IO流的图解如下：
IO流图解副本.jpg
测试对比
/*
* 数据源
* 神话.mp4
* 目的地
* sh.mp4
*
* 基本字节流一次读取一个字节：共耗时61298毫秒
* 基本字节流一次读取一个字节数组：共耗时83毫秒
* 高效字节流一次读取一个字节数组：共耗时651毫秒
* 高效字节流一次读取一个字节数组：共耗时32毫秒
*/
public static void main(String[] args) throws IOException {
long start = System.currentTimeMillis();
//1.基本字节流一次读取一个字节
// method1("神话.mp4", "sh.mp4");
//2.基本字节流一次读取一个字节数组
// method2("神话.mp4", "sh.mp4");
//3.高效字节流一次读取一个字节
// method3("神话.mp4", "sh.mp4");
//4.高效字节流一次读取一个字节数组
method4("神话.mp4", "sh.mp4");
long end = System.currentTimeMillis();
System.out.println("共耗时" + (end - start) + "毫秒");
}
//4.高效字节流一次读取一个字节数组
private static void method4(String srcString, String destString)
throws IOException {
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
srcString));
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream(destString));
byte[] bys = new byte[1024];
int len = 0;
while ((len = bis.read(bys)) != -1) {
bos.write(bys, 0, len);
}
bos.close();
bis.close();
}
//3.高效字节流一次读取一个字节
private static void method3(String srcString, String destString)
throws IOException {
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(
srcString));
BufferedOutputStream bos = new BufferedOutputStream(
new FileOutputStream(destString));
int by = 0;
while ((by = bis.read()) != -1) {
bos.write(by);
}
bos.close();
bis.close();
}
//2.基本字节流一次读取一个字节数组
private static void method2(String srcString, String destString)
throws IOException {
FileInputStream fis = new FileInputStream(srcString);
FileOutputStream fos = new FileOutputStream(destString);
byte[] bys = new byte[1024];
int len = 0;
while ((len = fis.read(bys)) != -1) {
fos.write(bys, 0, len);
}
fos.close();
fis.close();
}
//1.基本字节流一次读取一个字节
private static void method1(String srcString, String destString)
throws IOException {
FileInputStream fis = new FileInputStream(srcString);
FileOutputStream fos = new FileOutputStream(destString);
int by = 0;
while ((by = fis.read()) != -1) {
fos.write(by);
}
fos.close();
fis.close();
}
实践：
1.数据复制
（A.）数据源是文件 目的是文件
/**
* 数据源 目的地
*
* a.txt b.txt
*/
public static void main(String[] args) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new FileReader("a.txt"));
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("b.txt"));
String string = null;
while ((string = bufferedReader.readLine())!=null) {
bufferedWriter.write(string);
bufferedWriter.newLine();
bufferedWriter.flush();
}
bufferedReader.close();
bufferedWriter.close();
}
（B.）数据源是文件 目的地是控制台
/**
* 数据源 目的地
*
* a.txt 控制台
*/
public static void main(String[] args) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new FileReader("a.txt"));
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(System.out));
String string = null;
while ((string = bufferedReader.readLine())!=null) {
bufferedWriter.write(string);
bufferedWriter.newLine();
bufferedWriter.flush();
}
bufferedReader.close();
bufferedWriter.close();
}
（C.）数据源是键盘录入 目的地是文本文件
/**
* 数据源 目的地
*
* 键盘录入 a.txt
*/
public static void main(String[] args) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("a.txt"));
String string = null;
while ((string = bufferedReader.readLine())!=null) {
if ("over".equals(string)) {
break;
}
bufferedWriter.write(string);
bufferedWriter.newLine();
bufferedWriter.flush();
}
bufferedReader.close();
bufferedWriter.close();
}
（D.）数据源键盘录入 目的地控制台
/**
* 数据源 目的地
*
* 键盘录入 控制台
*/
public static void main(String[] args) throws IOException {
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(System.out));
String string = null;
while ((string = bufferedReader.readLine())!=null) {
if ("over".equals(string)) {
break;
}
bufferedWriter.write(string);
bufferedWriter.newLine();
//bufferedWriter.flush();
}
bufferedReader.close();
bufferedWriter.close();
}
（E.）键盘录入数据写到文本文件a.txt，然后把a.txt的数据写到b.txt，最后把b.txt的数据显示到控制台(录入---->文件--->文件---->控制台)
public static void main(String[] args) throws IOException {
//第一步： 键盘录入数据写到文本文件a.txt 数据源--->键盘录入 目的地--->a.txt
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
BufferedWriter aBufferedWriter = new BufferedWriter(new FileWriter("a.txt"));
fileWR(bufferedReader, aBufferedWriter);
//第二步： a.txt的数据写到b.txt 数据源--->a.txt 目的地--->b.txt
BufferedReader aBufferedReader = new BufferedReader(new FileReader("a.txt"));
BufferedWriter bBufferedWriter = new BufferedWriter(new FileWriter("b.txt"));
fileWR(aBufferedReader, bBufferedWriter);
//第三步：b.txt的数据显示到控制台
BufferedReader bBufferedReader = new BufferedReader(new FileReader("b.txt"));
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(System.out));
fileWR(bBufferedReader,bufferedWriter);
}
public static void fileWR(BufferedReader reader , BufferedWriter writer) throws IOException {
String string = null;
while ((string = reader.readLine())!=null) {
if ("over".equals(string)) {
break;
}
writer.write(string);
writer.newLine();
//writer.flush();
}
writer.close();
reader.close();
}
(F.)数据源 ArrayList 目的地a.txt (集合到文件)
public static void main(String[] args) throws IOException {
ArrayList<String> list = new ArrayList<String>();
list.add("hello");
list.add("word");
list.add("java");
BufferedWriter writer = new BufferedWriter(new FileWriter("a.txt"));
for(String string : list){
writer.write(string);
writer.newLine();
writer.flush();
}
writer.close();
}
(G.)数据源 a.txt 目的地ArrayList (文件到集合)
public static void main(String[] args) throws IOException {
BufferedReader reader = new BufferedReader(new FileReader("a.txt"));
ArrayList<String> list = new ArrayList<String>();
String string = null;
while ((string = reader.readLine())!=null) {
list.add(string);
}
for(String string2 : list){
System.out.println(string2);
}
reader.close();
}
（F.）复制单击文件夹
public static void main(String[] args) throws IOException {
File srcFile = new File("/Users/xz/Desktop/java_api");
if (!srcFile.exists()) {
System.out.println("找不到源文件");
srcFile.exists();
}
File[] fileArr = srcFile.listFiles();
File desFile = new File("/Users/xz/Desktop/java_api_fuben");
if (!desFile.exists()) {
desFile.mkdirs();
}
for(File fi:fileArr){
System.out.println(fi.getName());
File dessFile = new File(desFile, fi.getName());
Copy(fi, dessFile);
}
}
public static void Copy(File file , File desFile) throws IOException {
BufferedInputStream inputStream = new BufferedInputStream(new FileInputStream(file));
BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(desFile));
byte[] by = new byte[1024];
int i = 0;
while ((i = inputStream.read(by))!= -1) {
outputStream.write(i);
}
inputStream.close();
outputStream.close();
}
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