我对java IO流简单的理解

一、Java IO流按流向可分为输入流（读数据）和输出流(写数据)，按操作对象分可分为字符流和字节流。下面是IO流相关类的关系图：

二、文件的复制：

/**
	 * @param fileSource  要复制的文件
	 * @param fileCopy    复制后的文件
	 */
	private static void copyFile(File fileSource, File fileCopy) {
		InputStream is = null;
		OutputStream os = null;
		byte[] buffer = new byte[512];//每次读取512字节大小的数据
		int totalBytes = 0;
		try {
			is = new FileInputStream(fileSource);
			os = new FileOutputStream(fileCopy);

			while ((totalBytes = is.read(buffer)) != -1) {
				
				os.write(buffer, 0, totalBytes);

			}

		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (is != null && os != null) {
				try {
					is.close();
					os.close();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}

			}
		}
	}
 
  
 
  
	/**用字符流读取文件txt格式的文件*/
	private static void readFileByChar() {
		Reader reader = null;
		try {	
			File file=new File("d:/测试.txt");
			//设置读取的编码格式为“gbk”,如果读取的编码格式和该文件的编码格式不一致，则读出来的会是乱码
			reader = new InputStreamReader(new FileInputStream(file),"gbk");
			int tempchar;
			while ((tempchar = reader.read()) != -1) {			
				// 对于windows下，\r\n这两个字符在一起时，表示一个换行。
				// 但如果这两个字符分开显示时，会换两次行。
				// 因此，屏蔽掉\r，或者屏蔽\n。否则，将会多出很多空行。
				if (((char) tempchar) != '\r') {
					System.out.print((char) tempchar);
				}
			}
			reader.close();
		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			try {
				reader.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}
	}
 
  
 
  
 
  
 
  
/** 每次读一个字节数组大小的数据 ***/
	private static void readByByteArray() {
		File file = new File("d:/测试.txt");
		InputStream is = null;
		try {
			StringBuilder sb = new StringBuilder();
			is = new FileInputStream(file);
			byte[] bytes = new byte[1024];

			String str = "";
			int length=0;
			while ((length=is.read(bytes)) != -1) {
				str = new String(bytes,0,length,"gbk");
				sb.append(str);
			}
			
			System.out.println("-------sb---=" + sb.toString());

		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				is.close();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		}

	}
 
  
 
  
 
  
 
  
 
  
 
  
/* 用缓冲流读取文件 **/
	private static void bufferReadFile() {

		File file = new File("d:/测试.txt");
		StringBuffer sb = new StringBuffer();
		String s = "";

		try {
			BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), "gbk"));
			while (((s = reader.readLine()) != null)) {
				sb.append(s + "\n");
			}
			System.out.println("----readResult--=" + sb.toString());
			reader.close();

		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}
 
  
 
  
 
  
 
  
	/** 用StringReader读字符数据 **/
	
	private static void stringReadTest() {

		StringReader sr = new StringReader("马克思主义");
		int totalChar;

		char[] chars = new char[10];

		StringBuilder sb = new StringBuilder();
		String s = "";

		try {
			while ((totalChar = sr.read(chars)) != -1) {
				s = new String(chars, 0, totalChar);
				sb.append(s);
			}

			System.out.println("----result--=" + sb.toString());
			sr.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}
 
  

 
  

 
  
/**用PrintWriter写数据**/
	
	private static void printWriterTest() {
		File file = new File("d:/测试.txt");
		PrintWriter writer = null;
		OutputStream os = null;
		try {
			os = new FileOutputStream(file,true);//“true”  写操作是追加 在文件末尾的
			writer = new PrintWriter(os);
			writer.write("----哈哈，马克思");

		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} finally {
			writer.close();
		}

	}