Java IO-3 转换流和缓冲流

Posted 2020-09-20

1.转换流

OutputStreamWriter和InputStreamReader

 1 package demo04;
 2 
 3 import java.io.FileInputStream;
 4 import java.io.IOException;
 5 import java.io.InputStreamReader;
 6 
 7 public class InputStreamReaderDemo {
 8     public static void main(String[] args) throws IOException {
 9         FileInputStream in = new FileInputStream("c:\\gbk.txt");
10         InputStreamReader r = new InputStreamReader(in);
11         char[] ch = new char[1024];
12         int len = r.read(ch);
13         System.out.println(new String(ch, 0, len));
14         r.close();
15     }
16 }

 1 package demo04;
 2 
 3 import java.io.FileOutputStream;
 4 import java.io.IOException;
 5 import java.io.OutputStreamWriter;
 6 
 7 public class OutputStreamWriterDemo {
 8     public static void main(String[] args) throws IOException {
 9         FileOutputStream out = new FileOutputStream("c:\\utf8.txt");
10         //默认GBK编码 占4个字节
11         //OutputStreamWriter os = new OutputStreamWriter(out);
12         //UTF-8编码  占6个字节
13         OutputStreamWriter os = new OutputStreamWriter(out, "UTF-8");
14         os.write("你好");
15         os.close();
16     }
17 }

2.字节缓冲流

分为BufferedInputStream和BufferedOutputStream, 它们的构造方法分别接受InputStream和OutputStream类型的参数作为被包装对象, 在读写数据时提供缓冲功能

 1 package demo04;
 2 
 3 import java.io.BufferedInputStream;
 4 import java.io.FileInputStream;
 5 import java.io.IOException;
 6 
 7 public class BufferedInputStreamDemo {
 8     public static void main(String[] args) throws IOException {
 9         BufferedInputStream ins = new BufferedInputStream(new FileInputStream("c:\\buffer.txt"));
10         byte[] bytes = new byte[20];
11         int len = 0;
12         while ((len = ins.read(bytes)) != -1 ) {
13             System.out.println(new String(bytes, 0, len));
14         }
15         ins.close();
16     }
17 }

 1 package demo04;
 2 
 3 import java.io.BufferedOutputStream;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 
 7 public class BufferedOutputStreamDemo {
 8     public static void main(String[] args) throws IOException {
 9         FileOutputStream out = new FileOutputStream("c:\\buffer.txt");
10         BufferedOutputStream buf = new BufferedOutputStream(out);
11         buf.write(100);
12         buf.close();
13     }
14 }

3.字符缓冲流

分为BufferedWriter和BufferedReader

 1 package demo04;
 2 
 3 import java.io.BufferedReader;
 4 import java.io.FileReader;
 5 import java.io.IOException;
 6 
 7 public class BufferedReaderDemo {
 8     public static void main(String[] args) throws IOException {
 9         BufferedReader bfr = new BufferedReader(new FileReader("c:\\reader.txt")); 
10         String line = null;
11         while ((line = bfr.readLine()) != null) {
12             System.out.println(line);
13         }
14         bfr.close();
15     }
16 }

 1 package demo04;
 2 
 3 import java.io.BufferedWriter;
 4 import java.io.FileWriter;
 5 import java.io.IOException;
 6 
 7 public class BufferedWriterDemo {
 8     public static void main(String[] args) throws IOException {
 9         FileWriter fw = new FileWriter("c:\\buffer.txt");
10         BufferedWriter bfw  = new BufferedWriter(fw);
11         bfw.write(100);
12         bfw.flush();
13         
14         bfw.write("你好".toCharArray());
15         bfw.flush();
16         
17         //换行 与平台无关
18         bfw.newLine();
19         bfw.write("你好".toCharArray());
20         bfw.flush();
21         
22         bfw.close();
23     }
24 }