本文共 3985 字，大约阅读时间需要 13 分钟。

写文件

package com.xiaobu.note.daily.autoCloseAble;import lombok.SneakyThrows;import org.springframework.util.StopWatch;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileOutputStream;import java.io.FileWriter;/** * @author xiaobu * @version JDK1.8.0_171 * @date on  2019/7/31 17:33 * @description */public class WriteFile {
       public static void main(String[] args) {
           StopWatch stopWatch = new StopWatch();        stopWatch.start("FileOutputStream 写文件");        writeByFileOutStream();        stopWatch.stop();        stopWatch.start("BufferedOutputStream 写文件");        writeByBufferedOutputStream();        stopWatch.stop();        stopWatch.start("FileWriter 写文件");        writeByFileWriter();        stopWatch.stop();        System.out.println("stopWatch.prettyPrint() = " + stopWatch.prettyPrint());    }    @SneakyThrows    public static void writeByFileOutStream() {
           FileOutputStream out = null;        int count = 1000;//写文件行数        out = new FileOutputStream(new File("D:\\data1.txt"));        for (int i = 0; i < count; i++) {
               out.write("测试java 文件操作\r\n".getBytes());        }    }    @SneakyThrows    public static void writeByBufferedOutputStream() {
           FileOutputStream outSTr = new FileOutputStream(new File("D:\\data2.txt"));        BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outSTr);        int count = 1000;//写文件行数        for (int i = 0; i < count; i++) {
               bufferedOutputStream.write("测试java 文件操作\r\n".getBytes());        }    }    @SneakyThrows    public static void writeByFileWriter() {
           FileWriter fw = new FileWriter("D:\\data3.txt");        int count = 1000;//写文件行数        for (int i = 0; i < count; i++) {
               fw.write("测试java 文件操作\r\n");        }    }}

可以看出写文件最快的是BufferedOutputStream

读文件

package com.xiaobu.note.daily.autoCloseAble;import lombok.SneakyThrows;import org.springframework.util.StopWatch;import java.io.*;/** * @author xiaobu * @version JDK1.8.0_171 * @date on  2019/7/31 17:33 * @description */public class ReadFile {
       public static void main(String[] args) {
           StopWatch stopWatch = new StopWatch();        stopWatch.start("开始执行 readByFileInputStream 方法");        readByFileInputStream();        stopWatch.stop();        stopWatch.start("开始执行 readByBuffReader 方法");        readByBuffReader();        stopWatch.stop();        stopWatch.start("开始执行 readByFileReader 方法");        readByFileReader();        stopWatch.stop();        System.out.println("stopWatch.prettyPrint() = " + stopWatch.prettyPrint());    }    @SneakyThrows    public static void readByFileInputStream(){
           File file = new File("D:/data1.txt");        try (FileInputStream fileInputStream = new FileInputStream(file);             //FileOutputStream fileOutputStream = new FileOutputStream(file)        ) {
               byte[] buf = new byte[1024];            int length=0;            String result = null;            while ((length=fileInputStream.read(buf))!=-1){
                   result = new String(buf,0,length);            }            System.out.println("result = " + result);;        }    }    @SneakyThrows    public static void readByFileReader(){
           File file = new File("D:/data2.txt");        FileReader fileReader = new FileReader(file);        char[] buf = new char[1024];        int length=0;        String result=null;        while ((length=fileReader.read(buf))!=-1){
               result = new String(buf,0,length);        }        System.out.println("result = " + result);    }    @SneakyThrows    public static void readByBuffReader(){
           File file = new File("D:/data3.txt");        FileReader fileReader = new FileReader(file);        BufferedReader bufferedReader = new BufferedReader(fileReader);        String result=null;        while ((result=bufferedReader.readLine())!=null){
               System.out.println("result = " + result);        }    }}

可以看出读效率最快的是FileReader

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