字节流和字符流的read方法
public class Test { public void fileOutput() throws Exception { File file = new File("D:/2.txt"); FileOutputStream fileOutputStream = new FileOutputStream(file); String s = "abcdefg"; fileOutputStream.write(s.getBytes()); fileOutputStream.close(); } /** * fileInputStream.read()是一个字节一个字节的读,返回值为根据ascii码表转成的int值 * 输出结果 97 a 98 b 99 c 100 d 101 e 102 f 103 g * * @throws Exception */ public void fileInput() throws Exception { File file = new File("D:/2.txt"); FileInputStream fileInputStream = new FileInputStream(file); int a; while ((a = fileInputStream.read()) != -1) { System.out.println(a); System.out.println((char)a); } fileInputStream.close(); } /** * 输出结果: * 97 * 98 * 99 * 100 * 101 * 102 * 103 * [B@5a8e6209 * abcdefg * * @throws Exception */ public void fileInput2() throws Exception { File file = new File("D:/2.txt"); FileInputStream fileInputStream = new FileInputStream(file); int a; int[] b = new int[10]; byte[] c = new byte[10]; int len = 0; while ((a = fileInputStream.read()) != -1) { b[len] = a; c[len] = (byte) a; len++; } for (int i = 0; i < len; i++) { System.out.println(b[i]); } System.out.println(c.toString()); System.out.println(new String(c)); fileInputStream.close(); } /** * 带参数read(byte[] b)方法,读取参数b字节大小 * 其返回值为int类型,the total number of bytes read into the buffer, or <code>-1</code> if there is no more data because the end of the file has been reached. * 输出结果: * 7 * -1 * abcdefg * * @throws Exception */ public void fileInput3() throws Exception { File file = new File("D:/2.txt"); FileInputStream fileInputStream = new FileInputStream(file); byte[] b = new byte[10]; byte[] bb = new byte[5]; int a = fileInputStream.read(b); int c = fileInputStream.read(bb); System.out.println(a); System.out.println(c); System.out.println(new String(b)); fileInputStream.close(); } /** * 输出结果 * 7 * abcdefg * * @throws Exception */ public void fileInput4() throws Exception { File file = new File("D:/2.txt"); FileInputStream fileInputStream = new FileInputStream(file); byte[] b = new byte[10]; int a = fileInputStream.read(b, 0, new Long(file.length()).intValue()); System.out.println(a); System.out.println(new String(b)); fileInputStream.close(); } /** * 输出结果: * 97 * 98 * 99 * 100 * 101 * 102 * 103 * @throws Exception */ public void fileReader() throws Exception { File file = new File("D:/2.txt"); FileReader fileReader = new FileReader(file); int a; while ((a=fileReader.read())!=-1){ System.out.println(a); } fileReader.close(); } /** * 输出结果: * abcdefg * @throws Exception */ public void fileReader2() throws Exception { File file = new File("D:/2.txt"); FileReader fileReader = new FileReader(file); int a; int len=0; byte[] b=new byte[10]; while ((a=fileReader.read())!=-1){ b[len]=(byte) a; len++; } System.out.println(new String(b)); fileReader.close(); } /** * 输出结果: * abcdefg * @throws Exception */ public void fileReader3() throws Exception { File file = new File("D:/2.txt"); FileReader fileReader = new FileReader(file); char[] cbuf=new char[10]; fileReader.read(cbuf); System.out.println(new String(cbuf)); fileReader.close(); } public static void main(String[] args) throws Exception { Test test = new Test(); test.fileInput();
} }