1.字节流介绍
InputStream和OutputStream是字节流的顶级父类, 所有的字节输入流继承自InputStream, 所有的字节输出流继承自OutputStream
2.FileOutputStream
1 package deom03;
2
3 import java.io.FileOutputStream;
4 import java.io.IOException;
5
6 public class FileOutputStreamDemo {
7 public static void main(String[] args) throws IOException {
8 FileOutputStream out = new FileOutputStream("c:\\out.txt");
9 //void write(int b) 向输出流写入一个字节 d
10 out.write(100);
11 out.close();
12
13 byte[] bytes = {65,66,67,68};
14 FileOutputStream out1 = new FileOutputStream("c:\\out1.txt");
15 //void write(byte[] b) 写入字节数组 ABCD
16 out1.write(bytes);
17 out1.close();
18
19 FileOutputStream out2 = new FileOutputStream("c:\\out2.txt");
20 //向文件中写入一个字符串
21 out2.write("hello".getBytes());
22 out2.close();
23
24 //追加写入
25 FileOutputStream out3 = new FileOutputStream("c:\\out3.txt", true);
26 //向文件中写入一个字符串
27 out3.write("hello".getBytes());
28 out3.write("world".getBytes());
29 out3.close();
30
31 //追加 换行写入
32 FileOutputStream out4 = new FileOutputStream("c:\\out4.txt", true);
33 //向文件中写入一个字符串
34 out4.write("hello".getBytes());
35 out4.write("\r\n".getBytes());
36 out4.write("world".getBytes());
37 out4.close();
38
39 //异常处理
40 MyException();
41 }
42
43 //异常处理
44 public static void MyException() {
45 FileOutputStream out5 = null;
46 try {
47 out5 = new FileOutputStream("c:\\out5.txt");
48 out5.write(100);
49 } catch (IOException e) {
50 System.out.println(e.getMessage());
51 throw new RuntimeException("文件写入失败");
52 } finally {
53 try {
54 if (out5 != null) {
55 out5.close();
56 }
57 } catch (IOException e2) {
58 System.out.println(e2.getMessage());
59 throw new RuntimeException("关闭资源失败");
60 }
61
62 }
63 }
64 }
3.FileInputStream
1 package deom03;
2
3 import java.io.FileInputStream;
4 import java.io.IOException;
5
6 //input1.txt 内容 abc
7 public class FileInputStreamDemo {
8 public static void main(String[] args) throws IOException {
9 FileInputStream in = new FileInputStream("c:\\input1.txt");
10
11 //int read() 读取一个字节转换为整数并返回这一整数
12 int i = 0;
13 while ((i = in.read()) != -1) {
14 System.out.println(i);
15 }
16 in.close();
17
18 //int read(byte[] b) 读取若干字节并保存到字节数组中
19 FileInputStream in1 = new FileInputStream("c:\\input1.txt");
20 byte[] b = new byte[3];
21 int len = in1.read(b);
22 System.out.println(new String(b)); //abc
23 System.out.println(len); //3
24 in1.close();
25 }
26 }
4.文件复制
第一种方式
1 package deom03;
2
3 import java.io.FileInputStream;
4 import java.io.FileOutputStream;
5 import java.io.IOException;
6
7 //文件复制-效率低
8 public class Copy {
9 public static void main(String[] args) {
10 FileInputStream in = null;
11 FileOutputStream out = null;
12 try {
13 in = new FileInputStream("c:\\xampp安装包.zip");
14 out = new FileOutputStream("c:\\11.zip");
15
16 int len = 0;
17 while ((len = in.read()) != -1) {
18 out.write(len);
19 }
20 } catch (IOException e) {
21 System.out.println(e);
22 System.out.println("文件复制失败");
23 } finally {
24 try {
25 if (out != null) {
26 out.close();
27 }
28 } catch (IOException e1) {
29 throw new RuntimeException("释放资源失败");
30 } finally {
31 try {
32 if (in != null) {
33 in.close();
34 }
35 } catch (IOException e2) {
36 throw new RuntimeException("释放资源失败");
37 }
38 }
39 }
40 }
41 }
第二种方式
1 package deom03;
2
3 import java.io.FileInputStream;
4 import java.io.FileOutputStream;
5 import java.io.IOException;
6
7 //文件复制-效率高
8 public class CopyFast {
9 public static void main(String[] args) {
10 FileInputStream in = null;
11 FileOutputStream out = null;
12
13 try {
14 in = new FileInputStream("c:\\xampp安装包.zip");
15 out = new FileOutputStream("c:\\11.zip");
16 byte[] bytes = new byte[1024];
17 int len = 0;
18 while ((len = in.read(bytes)) != -1) {
19 out.write(bytes, 0, len);
20 }
21 } catch (IOException e) {
22 System.out.println(e);
23 System.out.println("文件复制失败");
24 } finally {
25 try {
26 if (out != null) {
27 out.close();
28 }
29 } catch (IOException e1) {
30 throw new RuntimeException("释放资源失败");
31 } finally {
32 try {
33 if (in != null) {
34 in.close();
35 }
36 } catch (IOException e2) {
37 throw new RuntimeException("释放资源失败");
38 }
39 }
40 }
41 }
42 }
5.字符流介绍
Reader和Writer是字符流的顶级父类, 所有的字符输入流继承自Reader, 所有的字符输出流继承自Writer
6.FileReader
1 package deom03;
2
3 import java.io.FileReader;
4 import java.io.IOException;
5
6 public class ReaderDemo {
7 public static void main(String[] args) throws IOException {
8 FileReader fr = new FileReader("c:\\1.txt");
9 int len = 0;
10 while ((len = fr.read()) != -1) {
11 System.out.print((char)len);
12 }
13 fr.close();
14
15 FileReader fr1 = new FileReader("c:\\1.txt");
16 char[] ch = new char[1024];
17 int len1 = 0;
18 while ((len1 = fr1.read(ch)) != -1) {
19 System.out.println(new String(ch, 0, len1));
20 }
21 }
22 }
7.FileWriter
1 package deom03;
2
3 import java.io.FileWriter;
4 import java.io.IOException;
5
6 public class WriterDemo {
7 public static void main(String[] args) throws IOException {
8 FileWriter fw = new FileWriter("c:\\1.txt");
9
10 //写一个字符
11 fw.write(100);
12 fw.flush();
13
14 //写一个字符数组
15 char[] c = {‘a‘,‘b‘,‘c‘};
16 fw.write(c);
17 fw.flush();
18
19 //写一个字符数组一部分
20 fw.write(c,0,2);
21 fw.flush();
22
23 //写一个字符串
24 fw.write("你好");
25 fw.flush();
26
27 fw.close();
28 }
29 }
时间： 2024-07-31 07:01:10