Java IO开销测试比较

修改了下代码:

<pre name="code" class="java">package ringBuffer;

import java.io.BufferedWriter;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.RandomAccessFile;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.FileChannel.MapMode;

public class PerformanceWriteTest {
	/**
	 * @param args
	 */
	public static void main(String[] args) {

		String outputFile = "F:\\test\\ioTest.txt";
		Long length = 0L ; 
		Long totalTime = 0L;
		
        try {
   	   		raf = new RandomAccessFile("F:\\test\\ioTest.txt", "rw");
   	   		FileChannel fc = raf.getChannel();
   	   		mbb = fc.map(MapMode.READ_WRITE, 0, 85*1024*1024);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		for (int j = 0; j < 5; j++) {
//			for (int j = 0; j < 5; j++) {
				StringBuffer sb = new StringBuffer();
				for (Integer i = 0; i < 1000000; i++) {
//				for (Integer i = 0; i < 100000; i++) {
					sb.append(j+i.toString() + "V");
				}
				sb.append("S");
//				byte[] msgs = sb.toString().getBytes();
				length = (long) sb.toString().length() ;
			    long start =  System.currentTimeMillis() ;
				appendFileTest(outputFile,sb.toString());
				totalTime = totalTime + (System.currentTimeMillis() - start) ;
		}
		System.out.println(" Total Data is : " + length*5/1000 + " Kbytes! ") ;
		System.out.println(" Total Time is : " + totalTime) ;
		System.out.println(" Averge Speed is :" + length*5/(totalTime*1000) + " Kbytes");
	}

	private static void appendFileTest(String outputFile, String msgs) {
//             append1(outputFile, msgs) ;  //FileOutputStream
//             append2(outputFile, msgs) ;  //FileWriter
//             append3(outputFile, msgs) ;  //RandomAccessFile 
			   append4(outputFile, msgs) ;  //RandomAccessFile 
	}

	private static void append1(String outputFile, String msgs) {
		BufferedWriter out = null;   
	    try {   
	         out = new BufferedWriter(new OutputStreamWriter(   
	                  new FileOutputStream(outputFile, true)));   
	         out.append(msgs) ;
	        } catch (Exception e) {   
	            e.printStackTrace();   
	        } finally {   
	            try {   
	                out.close();   
	            } catch (IOException e) {   
	                e.printStackTrace();   
	            }   
	        }   
	}

	private static void append2(String outputFile, String msgs) {
		try {   
            FileWriter writer = new FileWriter(outputFile, true);     // 打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件   
            writer.write(msgs);   
            writer.close();   
        } catch (IOException e) {   
            e.printStackTrace();   
        }   
	}

	private static void append3(String outputFile, String msgs) {
		  try {   
	            RandomAccessFile randomFile = new RandomAccessFile(outputFile, "rw");    // 打开一个随机访问文件流，按读写方式   
	            long fileLength = randomFile.length();    // 文件长度，字节数   
	            randomFile.seek(fileLength);    // 将写文件指针移到文件尾
	            randomFile.writeBytes(msgs);   
	            randomFile.close();   
	        } catch (IOException e) {   
	            e.printStackTrace();   
	        }   
	}
	
	private static void append4(String outputFile, String msgs) {
		  try {   
			    mbb.position(pos) ;
			    mbb.put(msgs.getBytes());
			    pos = pos + msgs.getBytes().length ;
			    raf.close();   
	        } catch (IOException e) {   
	            e.printStackTrace();   
	        }   
	}

	static RandomAccessFile raf ;
	static MappedByteBuffer mbb  ;
	static Integer pos = 0 ;
}

测试时为了增加内存开销，增加了 -XX:+PrintGC 选项，如果大家知道更好的测试内存消耗的方法，请告诉我哈。

</pre><pre code_snippet_id="600488" snippet_file_name="blog_20150208_4_5933734" name="code" class="java">[GC 32704K->2872K(124992 K), 0.0015308 secs]
[GC 35576K->5152K(157696K), 0.0018430 secs]
[GC 70560K->9768K(157696K), 0.0032342 secs]
[GC 75176K->28240K(223104K), 0.0056030 secs]
[GC 159056K->28888K(223104K), 0.0009104 secs]
[GC 159704K->37464K(353856K), 0.0033345 secs]
[GC 299096K->42152K(354048K), 0.0022436 secs]
[GC 303784K->39848K(615 744K), 0.0009303 secs]
[GC 563112K->55968K(616 192K), 0.0087540 secs]
Total Data is : 39444 Kbytes!
Total Time is : 159
Averge Speed is :248 Kbytes
2.826G

[GC 32704K->2872K(124992K), 0.0136790 secs]
[GC 35576K->5184K(157696K), 0.0019457 secs]
[GC 70592K->9792K(157696K), 0.0031822 secs]
[GC 75200K->28240K(223104K), 0.0056500 secs]
[GC 152655K->43624K(223104K), 0.0051765 secs]
[GC 174440K->52848K(353856K), 0.0034980 secs]
[GC 314480K->55276K(354176K), 0.0013858 secs]
[GC 314139K->71372K(615488K), 0.0058115 secs]
[Full GC 71372K->18926K(610816K), 0.0094205 secs]
[GC 542190K->43678K(610880K), 0.0038294 secs]
Total Data is : 39444 Kbytes!
Total Time is : 153
Averge Speed is :257 Kbytesa
3.43G

[GC 32704K->2872K(124992K), 0.0012018 secs]
[GC 35576K->5184K(124992K), 0.0021390 secs]
[GC 37888K->9800K(124992K), 0.0031359 secs]
[GC 42504K->9824K(157696K), 0.0005724 secs]
[GC 75232K->28208K(157696K), 0.0059463 secs]
[GC 93616K->28224K(223040K), 0.0007707 secs]
[GC 159040K->32852K(223360K), 0.0095536 secs]
[GC 163668K->46740K(354880K), 0.0055367 secs]
[GC 308372K->55892K(355008K), 0.0032216 secs]
[GC 317524K->60484K(511168K), 0.0017500 secs]
[GC 478468K->65092K(511808K), 0.0033206 secs]
Total Data is : 39444 Kbytes!
Total Time is : 68
Averge Speed is :580 Kbytes
2.87G

[GC 32704K->2880K(124992K), 0.0132009 secs]
[GC 35584K->5192K(157696K), 0.0017013 secs]
[GC 70600K->9800K(157696K), 0.0035649 secs]
[GC 75208K->28232K(223104K), 0.0057867 secs]
[GC 151138K->43680K(223104K), 0.0055066 secs]
[GC 174496K->48256K(353344K), 0.0020662 secs]
[GC 298339K->59048K(354496K), 0.0054248 secs]
[GC 319528K->77512K(614592K), 0.0058665 secs]
[Full GC 77512K->18933K(612224K), 0.0097774 secs]
[GC 521588K->34405K(612352K), 0.0027320 secs]
Total Data is : 39444 Kbytes!
Total Time is : 137
Averge Speed is :287 Kbytes
3.4G

这里很奇怪，理论上Mbb的性能应该远大于这个，可能是我的测试数据量太小的缘故.

综上可见，RandomAccessFile 性价比最高。