java - 测试hadoop map程序报错的MRUnit测试

Question

我正在尝试使用 MRUnit 对 Mapper 程序进行单元测试(来自 Hadoop:权威指南，第 153 页，部分:使用 MRUnit 编写单元测试:Mapper)。我正在使用 intellij Idea，它显示方法错误

new org.apache.hadoop.mrunit.MapDriver<>().withMapper(myMapper)

错误消息说，MapDriver中的withMapper(org.apache.hadoop.mapreduce.Mapper)不能应用于(complexmapreduce.MaxTempMapper)

MaxTempMapper 声明为 org.apache.hadoop.mapreduce.Mapper 的子类，所以我不太确定这里出了什么问题。

这是完整的映射器和单元测试类

最大温度映射器

package complexmapreduce;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import java.io.IOException;

public class MaxTempMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
    private static final int MISSING = 9999;
    private NDCRecordParser myParser = new NDCRecordParser();

    @Override
    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

        myParser.parse(value);
        if (myParser.isValidTemperature()) {
            context.write(new Text(myParser.getYear()), new IntWritable(myParser.getMaxTemperature()));
        }
    }
}

最大温度单元测试

    package complexmapreduce;
    import org.apache.hadoop.io.IntWritable;
    import org.apache.hadoop.io.LongWritable;
    import org.apache.hadoop.io.Text;
    import org.junit.Test;
    import java.io.IOException;

    public class MaxTempSingleLineUnitTest {

        @Test
        public void testMaxTempMapper() throws IOException {
            Text value = new Text("0029029070999991901010106004+64333+023450FM-12+000599999V0202701N015919999999N0000001N9-00781+99999102001ADDGF108991999999999999999999");
            LongWritable key = new LongWritable(0);
            MaxTempMapper myMapper = new MaxTempMapper();
            new org.apache.hadoop.mrunit.mapreduce.MapDriver<>()
                    .withMapper(myMapper)     // <<<===Error here
                    .withInput(key, value)
                    .withOutput(new Text("1901"), 
                     new IntWritable(0210))
                    .runTest();
        }
    }

注意:已经尝试过解决方案here , 但没有运气。

这是Intellij的截图

Screenshot

Answer 1

你需要改变:

new org.apache.hadoop.mrunit.mapreduce.MapDriver<>()

到

new org.apache.hadoop.mrunit.mapreduce.MapDriver<LongWritable, Text, Text, IntWritable>()

您需要添加通用类型，以便它知道如何运行映射器。