), new String[0]);                    this.dataWithClusterFiles[i] = this.dataFiles[i].resolve(clusterName.value());                }            }            else {                this.dataFiles = new Path[] { homeFile.resolve("data") };                this.dataWithClusterFiles = new Path[] { homeFile.resolve("data").resolve(clusterName.value()) };            }            if (Environment.PATH_SHARED_DATA_SETTING.exists(settings)) {                this.sharedDataFile = PathUtils.get((String)Environment.PATH_SHARED_DATA_SETTING.get(settings), new String[0]).normalize();            }            else {                this.sharedDataFile = null;            }            final List
     
       repoPaths = (List
      
       )Environment.PATH_REPO_SETTING.get(settings);            if (!repoPaths.isEmpty()) {                this.repoFiles = new Path[repoPaths.size()];                for (int j = 0; j < repoPaths.size(); ++j) {                    this.repoFiles[j] = PathUtils.get((String)repoPaths.get(j), new String[0]);                }            }            else {                this.repoFiles = new Path[0];            }            if (Environment.PATH_LOGS_SETTING.exists(settings)) {                this.logsFile = PathUtils.get((String)Environment.PATH_LOGS_SETTING.get(settings), new String[0]).normalize();            }            else {                this.logsFile = homeFile.resolve("logs");            }            if (Environment.PIDFILE_SETTING.exists(settings)) {                this.pidFile = PathUtils.get((String)Environment.PIDFILE_SETTING.get(settings), new String[0]).normalize();            }            else {                this.pidFile = null;            }            this.binFile = homeFile.resolve("bin");            this.libFile = homeFile.resolve("lib");            this.modulesFile = homeFile.resolve("modules");            final Settings.Builder finalSettings = Settings.builder().put(settings);            finalSettings.put(new Object[] { Environment.PATH_HOME_SETTING.getKey(), homeFile });            if (Environment.PATH_DATA_SETTING.exists(settings)) {                finalSettings.putArray(Environment.PATH_DATA_SETTING.getKey(), (List)dataPaths);            }            finalSettings.put(new Object[] { Environment.PATH_LOGS_SETTING.getKey(), this.logsFile });            this.settings = finalSettings.build();            return;        }        throw new IllegalStateException(Environment.PATH_HOME_SETTING.getKey() + " is not configured");    }
      
     
    
   

我们重点看看这句：

this.tmpFile = PathUtils.get(System.getProperty("java.io.tmpdir"), new String[0]);

很明显，通过jdk提供的方法，获取到了，当前操作系统的临时文件tmp。

看到这里也就说明，不能通过配置文件的方式来修改，毕竟源码写死啦！

不过我又对上面代码中的第二个参数new String[0],产生了兴趣，虽然弄到了凌晨1点，但是还是坚持多看了几眼。

为什么要传一个字符串数组呢？还是一个大小为0的！

从源码角度来看，这个参数是选参，可传可不传；

PathUtils类的源码：

public static Path get(final String first, final String... more) {        return PathUtils.DEFAULT.getPath(first, more);    }

而其中getPath又是jdk里的方法：

// 类 FileSystem public abstract Path getPath(String first, String... more);

在往下就是java底层如何去获取文件的路径啦！我就不分析啦！

那它需要这目录干什么呢？

转载地址：http://xdfh.baihongyu.com/