java IO流

 1 /*输出流必须执行flush(),不然写不进去*/
 2 import java.io.*;
 3 public class TestIO {
 4     public static void main(String[] args) throws Exception {
 5       /*单个字符的读取： int read();一个字符被拆成2个8字节，每个8字节占有int的低8位，
 6       作为一个整数返回。*/
 7         Reader r1 = new FileReader("C:/Users/well/Desktop/IO测试.txt");
 8         int b = 0;
 9         while((b = r1.read())!=-1) {
10             System.out.print((char)b);
11         }
12         System.out.println();
13         /*读取的字符暂存到字符数组中，返回本次读取字符的长度*/
14       Reader r2 = new FileReader("C:/Users/well/Desktop/IO测试.txt");
15         char[] ch = new char[5];
16         int len;
17         while((len = r2.read(ch))!=-1) {
18             System.out.println(new String(ch,0,len));
19         }
20         /*写入一个字符串*/
21         Writer w1 = new FileWriter("C:/Users/well/Desktop/新建.txt");
22         w1.write("hello java");
23         w1.flush();
24         /*字符数组写入*/    /*true,不覆盖文档原来的内容*/
25         Writer w2 = new FileWriter("C:/Users/well/Desktop/新建.txt",true);
26         String str = new String("      aha 算法");
27         char[] ch2 = str.toCharArray();//字符串转换成字符数组
28         w2.write(ch2);
29         w2.flush();
30         /*单个字符写入*/
31         Writer w3 = new FileWriter("C:/Users/well/Desktop/新建.txt",true);
32         int k = 65;
33         w3.write(k);
34         w3.flush();
35     }
36 }

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缓冲流

 1 /*输出流必须执行flush(),不然写不进去*/
 2 import java.io.*;
 3 public class TestIO {
 4     public static void main(String[] args) throws Exception {
 5         /*buffered类不仅提供缓冲机制，额外提供两种针对字符的读写方法
 6           （1）按行读取   String readLine();
 7           （2）写入时随时插入换行 newLine();
 8           */
 9       BufferedReader br = new BufferedReader(new FileReader("C:/Users/well/Desktop/IO测试.txt"));
10         String str = null;
11         while((str = br.readLine())!=null)
12             System.out.println(str);
13             
14         BufferedWriter bw = new BufferedWriter(new FileWriter("C:/Users/well/Desktop/新建.txt"));
15         bw.write("Jack Alibaba hangzhou");
16         bw.newLine();
17         bw.write("Pony tengxun shenzhen");
18         bw.newLine();
19         bw.write("BaoLuo baidu beijing");
20         bw.newLine();
21         bw.flush();
22     }
23 }

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数据流

InputStream和OutputStream

 1 import java.io.*;
 2 public class TestIO {
 3     public static void main(String[] args) throws Exception {
 4         InputStream is = new FileInputStream("C:/Users/well/Desktop/IO测试.txt");
 5         int a;
 6         while((a = is.read())!=-1)
 7         System.out.print((char)a);
 8         
 9       InputStream is1 = new FileInputStream("C:/Users/well/Desktop/IO测试.txt");
10         byte[] bt = new byte[500];
11         int b;
12         while((b = is1.read(bt))!=-1) {
13             System.out.print(new String(bt,0,b)); 
14         }
15         
16         OutputStream os = new FileOutputStream("C:/Users/well/Desktop/IO测试.txt",true);
17         os.write(65);
18         os.flush();
19         byte by = (byte)0x40;
20         os.write(by);
21         os.flush();
22     }
23 }

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