将svg 转换成png/jpg格式出线xlink:href

用Java实现svg 转换png

 String newPath = befores[0]+"before/word.png";
        File f=new File(path);
        File destFile=new File(newPath);
        InputStream in = new FileInputStream(f);
        OutputStream out = new FileOutputStream(destFile);
        out = new BufferedOutputStream(out);
        Transcoder transcoder = new PNGTranscoder();
        try {
            TranscoderInput input = new TranscoderInput(in);
            try {
                TranscoderOutput output = new TranscoderOutput(out);
                transcoder.transcode(input, output);
            } finally {
                out.close();
            }
        } finally {
            in.close();
        }

问题: 转换格式要求，用href可以正常添加到svg 中，却不能用xlink:href添加到svg中，在转换成png 时必须用到xlink:href，怎么办？

Enclosed Exception:
null:-1
The attribute "xlink:href" of the element <use> is required] with root cause

org.apache.batik.transcoder.TranscoderException: null
Enclosed Exception:
null:-1
The attribute "xlink:href" of the element <use> is required
    at org.apache.batik.transcoder.SVGAbstractTranscoder.transcode(Unknown Source) ~[batik-transcoder-1.6-1.jar:na]
    at org.apache.batik.transcoder.image.ImageTranscoder.transcode(Unknown Source) ~[batik-transcoder-1.6-1.jar:na]

求解？