xStream 重写FileConverter，存入十六进制

xStream中的FileConverter，默认实现是把File文件的路径存入xml中，现在重新定义FileConverter，实现把File以十六进制字节码存入xml中。

定义自定义MyFileConverter

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Random;

import com.thoughtworks.xstream.converters.extended.FileConverter;

public class MyFileConverter extends FileConverter {

    private String bytesToHexString(byte[] bArray) {
        StringBuffer sb = new StringBuffer(bArray.length);
        String sTemp;
        for (int i = 0; i < bArray.length; i++) {
            sTemp = Integer.toHexString(0xFF & bArray[i]);
            if (sTemp.length() < 2)
                sb.append(0);
            sb.append(sTemp.toUpperCase());
        }
        return sb.toString();
    }

    @Override
    public boolean canConvert(Class clazz) {
        return clazz.equals(File.class);
    }

    @Override
    public Object fromString(String text) {
        String fileName = text.substring(text.indexOf('|') + 1, text.length());
        Random rm = new Random();
        long rmNum = rm.nextLong();
        File file = new File(rmNum + fileName);
        FileOutputStream fos = null;
        try {
            fos = new FileOutputStream(file);
            text = text.substring(0, text.indexOf('|'));
            fos.write(hexStringToByte(text));
        } catch (NumberFormatException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                fos.close();
                return file;
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    private byte[] getBytesFromFile(File file) throws IOException {
        InputStream is = new FileInputStream(file);
        long length = file.length();
        if (length > Integer.MAX_VALUE) {
            return null;
        }
        byte[] bytes = new byte[(int) length];

        int offset = 0;
        int numRead = 0;
        while (offset < bytes.length
                && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {
            offset += numRead;
        }

        if (offset < bytes.length) {
            throw new IOException("Could not completely read file "
                    + file.getName());
        }

        is.close();
        return bytes;
    }

    /**
     * 把16进制字符串转换成字节数组
     * 
     * @param hex
     * @return
     */
    private byte[] hexStringToByte(String hex) {
        int len = (hex.length() / 2);
        byte[] result = new byte[len];
        char[] achar = hex.toCharArray();
        for (int i = 0; i < len; i++) {
            int pos = i * 2;
            result[i] = (byte) (toByte(achar[pos]) << 4 | toByte(achar[pos + 1]));
        }
        return result;
    }

    private byte toByte(char c) {
        byte b = (byte) "0123456789ABCDEF".indexOf(c);
        return b;
    }

    public String toString(Object obj) {
        File file = (File) obj;
        try {
            return bytesToHexString(getBytesFromFile(file)) + "|"
                    + file.getName();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return ((File) obj).getPath();
    }
}

 

测试实体类：

import java.io.File;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

public class Entity implements Serializable{
    private int id;
    private String name;
    private File image;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public File getImage() {
        return image;
    }

    public void setImage(File image) {
        this.image = image;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
    public String toString(){
        return "id:"+id+",name:"+name+",image:"+image.getAbsolutePath();
    }
}

主函数：

public static void main(String[] args) throws IOException {
        Entity enty = new Entity();
        enty.setId(1);
        enty.setName("helloWord");
        enty.setImage(new File ("1.jpg"));
        
        XStream xs = new XStream();

        try {
            FileOutputStream fs = new FileOutputStream(
                    "test.xml");
            xs.registerConverter(new MyFileConverter());
            xs.toXML(enty,fs);
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
        }
        
        Object obj = xs.fromXML(new File("test.xml"));
        System.out.println(obj);
    }