Java IO (5) - 总结
0. 目录
- FileInputStream
- FileOutputStream
- FileReader
- FileWriter
- BufferedReader
- BufferedWriter
- InputStreamReader
- OutStreamWriter
1. FileInputStream
FileInputStream主要用来读取二进制数据，当然，也能读取文本文件。在读取文本文件时，通常用做InputStreamReader的输入。
public static void main(String[] args) throws IOException {
FileInputStream fis = new FileInputStream("d:/1234.txt");
byte[] b = new byte[100];
fis.read(b);
System.out.println(new String(b));
fis.close();
}
2. FileOutputStream
同FileInputStream一样，通常用来写二进制文件。
public static void main(String[] args) throws IOException {
FileOutputStream fos = new FileOutputStream("d:/1234.txt", true);
String s = "今天是周五";
fos.write(s.getBytes());
fos.close();
}
3. FileReader
FileReader用来直接读取文件，其编码集是系统默认编码集，会出现乱码问题。
public static void main(String[] args) throws IOException {
FileReader fr = new FileReader("d://1234.txt");
char[] cbuf = new char[100];
fr.read(cbuf);
System.out.println(new String(cbuf));
fr.close();
}
4. FileWriter
FileWriter和FileReader对应，也会出现乱码问题。FileWriter可以追加写。
public static void main(String[] args) throws IOException {
FileWriter fw = new FileWriter("d:/1234.txt", true);
fw.append("你好");
fw.write("world");
fw.close();
}
5. BufferedReader
BufferedReader能够更有效的读文件，提供了readline这个方法，别的reader是没有的。不过BufferedReader需要传入一个Reader。
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new FileReader("d:/1234.txt"));
for (;;) {
String s = br.readLine();
if (s == null || s.equals("")) {
break;
}
System.out.println(s);
}
br.close();
}
6. BufferedWriter
BufferedWriter与BufferedReader对应，提供了writeline方法。BufferedWriter如果要追加写，需要用FileWriter。
public static void main(String[] args) throws IOException {
BufferedWriter bw = new BufferedWriter(new FileWriter("d:/1234.txt",true));
bw.newLine();
bw.write("hahaha");
bw.close();
}
7. InputStreamReader
InputStreamReader用来处理编码问题,也是stream转为reader的桥梁。需要传入一个stream。
public static void main(String[] args) throws IOException {
InputStreamReader isr = new InputStreamReader(new FileInputStream("d:/1234.txt"),"GBK");//UTF-8是乱码
char[] cbuf = new char[1024];
isr.read(cbuf);
System.out.println(new String(cbuf));
isr.close();
}
8. OutStreamWriter
OutStreamWriter同样处理写文件的乱码，与InputStreamReader对应。
public static void main(String[] args) throws IOException {
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream(
"d:/1234.txt", true), "GBK");
osw.write("今天放假");
osw.close();
}