java中流的簡單應用

知識點一：從網上讀取某一網址內容後寫入到一個檔案

public class BufferedTest {
    public void test() throws IOException {

        URL url =new URL("https://www.baidu.com/");
        InputStream inputStream =url.openStream();
        InputStreamReader inputStreamReader =new InputStreamReader(inputStream);
        BufferedReader bufferedReader =new BufferedReader(inputStreamReader);

        FileOutputStream fileOutputStream =new FileOutputStream("E:/io/test.html");
        OutputStreamWriter outputStreamWriter =new OutputStreamWriter(fileOutputStream);
        BufferedWriter bufferedWriter =new BufferedWriter(outputStreamWriter);
        String s=new String();
        while ((s=bufferedReader.readLine())!=null){
            bufferedWriter.write(s);
        }
        bufferedReader.close();
        bufferedWriter.close();
        System.out.println("ok");
    }
    public static void main(String[] args) throws IOException {
        BufferedTest bufferedTest =new BufferedTest();
        bufferedTest.test();

    }
}
 

知識點二：用位元組流讀入讀出檔案內容：

 File file =new File("E:/io/ioTest.txt");
        FileInputStream fileInputStream =new FileInputStream(file);
        FileOutputStream fileOutputStream =new FileOutputStream("E:/io/huahua.txt");
        byte[] bytes =new byte[1024];
        int num;
        while ((num=fileInputStream.read(bytes))!=-1){
            String s=new String(bytes, 0, num);
            fileOutputStream.write(bytes, 0, num);
        }
 

知識點三：用字元流讀入讀出檔案內容：

 File file =new File("E:/io/ioTest.txt");
        FileReader fileReader =new FileReader(file);
        FileWriter fileWriter =new FileWriter("E:/io/test.txt");
        char[] chars=new char[1024];
        int num=0;
        while ((num=fileReader.read(chars))!=-1){
            String s=new String(chars, 0, num);
            fileWriter.write(s);
        }
        fileReader.close();
        fileWriter.close();