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();
    }
}