Java 中文编码问题

import java.io.UnsupportedEncodingException;


public class t {

	/**
	 * @param args 可以通过Windows preferences general WorkSpace 设置
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
	
		String str = "我";
		
		byte[] bytes = null;
		try {
			bytes = str.getBytes("GBK"); //2
			System.out.println(bytes.length);
			
			bytes = str.getBytes("UTF-8");//3
			System.out.println(bytes.length);
			
			//str = "我" 报错  此编码方式不支持
			//但是这个为什么输出1 呢  求解
			bytes = str.getBytes("ISO8859_1");
			System.out.println(bytes.length);
		} catch (UnsupportedEncodingException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}