傳遞變量「ARGS」到地圖類

Question

爲例：罐子類ARG1參數3

輸入格式ARG 1，ARG 2爲輸出格式是這樣的：

public static void main(String[] args) 
{ 
FileInputFormat.addInputPath(conf, new Path(args[0])); 
FileOutputFormat.setOutputPath(conf, new Path(args[1])); 
. 
. 
. 
. 
} 

我需要發送ARG3「ARGS [2]」映射類.....

public class JoinMultiMap extends MapReduceBase 
    implements Mapper<LongWritable, Text, Text, Text> 
{ 
i need arg3 her 
} 

Answer 1

您可以使用Configuration類這樣的設置和獲取自定義配置屬性：

在驅動程序代碼：

import org.apache.hadoop.conf.Configuration; 
// other imports ignored for brevity 
// ... 

public class YourDriver extends Configured implements Tool { 
    public int run(String[] args) { 
    Configuration conf = getConf(); 
    conf.set("yourcustom.property", args[2]); 
    // other driver code ignored 
    // ... 
    } 

    public static void main(String[] args) { 
    int res = ToolRunner.run(new Configuration(), new YourDriver(), args); 
    System.exit(res); 
    } 
} 

從映射代碼：

public class YourMapper extends Mapper<...> { 
    private String yourArgument; 

    @Override 
    protected void setup(Context context) { 
     Configuration c = context.getConfiguration(); 
     yourArgument = c.get("yourcustom.property"); 
    } 

    @Override 
    protected void map(...) { 
    // use your argument 
    } 
}