MR整合MongoDB

深藏阁楼爱情的钟 2024-04-18 11:41 56阅读 0赞

**注意重写连接方式**  
本文引用的是MongoDB-2.9.2的依赖，3.0以后连接数据库的方式不一样了，注意更改，或者导入2.9.2的包也行

##### 1. 导入依赖pom.xml #####

<dependency>
                <groupId>org.mongodb</groupId>
                <artifactId>mongo-java-driver</artifactId>
                <version>2.9.2</version>
            </dependency>

**数据：**

db.students.insert({name:"bingbing",age:16,sex:"F"})
    db.students.insert({name:"zhiyin",sex:"M"})
    db.students.insert({name:"kaige",age:16})
    db.students.insert({name:"yejie",age:16,sex:"F"})
    db.students.insert({name:"boduo",age:18})
    db.students.insert({name:"cunshang",age:15,sex:"F"})
    db.students.insert({name:"dubian",age:18,sex:"F"})

**结果：**

{"age":15,"coount":1}
    {"age":16,"coount":3}
    {"age":18,"coount":2}

**思路：**

MongoDBInputFormat: 继承InputFormat，并实现两个核心方法：getSplits() 和 createRecordReader()
    MongoDBOutputFormat:继承outputFormat，并实现三个核心方法：getRecordWriter()、checkOutputSpecs()、getOutputCommitter()
    MongoDBWritable : Write(dbCollections db)   readFields(dbObject d)

**自定义MongoInputFormat**

package MongoDBMR;
    
    import java.io.DataInput;
    import java.io.DataOutput;
    import java.io.IOException;
    import java.util.ArrayList;
    import java.util.List;
    
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.io.LongWritable;
    import org.apache.hadoop.io.Writable;
    import org.apache.hadoop.mapreduce.InputFormat;
    import org.apache.hadoop.mapreduce.InputSplit;
    import org.apache.hadoop.mapreduce.JobContext;
    import org.apache.hadoop.mapreduce.RecordReader;
    import org.apache.hadoop.mapreduce.TaskAttemptContext;
    import org.apache.hadoop.util.ReflectionUtils;
    
    import com.mongodb.DB;
    import com.mongodb.DBAddress;
    import com.mongodb.DBCollection;
    import com.mongodb.DBCursor;
    import com.mongodb.DBObject;
    import com.mongodb.Mongo;
    
    /**
     * 自定义mongodb的输入格式化器
     * @author gpy
     *
     */
    
    public class MongoDBInputFormat<V extends MongoDBWritable> extends InputFormat<LongWritable, V>{
        
    
    	
    	/**
    	 * 自定义输入数据分片信息类
    	 * @author gpy
    	 *
    	 */
    	public static class MongoDBInputSplit extends InputSplit implements Writable{
        
    
    		private long start = 0; //分片的起始位置
    		private long end = 0; //分片的结束位置
    		
    		public MongoDBInputSplit(){
        
    			
    		}
    		
    		public MongoDBInputSplit(long start, long end) {
        
    			super();
    			this.start = start;
    			this.end = end;
    		}
    
    		public void write(DataOutput out) throws IOException {
        
    			out.writeLong(start);
    			out.writeLong(end);
    		}
    
    		public void readFields(DataInput in) throws IOException {
        
    			this.start = in.readLong();
    			this.end = in.readLong();
    		}
    
    		@Override
    		public long getLength() throws IOException, InterruptedException {
        
    			return end - start;
    		}
    
    		@Override
    		public String[] getLocations() throws IOException, InterruptedException {
        
    			return new String[0];
    			//return new String[] {};
    		}
    	}
    	
    	/**
    	 * 获取分片(将mongodb里面的数据取出来进行分片)
    	 */
    	@Override
    	public List<InputSplit> getSplits(JobContext context) throws IOException,
    			InterruptedException {
        
    		//获取mongodb的连接
    		DB db =  Mongo.connect(new DBAddress("192.168.159.100", "hadoop"));
    		//获取集合
    		DBCollection dbCollection = db.getCollection("students");
    		//定义分片大小，多少条数据一个分片
    		long chunk = 2;
    		//获取mongdb的collection的总的记录数
    		long count = dbCollection.count();
    		//计算分片有多少个
    		long chunksize = (count / chunk);
    		
    		//定义一个集合存储分片
    		List<InputSplit> li = new ArrayList<InputSplit>();
    		
    		//循环分片，注意不能刚好分片
    		for (int i = 0; i < chunksize; i++) {
        
    			/*
    			 * 1-2
    			 * 3-4
    			 * 5-6
    			 */
    			MongoDBInputSplit is = null;
    			if(i+1 == chunksize){
        
    				is = new MongoDBInputSplit(i*chunk, count); //
    				li.add(is);
    			} else {
        
    				is = new MongoDBInputSplit(i*chunk, i*chunk + chunk);
    				li.add(is);
    			}
    		}
    		return li;
    	}
    
    	/**
    	 * 自定义一个Null类型
    	 * @author gpy
    	 *
    	 */
    	public static class NULLMongoDBWritable implements MongoDBWritable{
        
    
    		public void write(DataOutput out) throws IOException {
        
    		}
    
    		public void readFields(DataInput in) throws IOException {
        
    		}
    
    		public void write(DBCollection dbCollection) {
        
    		}
    
    		public void readFields(DBObject dbObject) {
        
    		}
    	}
    	
    	/**
    	 * 自定义分片记录器
    	 * @author gpy
    	 *
    	 * @param <V>
    	 */
    	public static class MongoDBRecordReader<V extends MongoDBWritable> extends RecordReader<LongWritable, V>{
        
    		//分片信息
    		private MongoDBInputSplit split;
    		//结果集(游标)
    		private DBCursor dbcursor;
    		//定义索引
    		private int index;
    		private LongWritable key;
    		private V value;
    		
    		public MongoDBRecordReader(){
        
    			
    		}
    		
    		/**
    		 * 
    		 * @param split
    		 * @param context
    		 * @throws InterruptedException 
    		 * @throws IOException 
    		 */
    		public MongoDBRecordReader(InputSplit split,TaskAttemptContext context) throws IOException, InterruptedException{
        
    			super();
    			initialize(split,context);
    		}
    		
    
    		public MongoDBRecordReader(MongoDBInputSplit split, DBCursor dbcursor,
    				int index, LongWritable key, V value) {
        
    			super();
    			this.split = split;
    			this.dbcursor = dbcursor;
    			this.index = index;
    			this.key = key;
    			this.value = value;
    		}
    
    		/**
    		 * 初始化
    		 */
    		@Override
    		public void initialize(InputSplit split, TaskAttemptContext context)
    				throws IOException, InterruptedException {
        
    			//初始化分片
    			this.split = (MongoDBInputSplit) split;
    			//初始化key
    			key =  new LongWritable();
    			//初始化类
    			Configuration conf = context.getConfiguration();
    			Class classz = conf.getClass("mapred.mongo.split.value.class", NULLMongoDBWritable.class);
    			//初始化value值
    			value = (V) ReflectionUtils.newInstance(classz, conf);
    		}
    
    		/**
    		 * 获取下一个keyvalue值
    		 */
    		@Override
    		public boolean nextKeyValue() throws IOException, InterruptedException {
        
    			//判断dbcursor是否为null
    			if(this.dbcursor == null){
        
    				//获取dbcursor的值
    				DB db = Mongo.connect(new DBAddress("192.168.159.100", "hadoop"));
    				//获取集合
    				DBCollection dbCollection = db.getCollection("students");
    				//获取游标
    				dbcursor = dbCollection.find().skip((int)this.split.start).limit((int)this.split.getLength());
    			}
    			//操作游标
    			boolean hasNext = this.dbcursor.hasNext();
    			if(hasNext){
        
    				//获取游标的下一个值
    				DBObject dbObject = this.dbcursor.next();
    				//下一个的key
    				this.key.set(this.split.start+index);
    				index ++;
    				//下一个value
    				this.value.readFields(dbObject);
    			}
    			return hasNext;
    		}
    
    		@Override
    		public LongWritable getCurrentKey() throws IOException,
    				InterruptedException {
        
    			return this.key;
    		}
    
    		@Override
    		public V getCurrentValue() throws IOException, InterruptedException {
        
    			return this.value;
    		}
    
    		/**
    		 * 创建记录的进度
    		 */
    		@Override
    		public float getProgress() throws IOException, InterruptedException {
        
    			return 0;
    		}
    
    		/**
    		 *关闭之前开启的对象 
    		 */
    		@Override
    		public void close() throws IOException {
        
    			dbcursor.close();
    		}
    	}
    	
    	
    	@Override
    	public RecordReader<LongWritable, V> createRecordReader(InputSplit split,
    			TaskAttemptContext context) throws IOException,
    			InterruptedException {
        
    		/**
    		 * 创建输入记录器
    		 */
    		return new MongoDBRecordReader<>(split,context);
    	}
    	
    }

**自定义OutPutFormat**

package MongoDBMR;
    
    import java.io.IOException;
    import java.net.UnknownHostException;
    
    import org.apache.hadoop.io.NullWritable;
    import org.apache.hadoop.mapreduce.JobContext;
    import org.apache.hadoop.mapreduce.OutputCommitter;
    import org.apache.hadoop.mapreduce.OutputFormat;
    import org.apache.hadoop.mapreduce.RecordWriter;
    import org.apache.hadoop.mapreduce.TaskAttemptContext;
    import org.apache.hadoop.mapreduce.lib.output.FileOutputCommitter;
    import com.mongodb.DB;
    import com.mongodb.DBAddress;
    import com.mongodb.DBCollection;
    import com.mongodb.Mongo;
    
    /**
     * 自定义输出格式化器
     * @author gpy
     *
     */
    public class MongoDBOutPutFormat<V extends MongoDBWritable> extends OutputFormat<NullWritable, V>{
        
    
    	/**
    	 * 
    	 * @author gpy
    	 *
    	 * @param <V>
    	 */
    	public static class MongoDBRecordWriter<V extends MongoDBWritable> extends RecordWriter<NullWritable, V>{
        
    		public DBCollection dbCollection = null;
    		
    		public MongoDBRecordWriter() {
        
    		}
    		
    		public MongoDBRecordWriter(TaskAttemptContext context){
        
    			try {
        
    				//获取mongodb的连接
    				DB db = Mongo.connect(new DBAddress("192.168.159.100", "hadoop"));
    				dbCollection = db.getCollection("result");
    			} catch (UnknownHostException e) {
        
    				e.printStackTrace();
    			}
    		}
    		
    		@Override
    		public void write(NullWritable key, V value) throws IOException,
    				InterruptedException {
        
    			/**
    			 * 使用value 的write。本质是使用MongoDBWritable的write()
    			 */
    			value.write(this.dbCollection);
    		}
    
    		@Override
    		public void close(TaskAttemptContext context) throws IOException,
    				InterruptedException {
        
    			//do nothing
    		}
    		
    	}
    	
    	
    	@Override
    	public RecordWriter<NullWritable, V> getRecordWriter(
    			TaskAttemptContext context) throws IOException,
    			InterruptedException {
        
    		//使用泛型为空的时候需要使用 jdk 1.7
    		return new MongoDBRecordWriter<>(context);
    	}
    
    	@Override
    	public void checkOutputSpecs(JobContext context) throws IOException,
    			InterruptedException {
        
    		//do nothing
    	}
    
    	/**
    	 * 输出对象的提交
    	 */
    	@Override
    	public OutputCommitter getOutputCommitter(TaskAttemptContext context)
    			throws IOException, InterruptedException {
        
    		/**
    		 * 没有输出文件路径   ，为null则可以
    		 */
    		return new FileOutputCommitter(null, context);
    	}
    }

**自定义MongoDBWritable接口**

package MongoDBMR;
    
    import org.apache.hadoop.io.Writable;
    
    import com.mongodb.DBCollection;
    import com.mongodb.DBObject;
    
    /**
     * 自定义数据类型的方法
     * @author gpy
     *
     */
    public interface MongoDBWritable extends Writable {
        
    	 /**
    	  * 向mongodb写数据的对象
    	   */
    		public void write(DBCollection dbCollection);
    		
    		/**
    		 * 读mongodb表里面的数据对象
    		 */
    		public void readFields(DBObject dbObject); 
    }

**自定义数据类型**

package MongoDBMR;
    
    import java.io.DataInput;
    import java.io.DataOutput;
    import java.io.IOException;
    import com.mongodb.BasicDBObjectBuilder;
    import com.mongodb.DBCollection;
    import com.mongodb.DBObject;
    
    /**
     * 自定义数据类型
     * @author gpy
     *
     */
    public class PersonsMongoDBWritable implements MongoDBWritable{
        
    
    	public String name;
    	public Integer age;
    	public String sex;
    	public Integer counter = 1;
    	
    
    	/**
    	 * 注意处理空的值
    	 */
    	public void write(DataOutput out) throws IOException {
        
    		out.writeUTF(name);
    		if(age == null || sex == null){
        
    			out.writeBoolean(false);
    		} else {
        
    			out.writeBoolean(true);
    			out.writeInt(age);
    			out.writeUTF(sex);
    		}
    		out.writeInt(counter);
    	}
    
    	public void readFields(DataInput in) throws IOException {
        
    		this.name = in.readUTF();
    		if(in.readBoolean()){
        
    			this.sex = in.readUTF();
    			this.age = in.readInt();
    		} else {
        
    			this.sex = null;
    			this.age = null;
    		}
    		this.counter = in.readInt();
    				
    	}
    
    	/**
    	 * 写数据
    	 */
    	public void write(DBCollection dbCollection) {
        
    		DBObject dbObject = BasicDBObjectBuilder.start().add("age", this.age).add("counter",this.counter).get();
    		//将dbobject插入
    		dbCollection.insert(dbObject);
    	}
    
    	/**
    	 * 读数据
    	 */
    	public void readFields(DBObject dbObject) {
        
    		this.name = dbObject.get("name").toString();
    		if(dbObject.get("age") != null){
        
    			this.age = Double.valueOf(dbObject.get("age").toString()).intValue();
    		} else {
        
    			this.age = null;
    		}
    	}
    	
    	/**
    	 * @return the name
    	 */
    	public String getName() {
        
    		return name;
    	}
    
    	/**
    	 * @param name the name to set
    	 */
    	public void setName(String name) {
        
    		this.name = name;
    	}
    
    	/**
    	 * @return the age
    	 */
    	public Integer getAge() {
        
    		return age;
    	}
    
    	/**
    	 * @param age the age to set
    	 */
    	public void setAge(Integer age) {
        
    		this.age = age;
    	}
    
    	/**
    	 * @return the sex
    	 */
    	public String getSex() {
        
    		return sex;
    	}
    
    	/**
    	 * @param sex the sex to set
    	 */
    	public void setSex(String sex) {
        
    		this.sex = sex;
    	}
    
    	/**
    	 * @return the counter
    	 */
    	public Integer getCounter() {
        
    		return counter;
    	}
    
    	/**
    	 * @param counter the counter to set
    	 */
    	public void setCounter(Integer counter) {
        
    		this.counter = counter;
    	}
    
    }