java_IO_3

Posted 2020-08-17 Practical

Reader和Writer针对字符文件  对图片类文件可能就显得无能为力了  会损坏文件

package iostudy;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

/*
1.创建源
2.选择流
3.操作
4.释放资源
*/
public class IOstudy5 {
    public static void main(String[] args) {
        File file = new File("test.txt");
        //针对字符文件
        Reader reader = null;
        try {
            reader = new FileReader(file);
            char[] buffer = new char[1024];
            int len;
            while ((len = reader.read(buffer)) != -1) {    //一次读取多个
                String s = new String(buffer,0,len);
                System.out.print(s);
            }
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally {
            if(reader!=null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    }
}

View Code

 

 1 package ioStudy;
 2 
 3 import java.io.File;
 4 import java.io.FileNotFoundException;
 5 import java.io.FileWriter;
 6 import java.io.IOException;
 7 import java.io.Writer;
 8 
 9 /*
10 1.创建源
11 2.选择流
12 3.操作
13 4.释放资源
14 */
15 public class IOstudy6 {
16     public static void main(String[] args) {
17         File file = new File("output.txt"); // 不存在会自动创建
18         Writer writer = null;
19 
20         try {
21             writer = new FileWriter(file,true);  //开启向后追加  不然每次都删掉原来的 再写  默认的是false
22             String temp = "hello world!\\r\\n哈哈哈哈，测试中文可以用嘛";
23 //            byte[] b = temp.getBytes();
24             writer.write(temp);
25             writer.flush();   //刷新内存
26         } catch (FileNotFoundException e) {
27             // TODO Auto-generated catch block
28             e.printStackTrace();
29         } catch (IOException e) {
30             // TODO Auto-generated catch block
31             e.printStackTrace();
32         } finally {
33             if (writer != null) {
34                 try {
35                     writer.close();
36                 } catch (IOException e) {
37                     // TODO Auto-generated catch block
38                     e.printStackTrace();
39                 }
40             }
41         }
42     }
43 }

View Code