编写下面的程序代码,分析和观察程序的运行结果:
import Java.io.*;
public class TestCodeIO {
public static void main(String[] args) throws Exception{
InputStreamReader isr = new InputStreamReader(System.in,"iso8859-1");
BufferedReader br = new BufferedReader (isr);
String strLine = br.readLine();
br.close();
isr.close();
System.out.println(strLine);
}
}
运行程序后,输入“中国”两个字,输出结果为 ???ú
请按照下面两种方法修改上述程序,是输入的中文能够正常输出
1。修改程序中的语句
InputStreamReader isr = new InputStreamReader(System.in,"iso8859-1");
2。不修改上面的语句,修改下面的语句
System.out.println(strLine);
第一种该法很简单,只要改成下面这样就可以了,这里不详细讨论
InputStreamReader isr = new InputStreamReader(System.in,"gb2312");
这里我要详细讨论的是第二种该法怎么改
起初我是这样改的
System.out.println(new String (strLine.getBytes(),"iso8859-1"));
输入“中国”后输出的结果虽然不是上面所述的乱码,但是还是乱码,显然这种该法是不正确的!
这里我要感谢 软件民工 告诉我的正确改法,使我恍然大悟
System.out.println(new String (strLine.getBytes("iso8859-1")));
这两种改法究竟有什么区别呢?为了方便大家阅读,我先把正确和错误的改法帖出来:
import Java.io.*;
public class TestCodeIO {
public static void main(String[] args) throws Exception{
InputStreamReader isr = new InputStreamReader(System.in,"iso8859-1");
//Create an InputStreamReader that uses the given charset decoder
BufferedReader br = new BufferedReader (isr);
String strLine = br.readLine();
br.close();
isr.close();
System.out.println(strLine);
System.out.println(new String (strLine.getBytes(),"iso8859-1"));//错误改法
//Encodes this String (strLine) into a sequence of bytes using the platform’s
//default charset(gb2312) then constructs a new String by decoding the
//specified array of bytes using the specified charset (iso8859-1)
//because this String (strLine) uses the charset decoder "iso8859-1",so it can
//only be encoded by "iso8859-1",cann’t be encoded by the platform’s default
//charset "gb2312",so this line is wrong.
System.out.println(new String (strLine.getBytes("iso8859-1")));//正确改法
//Encodes this String (strLine) into a sequence of bytes using the named
//charset (iso8859-1),then constructs a new String by decoding the
//specified array of bytes using the platform’s default charset (gb2312).
//This line is right.
}
}
上面的英文注释已经说得很清楚了,这里我还是解释一下吧:
首先是错误的改法 System.out.println(new String (strLine.getBytes(),"iso8859-1"));
这句代码是将strLine中的字符串用系统默认的编码方式(这里是gb2312)
转换为字节序列,然后用指定的编码方式(这里是iso8859-1)构造一个新的
String对象,并打印到屏幕上。
错误在哪里呢?
请注意这一段代码
InputStreamReader isr = new InputStreamReader(System.in,"iso8859-1");
BufferedReader br = new BufferedReader (isr);
String strLine = br.readLine();
这里strLine存储的内容是用指定的编码方式(iso8859-1)存储的,而转换成字节码
的时候(这句代码strLine.getBytes())却使用了系统默认的gb2312编码,所以当然就
输出乱码了!然后用gb2312编码的字节序列构建新的String对象的时候又使用了
iso8859-1编码,所以输出的乱码和System.out.println(strLine)有所不同。
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