DataInputStream数据读取 Vs ByteBuffer数据读取的巨大性能差距

背景：

今天在查找一个序列化和反序列化相关的问题时，意外发现使用DataInputStream读取和ByteBuffer读取之间性能相差巨大，本文就来记录下这两者在读取整数类型时的性能差异，以便在平时使用的过程中引起注意

DataInputStream数据读取 Vs ByteBuffer数据读取

我们会分别使用DataInputStream和ByteBuffer读取不同长度的字节数组，分别测试读取Short,Int,Long三类整数，然后分别看一下他们的性能

性能测试代码如下：

package org.example.jmh.deserialize;import static java.util.concurrent.TimeUnit.MICROSECONDS;
import static org.example.jmh.deserialize.DataUtil.createByteArray;import java.io.ByteArrayInputStream;
import java.io.DataInput;
import java.io.DataInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;@Warmup(iterations = 2, time = 2)
@Measurement(iterations = 3, time = 10)
@Fork(1)
@OutputTimeUnit(MICROSECONDS)
public class ByteBufferVsByteArrayDataInputBenchmark {@State(Scope.Benchmark)public static class ByteBufferBackedDataInputState {ByteBuffer buffer;DataInput dataInput;@Param({"8", "32", "64", "128"})int size;byte[] data;public void createData() {this.data = createByteArray(size);}@Setup(Level.Trial)public void init() {createData();this.buffer = ByteBuffer.wrap(data);this.dataInput = new BufferDataInput(buffer);}void reset() {buffer.position(0);}}@State(Scope.Benchmark)public static class StreamBackedDataInpuState {ByteArrayInputStream bis;DataInput dataInput;@Param({"8", "32", "64", "128"})int size;byte[] data;public void createData() {this.data = createByteArray(size);}@Setup(Level.Trial)public void init() {createData();this.bis = new ByteArrayInputStream(data);this.dataInput = new DataInputStream(bis);}void reset() {bis.reset();}}@Benchmarkpublic void streamBackedDataInputReadShort(StreamBackedDataInpuState state, Blackhole bh) throws IOException {DataInput input = state.dataInput;int size = state.size;int pos = 0;while (pos < size) {bh.consume(input.readShort());pos += 2;}state.reset();}@Benchmarkpublic void bufferBackedDataInputReadShort(ByteBufferBackedDataInputState state, Blackhole bh) throws IOException {DataInput input = state.dataInput;int size = state.size;int pos = 0;while (pos < size) {bh.consume(input.readShort());pos += 2;}state.reset();}@Benchmarkpublic void streamBackedDataInputReadInt(StreamBackedDataInpuState state, Blackhole bh) throws IOException {DataInput input = state.dataInput;int size = state.size;int pos = 0;while (pos < size) {bh.consume(input.readInt());pos += 4;}state.reset();}@Benchmarkpublic void bufferBackedDataInputReadInt(ByteBufferBackedDataInputState state, Blackhole bh) throws IOException {DataInput input = state.dataInput;int size = state.size;int pos = 0;while (pos < size) {bh.consume(input.readInt());pos += 4;}state.reset();}@Benchmarkpublic void streamBackedDataInputReadLong(StreamBackedDataInpuState state, Blackhole bh) throws IOException {DataInput input = state.dataInput;int size = state.size;int pos = 0;while (pos < size) {bh.consume(input.readLong());pos += 8;}state.reset();}@Benchmarkpublic void bufferBackedDataInputReadLong(ByteBufferBackedDataInputState state, Blackhole bh) throws IOException {DataInput input = state.dataInput;int size = state.size;int pos = 0;while (pos < size) {bh.consume(input.readLong());pos += 8;}state.reset();}public static class BufferDataInput implements DataInput {private final ByteBuffer data;public BufferDataInput(ByteBuffer data) {this.data = data;}@Overridepublic void readFully(byte[] bytes) {}@Overridepublic void readFully(byte[] bytes, int i, int i1) {}@Overridepublic int skipBytes(int i) {data.position(data.position() + i);return data.position();}@Overridepublic boolean readBoolean() {return data.get() != 0;}@Overridepublic byte readByte() {return data.get();}@Overridepublic int readUnsignedByte() {return data.get() & 0xFF;}@Overridepublic short readShort() {return data.getShort();}@Overridepublic int readUnsignedShort() {return data.getShort() & 0xffff;}@Overridepublic char readChar() {return data.getChar();}@Overridepublic int readInt() {return data.getInt();}@Overridepublic long readLong() {return data.getLong();}@Overridepublic float readFloat() {return data.getFloat();}@Overridepublic double readDouble() {return data.getDouble();}@Overridepublic String readLine() {return null;}@Overridepublic String readUTF() {return null;}}}

jmh的测试结果：

从结果可以看出，不论是读取Short，Int还是Long，ByteBuffer都比DataInputStream有很大的性能优势，大概3-4倍的差异，那么你知道造成这种性能差距的原因是什么吗，留个悬念