Reader和Writer是所有字符流类的抽象基类，用于简化对字符串的输入输出编程，即用于读写文本数据
实例：
[java]
import java.io.*;
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public class FileReaderWriterTest {
public static void main(String [] args) {
try {
FileWriter writer = new FileWriter("hello.txt");
writer.write("love_snooker");
writer.close();
FileReader reader = new FileReader("hello.txt");
char[] buf = new char[12];
int len = reader.read(buf);
System.out.println(new String(buf, 0, len));
} catch (Exception e) {
e.printStackTrace();
}
}
}
其它函数用法请参照jdk帮助文档