Java IO流相关知识代码解析

一、IO流的分类

字符流

Reader
InputStreamReader（节点流）
BufferedReader（处理流）
Writer
OutputStreamWriter（节点流）
BufferedWriter（处理流）
PrintWriter

字节流

InputStream
FileInputStream（节点流）
BufferedInputStream（处理流）
ObjectInputStream（处理流）
PrintStream
OutputStream
FileOutputStream（节点流）
BufferedOutputStream（处理流）
ObjectOutputStream（处理流）

断点处理的流

RandomAccessfile

二、IO流的用法

1、转换流的用法

FileInputStream in = new FileInputStream(newFile(""));

Readerreader = new InputStreamReader(in);//字节转字符

FileOutputStreamout = new FileOutputStream(newFile(""));

Writer writer = new OutputStreamWriter(out);//字符转字节

2、对象序列化,对象需要实现Serializable接口

FileOutputStreamfileOutputStream = new FileOutputStream("C:\\\\Users\\\\lx\\\\Desktop\\\\Record.txt");

ObjectOutputStreamobjectOutputStream = new ObjectOutputStream(fileOutputStream);

objectOutputStream.writeObject(object);//向指定文件写入对象object

objectOutputStream.close();

FileInputStreamfileInputStream = new FileInputStream("C:\\\\Users\\\\lx\\\\Desktop\\\\Record.txt");

ObjectInputStreamobjectInputStream = new ObjectInputStream(fileInputStream);

object = objectInputStream.readObject();//读取得到对象object

fileInputStream . lose();

3、断点的运用

public class Copy extends Thread{

//可以利用多线程实现拷贝

longstart;

longend;

Filesorce;

Filetargetdir;

publicCopy() {

}

publicCopy(longstart,long end, File sorce, File targetdir) {

//利用构造方法传递需要拷贝的长度，拷贝开始位置，以及目标文件和源文件

super();

this.start= start;

this.end= end;

this.sorce= sorce;

this.targetdir= targetdir;

}

@Override

publicvoid run(){

try{

RandomAccessFilesouceRaf = new RandomAccessFile(sorce,"r");

RandomAccessFiletargetRaf = new RandomAccessFile(newFile(targetdir,sorce.getName()),"rw");

souceRaf.seek(start);

targetRaf.seek(start);

intlen= 0;

byte[]bs = new byte[1024];

longseek;

System.out.println(start+"---->"+end+this.getName());

while((len= souceRaf.read(bs))!=-1){

targetRaf.write(bs, 0, len);

seek= souceRaf.getFilePointer();

//获取断点位置

if(seek== end){

break;

}

targetRaf.close();

souceRaf.close();

}

catch (IOException e) {

e.printStackTrace();

}

4、字节流的用法

public class Test_InputStream {

//利用字节流获取文本文件内容，但是容易出现问题

/*

//可能出现int长度越界

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

InputStream inputStream = new FileInputStream(new File("C:\\\\Users\\\\lx\\\\Desktop\\\\test\\\\33.txt"));

byte[] b = new byte[inputStream.available()];

inputStream.read(b);

String str = new String(b);

System.out.println(str);

}

*/

//可能出现乱码

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

File file = new File("C:\\\\Users\\\\lx\\\\Desktop\\\\test\\\\33.txt");

InputStream inputStream = new FileInputStream(file);

//统计每次读取的实际长度

int len = 0;

//声明每次读取1024个字节

byte[] b = new byte[2];

StringBuffer sBuffer = new StringBuffer();

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

sBuffer.append(new String(b,0,len));

}

System.out.println(sBuffer.toString());

}

//利用字节流拷贝文件

public void copy(File sourceFile, File targetDir) {

//

FileInputStreamfileInputStream = null;

FileOutputStreamfileOutputStream = null;

fileInputStream= new FileInputStream(sourceFile);

FiletargetFile = new File(targetDir,sourceFile.getName());

fileOutputStream= new FileOutputStream(targetFile);

byte[]b = new byte[1024];

intlen = 0;

while((len= fileInputStream.read(b)) != -1) {

fileOutputStream.write(b, 0, len);

}

5、缓存字符流的用法

Java IO流相关知识代码解析

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