JAVA字元流InputStreamReader讀取文本

二.字元流

1.單個字元讀取

public static void main(String[] args){
		try {
			InputStreamReader in = new InputStreamReader(
					new FileInputStream("D:\\bf\\Desktop\\test.txt"), "UTF-8");
			int n ;
			while((n = in.read()) != -1){
				System.out.print((char)n); 
			}
			in.close();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		 
	}
           

2.按行讀取，利用BufferedReader對象提供的readLine()方法

public static void main(String[] args) {
		BufferedReader reader=null;
		try {
			InputStreamReader read = new InputStreamReader(new FileInputStream("D:\\bf\\Desktop\\test.txt"), "UTF-8");
			reader = new BufferedReader(read);
			String line=null;
						
			while((line =reader.readLine()) != null){
				System.out.println(line);						
			}			
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		} catch (IOException e) {			
			e.printStackTrace();
		}finally {
			if (reader !=null) {
				try {
					reader.close();
				} catch (IOException e) {					
					e.printStackTrace();
				}
			}
		}
		
	}
           

InputStreamReader是一個一個字元讀取的，每次讀取都會執行一次IO,IO操作很浪費時間，這就導緻程式效率降低，而BufferedReader可以一次讀取大量的資料，大大減少了IO次數，提升效率。