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

publicstatic void main(String[] args) throws IOException {//缓存字符流实现写入文件InputStreamin = System.in;Readerreader = new InputStreamReader(in);BufferedReaderbr = new BufferedReader(reader);BufferedWriterbw = new BufferedWriter(new FileWriter(new File("src/1.txt")));Strings="";while((s=br.readLine())!=null) {bw.write(s);bw.newLine();bw.flush();//字符流千万不要忘了flush!!!!!!!!!!!!!!!!!!!!!!!!!!!!!}}

总结

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