Hadoop基础教程之重新认识Hadoop

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alert("I‘d like some Spaghetti!");

alert("I‘d like some ChocolateMousse!");

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function SwedishChef(food)

{

alert("I‘d like some " + food + " !");

}

SwedishChef("Spaghetti");

SwedishChef("Chocolate Mousse");

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alert("get the lobster");

PutInPot("lobster");

PutInPot("water");

alert("get the chicken");

BoomBoom("chicken");

BoomBoom("coconut");

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function Cook(i1,i2,f)

{

alert("get the " + i1);

f(i1);

f(i2);

}

Cook("lobster","water",PutInPot);

Cook("chicken","coconut",BoomBoom);

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Cook("lobster","water",

Function(x) { alert("pot " + x); } );

Cook("chicken","coconut",

Function(x) { alert("boom" + x); } );

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var a=[1,2,3];

for(i = 0; I < a.length; i++)

{

a[i] = a[i] * 2;

}

for(i = 0; I < a.length; i++)

{

alert(a[i]);

}

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function map(fn,a)

{

for(i = 0; i < a.length; i++)

{

a[i] = fn(a[i]);

}

}

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map(function (x) {return x*2; } , a);

map(alert, a);

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function sum(a)

{

var s = 0;

for( i = 0; i < a.length ;i ++)

s += a[i];

return s;

}

function join(a)

{

var s = "";

for( i = 0; i < a.length ;i ++)

s += a[i];

return s;

}

alert(sum([1,2,3]);

alert(join(["a","b","c"]);

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function reduce(fn, a, init)

{

var s = init;

for (i= 0;i < a.length; i++)

s = fn(s, a[i]);

return s;

}

function sum(a)

{

return reduce( function(a,b){return a+b;}, a, 0);

}

Function join(a)

{

return reduce( function(a,b){return a+b;}, a, "");

}

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public static class TokenizerMapper

extends Mapper<Object, Text, Text, IntWritable>{

private final static IntWritable one = new IntWritable(1);

private Text word = new Text();

public void map(Object key, Text value, Context context

) throws IOException, InterruptedException {

System.out.println("key=" +key.toString());

System.out.println("Value=" + value.toString());

StringTokenizer itr = new StringTokenizer(value.toString());

while (itr.hasMoreTokens()) {

word.set(itr.nextToken());

context.write(word, one);

}

}

}

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public static class IntSumReducer

extends Reducer<Text,IntWritable,Text,IntWritable> {

private IntWritable result = new IntWritable();

public void reduce(Text key, Iterable<IntWritable> values,

Context context

) throws IOException, InterruptedException {

int sum = 0;

for (IntWritable val : values) {

sum += val.get();

}

result.set(sum);

context.write(key, result);

}}

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public static void main(String[] args) throws Exception {

Configuration conf = new Configuration();

System.out.println("url:" + conf.get("fs.default.name"));

String[] otherArgs = new GenericOptionsParser(conf, args).getRemainingArgs();

if (otherArgs.length != 2) {

System.err.println("Usage: wordcount <in> <out>");

System.exit(2);

}

Job job = new Job(conf, "word count");

job.setJarByClass(WordCount.class);

job.setMapperClass(TokenizerMapper.class);

job.setCombinerClass(IntSumReducer.class);

job.setReducerClass(IntSumReducer.class);

job.setOutputKeyClass(Text.class);

job.setOutputValueClass(IntWritable.class);

FileInputFormat.addInputPath(job, new Path(otherArgs[0]));

FileOutputFormat.setOutputPath(job, new Path(otherArgs[1]));

System.exit(job.waitForCompletion(true) ? 0 : 1);

}