Java tutorial
/* * Copyright 2010-2013 10gen Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.zjy.mongo.io; import com.mongodb.BasicDBObject; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.io.AbstractMapWritable; import org.apache.hadoop.io.ArrayWritable; import org.apache.hadoop.io.BooleanWritable; import org.apache.hadoop.io.ByteWritable; import org.apache.hadoop.io.BytesWritable; import org.apache.hadoop.io.DataInputBuffer; import org.apache.hadoop.io.DataOutputBuffer; import org.apache.hadoop.io.DoubleWritable; import org.apache.hadoop.io.FloatWritable; import org.apache.hadoop.io.IntWritable; import org.apache.hadoop.io.LongWritable; import org.apache.hadoop.io.NullWritable; import org.apache.hadoop.io.Text; import org.apache.hadoop.io.Writable; import org.apache.hadoop.io.WritableComparable; import org.apache.hadoop.io.WritableComparator; import org.bson.BSONCallback; import org.bson.BSONDecoder; import org.bson.BSONEncoder; import org.bson.BSONObject; import org.bson.BasicBSONCallback; import org.bson.BasicBSONDecoder; import org.bson.BasicBSONEncoder; import org.bson.BasicBSONObject; import org.bson.io.BasicOutputBuffer; import org.bson.io.Bits; import java.io.DataInput; import java.io.DataOutput; import java.io.IOException; import java.util.Map; @SuppressWarnings("deprecation") public class BSONWritable implements WritableComparable { private static final byte[] HEX_CHAR = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; private static final Log LOG = LogFactory.getLog(BSONWritable.class); static { WritableComparator.define(BSONWritable.class, new BSONWritableComparator()); } private BSONObject doc; public BSONWritable() { doc = new BasicBSONObject(); } public BSONWritable(final BSONObject doc) { this(); setDoc(doc); } public void setDoc(final BSONObject doc) { this.doc = doc; } public BSONObject getDoc() { return doc; } /** * {@inheritDoc} * * @see Writable#write(DataOutput) */ public void write(final DataOutput out) throws IOException { BSONEncoder enc = new BasicBSONEncoder(); BasicOutputBuffer buf = new BasicOutputBuffer(); enc.set(buf); enc.putObject(doc); enc.done(); buf.pipe(new DataOutputOutputStreamAdapter(out)); } /** * {@inheritDoc} * * @see Writable#readFields(DataInput) */ public void readFields(final DataInput in) throws IOException { BSONDecoder dec = new BasicBSONDecoder(); BSONCallback cb = new BasicBSONCallback(); // Read the BSON length from the start of the record byte[] l = new byte[4]; try { in.readFully(l); int dataLen = Bits.readInt(l); if (LOG.isDebugEnabled()) { LOG.debug("*** Expected DataLen: " + dataLen); } byte[] data = new byte[dataLen + 4]; System.arraycopy(l, 0, data, 0, 4); in.readFully(data, 4, dataLen - 4); dec.decode(data, cb); doc = (BSONObject) cb.get(); if (LOG.isTraceEnabled()) { LOG.trace("Decoded a BSON Object: " + doc); } } catch (Exception e) { /* If we can't read another length it's not an error, just return quietly. */ // TODO - Figure out how to gracefully mark this as an empty LOG.info("No Length Header available." + e); doc = new BasicDBObject(); } } /** * {@inheritDoc} */ @Override public String toString() { return "<BSONWritable:" + doc + ">"; } /** * Used by child copy constructors. * @param other the Writable to copy. */ protected synchronized void copy(final Writable other) { if (other != null) { try { DataOutputBuffer out = new DataOutputBuffer(); other.write(out); DataInputBuffer in = new DataInputBuffer(); in.reset(out.getData(), out.getLength()); readFields(in); } catch (IOException e) { throw new IllegalArgumentException("map cannot be copied: " + e.getMessage()); } } else { throw new IllegalArgumentException("source map cannot be null"); } } public int compareTo(final Object o) { return new BSONWritableComparator().compare(this, o); } protected static void dumpBytes(final BasicOutputBuffer buf) {// Temp debug output dumpBytes(buf.toByteArray()); } protected static void dumpBytes(final byte[] buffer) { StringBuilder sb = new StringBuilder(2 + 3 * buffer.length); for (byte b : buffer) { sb.append("0x").append((char) HEX_CHAR[(b & 0x00F0) >> 4]).append((char) HEX_CHAR[b & 0x000F]) .append(" "); } LOG.info("Byte Dump: " + sb); } /** * Unwrap a (usually Writable) Object, getting back a value suitable for * putting into a BSONObject. If the given object is not Writable, then * simply return the Object back. * * @param x the Object to turn into BSON. * @return the BSON representation of the Object. */ @SuppressWarnings("unchecked") public static Object toBSON(final Object x) { if (x == null) { return null; } if (x instanceof Text) { return x.toString(); } if (x instanceof BSONWritable) { return ((BSONWritable) x).getDoc(); } if (x instanceof Writable) { if (x instanceof AbstractMapWritable) { if (!(x instanceof Map)) { throw new IllegalArgumentException(String.format( "Cannot turn %s into BSON, since it does " + "not implement java.util.Map.", x.getClass().getName())); } Map<Writable, Writable> map = (Map<Writable, Writable>) x; BasicBSONObject bson = new BasicBSONObject(); for (Map.Entry<Writable, Writable> entry : map.entrySet()) { bson.put(entry.getKey().toString(), toBSON(entry.getValue())); } return bson; } if (x instanceof ArrayWritable) { Writable[] o = ((ArrayWritable) x).get(); Object[] a = new Object[o.length]; for (int i = 0; i < o.length; i++) { a[i] = toBSON(o[i]); } return a; } if (x instanceof NullWritable) { return null; } if (x instanceof BooleanWritable) { return ((BooleanWritable) x).get(); } if (x instanceof BytesWritable) { return ((BytesWritable) x).getBytes(); } if (x instanceof ByteWritable) { return ((ByteWritable) x).get(); } if (x instanceof DoubleWritable) { return ((DoubleWritable) x).get(); } if (x instanceof FloatWritable) { return ((FloatWritable) x).get(); } if (x instanceof LongWritable) { return ((LongWritable) x).get(); } if (x instanceof IntWritable) { return ((IntWritable) x).get(); } // TODO - Support counters } return x; } @Override public boolean equals(final Object obj) { if (obj == null || getClass() != obj.getClass()) { return false; } final BSONWritable other = (BSONWritable) obj; return !(doc != other.doc && (doc == null || !doc.equals(other.doc))); } @Override public int hashCode() { return doc != null ? doc.hashCode() : 0; } }