CharArrayReader 是字符数组输入流。它和ByteArrayInputStream类似，只不过ByteArrayInputStream是字节数组输入流，而CharArray是字符数组输入流。

import java.io.*;
import java.lang.Math;
public class Test{
    public static void main(String args[]) throws IOException {
    //    CharArrayReader和CharArrayWriter类是字符数组流，字符数组流分别使用字符数组作为流的源和目标
        
        String str = "Hello world!";
        // 构建字符输入流
        CharArrayReader reader = new CharArrayReader(str.toCharArray());
        // 从字符输入流读取字符
        char[] chars = new char[1024];
        int len = reader.read(chars);
        System.out.println(new String(chars, 0, len));

        CharArrayWriter writer = new CharArrayWriter(1024 * 1024);
        // 将字符串写入到CharArrayWriter
        String msg = "hello world！！！22121";
        writer.write(msg.toCharArray());
        System.out.println(writer.toString());
        writer.close();
    }
}