Java面试：请手写一个文件读取的方法

1.在堆中开辟对象所需空间，分配地址
2.初始化对象
3.将内存地址返回给栈中的引用变量

public class IOTest {
  String filePath = "c:/1.txt";
  @Test
  public void dataStream() throws Exception{
    File file = new File(filePath);
    FileInputStream fis = new FileInputStream(file);
    byte[] bytes = new byte[(int) file.length()]; //打算一口气读完
    fis.read(bytes); //把字节全部读到数组里面
    System.out.println(new String(bytes));
  }
}

@Test
public void CharStream() throws Exception{
  File file = new File(filePath);
  FileReader fr = new FileReader(file);
  char[] cbuf = new char[(int) file.length()]; //打算一口气读完
  fr.read(cbuf);//把字符全部读到数组里面
  System.out.println(new String(cbuf));
}

@Test
public void BufferStream() throws Exception{
  File file = new File(filePath);
  FileReader fr = new FileReader(file);
  BufferedReader br = new BufferedReader(fr);
  String line = null;
  while((line = br.readLine()) != null){
    System.out.println(line);
  }
}