转自博文《Java文件编码格式转换》：
默认被转换的格式为GBK,转换成的格式为UTF-8
import info.monitorenter.cpdetector.CharsetPrinter;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
public class EncodeFormatTransfer {
public static String DefaultSrcEncodeFormat = "GBK";
public static String DefaultDestEncodeFormat = "UTF-8";
public static String UnsupportedEncodingExceptionError = "编码格式错误！";
public static String FileNotFoundExceptionError = "文件不存在！";
public static String IOExceptionError = "文件读写错误！";
public static String IsUtf8File = "文件是UTF-8编码格式！";
public static String IsNotUtf8File = "文件不是UTF-8编码格式！";
public static String readFile(String path,String encodeFormat){
if((encodeFormat==null || encodeFormat.equals(""))){
if(isUTF8File(path))
encodeFormat = DefaultDestEncodeFormat;
else
encodeFormat = DefaultSrcEncodeFormat;
}
try {
String context = "";
InputStreamReader isr;
isr = new InputStreamReader(new FileInputStream(path),encodeFormat);
BufferedReader br=new BufferedReader(isr);
String line;
while((line=br.readLine())!=null){
context += line + "\r\n";
System.out.println(line);
}
br.close();
return context;
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
System.out.println(UnsupportedEncodingExceptionError);
e.printStackTrace();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
System.out.println(FileNotFoundExceptionError);
e.printStackTrace();
}catch (IOException e) {
// TODO Auto-generated catch block
System.out.println(IOExceptionError);
e.printStackTrace();
};
return "";
}
/*public static boolean isUTF8File(String path){
try {
File file = new File(path);
CharsetPrinter detector = new CharsetPrinter();
String charset = detector.guessEncoding(file);
InputStream in = new java.io.FileInputStream(file);
byte[] b = new byte[3];
in.read(b);
in.close();
System.out.println(b[0] + " " + b[1] + " " + b[2]);
if (b[0] == 0xEF && b[1] == 0xBB && b[2] == 0XBF){
System.out.println(IsUtf8File);
return true;
}
if (b[0] == -17 && b[1] == -69 && b[2] == -65){
System.out.println(IsUtf8File);
return true;
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(FileNotFoundExceptionError);
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(IOExceptionError);
}
System.out.println(IsNotUtf8File);
return false;
}*/
public static boolean isUTF8File(String path){
try {
File file = new File(path);
CharsetPrinter detector = new CharsetPrinter();
String charset = detector.guessEncoding(file);
if(charset.equalsIgnoreCase(DefaultDestEncodeFormat)){
System.out.println(IsUtf8File);
return true;
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(FileNotFoundExceptionError);
}catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(IOExceptionError);
}
System.out.println(IsNotUtf8File);
return false;
}
public static String transfer(String context,String encodeFormat) {
if(encodeFormat==null || encodeFormat.equals(""))
encodeFormat = DefaultDestEncodeFormat;
try {
byte[] content = context.getBytes();
String result = new String(content,encodeFormat);
return result;
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
System.out.println(UnsupportedEncodingExceptionError);
e.printStackTrace();
}
return "";
}
public static void writeFile(String context,String path,String destEncode){
File file = new File(path);
if(file.exists())
file.delete();
BufferedWriter writer;
try {
FileOutputStream fos = new FileOutputStream(path,true);
writer = new BufferedWriter(new OutputStreamWriter(fos, destEncode));
writer.append(context);
writer.close();
} catch (IOException e) {
System.out.println(IOExceptionError);
e.printStackTrace();
}
}
public static void writeFile(String context,String path){
File file = new File(path);
if(file.exists())
file.delete();
Writer writer;
try {
writer = new FileWriter(file, true);
writer.append(context);
writer.close();
} catch (IOException e) {
System.out.println(IOExceptionError);
e.printStackTrace();
}
}
public static void transfer(String srcPath,String destPath,String srcEncode,String destEncode){
if(destPath==null || destPath.equals(""))
destPath = srcPath;
String context = readFile(srcPath,srcEncode);
context = transfer(context,destEncode);
writeFile(context,destPath,destEncode);
}
public static void transfer(String srcPath,String destPath,String destEncode){
if(isUTF8File(srcPath)){
transfer(srcPath,destPath,DefaultDestEncodeFormat,destEncode);
}else{
transfer(srcPath,destPath,DefaultSrcEncodeFormat,destEncode);
}
}
public static void main(String args[]){
String path1 = "f:/Notepad1.java";
String path2 = "f:/Notepad2.java";
transfer(path1,path2,"UTF-8");
transfer(path1,path2,"UTF-8","UTF-8");
}
}
java读取文件，处理过程中，可能因为文件的编码问题导致了中文乱码。有时需要将UTF-8的改为ANSI的编码。以下代码就可以判断文件是什么编码方式。
主要jar包：cpdetector.jar
下载地址： http://cpdetector.sourceforge.net/
同时还需jchardet-1.0.jar这个包，否则detector.add(cpdetector.io.JChardetFacade.getInstance()); 会报错；
下载地址： http://www.jarfinder.com/index.php/jars/versionInfo/40297
还有一个antlr.jar，不然运行过程中detector.add(new ParsingDetector(false));会报错；
下载地址： http://www.java2s.com/Code/Jar/ABC/Downloadantlrjar.htm