package string;
import java.nio.charset.Charset;
public class UTF82GBK {
    public static void main(String[] args) throws Exception {
        //系統(tǒng)的默認(rèn)編碼是GBK
        System.out.println("Default Charset=" + Charset.defaultCharset());
        String t = "hfjkds中國中國中國中國中國中國中國中國中國中國中國中國中國中國中國中國中國中國中國中國hfsdkj<img src=‘sasa‘ /> fjldsajflkdsjaflkdsjalf <img src=‘sada‘ ait=‘‘/>sfdsfadas";  
        //思路：先轉(zhuǎn)為Unicode，然后轉(zhuǎn)為GBK
        String utf8 = new String(t.getBytes( "UTF-8"));
        //等同于:
//        String utf8 = new String(t.getBytes( "UTF-8"),Charset.defaultCharset());
        System.out.println(utf8);  
        String unicode = new String(utf8.getBytes(),"UTF-8");   
        //等同于:
//        String unicode = new String(utf8.getBytes(Charset.defaultCharset()),"UTF-8");   
        System.out.println(unicode);  
        String gbk = new String(unicode.getBytes("GBK"));  
        //等同于:
//        String gbk = new String(unicode.getBytes("GBK"),Charset.defaultCharset());  
        System.out.println(gbk);  
    }
}

package com.mkyong;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
public class UTF8ToGBK {
    public static void main(String[] args) throws Exception {
        File fileDir = new File("/home/user/Desktop/Unsaved Document 1");
        BufferedReader in = new BufferedReader(new InputStreamReader(
                new FileInputStream(fileDir), "UTF-8"));
        String str;
        while ((str = in.readLine()) != null) {
            System.out.println(str);// java內(nèi)部只有unicode編碼 所以str是unicode編碼
            String str2 = new String(str.getBytes("GBK"), "GBK");// str.getBytes("GBK")是gbk編碼，但是str2是unicode編碼
            System.out.println(str2);
        }
        in.close();
    }
}

String fullStr = new String(str.getBytes("UTF-8"), "UTF-8");//正常
String fullStr2 = new String(str.getBytes("UTF-8"), "GBK");//不正常，java內(nèi)置的編碼->utf8  被當(dāng)成GBK編碼轉(zhuǎn)換成java內(nèi)置的編碼

public String(byte[] bytes,
      Charset charset)

String str3 = new String(str.getBytes("GBK"),"ISO-8859-1");
System.out.println(new String(str3.getBytes("ISO-8859-1"),"GBK"));

FileInputStream fileInputStream = new FileInputStream("gbk.txt");
    InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "GBK");
    FileOutputStream fileOutputStream = new FileOutputStream("utf-8.txt");
    OutputStreamWriter outputStreamWriter = new OutputStreamWriter(fileOutputStream, "UTF-8");
    int length = 0;
    char[] buffer = new char[1024];
    while ((length = inputStreamReader.read(buffer)) != -1) {
        outputStreamWriter.write(buffer, 0, length);
    }
    outputStreamWriter.close();
    fileOutputStream.close();
    inputStreamReader.close();
    fileInputStream.close();

String strGBK = "這是一段GBK編碼的字符串";
    byte[] bytes = strGBK.getBytes("GBK");
    String strUTF = new String(bytes,"UTF-8");
    System.out.println(strUTF);

String strGBK = "這是一段GBK編碼的字符串";
    Charset gbkCharset = Charset.forName("GBK");
    Charset utf8Charset = Charset.forName("UTF-8");
    ByteBuffer byteBuffer = gbkCharset .encode(strGBK);
    CharBuffer charBuffer = utf8Charset .decode(byteBuffer);
    System.out.println(charBuffer.toString());