java - 使用 java 代码读取存储在 hdfs 中的 .properties 文件

Question

我需要阅读 hdfs 中可用的 .properties 文件。我正在使用下面的代码，但它会引发运行时错误。

FileSystem fs = FileSystem.get(config);

    Properties conf = wc.createConfiguration();
    Properties prop = new Properties();
    String appPath = "hdfs://clusterdb05.com:8020/user/cmahajan/" + version + "/apps/apps/";
    conf.setProperty(OozieClient.APP_PATH,appPath);
    FileInputStream f = new FileInputStream("hdfs://clusterdb05.com:8020/user/cmahajan/app.properties");
    ObjectInputStream f = new ObjectInputStream(fs.open(new Path("/user/cmahajan/app.properties")));

运行时错误是：

LaunchJob.java:28: cannot find symbol

symbol  : class ObjectInputStream
location: class LaunchJob
    ObjectInputStream f = new ObjectInputStream(fs.open(new Path("/user/cmahajan/app.properties")));
    ^
LaunchJob.java:28: cannot find symbol
symbol  : class ObjectInputStream
location: class LaunchJob
    ObjectInputStream f = new ObjectInputStream(fs.open(new Path("/user/cmahajan/app.properties")));

Answer 1

从 hdfs 加载属性文件：

1. 确保你的 core-site.xml，hdfs-site xml文件路径
2. hdfs 端口号（它将在core-site.xml中可用）

3. 替换getProperty中的键。

          String CURRENCIES_DIM1 = null;
          String DATES_DIM2 = null; 
          Configuration conf = new Configuration();
           conf.addResource(new Path("/usr/local/hadoop/etc/hadoop/core-site.xml"));
           conf.addResource(new Path("/usr/local/hadoop/etc/hadoop/hdfs-site.xml"));
           String filePath = "hdfs://localhost:54310/user/CurrencyCache.properties";
           Path path = new Path(filePath);
           FileSystem fs = path.getFileSystem(conf);
           try (FSDataInputStream currencyInputStream = fs.open(path)) {
               Properties currencyProp = new Properties();
               currencyProp.load(currencyInputStream);
               CURRENCIES_DIM1= currencyProp.getProperty("key");//getting the 'CURRENCIES_DIM' file path from properties file
               DATES_DIM2= currencyProp.getProperty("key");            //getting the 'DATES_DIM' file path from properties file
   
           } catch (IOException e) {
   
               e.printStackTrace();
           }
           fs.close();
   

Answer 2

使用类的完全限定名称：

java.io.ObjectInputStream 

或者

使用以下行导入类：

import java.io.ObjectInputStream;