1. java IO流的分類：按照流向可分為輸入流和輸出流，按照資料型別可分為位元組流和字元流。
2. IO流的適用場景和效率：在處理音訊，視訊，圖片這些檔案時一般使用位元組流，而使用緩衝位元組流(BufferedInputStream和BufferedOutputStream)會比檔案位元組流(FileInputStream和FileOutputStream)的效率高；在處理文字檔案時一般使用字元流，而使用緩衝字元流(BufferedReader和BufferedWriter)會比檔案字元流(FileReader和FileWriter)的效率高。

3. 下面用一張圖來概括IO流體系：
   

4. 用位元組流複製視訊並比較效率

package com.yixun.cn;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import org.junit.Test;

public class CopyPicture {
    public static void main(String[] args) {
        long
 
 startTime = System.currentTimeMillis();
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            fis = new FileInputStream(new File("C:\\Users\\mayu\\Desktop\\Wildlife.wmv"));
            fos = new FileOutputStream(new File("C:\\Users\\mayu\\Desktop\\test\\Wildlife1.wmv"
 
));
            byte[] b = new byte[64];
            int len = 0;
            while ((len = fis.read(b)) != -1) {
                fos.write(b, 0, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fos != null) {
                try {
                    fos.flush();
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fis != null) {
                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        long endTime = System.currentTimeMillis();
        System.out.println("檔案位元組流複製視訊花費時間為：" + (endTime - startTime));
    }

    @Test
    public void test() {
        long startTime = System.currentTimeMillis();
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
            bis = new BufferedInputStream(new FileInputStream(new File("C:\\Users\\mayu\\Desktop\\Wildlife.wmv")));
            bos = new BufferedOutputStream(
                    new FileOutputStream(new File("C:\\Users\\mayu\\Desktop\\test\\Wildlife1.wmv")));
            byte[] b = new byte[64];
            int len = 0;
            while ((len = bis.read(b)) != -1) {
                bos.write(b, 0, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (bos != null) {
                try {
                    bos.flush();
                    bos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (bis != null) {
                try {
                    bis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        long endTime = System.currentTimeMillis();
        System.out.println("緩衝位元組流複製視訊花費時間為：" + (endTime - startTime));
    }
}

 5. 用字元流複製文字檔案並比較效率

package com.yixun.cn;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

import org.junit.Test;

public class CopyText {
    public static void main(String[] args) {
        long startTime = System.currentTimeMillis();
        FileReader fr = null;
        FileWriter fw = null;
        try {
            fr = new FileReader(new File(
                    "C:\\Users\\mayu\\Desktop\\xxx.txt"));
            fw = new FileWriter(new File("C:\\Users\\mayu\\Desktop\\test\\xxx.txt"));
            char[] c = new char[64];
            int len = 0;
            while ((len = fr.read(c)) != -1) {
                fw.write(c, 0, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (fw != null) {
                try {
                    fw.flush();
                    fw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (fr != null) {
                try {
                    fr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        long endTime = System.currentTimeMillis();
        System.out.println("檔案字元流複製文字花費時間為：" + (endTime - startTime));
    }

    @Test
    public void test() {
        long startTime = System.currentTimeMillis();
        BufferedReader br = null;
        BufferedWriter bw = null;
        try {
            br = new BufferedReader(new InputStreamReader(new FileInputStream(new File(
                    "C:\\\\Users\\\\mayu\\\\Desktop\\\\xxx.txt"))));
            bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(
                    new File("C:\\Users\\mayu\\Desktop\\test\\x"))));
            char[] c = new char[64];
            int len = 0;
            while ((len = br.read(c)) != -1) {
                bw.write(c, 0, len);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (bw != null) {
                try {
                    bw.flush();
                    bw.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        long endTime = System.currentTimeMillis();
        System.out.println("緩衝字元流複製文字花費時間為：" + (endTime - startTime));
    }
}