字符输入流-Reader demo 2

package reader.cn;

import java.io.File;
import java.io.FileReader;
import java.io.Reader;

/*
 * 改进2 使用循环的方式读取内容
 */
public class ReaderDemo2 {
    public static void main(String[] args) throws Exception {
        //利用file 指定路径
        File f = new File("d:"+File.separator+"test.txt");
        //通过子类实例化父类对象
        Reader r = new FileReader(f);
        //开辟一个字符空间
        char[] ch = new char[(int)f.length()];
        int temp;
        int len = 0;
        while ((temp = r.read())!=-1) {
             ch[len] = (char)temp;
             len++;        
        }
        
        System.out.println(new String (ch));
        
    }

}