Java IO流和文件操作实现过程解析

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int read() throws IOException

String readLine() throws IOException

void write(int byteval)

//构造方法1
InputStream f=new FileInputStream("c:/java/hello");
//构造方法2
File f= new File("C:/java/hello");
InputStream out = new FileInputStream(f);

//构造方法1
OutputStream f = new FileOutputStream("C:/java/hello")
//构造方法2
File f = new File("C:/java/hello");
OutputStream f = new FileOutputStream(f);

import java.io.*;
 
public class fileStreamTest2 {
  public static void main(String[] args) throws IOException {
 
    File f = new File("a.txt");
    FileOutputStream fop = new FileOutputStream(f);
    // 构建FileOutputStream对象,文件不存在会自动新建
 
    OutputStreamWriter writer = new OutputStreamWriter(fop, "UTF-8");
    // 构建OutputStreamWriter对象,参数可以指定编码,默认为操作系统默认编码,windows上是gbk
 
    writer.append("中文输入");
    // 写入到缓冲区
 
    writer.append("\r\n");
    // 换行
 
    writer.append("English");
    // 刷新缓存冲,写入到文件,如果下面已经没有写入的内容了,直接close也会写入
 
    writer.close();
    // 关闭写入流,同时会把缓冲区内容写入文件,所以上面的注释掉
 
    fop.close();
    // 关闭输出流,释放系统资源
 
    FileInputStream fip = new FileInputStream(f);
    // 构建FileInputStream对象
 
    InputStreamReader reader = new InputStreamReader(fip, "UTF-8");
    // 构建InputStreamReader对象,编码与写入相同
 
    StringBuffer sb = new StringBuffer();
    while (reader.ready()) {
      sb.append((char) reader.read());
      // 转成char加到StringBuffer对象中
    }
    System.out.println(sb.toString());
    reader.close();
    // 关闭读取流
 
    fip.close();
    // 关闭输入流,释放系统资源
 
  }
}

import java.io.File;
 
public class CreateDir {
  public static void main(String args[]) {
    String dirname = "/tmp/user/java/bin";
    File d = new File(dirname);
    // 现在创建目录
    d.mkdirs();
  }
}

import java.io.File;
 
public class DirList {
  public static void main(String args[]) {
    String dirname = "/tmp";
    File f1 = new File(dirname);
    if (f1.isDirectory()) {
      System.out.println("目录 " + dirname);
      String s[] = f1.list();
      for (int i = 0; i < s.length; i++) {
        File f = new File(dirname + "/" + s[i]);
        if (f.isDirectory()) {
          System.out.println(s[i] + " 是一个目录");
        } else {
          System.out.println(s[i] + " 是一个文件");
        }
      }
    } else {
      System.out.println(dirname + " 不是一个目录");
    }
  }
}

import java.io.File;
 
public class DeleteFileDemo {
  public static void main(String args[]) {
    // 这里修改为自己的测试目录
    File folder = new File("/tmp/java/");
    deleteFolder(folder);
  }
 
  // 删除文件及目录
  public static void deleteFolder(File folder) {
    File[] files = folder.listFiles();
    if (files != null) {
      for (File f : files) {
        if (f.isDirectory()) {
          deleteFolder(f);
        } else {
          f.delete();
        }
      }
    }
    folder.delete();
  }
}