java IO写入文件效率——几种方法比较
测试写入类
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/**
? * 测试结果
? *
? * 1.file's long:16kb
? *
? fileWrite's time----------36
? outputStreamTest's time----------167
? bufferedOutputTest's time----------17
? bufferedWriteTest's time----------14
? bufferedWrite And FileWriterTest's time----------9
? bufferedWrite And BufferedOutputStreamTest's time----------12
? *
? * 2.file's long:1600kb
? fileWrite's time----------69
? outputStreamTest's time----------1282
? bufferedOutputTest's time----------68
? bufferedWriteTest's time----------40
? bufferedWrite And FileWriterTest's time----------52
? bufferedWrite And BufferedOutputStreamTest's time----------37
? *
? * 3.file's long:16000kb
? fileWrite's time----------555
? outputStreamTest's time----------12448
? bufferedOutputTest's time----------599
? bufferedWriteTest's time----------346
? bufferedWrite And FileWriterTest's time----------316
? bufferedWrite And BufferedOutputStreamTest's time----------358
?
? 4.file's long:160000kb
?
? fileWrite's time----------5203
? outputStreamTest's time----------127182
? bufferedOutputTest's time----------5972
? bufferedWriteTest's time----------3445??????? 最优
? bufferedWrite And FileWriterTest's time----------5904
? bufferedWrite And BufferedOutputStreamTest's time----------5353
?
?
? 5.file's long:1600000kb
?
? fileWrite's time----------50416
? outputStreamTest's time----------1303242
? bufferedOutputTest's time----------60931
? bufferedWriteTest's time----------46697
? bufferedWrite And FileWriterTest's time----------48710
? bufferedWrite And BufferedOutputStreamTest's time----------64354
? */
?public static void main(String[] args) {
? String str = "abcdefghiJKLMN！";
? int count = 1000000;
? TestOutputStream t = new TestOutputStream();
? long start = System.currentTimeMillis();
? t.fileWriteTest(count, str);
? long end = System.currentTimeMillis();
? System.out.println("fileWrite's time---------" + (start - end));
? start = System.currentTimeMillis();
? t.outputStreamTest(count, str);
? end = System.currentTimeMillis();
? System.out.println("outputStreamTest's time---------" + (start - end));
? start = System.currentTimeMillis();
? t.bufferedOutputTest(count, str);
? end = System.currentTimeMillis();
? System.out
??? .println("bufferedOutputTest's time---------" + (start - end));
?
? start = System.currentTimeMillis();
? t.bufferedWriteTest(count, str);
? end = System.currentTimeMillis();
? System.out.println("bufferedWriteTest's time---------" + (start - end));
?
? start = System.currentTimeMillis();
? t.bufferedWriteAndFileWriterTest(count, str);
? end = System.currentTimeMillis();
? System.out.println("bufferedWrite And FileWriterTest's time---------" + (start - end));
?
? start = System.currentTimeMillis();
? t.bufferedWriteAndBufferedOutputStreamTest(count, str);
? end = System.currentTimeMillis();
? System.out.println("bufferedWrite And BufferedOutputStreamTest's time---------" + (start - end));
?
?
?
?}
?
?/**
? *1 按字节写入 FileOutputStream
? *
? * @param count 写入循环次数
? * @param str 写入字符串
? */
?public void outputStreamTest(int count, String str) {
? File f = new File("f:test1.txt");
? OutputStream os = null;
? try {
?? os = new FileOutputStream(f);
?? for (int i = 0; i < count; i++) {
??? os.write(str.getBytes());
?? }
?? os.flush();
?? System.out.println("file's long:" + f.length());
? } catch (FileNotFoundException e) {
?? e.printStackTrace();
? } catch (IOException e) {
?? e.printStackTrace();
? } finally {
?? try {
??? os.close();
?? } catch (IOException e) {
??? e.printStackTrace();
?? }
? }
?}
?/**
? *2 按字节缓冲写入 BufferedOutputStream
? *
? * @param count 写入循环次数
? * @param str 写入字符串
? */
?public void bufferedOutputTest(int count, String str) {
? File f = new File("f:test2.txt");
? BufferedOutputStream bos = null;
? try {
?? OutputStream os = new FileOutputStream(f);
?? bos = new BufferedOutputStream(os);
?? for (int i = 0; i < count; i++) {
??? bos.write(str.getBytes());
?? }
?? bos.flush();
? } catch (FileNotFoundException e) {
?? e.printStackTrace();
? } catch (IOException e) {
?? e.printStackTrace();
? } finally {
?? try {
??? bos.close();
?? } catch (IOException e) {
??? e.printStackTrace();
?? }
? }
?}
?
?/**
? *3 按字符写入 FileWriter
? *
? * @param count 写入循环次数
? * @param str 写入字符串
? */
?public void fileWriteTest(int count, String str) {
? File f = new File("f:test.txt");
? Writer writer = null;
? try {
?? writer = new FileWriter(f);
?? for (int i = 0; i < count; i++) {
??? writer.write(str);
?? }
?? writer.flush();
? } catch (IOException e) {
?? e.printStackTrace();
? } finally {
?? try {
??? writer.close();
?? } catch (Exception e) {
??? e.printStackTrace();
?? }
? }
?}
?/**
? *4 按字符缓冲写入 BufferedWriter
? *
? * @param count 写入循环次数
? * @param str 写入字符串
? */
?public void bufferedWriteTest(int count, String str) {
? File f = new File("f:test3.txt");
? OutputStreamWriter writer = null;
? BufferedWriter bw = null;
? try {
?? OutputStream os = new FileOutputStream(f);
?? writer = new OutputStreamWriter(os);
?? bw = new BufferedWriter(writer);
?? for (int i = 0; i < count; i++) {
??? bw.write(str);
?? }
?? bw.flush();
?? if(f.exists()){
??? f.delete();
?? }
? } catch (FileNotFoundException e) {
?? e.printStackTrace();
? } catch (IOException e) {
?? e.printStackTrace();
? } finally {
?? try {
??? bw.close();
?? } catch (IOException e) {
??? e.printStackTrace();
?? }
? }
?}
?
?/**
? *5 按字符缓冲写入 BufferedWriter and BufferedOutputStream
? *
? * @param count 写入循环次数
? * @param str 写入字符串
? */
?public void bufferedWriteAndBufferedOutputStreamTest(int count, String str) {
? File f = new File("f:test4.txt");
? BufferedOutputStream bos=null;
? OutputStreamWriter writer = null;
? BufferedWriter bw = null;
? try {
?? OutputStream os = new FileOutputStream(f);
?? bos=new BufferedOutputStream(os);
?? writer = new OutputStreamWriter(bos);
?? bw = new BufferedWriter(writer);
?? for (int i = 0; i < count; i++) {
??? bw.write(str);
?? }
?? bw.flush();
?? if(f.exists()){
??? f.delete();
??? System.out.println("delete---");
?? }
? } catch (FileNotFoundException e) {
?? e.printStackTrace();
? } catch (IOException e) {
?? e.printStackTrace();
? } finally {
?? try {
??? bw.close();
?? } catch (IOException e) {
??? e.printStackTrace();
?? }
? }
?}
?
?/**
? *6 按字符缓冲写入 BufferedWriter and FileWriter
? *
? * @param count 写入循环次数
? * @param str 写入字符串
? */
?public void bufferedWriteAndFileWriterTest(int count, String str) {
? File f = new File("f:test5.txt");
? FileWriter fw=null;
? BufferedWriter bw = null;
? try {
?? fw=new FileWriter(f);
?? bw = new BufferedWriter(fw);
?? for (int i = 0; i < count; i++) {
??? bw.write(str);
?? }
?? bw.flush();
? } catch (FileNotFoundException e) {
?? e.printStackTrace();
? } catch (IOException e) {
?? e.printStackTrace();
? } finally {
?? try {
??? bw.close();
??? if(f.exists()){
???? f.delete();
??? }
?? } catch (IOException e) {
??? e.printStackTrace();
?? }
? }
?}
?
总结：
如果按字符和字节来分类，除方法1和2，其余都是按字符写入文件，字符写入一般比字节快；看java API可知，FileWriter的父类就是OutputStreamWriter，他俩都是实现Writer类，从这点上来说，方法4和6几乎没区别，时间有些微的差别，但内部机制是一样的，而且方法6较简单，定义变量稍，以前总用方法4，看来以后得改变下了。
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