jchardet

来源：互联网发布：路面弯沉计算软件编辑：程序博客网时间：2024/05/29 02:57

有时需要InputStreamReader(InputStream in, Charset cs)这个构造来处理字符流。然而Charset不一定知道。这个时候就需要检测编码方式了。jchardet是firefox使用的字节流编码检测算法的java开源实现，协议为MPL(Mozilla Public License)，对商业友好。下载源代码后发现示例并不怎么好使用，于是封装了一下。下面就封装类和使用Demo。

CharsetDetector 这个封装了内部实现，用户直接new这个类就可以检测字节流编码

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packagecn.xddai.chardet;
 
importjava.io.BufferedInputStream;
importjava.io.IOException;
importjava.io.InputStream;
importorg.mozilla.intl.chardet.nsDetector;
importorg.mozilla.intl.chardet.nsICharsetDetectionObserver;
importorg.mozilla.intl.chardet.nsPSMDetector;
 
/**
 *
 * @author xddai
 */
publicclass CharsetDetector
{
 
    privateboolean found = false;
    privateString result;
    privateint lang;
 
    publicString[] detectChineseCharset(InputStream in) throwsIOException
    {
        lang = nsPSMDetector.CHINESE;
        String[] prob;
        // Initalize the nsDetector() ;
        nsDetector det = newnsDetector(lang);
        // Set an observer...
        // The Notify() will be called when a matching charset is found.
 
        det.Init(newnsICharsetDetectionObserver()
        {
 
            publicvoid Notify(String charset)
            {
                found = true;
                result = charset;
            }
        });
        BufferedInputStream imp = newBufferedInputStream(in);
        byte[] buf = newbyte[1024];
        intlen;
        booleanisAscii = true;
        while((len = imp.read(buf, 0, buf.length)) != -1)
        {
            // Check if the stream is only ascii.
            if(isAscii)
                isAscii = det.isAscii(buf, len);
            // DoIt if non-ascii and not done yet.
            if(!isAscii)
            {
                if(det.DoIt(buf, len, false))
                    break;
            }
        }
        imp.close();
        in.close();
        det.DataEnd();
        if(isAscii)
        {
            found = true;
            prob = newString[]
                    {
                        "ASCII"
                    };
        }elseif (found)
        {
            prob = newString[]
                    {
                        result
                    };
        }else
        {
            prob = det.getProbableCharsets();
        }
        returnprob;
    }
 
    publicString[] detectAllCharset(InputStream in) throwsIOException
    {
        try
        {
            lang = nsPSMDetector.ALL;
            returndetectChineseCharset(in);
        }catch(IOException e)
        {
            throwe;
        }
    }
}

Demo:这个演示CharsetDetector用法示例

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packagecn.xddai.chardet;
 
importjava.io.IOException;
importjava.net.URL;
 
/**
 *
 * @author xddai
 */
publicclass Demo
{
    publicstatic void main(String[] args)throwsIOException
    {
        CharsetDetector charDect = newCharsetDetector();
        URL url = newURL("http://www.oschina.net/");
        String[] probableSet = charDect.detectChineseCharset(url.openStream());
        for(String charset : probableSet)
        {
            System.out.println(charset);
        }
    }
}

封装后的jar包下载地址 http://codeinplatform.googlecode.com/files/CharsetDetector.jar

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