【Java筑基】IO流基础之常见工具流和进程通信

    public class KeyinTest {
    	public static void main(String[] args) {
    		try (InputStreamReader reader = new InputStreamReader(System.in);
                 	//BufferedReader has readLine() to read by Line
    				BufferedReader br = new BufferedReader(reader)) {
    			String line = null;
    			while ((line = br.readLine()) != null) {
    				if (line.equals("exit")) {
    					System.exit(1);
    				}
    				;
    				System.out.println("输出的内容是:" + line);
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    }

    public class PushbackTest {
    	public static void main(String[] args) {
    		// 指定推回缓冲区长度为64.
    		try (PushbackReader pr = new PushbackReader(new FileReader(
    				"src/inputandoutput/PushbackTest.java"), 64)) {
    			char[] buff = new char[32];
    			String lastContent = "";
    			int hasRead = 0;
    			while ((hasRead = pr.read(buff)) > 0) {
    				String content = new String(buff, 0, hasRead);
    				int targetIndex = 0;
    				if ((targetIndex = (content + lastContent)
    						.indexOf("new PushbackIndex")) > 0) {
    					pr.unread((lastContent + content).toCharArray());
    					if (targetIndex > 32) {
    						buff = new char[targetIndex];
    					}
    					pr.read(buff, 0, targetIndex);
    					System.out.print(new String(buff, 0, targetIndex));
    					System.exit(0);
    				} else {
    					System.out.println(lastContent);
    					lastContent = content;
    				}
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    }

public class RedirectOut {
	public static void main(String[] args) {
		try (PrintStream ps = new PrintStream(new FileOutputStream("out.txt"))) {
			// redirect the output to ps
			System.setOut(ps);
			System.out.println("hello");
			System.out.println(new RedirectOut());
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

    public class RedirectIn {
    	public static void main(String[] args) {
    		try (FileInputStream in = new FileInputStream(
    				"src/inputandoutput/RedirectIn.java")) {
    			System.setIn(in);
    			Scanner scan = new Scanner(System.in);
    			// only use \n as Delimiter
    			scan.useDelimiter("\n");
    			while (scan.hasNext()) {
    				System.out.println("content:" + scan.next());
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    }

    public class ReadFromTest {
    	public static void main(String[] args) throws IOException {
    		Process p = Runtime.getRuntime().exec("javac");
    		try (BufferedReader br = new BufferedReader(new InputStreamReader(
    				p.getErrorStream()))) {
    			String buff = null;
    			while ((buff = br.readLine()) != null) {
    				System.out.println(buff);
    			}
    		}
    	}
    }

    public class WriteToProcess {
    	public static void main(String[] args) throws IOException {
    		Process p = Runtime.getRuntime().exec("java ReadStandard");
    		try (
    		// 以p进程的输出流创建PrintStream，该输出流对本进程为输出流，对p进程则为输入流
    		PrintStream ps = new PrintStream(p.getOutputStream())) {
    			ps.println("normal string");
    			ps.println(new WriteToProcess());
    		}
    	}
    }
    
    class ReadStandard {
    	public static void main(String[] args) throws FileNotFoundException {
    		try (Scanner scan = new Scanner(System.in);
    				PrintStream ps = new PrintStream(
    						new FileOutputStream("out.txt"))) {
    			scan.useDelimiter("\n");
    			while (scan.hasNext()) {
    				ps.println("KeyBoards input:" + scan.next());
    			}
    		} catch (IOException e) {
    			e.printStackTrace();
    		}
    	}
    }