黑马程序员 java基础IO FileReader FileWriter

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/*

* 字符流

* FileReader

* FileWriter

*

* BufferedReader

* BufferedWriter

*

* 字节流(操作图片)

* FileInputStream

* FileOutputStream

*

* BufferedInputStream

* BUfferedOutputStream

*

* 需求：

* InputStream（读） OutputStream(写)

* 想要操作图片数据 这时就要用到字节流

*

*/

public class OutputStreamDemo {

/**

* @param args

* @throws IOException

*/

public static void main(String[] args) throws IOException {

// TODO Auto-generated method stub

// writerFile();

readFile_3();

}

public static void readFile_3() throws IOException {

FileInputStream fis = new FileInputStream("copyByBuf.txt");

int num = fis.available();

System.out.println(num);

byte[] buf = new byte[num];// 定义个刚刚好的缓冲区 不用循环了

fis.read(buf);

System.out.println(new String(buf));

fis.close();

}

public static void readFile_2() throws IOException {

FileInputStream fis = new FileInputStream("fos.txt");

byte[] buf = new byte[1024];

int len = 0;

while ((len = fis.read(buf)) != -1) {

System.out.println(new String(buf, 0, len));

}

fis.close();

}

public static void readFile_1() throws IOException {

FileInputStream fis = new FileInputStream("fos.txt");

int ch = 0;

while ((ch = fis.read()) != -1) {

System.out.println((char) ch);

}

fis.close();

}

public static void writerFile() throws IOException {

FileOutputStream fos = new FileOutputStream("fos.txt");

fos.write("asdasd".getBytes());

fos.close();

}

}

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