Java中IO流常见的几种流

最新推荐文章于 2025-02-20 18:24:59 发布

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最新推荐文章于 2025-02-20 18:24:59 发布

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分类专栏： [---javaSE---] 文章标签： java 字符流 io流

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本文介绍了Java中的IO流，包括序列流如何合并和切割文件，打印流的操作过程，以及流的编码解码基础案例。同时，详细探讨了转换流的使用，帮助理解Java IO流在实际开发中的应用。

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序列流

序列流合并文件

package com.cloud.day5;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.SequenceInputStream;

import java.util.ArrayList;

import java.util.Enumeration;

import java.util.Vector;

SequenceInputStream(序列流)

public class Demo1 {

public static void main(String[] args) throws IOException {

merge1();

}

//把3个文件合并成一个文件

public static void merge3() throws IOException{

File file1 = new File("F:\\a.txt");

File file2 = new File("F:\\b.txt");

File file3 = new File("F:\\c.txt");

File file4 = new File("F:\\d.txt");

//建立对应的输入输出流对象

FileOutputStream fileOutputStream = new FileOutputStream(file4);

FileInputStream fileInputStream1 = new FileInputStream(file1);

FileInputStream fileInputStream2 = new FileInputStream(file2);

FileInputStream fileInputStream3 = new FileInputStream(file3);

//创建序列流对象

Vector<FileInputStream> vector = new Vector<FileInputStream>();

vector.add(fileInputStream1);

vector.add(fileInputStream2);

vector.add(fileInputStream3);

Enumeration<FileInputStream> e = vector.elements();

SequenceInputStream sequenceInputStream = new SequenceInputStream(e);

//读取文件数据

byte[] buf = new byte[1024];

int length = 0;

while((length = sequenceInputStream.read(buf))!=-1){

fileOutputStream.write(buf, 0, length);

}

sequenceInputStream.close();

fileOutputStream.close();

}

//SequenceInputStream合并文件夹

public static void meege2() throws IOException{

File inFile1 = new File("F:\\a.txt");

File inFile2 = new File("F:\\b.txt");

File outFile = new File("F:\\c.txt");

FileOutputStream fileOutputStream = new FileOutputStream(outFile);

FileInputStream fileInputStream1 = new FileInputStream(inFile1);

FileInputStream fileInputStream2 = new FileInputStream(inFile2);

//建立序列流对象

SequenceInputStream inputStream = new SequenceInputStream(fileInputStream1, fileInputStream2);

byte[] buf = new byte[1024];

int len=0;

while((len = inputStream.read(buf))!=-1){

fileOutputStream.write(buf, 0, len);

}

inputStream.close();

fileOutputStream.close();

}

//合并a.txt和b.txt内容

public static void merge1() throws IOException{

File inFile1 = new File("F:\\a.txt");

File inFile2 = new File("F:\\b.txt");

File outFile = new File("F:\\c.txt");

FileOutputStream fileOutputStream = new FileOutputStream(outFile);

FileInputStream fileInputStream1 = new FileInputStream(inFile1);

FileInputStream fileInputStream2 = new FileInputStream(inFile2);

ArrayList<FileInputStream> list = new ArrayList<FileInputStream>();

list.add(fileInputStream1);

list.add(fileInputStream2);

byte[] buf = new byte[1024];

int length = 0;

for(int i=0;i<list.size();i++){

FileInputStream fileInputStream = list.get(i);

while((length = fileInputStream.read(buf))!=-1){

fileOutputStream.write(buf, 0, length);

}

fileInputStream.close();

}

fileOutputStream.close();

}

序列流切割文件

package com.cloud.day5;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.SequenceInputStream;

import java.util.Enumeration;

import java.util.Vector;

切割一首MP3再合并

public class Demo2 {

public static void main(String[] args) throws IOException {

File dir = new File("F:\\music");

Vector<FileInputStream> vector = new Vector<FileInputStream>();

File[] files = dir.listFiles();

for(File file:files){

if(file.getName().endsWith(".mp3")){

vector.add(new FileInputStream(file));

}

Enumeration<FileInputStream> e = vector.elements();

SequenceInputStream inputStream = new SequenceInputStream(e);

FileOutputStream fileOutputStream = new FileOutputStream("F:\\sum.mp3");

byte[] buf = new byte[1024];

int length = 0;

while((length = inputStream.read(buf))!=-1){

fileOutputStream.write(buf,0,length);

}

fileOutputStream.close();

inputStream.close();

}

//切割MP3

public static void cutFile() throws IOException{

File file = new File("F:\\1.mp3");

File dir = new File("F:\\music");

FileInputStream fileInputStream = new FileInputStream(file);

byte[] buf = new byte[1024*1024];

int length = 0;

for(int i=0;(length = fileInputStream.read(buf))!=-1;i++){

FileOutputStream fileOutputStream = new FileOutputStream(new File(dir,"part"+i+".mp3"));

fileOutputStream.write(buf, 0, length);

fileOutputStream.close();

}

fileInputStream.close();

}

打印流

打印流过程

package com.cloud.day1;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.PrintStream;

打印流（printStream）打印流可以打印任意类型的数据，而且打印数据之前都会先把数据转换成字符串再进行打印。

class Animal {

String name;

String color;

public Animal(String name, String color) {

this.name = name;

this.color = color;

}

@Override

public String toString() {

return "Animal [name=" + name + ", color=" + color + "]";

}

public class Demo1 {

public static void main(String[] args) throws IOException {

File file = new File("E:\\a.txt");

//创建一个打印流

PrintStream printStream = new PrintStream(file);

printStream.println(123);

printStream.println("spring");

Animal animal = new Animal("Cat","black");

printStream.println(animal);

//默认标准的输出流就是向控制台输出

System.out.println(printStream);

//收集日常的日志信息

File logFile = new File("E:\\execption.log");

PrintStream printStream = new PrintStream(new FileOutputStream(logFile,true));

try {

int c = 4/0;

System.out.println("c="+c);

int[] arr = null;

System.out.println(arr.length);

} catch (Exception e) {

e.printStackTrace();

}

流的编码解码问题

基本案例

package com.cloud.day1;

import java.util.Arrays;

编码和解码问题

编码：把看得懂的字符变成看懂码值，这个过程叫做编码

解码：把码值查找对应的字符，我们把这个过程称作为解码

注意：编码与解码一般我们都使用统一的码表。否则非常容易出乱码

public class Demo2 {

public static void main(String[] args) throws Exception {

String str = "中国";

//平台默认的编码表GBK

byte []buf = str.getBytes("utf-8");

System.out.println("数组的元素："+Arrays.toString(buf));

//默认使用GBK码表解码

str = new String(buf,"utf-8");

System.out.println("解码后的字符串："+str);

String str1 = "大家好";

//使用GBK进行编码

byte []buf1 = str1.getBytes();

System.out.println("字节数组："+Arrays.toString(buf1));

str1 = new String(buf1 , "iso8859-1");

//出现乱码后还原

byte []buf2 = str1.getBytes("iso8859-1");

str1 = new String(buf2 , "gbk");

System.out.println(str1);

}

转换流

转换流使用

package com.cloud.day1;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

转换流:

输入字节流的转换流：InputStreamReader 是字节流通向字符流的桥

InputStreamReader

输出字节流的转换流：

OutputStreamWriter 可以把输出字节流转换成输出字符流。

转换流的作用：

1. 如果目前所获取到的是一个字节流需要转换字符流使用，这时候就可以使用转换流。字节流----> 字符流

2. 使用转换流可以指定编码表进行读写文件。

public class Demo3 {

public static void main(String[] args) throws IOException {

//readTest();

//writeTest();

readTest2();

}

//使用输入字节流的转换流指定码表进行读取文件数据

public static void readTest2() throws IOException{

File file = new File("D:\\a.txt");

FileInputStream fileInputStream = new FileInputStream(file);

//这里的编码如果使用UTF-8会发生乱码

InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream,"gbk");

char []buf = new char[1024];

int length = 0;

while((length = inputStreamReader.read(buf))!=-1){

System.out.println(new String(buf , 0 , length));

}

public static void writeTest() throws IOException{

File file = new File("D:\\a.txt");

FileOutputStream fileOutputStream = new FileOutputStream(file);

OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream);

outputStreamWriter.write("Hello,春天");

outputStreamWriter.close();

}

/**

* 控制台输入：asa

* 内容：asa

* @throws IOException

public static void readTest() throws IOException{

//获取标准的输入流

InputStream in = System.in;

//字节流转换成字符流

InputStreamReader inputStreamReader = new InputStreamReader(in);

//使用字符流的缓冲类

BufferedReader bufferedReader = new BufferedReader(inputStreamReader);

String line = null;

while((line = bufferedReader.readLine())!=null){

System.out.println("内容："+line);

}