目前,我正在努力将普通的Java代码转换为Hadoop
MapReduce
结构。
我想像下面这样修改类Graph
,我仍然不知道如何序列化和反序列化HashMap
和float[]
类型。代码部分如下。
法典:
public class Graph implements WritableComparable, Cloneable {
private static long serialVersionUID = 3L;
public static int MAX_FREQUENCY = 3;
public static float[] freqWeight = { 1.0F, 1.6F, 2.0F };
int nNodes;
int nEdges;
String strName;
HashMap<String, Node> nodes;
boolean isMCS;
String taxonomyName;
@Override
public void write(DataOutput out) throws IOException {
// TODO Auto-generated method stub
out.writeBoolean(isMCS);
out.writeInt(nEdges);
out.writeInt(nNodes);
out.writeLong(serialVersionUID);
out.writeInt(MAX_FREQUENCY);
out.writeBytes(strName);
out.writeBytes(taxonomyName);
//ArrayWritable a=new ArrayWritable(FloatWritable.class);
//HashMap
//float[]
}
@Override
public void readFields(DataInput in) throws IOException {
// TODO Auto-generated method stub
isMCS=in.readBoolean();
nEdges=in.readInt();
nNodes=in.readInt();
serialVersionUID=in.readLong();
MAX_FREQUENCY=in.readInt();
strName=in.readLine();
taxonomyName=in.readLine();
//HashMap
//float[]
}
@Override
public int compareTo(Graph graph) {
// TODO Auto-generated method stub
return 0;
}
.........
使用 ArrayPrimitiveWritable:
// float[] floats
new ArrayPrimitiveWritable(floats).write(out);
ArrayPrimitiveWritable apw = (float[]) new ArrayPrimitiveWritable().readFields(in);
float[] floats = (float[]) apw.get();
对地图使用 MapWwriteable。 MapWritable基本上是一个键和值类型都是可写的映射。 与 ArrayPrimiveWriatable 一样,MapWritable 实现了用于序列化的 readFiles() 和 write() 方法。