读写文件

File file = new File("./test.txt");

if (!file.exists()) {

    try {

        file.createNewFile();

    } catch (Exception e) {

        e.printStackTrace();

        return;

    }

}

try {

    FileOutputStream out = new FileOutputStream(file);

    OutputStreamWriter writer = new OutputStreamWriter(out);

    writer.write("hello, world!");

    out.flush();

    out.close();

} catch (Exception e) {

    e.printStackTrace();

}

try {

    FileInputStream in = new FileInputStream(file);

    byte[] bytes = new byte[10];

    in.read(bytes);

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

} catch (Exception e) {

    e.printStackTrace();

}