常用操作

 1 import java.io.File;
 2 import java.io.FileReader;
 3 import java.io.FileWriter;
 4 
 5 public class FileDemo3 {
 6     public static void main(String[] args) throws Exception {
 7         // 字符流的操作
 8 
 9 // 字符流的读写类都是集成Reader/Writer
10 
11         File file = new File("demo.txt");
12 
13         FileWriter fw = new FileWriter(file);
14 
15         fw.write("abcdefg"); // 主要是可以写入字符串 比较方便 不需要转成byte[]
16 
17         fw.close();
18 
19         // 读取
20         FileReader fr = new FileReader(file);
21         StringBuffer strBuffer = new StringBuffer();
22 
23         char[] buf = new char[20];
24         int length;
25         while (-1 != (length = fr.read(buf, 0, buf.length))) {
26             strBuffer.append(buf, 0, length);
27         }
28         
29         fr.close();
30         
31         if(!file.delete())
32             System.out.println("删除文件失败");
33         
34         System.out.println(strBuffer.toString());
35     }
36 }