字符流：讀寫字符的

頂級父類是Reader和Writer

操作流程

在Java中IO操作也是有相應步驟的，以文件操作為例，主要的操作流程如下：

1. 使用File類打開一個文件
2. 通過字節流或字符流的子類，指定輸出的位置
3. 進行讀/寫操作
4. 關閉輸入/輸出

思維導圖

相關練習代碼。

  1 /**
  2  * Date   :  2017/7/1
  3  * Author :  Hsj
  4  * Description :字符流知識總結
  5  */
 

  6 public class Demo2 {
  7 
  8 
  9     //可以讀取字符
 10     @Test
 11     public void fun() throws IOException {
 12         FileReader fr = new FileReader("zzz.txt");
 13         int read = fr.read();
 14         System.out.println(read);
 15         char c = (char) read;
 16         System.out.println(c);
 
 17         fr.close();
 18     }
 19 
 20     //連續讀取文字
 21     @Test
 22     public void fun2() throws IOException {
 23         FileReader fr = new FileReader("zzz.txt");
 24         int len;
 25         while ((len = fr.read()) != -1) {
 26             System.out.print((char) len);
 27         }
 28
 
         fr.close();
 29     }
 30 
 31     //文字寫入
 32     @Test
 33     public void fun3() throws IOException {
 34         FileWriter fw = new FileWriter("kk.txt");
 35         fw.write("我是胡少君，你在哪裏");
 36         fw.close();
 37     }
 38 
 39     //字符拷貝
 40     @Test
 41     public void fun4() throws IOException {
 42         FileReader fr = new FileReader("kk.txt");
 43         FileWriter fw = new FileWriter("xxx.txt");
 44         int len;
 45         while ((len = fr.read()) != -1) {
 46             fw.write(len);
 47         }
 48         fr.close();
 49         fw.close();//有一個小的緩沖區不關流寫不進去
 50     }
 51 
 52     //自定義數組的拷貝
 53     @Test
 54     public void fun5() throws IOException {
 55         FileReader fr = new FileReader("kk.txt");
 56         FileWriter fw = new FileWriter("kj.txt");
 57         char[] chars = new char[1024 * 8];
 58         int len;
 59         while ((len = fr.read(chars)) != -1) {
 60             fw.write(chars, 0, len);
 61         }
 62         fr.close();
 63         fw.close();
 64 
 65     }
 66 
 67     @Test
 68     //緩沖字符流
 69     public void fun6() throws IOException {
 70         BufferedReader br = new BufferedReader(new FileReader("kj.txt"));
 71         BufferedWriter bw = new BufferedWriter(new FileWriter("hsj.txt"));
 72         int len;
 73         while ((len = br.read()) != -1) {
 74             bw.write(len);
 75         }
 76         br.close();
 77         bw.close();
 78     }
 79 
 80     //讀取一行
 81     @Test
 82     public void fun7() throws IOException {
 83         BufferedReader br = new BufferedReader(new FileReader("hsj.txt"));
 84         String s;
 85         while ((s = br.readLine()) != null) {//一行一行的讀取文件
 86             System.out.print(s);
 87         }
 88         br.close();
 89     }
 90 
 91     //添加換行符
 92     @Test
 93     public void fun8() throws IOException {
 94         BufferedReader br = new BufferedReader(new FileReader("hsj.txt"));
 95         BufferedWriter bw = new BufferedWriter(new FileWriter("lyb.txt"));
 96         String s;
 97         while ((s = br.readLine()) != null) {
 98             bw.write(s);
 99             bw.newLine();//換行
100         }
101         br.close();
102         bw.close();
103 
104     }
105 
106     //文本反轉
107     @Test
108     public void fun9() throws IOException {
109         List<String> slist = new ArrayList<>();
110         BufferedReader br = new BufferedReader(new FileReader("hsj.txt"));
111         BufferedWriter bw = new BufferedWriter(new FileWriter("tran.txt"));
112         String s;
113         while ((s = br.readLine()) != null) {
114             slist.add(s);
115         }
116 
117         for (int i = slist.size() - 1; i >= 0; i--) {
118             bw.write(slist.get(i));
119             bw.newLine();
120         }
121         bw.close();
122         br.close();
123     }
124 
125     //    LineNumberReader的使用
126     @Test
127     public void fun10() throws IOException {
128         LineNumberReader lnr = new LineNumberReader(new FileReader("hsj.txt"));
129         String line;
130         while ((line = lnr.readLine()) != null) {
131             System.out.println(lnr.getLineNumber() + ":" + line);
132 
133         }
134         lnr.close();
135     }
136 }

IO流之字符流知識總結