【java】打印流的基本实现及java.io.PrintStream、java.io.PrintWriter示例

 1 package 打印流;
 2 
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.OutputStream;
 7 
 8 class MyPrint{
 9     private OutputStream out;
10     public MyPrint(OutputStream out){
11         this.out=out;
12     }
13     public void print(String str) throws IOException{
14         out.write(str.getBytes());
15     }
16     public void print(int i) throws IOException{
17         print(String.valueOf(i));
18     }
19     public void print(byte b) throws IOException{
20         print(String.valueOf(b));
21     }
22     public void print(short s) throws IOException{
23         print(String.valueOf(s));
24     }
25     public void print(long l) throws IOException{
26         print(String.valueOf(l));
27     }
28     public void print(float f) throws IOException{
29         print(String.valueOf(f));
30     }
31     public void print(double d) throws IOException{
32         print(String.valueOf(d));
33     }
34     public void print(boolean b) throws Exception{
35         print(String.valueOf(b));
36     }
37     public void print(char c) throws IOException{
38         print(String.valueOf(c));
39     }
40     public void close() throws IOException{
41         out.close();
42     }
43 }
44 public class TestPrint {
45     public static void main(String[] args) throws IOException {
46         MyPrint myPrint=new MyPrint(new FileOutputStream(new File("D:"+File.separator+"testA.txt")));
47         myPrint.print(8.8);
48         myPrint.print('a');
49         myPrint.close();
50     }
51 }

MyPrint

 1 package 打印流;
 2 
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.FileWriter;
 6 import java.io.IOException;
 7 import java.io.PrintStream;
 8 import java.io.PrintWriter;
 9 
10 public class TestPrintStream {
11     public static void main(String[] args) throws IOException {
12         PrintStream printStream=new PrintStream(new FileOutputStream(new File("D:"+File.separator+"Test.txt")));
13         printStream.print(true);
14         printStream.println("abc中国人");
15         printStream.close();
16         
17         PrintWriter printWriter=new PrintWriter(new FileWriter(new File("D:"+File.separator+"testA.txt")));
18         printWriter.print(false);
19         printWriter.println(89898.23);
20         printWriter.close();
21     }    
22 }

PrintStream和PrintWriter

 1 package 打印流;
 2 
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.PrintStream;
 7 
 8 public class TestPrintStream {
 9     public static void main(String[] args) throws IOException {
10         String name = "张三";
11         int age = 20;
12         float height = 1.7586f;
13         PrintStream printStream = new PrintStream(new FileOutputStream(
14                 new File("D:" + File.separator + "Test.txt")));
15         printStream.printf("姓名：%s，年龄：%d，身高：%1.2f", name, age, height);
16         printStream.close();
17 
18         // PrintWriter printWriter=new PrintWriter(new FileWriter(new
19         // File("D:"+File.separator+"testA.txt")));
20         // printWriter.close();
21         System.out.println(String.format("姓名：%s，年龄：%d，身高：%1.2f", name, age,
22                 height));
23     }
24 }

格式化输出

输出操作建议用打印流，而不是输出流