import org.junit.Test; public class IOTest {  /**  * BufferedInputStream BufferedOutputStream  * 利用字节缓冲流实现文件的复制  * @throws IOException  * */ @Test public void bufferedInputStreamAndbufferedOutputStream() throws IOException{  //新建字节的输入输出  InputStream in = new FileInputStream("hellow.txt");  BufferedInputStream bStream = new BufferedInputStream(in);   OutputStream out = new FileOutputStream("hellow2.txt");  BufferedOutputStream bOutputStream = new BufferedOutputStream(out);  //创建缓冲数组  byte[] bytes = new byte[100];  //进行复制  int len = 0;  while((len = bStream.read(bytes))!= -1)  {   bOutputStream.write(bytes, 0, len);  }  //关闭流  bStream.close();  bOutputStream.close(); }/**  * bufferdeReader And bufferedWriter  * 利用缓冲流实现文件的复制  * @throws IOException  * **/ @Test public void bufferdeReaderAndbufferedWriter() throws IOException {  // 新建字符的输入输出  Reader in = new FileReader("hellow.txt");  BufferedReader bReader = new BufferedReader(in);  Writer out = new FileWriter("hellow2.txt");  BufferedWriter bWriter = new BufferedWriter(out);  // 进行复制  String line = null;  int i = 0;  while ((line = bReader.readLine()) != null) {   if (i != 0)    bWriter.write("\n");   bWriter.write(line, 0, line.length());   i++;  }  // 关闭流  bReader.close();  bWriter.close(); }/** *reader writer * 利用字符输入输出流, 完成 hello.txt 文件的复制. * 把该文件复制为 hello2.txt   */ @Test public void readerAndwriter() throws IOException {  //新建字符的输入输出  Reader reader = new FileReader("hellow.txt");  Writer writer = new FileWriter("hellow2.txt");  //定义数组，用于读写文件  char[] cbuf = new char[100];  //读写文件  int len;  while((len = reader.read(cbuf)) != -1)  {   writer.write(cbuf, 0, len);  }  //关闭流  reader.close();  writer.close(); }/***InputStream OutputStream  * 利用字节输入输出流, 完成 hello.txt 文件的复制. * 把该文件复制为 hello2.txt * @throws IOException */ @Test public void testCopyFile() throws IOException{ //1. 创建定位到 hello.txt 的文件的输入流 InputStream in = new FileInputStream("枚举类.avi"); //2. 创建定位到 hello2.txt 的文件输出流 OutputStream out = new FileOutputStream("枚举类2.avi"); //3. 创建一个 byte 数组, 用于读写文件 byte [] buffer = new byte[1024 * 10]; int len = 0; //4. 读写文件: //in.read(buffer); out.write(buffer, 0, len); while((len = in.read(buffer)) != -1){ out.write(buffer); } //5. 关闭流资源. out.close(); in.close(); } /** * 测试字节输出流  OutputStream* @throws IOException */ @Test public void testOutputStream() throws IOException{ OutputStream out = new FileOutputStream("abcd.txt"); String content = "www.atguigu.com\nHello Java!"; out.write(content.getBytes()); out.close(); } /** * 测试字符输入流.  Reader* @throws IOException */ @Test public void testReader() throws IOException{ //利用字符输入流读取 hello.txt 文档的内容, 输出到控制台. Reader reader = new FileReader("hello.txt"); char [] buffer = new char[10]; int len = 0; while((len = reader.read(buffer)) != -1){ for(int i = 0; i < len; i++){ System.out.print(buffer[i]); } } reader.close(); } /** * 测试字节输入流 InputStream* @throws IOException */ @Test public void testInputStream() throws IOException{ //1. 创建了一个字节输入流. InputStream in = new FileInputStream("hello.txt"); //2. 读取文件的内容 //2.1 第一读取一个字节. 效率很低, 不建议这样读. -1 表示读取到文件的结尾处 //     int result = in.read(); //    //     while(result != -1){ //     System.out.print((char)result); //     result = in.read(); //     } //2.2 一次读取一组: 一组字符. //返回一次实际读取的字节数, 若为 -1 表示读取到文件的结尾 //     byte [] buffer = new byte[10]; //     int len = 0; //    //     while((len = in.read(buffer)) != -1){ //     for(int i = 0; i < len; i++){ //     System.out.print((char)buffer[i]); //     } //     } //2.3 把内容读取到字节数组的部分连续的元素中. byte [] result = new byte[1024 * 10]; in.read(result, 10, in.available()); //3. 关闭流资源 in.close(); } /** * File: 代表物理的意义的文件或目录 * @throws IOException */ @Test public void testFile() throws IOException{ //1. 创建 File 对象 File file = new File("hello.txt"); //2. 测试 File 对象的方法. //2.1 文件名相关的方法 String fileName = file.getName(); System.out.println(fileName); //2.2 访问文件的绝对路径 String path = file.getAbsolutePath(); System.out.println(path); //2.3 为文件重命名 //file.renameTo(new File("d:\\hello.txt")); //3. 文件检测相关的方法 System.out.println(file.exists()); File dir = new File("atguigu"); System.out.println(dir.isFile()); //4. 获取文件的常规信息 System.out.println(file.length()); //5. 文件操作相关. File file2 = new File("abcd.txt"); file2.createNewFile(); } }