Java IO 流 -- 转换流: InputStreamReader OutputStreamWriter

java 中 转换流是以字符流的形式操作字节流，需要注意一下两点：
1、操作内容必须是纯文本
2、指定字符集避免乱码

操作控制台输入输出：

try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
				BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));) {
			String msg = "";
			while (!msg.equals("exit")) {
				msg = br.readLine();
				bw.write(msg);
				bw.newLine();
				bw.flush();
			}
		} catch (IOException e) {
			e.printStackTrace();
		}

这里没有指定字符集是因为控制台和工程的字符集一致，不会乱码

操作网络流：

try (BufferedReader read = new BufferedReader(
				new InputStreamReader(new URL("http://www.baidu.com").openStream(),"utf-8"));

				BufferedWriter writer = new BufferedWriter(
						new OutputStreamWriter(new FileOutputStream("baidu.html"),"utf-8"));

		) {
			String msg = "";
			while ((msg = read.readLine()) != null) {
				System.out.println(msg);
				writer.write(msg);
				writer.newLine();
			}
			writer.flush();
		} catch (IOException e) {
			e.printStackTrace();
		}

基本就这样的套路，一般为了提高性能都会套上BufferedRead 和 BufferredWrite。