IO流之字符流知识总结

字符流：读写字符的

顶级父类是Reader和Writer

操作流程

在Java中IO操作也是有相应步骤的，以文件操作为例，主要的操作流程如下：

1. 使用File类打开一个文件
2. 通过字节流或字符流的子类，指定输出的位置
3. 进行读/写操作
4. 关闭输入/输出

思维导图

相关练习代码。

 /**
  * Date   :  2017/7/1
  * Author :  Hsj
  * Description :字符流知识总结
  */
 public class Demo2 {

     //可以读取字符
     @Test
     public void fun() throws IOException {
         FileReader fr = new FileReader("zzz.txt");
         int read = fr.read();
         System.out.println(read);
         char c = (char) read;
         System.out.println(c);
         fr.close();
     }

     //连续读取文字
     @Test
     public void fun2() throws IOException {
         FileReader fr = new FileReader("zzz.txt");
         int len;
         while ((len = fr.read()) != -1) {
             System.out.print((char) len);
         }
         fr.close();
     }

     //文字写入
     @Test
     public void fun3() throws IOException {
         FileWriter fw = new FileWriter("kk.txt");
         fw.write("我是胡少君，你在哪里");
         fw.close();
     }

     //字符拷贝
     @Test
     public void fun4() throws IOException {
         FileReader fr = new FileReader("kk.txt");
         FileWriter fw = new FileWriter("xxx.txt");
         int len;
         while ((len = fr.read()) != -1) {
             fw.write(len);
         }
         fr.close();
         fw.close();//有一个小的缓冲区不关流写不进去
     }

     //自定义数组的拷贝
     @Test
     public void fun5() throws IOException {
         FileReader fr = new FileReader("kk.txt");
         FileWriter fw = new FileWriter("kj.txt");
         char[] chars = new char[1024 * 8];
         int len;
         while ((len = fr.read(chars)) != -1) {
             fw.write(chars, 0, len);
         }
         fr.close();
         fw.close();

     }

     @Test
     //缓冲字符流
     public void fun6() throws IOException {
         BufferedReader br = new BufferedReader(new FileReader("kj.txt"));
         BufferedWriter bw = new BufferedWriter(new FileWriter("hsj.txt"));
         int len;
         while ((len = br.read()) != -1) {
             bw.write(len);
         }
         br.close();
         bw.close();
     }

     //读取一行
     @Test
     public void fun7() throws IOException {
         BufferedReader br = new BufferedReader(new FileReader("hsj.txt"));
         String s;
         while ((s = br.readLine()) != null) {//一行一行的读取文件
             System.out.print(s);
         }
         br.close();
     }

     //添加换行符
     @Test
     public void fun8() throws IOException {
         BufferedReader br = new BufferedReader(new FileReader("hsj.txt"));
         BufferedWriter bw = new BufferedWriter(new FileWriter("lyb.txt"));
         String s;
         while ((s = br.readLine()) != null) {
             bw.write(s);
             bw.newLine();//换行
         }
         br.close();
         bw.close();

     }

     //文本反转
     @Test
     public void fun9() throws IOException {
         List<String> slist = new ArrayList<>();
         BufferedReader br = new BufferedReader(new FileReader("hsj.txt"));
         BufferedWriter bw = new BufferedWriter(new FileWriter("tran.txt"));
         String s;
         while ((s = br.readLine()) != null) {
             slist.add(s);
         }

         for (int i = slist.size() - 1; i >= 0; i--) {
             bw.write(slist.get(i));
             bw.newLine();
         }
         bw.close();
         br.close();
     }

     //    LineNumberReader的使用
     @Test
     public void fun10() throws IOException {
         LineNumberReader lnr = new LineNumberReader(new FileReader("hsj.txt"));
         String line;
         while ((line = lnr.readLine()) != null) {
             System.out.println(lnr.getLineNumber() + ":" + line);

         }
         lnr.close();
     }
 }