java – 如何使用VTDGenHuge将大型xml拆分成小块？

我想将大型xml分成小块.我正在使用VTDGen将xml文件拆分成小块,它适用于文件大小< 2 GB. VTD-xml使用IN-Memory来解析xml,我不想将xml加载到内存中.所以我试图使用VTDGenHuge映射内存. 代码适用于VTDGen,但是当我使用VTDGenHuge它不起作用.

        String prefix = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"+"\n";
    String suffix = "\n</Employees>\n";
    try {

        VTDGenHuge vg = new VTDGenHuge();
        if (vg.parseFile("C:\\Users\\abc\\Desktop\\latestxml\\Input_1.xml", true,VTDGenHuge.MEM_MAPPED)) {
            int splitBy = ;
           System.out.println("Started time"+ new Date());
            VTDNavHuge vn = vg.getNav();               
            AutoPilotHuge ap = new AutoPilotHuge(vn);
            ap.selectXPath("/Employees/Employee");
            FastLongBuffer flb = new FastLongBuffer(4);
            int i;
            byte[] xml = vn.getXML().getBytes();          
            while ((i = ap.evalXPath()) != -1) {  
                flb.append(vn.getElementFragment());
            }
            int size = flb.size();
            if (size != 0) {
                File fo = null;
                FileOutputStream fos = null;
                for (int k = 0; k < size; k++) {
                   if (k % splitBy == 0) {
                        if (fo != null) {
                            fos.write(suffix.getBytes());
                            fos.close();
                            fo = null;
                        }
                    }
                    if (fo == null) {
                        fo = new File("C:\\Users\\abc\\Desktop\\Test\\xml\\"+"out" + k + ".xml");
                        fos = new FileOutputStream(fo);
                        fos.write(prefix.getBytes());
                    }
                    fos.write("\n".getBytes());                       
                    fos.write(xml, flb.lower32At(k), flb.upper32At(k));
                }
                if (fo != null) {                       
                    fos.write(suffix.getBytes());                  
                    fos.close();
                    fo = null;
                }
            }

        }
    } catch (Exception e) {
        e.printStackTrace();
    }

我得到NUll值为“byte [] xml = vn.getXML().getBytes();”
当你做syso vn.getXML()时,你得到了对象的价值.但是“getBytes()”返回null.我不知道为什么.但是如果你做“byteAt(x)”x =任何长值它返回值.

我的xml文件是：

<?xml version="1.0" encoding="UTF-8"?>
<Employees>
<Employee id="1">
    <age>29</age>
    <name>Pankaj</name>
    <gender>Male</gender>
    <role>Java Developer</role>
</Employee>
<Employee id="2">
    <age>35</age>
    <name>Lisa</name>
    <gender>Female</gender>
    <role>CEO</role>
</Employee>
<Employee id="3">
    <age>40</age>
    <name>Tom</name>
    <gender>Male</gender>
    <role>Manager</role>
</Employee>
    <Employee id="1">
    <age>29</age>
    <name>Pankaj</name>
    <gender>Male</gender>
    <role>Java Developer</role>
</Employee>
<Employee id="2">
    <age>35</age>
    <name>Lisa</name>
    <gender>Female</gender>
    <role>CEO</role>
</Employee>
<Employee id="3">
    <age>40</age>
    <name>Tom</name>
    <gender>Male</gender>
    <role>Manager</role>
</Employee>
<Employees>

我想这样出来.

<?xml version="1.0" encoding="UTF-8"?>
 <Employees>
<Employee id="1">
    <age>29</age>
    <name>Pankaj</name>
    <gender>Male</gender>
    <role>Java Developer</role>
</Employee>
<Employee id="2">
    <age>35</age>
    <name>Lisa</name>
    <gender>Female</gender>
    <role>CEO</role>
</Employee>
<Employee id="3">
    <age>40</age>
    <name>Tom</name>
    <gender>Male</gender>
    <role>Manager</role>    
</Employee>
<Employees> 

<?xml version="1.0" encoding="UTF-8"?>
<Employees> 
    <Employee id="1">
    <age>29</age>
    <name>Pankaj</name>
    <gender>Male</gender>
    <role>Java Developer</role>
</Employee>
<Employee id="2">
    <age>35</age>
    <name>Lisa</name>
    <gender>Female</gender>
    <role>CEO</role>
</Employee>
<Employee id="3">
    <age>40</age>
    <name>Tom</name>
    <gender>Male</gender>
    <role>Manager</role>
</Employee>
<Employees>

解决方法:

我认为扩展vtd-xml的vn.getXML()返回一个与标准vtd-xml不同的IbyteBuffer接口对象.你可以调用名为writeOutputToFile()的inteface方法并将偏移量和值参数传递给它..对不起它的文档部分缺乏,但这是基本的低级…

标签：java,xml,vtd-xml
来源： https://codeday.me/bug/20190711/1433446.html