Java文件操作类效率对比

时间：2018-08-24 22:15:55 阅读：187 评论：0 收藏：0 [点我收藏+]

标签：\n eof 增加测试程序 indent dwr red throw end

前言

众所周知，Java中有多种针对文件的操作类，以面向字节流和字符流可分为两大类，这里以写入为例：

面向字节流的：FileOutputStream 和 BufferedOutputStream

面向字符流的：FileWriter 和 BufferedWriter

近年来发展出New I/O ，也叫NIO，里面又包装了两个类：NewOutputStream 和 NewBufferedWriter

现在，我们建立测试程序，比较这些类写入文件的性能。

机器配置

Processor Name: Intel Core i7
Processor Speed: 2.2 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 16 GB

测试程序

纵向比较：几种文件操作类向文件中写入相同行数的内容（每行内容均为“写入文件Data\n”），比较其耗费时间

横向比较：对于同一个文件操作类，比较写入不同行数内容情况下所耗费时间；本文以2的倍数不断增长行数

  1 import java.io.File;
  2 import java.io.FileOutputStream;
  3 import java.io.*;
  4 import java.nio.file.Files;
  5 import java.nio.file.Paths;
  6 
  7 public class testFileIO {
  8 
  9     public static void testDriver () throws IOException {
 10         int maxlineNum = 100000001;//写入文件的最大行数
 11         int startlineNum = 1;//写入文件的行数
 12         int Multiplying = 2;//行数增长倍率
 13 
 14         long begin = 0L;
 15         long end = 0L;
 16 
 17         //将时间统计写入文件Result.txt中
 18         FileWriter fileWriter = new FileWriter("./Result.txt", true);
 19         BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
 20 
 21         System.out.println("Test FileOutputStream begin.");
 22         for (int lineNum = startlineNum; lineNum < maxlineNum; lineNum *= Multiplying) {
 23             begin = System.currentTimeMillis();
 24             testFileOutputStream(lineNum);
 25             end = System.currentTimeMillis();
 26             long timeElapse_FileOutputStream = end - begin;
 27             bufferedWriter.write(String.valueOf(timeElapse_FileOutputStream)+"\t");
 28         }
 29         System.out.println("Test FileOutputStream end.\n");
 30 
 31         System.out.println("Test BufferedOutputStream begin.");
 32         bufferedWriter.write("\n");
 33         for (int lineNum = startlineNum; lineNum < maxlineNum; lineNum *= Multiplying) {
 34             begin = System.currentTimeMillis();
 35             testBufferedOutputStream(lineNum);
 36             end = System.currentTimeMillis();
 37             long timeElapse_BufferedOutputStream = end - begin;
 38             bufferedWriter.write(String.valueOf(timeElapse_BufferedOutputStream)+"\t");
 39         }
 40         System.out.println("Test BufferedOutputStream end.\n");
 41 
 42         System.out.println("Test FileWriter begin.");
 43         bufferedWriter.write("\n");
 44         for (int lineNum = startlineNum; lineNum < maxlineNum; lineNum *= Multiplying) {
 45             begin = System.currentTimeMillis();
 46             testFileWriter(lineNum);
 47             end = System.currentTimeMillis();
 48             long timeElapse_FileWriter = end - begin;
 49             bufferedWriter.write(String.valueOf(timeElapse_FileWriter)+"\t");
 50         }
 51         System.out.println("Test FileWriter end.\n");
 52 
 53         System.out.println("Test BufferedWriter begin.");
 54         bufferedWriter.write("\n");
 55         for (int lineNum = startlineNum; lineNum < maxlineNum; lineNum *= Multiplying) {
 56             begin = System.currentTimeMillis();
 57             testBufferedWriter(lineNum);
 58             end = System.currentTimeMillis();
 59             long timeElapse_BufferedWriter = end - begin;
 60             bufferedWriter.write(String.valueOf(timeElapse_BufferedWriter)+"\t");
 61         }
 62         System.out.println("Test BufferedWriter end.\n");
 63 
 64         System.out.println("Test NewOutputStream begin.");
 65         bufferedWriter.write("\n");
 66         for (int lineNum = startlineNum; lineNum < maxlineNum; lineNum *= Multiplying) {
 67             begin = System.currentTimeMillis();
 68             testNewOutputStream(lineNum);
 69             end = System.currentTimeMillis();
 70             long timeElapse_NewOutputStream = end - begin;
 71             bufferedWriter.write(String.valueOf(timeElapse_NewOutputStream)+"\t");
 72         }
 73         System.out.println("Test NewOutputStream end.\n");
 74 
 75         System.out.println("Test NewBufferedWriter begin.");
 76         bufferedWriter.write("\n");
 77         for (int lineNum = startlineNum; lineNum < maxlineNum; lineNum *= Multiplying) {
 78             begin = System.currentTimeMillis();
 79             testNewBufferedWriter(lineNum);
 80             end = System.currentTimeMillis();
 81             long timeElapse_NewBufferedWriter = end - begin;
 82             bufferedWriter.write(String.valueOf(timeElapse_NewBufferedWriter)+"\t");
 83         }
 84         System.out.println("Test NewOutputStream end.\n");
 85 
 86         bufferedWriter.close();
 87     }
 88 
 89     /************************** I/O *****************************/
 90     //面向字节
 91     public static void testFileOutputStream (int lineNum) throws IOException {
 92         FileOutputStream fileOutputStream = new FileOutputStream(new File("./testFileOutputStream.txt"));
 93         while (--lineNum > 0) {
 94             fileOutputStream.write("写入文件Data\n".getBytes());
 95         }
 96         fileOutputStream.close();
 97     }
 98 
 99     public static void testBufferedOutputStream (int lineNum) throws IOException {
100         FileOutputStream fileOutputStream = new FileOutputStream(new File("./testBufferedOutputStream.txt"));
101         BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
102         while (--lineNum > 0) {
103             bufferedOutputStream.write("写入文件Data\n".getBytes());
104         }
105         bufferedOutputStream.close();
106     }
107 
108     //面向字符
109     public static void testFileWriter (int lineNum) throws IOException {
110         FileWriter fileWriter = new FileWriter("./testFileWriter.txt");
111         while (--lineNum > 0) {
112             fileWriter.write("写入文件Data\n");
113         }
114         fileWriter.close();
115     }
116 
117     public static void testBufferedWriter (int lineNum) throws IOException {
118         FileWriter fileWriter = new FileWriter("./testBufferedWriter.txt");
119         BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
120         while (--lineNum > 0) {
121             bufferedWriter.write("写入文件Data\n");
122         }
123         bufferedWriter.close();
124     }
125 
126 
127     /************************** NIO ****************************/
128     public static void testNewOutputStream (int lineNum) throws IOException {
129         OutputStream outputStream = Files.newOutputStream(Paths.get("./testNewOutputStream.txt"));
130         while (--lineNum > 0) {
131             outputStream.write("写入文件Data\n".getBytes());
132         }
133         outputStream.close();
134     }
135 
136     public static void testNewBufferedWriter (int lineNum) throws IOException {
137         BufferedWriter newBufferedReader = Files.newBufferedWriter(Paths.get("./testNewBufferedWriter.txt"));
138         while (--lineNum > 0) {
139             newBufferedReader.write("写入文件Data\n");
140         }
141         newBufferedReader.close();
142     }
143 
144 
145     public static void main (String[] args) throws IOException {
146         //多次测试时可清空result.txt文件
147         FileWriter fileWriter = new FileWriter("./Result.txt");
148         testDriver();
149     }
150 }