需求：
小明 老王 如花 林志玲
老王 小明 凤姐
如花 小明 李刚 凤姐
林志玲 小明 李刚 凤姐 郭美美
李刚 如花 凤姐 林志玲
郭美美 凤姐 林志玲
凤姐 如花 老王 林志玲 郭美美
Step 1：
User.java
private String user;
private String other;
private int count;public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
public String getOther() {
return other;
}
public void setOther(String other) {
this.other = other;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}public void write(DataOutput out) throws IOException {
out.writeUTF(user);
out.writeUTF(other);
out.writeInt(count);
}
public void readFields(DataInput in) throws IOException {
this.user=in.readUTF();
this.other=in.readUTF();
this.count=in.readInt();
}
public int compareTo(User o) {
return this == o ?0:-1;
}Step 2：
Fof.java
public Fof (){
}
public Fof(String a,String b){
super(join(a, b));
}
/**
* zs,ls --> zs \t ls
* ls,zs --> zs \t ls
* @param a
* @param b
* @return
*/
public static String join(String a,String b){
if(StringUtils.isNotBlank(a)&& StringUtils.isNotBlank(b)){
if(a.compareTo(b)<0){
return a+"\t"+b;
}else{
return b+"\t"+a;
}
}
return null;
}Step 3：
RunJob.java
Mapper——1：
static class Mapper1 extends Mapper<Text, Text, Fof, IntWritable> {
protected void map(Text key, Text value, Context context)
throws IOException, InterruptedException {
String user = key.toString();
String[] friends = StringUtils.split(value.toString(), '\t');
for (int i = 0; i < friends.length; i++) {
String f1 = friends[i];
context.write(new Fof(user, f1), new IntWritable(2));
for (int j = i + 1; j < friends.length; j++) {
String f2 = friends[j];
Fof fof = new Fof(f1, f2);
context.write(fof, new IntWritable(1));
}
}
}
}Reducer——1：
static class Reducer1 extends Reducer<Fof, IntWritable, Fof, IntWritable> {
protected void reduce(Fof arg0, Iterable<IntWritable> arg1, Context arg2)
throws IOException, InterruptedException {
int sum = 0;
boolean f = true;
for (IntWritable t : arg1) {
if (t.get() == 2) {// 可以判断出该组中的fof就是直接好友
f = false;
break;
} else {
sum = sum + t.get();
}
}
if (f) {
arg2.write(arg0, new IntWritable(sum));
}
}
}Mapper——2：
static class Mapper2 extends Mapper<Text, Text, User, Text> {
protected void map(Text key, Text value, Context context)
throws IOException, InterruptedException {
String user =key.toString();
String other =value.toString().split("\t")[0];
int count =Integer.parseInt(value.toString().split("\t")[1]);
User u1 =new User();
u1.setUser(user);
u1.setOther(other);
u1.setCount(count);
User u2 =new User();
u2.setUser(other);
u2.setOther(user);
u2.setCount(count);
context.write(u1, new Text(other+":"+count));
context.write(u2, new Text(user+":"+count));
}
}FriendsSort ：
static class FriendsSort extends WritableComparator{
public FriendsSort() {
super(User.class,true);
}
public int compare(WritableComparable a, WritableComparable b) {
User u1=(User) a;
User u2=(User) b;
int r =u1.getUser().compareTo(u2.getUser());
if(r==0){
return -Integer.compare(u1.getCount(), u2.getCount());
}
return r;
}
}FriendsGroup：
static class FriendsGroup extends WritableComparator{
public FriendsGroup() {
super(User.class,true);
}
public int compare(WritableComparable a, WritableComparable b) {
User u1=(User) a;
User u2=(User) b;
return u1.getUser().compareTo(u2.getUser());
}
}Reducer——2：
static class Reducer2 extends Reducer<User, Text, Text, Text> {
protected void reduce(User arg0, Iterable<Text> arg1, Context arg2)
throws IOException, InterruptedException {
StringBuilder sb =new StringBuilder();
// sb.append(arg0.getUser()+"\t");
for(Text t: arg1){
sb.append(t.toString()+",");
}
arg2.write(new Text(arg0.getUser()), new Text(sb.toString()));
}
}Main：
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://node12:8020");
// conf.set("mapred.jar", "C:\\Users\\Administrator\\Desktop\\wc.jar");
//hdfs dfs -chmod 777 /usr/output/ 增加权限
try {
FileSystem fs = FileSystem.get(conf);
Job job = Job.getInstance(conf, "weather");
job.setJarByClass(RunJob.class);
job.setMapperClass(Mapper1.class);
job.setReducerClass(Reducer1.class);
job.setMapOutputKeyClass(Fof.class);
job.setMapOutputValueClass(IntWritable.class);
// 以第一个隔开符（\t）隔开一行数据，左侧为key，右侧为value
job.setInputFormatClass(KeyValueTextInputFormat.class);
FileInputFormat.addInputPath(job, new Path("/usr/input/friend"));
Path output = new Path("/usr/output/friend");
if (fs.exists(output)) {
fs.delete(output, true);
}
FileOutputFormat.setOutputPath(job, output);
boolean f = job.waitForCompletion(true);
if (f) {
System.out.println("第一个 mr —job 执行成功");
System.out.println("开始执行第二个mapreduce");
job =Job.getInstance(conf, "friend");
job.setJarByClass(RunJob.class);
job.setMapperClass(Mapper2.class);
job.setReducerClass(Reducer2.class);
job.setMapOutputKeyClass(User.class);
job.setMapOutputValueClass(Text.class);
job.setSortComparatorClass(FriendsSort.class);
job.setGroupingComparatorClass(FriendsGroup.class);
// 以第一个隔开符（\t）隔开一行数据，左侧为key，右侧为value
job.setInputFormatClass(KeyValueTextInputFormat.class);
FileInputFormat.addInputPath(job, new Path("/usr/output/friend"));
output = new Path("/usr/output/friend2");
if (fs.exists(output)) {
fs.delete(output, true);
}
FileOutputFormat.setOutputPath(job, output);
f = job.waitForCompletion(true);
if(f){
System.out.println("第二个mr执行成功！");
}
}
} catch (Exception e) {
e.printStackTrace();
}
}