Java读写hdfs上的avro文件

1、通过Java往hdfs写avro文件

 1 import java.io.File;
 2 import java.io.IOException;
 3 import java.io.OutputStream;
 4 import java.nio.ByteBuffer;
 5
 6 import org.apache.avro.Schema;
 7 import org.apache.avro.file.CodecFactory;
 8 import org.apache.avro.file.DataFileWriter;
 9 import org.apache.avro.generic.GenericData;
10 import org.apache.avro.generic.GenericDatumWriter;
11 import org.apache.avro.generic.GenericRecord;
12 import org.apache.commons.io.FileUtils;
13 import org.apache.hadoop.conf.Configuration;
14 import org.apache.hadoop.fs.FileSystem;
15 import org.apache.hadoop.fs.Path;
16 import org.apache.hadoop.io.IOUtils;
17
18 public class HdfsAvroTest {
19
20     public static final String SCHEMA_JSON = "{\"type\": \"record\",\"name\": \"SmallFilesTest\", "
21             + "\"fields\": ["
22             + "{\"name\":\""
23             + "username"
24             + "\",\"type\":\"string\"},"
25             + "{\"name\":\""
26             + "password"
27             + "\", \"type\":\"string\"}]}";
28     public static final Schema SCHEMA = new Schema.Parser().parse(SCHEMA_JSON);
29
30     public static void writeToAvro(File srcPath, OutputStream outputStream)
31             throws IOException {
32         DataFileWriter<Object> writer = new DataFileWriter<Object>(
33                 new GenericDatumWriter<Object>()).setSyncInterval(100);
34         writer.setCodec(CodecFactory.snappyCodec());
35         writer.create(SCHEMA, outputStream);
36         for (Object obj : FileUtils.listFiles(srcPath, null, false)) {
37             File file = (File) obj;
38             String filename = file.getAbsolutePath();
39             byte content[] = FileUtils.readFileToByteArray(file);
40             GenericRecord record = new GenericData.Record(SCHEMA);
41             record.put("username", filename);
42             record.put("password", ByteBuffer.wrap(content));
43             writer.append(record);
44         }
45         IOUtils.cleanup(null, writer);
46         IOUtils.cleanup(null, outputStream);
47     }
48
49     public static void main(String[] args) throws Exception {
50         Configuration config = new Configuration();
51         FileSystem hdfs = FileSystem.get(config);
52         File sourceDir = new File(args[0]);
53         Path destFile = new Path(args[1]);
54         OutputStream os = hdfs.create(destFile);
55         writeToAvro(sourceDir, os);
56     }
57 }

2、Java读hdfs上的avro文件

 1 import java.io.IOException;
 2 import java.io.InputStream;
 3
 4 import org.apache.avro.file.DataFileStream;
 5 import org.apache.avro.generic.GenericDatumReader;
 6 import org.apache.avro.generic.GenericRecord;
 7 import org.apache.hadoop.conf.Configuration;
 8 import org.apache.hadoop.fs.FileSystem;
 9 import org.apache.hadoop.fs.Path;
10 import org.apache.hadoop.io.IOUtils;
11
12 public class HdfsReadAvro {
13
14
15     public static void readFromAvro(InputStream is) throws IOException {
16         DataFileStream<Object> reader = new DataFileStream<Object>(is,
17                 new GenericDatumReader<Object>());
18         for (Object o : reader) {
19             GenericRecord r = (GenericRecord) o;
20             System.out.println(r.get("username")+ ":"+r.get("password"));
21         }
22         IOUtils.cleanup(null, is);
23         IOUtils.cleanup(null, reader);
24     }
25
26     public static void main(String[] args) throws Exception {
27         Configuration config = new Configuration();
28         FileSystem hdfs = FileSystem.get(config);
29         Path destFile = new Path(args[0]);
30         InputStream is = hdfs.open(destFile);
31         readFromAvro(is);
32     }
33 }