转：使用StringReader和StringWriter操作字符串

编程举例：写一函数把StringReader中输入流中的字符串全部转换成大写，然后将结果写到一个StringWriter中，然后使用这一函数将以字符串全部转成大写。

 

package cn.itcast.stringstream;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
public class StringStreamTest {
    public static void main(String[] args) {
        String str = "abcdefghijklmn";
        transform(str);
    }
    public static void transform(String str) {
        StringReader sr = new StringReader(str);
        StringWriter sw = new StringWriter();
        char[] chars = new char[1024];
        try {
            int len = 0;
            while ((len = sr.read(chars)) != -1) {
                String strRead = new String(chars, 0, len).toUpperCase();
                System.out.println(strRead);
                sw.write(strRead);
                sw.flush();
            }
            sr.close();
            sw.close();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            sr.close();
            try {
                sw.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}