通过参数在Hadoop中初始化公共静态变量

Question

我在Hadoop中更改公共静态变量时遇到问题。 我想从命令行将一些值作为参数传递给jar文件。

这里是我的代码：

public class MyClass { 
    public static long myvariable1 = 100; 
    public static class Map extends Mapper<Object, Text, Text, Text> { 
    public static long myvariabl2 = 200; 
    public void map(Object key, Text value, Context context) throws IOException, InterruptedException { 

    } 
    } 
    public static class Reduce extends Reducer<Text, Text, Text, Text> { 
    public void reduce(Text key, Iterable<Text> values, Context context) 
    throws IOException, InterruptedException { 

    } 
    } 
    public static void main(String[] args) throws Exception { 
    col_no = Long.parseLong(args[0]); 
    Map.myvariable1 = Long.parseLong(args[1]); 
    Map.myvariable2 = Long.parseLong(args[1]); 
    other stuff here 
    } 
} 

但它不工作，myvariable1 & myvaribale2总是有100 我用的Hadoop 0.20.203与Ubuntu 10.04

Answer 1

你可以做什么获得相同的行为是将变量存储在用于启动作业的配置中。

public static class Map extends Mapper<Object, Text, Text, Text> { 
    public void map(Object key, Text value, Context context) throws IOException, InterruptedException { 

    Configuration conf = context.getConfiguration(); 
    String var2String = conf.get("myvariable2"); 
    long myvariable2 = Long.parseLong(var2String); 
    //etc. 
    } 
} 

public static void main(String[] args) throws Exception { 
    col_no = Long.parseLong(args[0]); 
    String myvariable1 = args[1]; 
    String myvariable2 = args[1]; 

    // add values to configuration 
    Configuration conf = new Configuration(); 
    conf.set("myvariable1", myvariable1); 
    conf.set("myvariable2", myvariable2); 

    //other stuff here 
}