Java统计Xml节点数量

深碍√TFBOYSˉ_ 2022-02-03 15:17 512阅读 0赞

1.首先，统计方式分为两种，一个是通过java内置的**xpath**统计，另一个是通过**StAX**统计

2.**xpath统计**

1) 很遗憾的是，这种方式如果xml文件比较大的话会导致内存溢出。

import javax.xml.stream.XMLInputFactory;
    import javax.xml.stream.XMLStreamException;
    import javax.xml.stream.XMLStreamReader;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileNotFoundException;
    import java.io.InputStream;
    
    /**
     * @create: 2019/5/3 10:25
     **/
    public class testXml {
        public static void main(String[] args) throws FileNotFoundException, XMLStreamException {
            // 解析xml获得数据
            XMLInputFactory inputFactory = XMLInputFactory.newInstance();
            inputFactory.setProperty("http://www.oracle.com/xml/jaxp/properties/getEntityCountInfo", "yes");
            // 设置entity size , 否则会报 JAXP00010004 错误
            inputFactory.setProperty("http://www.oracle.com/xml/jaxp/properties/totalEntitySizeLimit", Integer.MAX_VALUE);
            File file = new File("D:\\workplace\\xml.xml");
    
            InputStream isS = new FileInputStream(file);
            XMLStreamReader streamReader = inputFactory.createXMLStreamReader(isS);
    
            int count = 0;
            while (streamReader.hasNext()) {
                streamReader.next();
                if (streamReader.getEventType() == XMLStreamReader.START_ELEMENT) {
                    // System.out.println(streamReader.getLocalName());
                    if (streamReader.getLocalName().equals("jiedian1")) {
                        count++;
                    }
                }
            }
            System.out.println("count: " + count);
        }
    
    }

其他匹配模式可以参考：[https://blog.csdn.net/luoww1/article/details/49736559][https_blog.csdn.net_luoww1_article_details_49736559]

3.**StAX统计**

1) 首先是统计元素的方法，大文件也能统计

/**
         * 根据xml文件路径,统计指定元素的数量
         * @param xpath 文件路径
         * @param elementName 元素名称
         * @return 统计的数量
         */
        public int xpathForCountByEN(String xpath, String elementName) throws FileNotFoundException, XMLStreamException {
            File file = new File(xpath);
    
            InputStream is = new FileInputStream(file);
            XMLStreamReader streamReader = inputFactory.createXMLStreamReader(is);
    
            int count = 0;
            while (streamReader.hasNext()) {
                streamReader.next();
                if (streamReader.getEventType() == XMLStreamReader.START_ELEMENT) {
                    // System.out.println(streamReader.getLocalName());
                    if (streamReader.getLocalName().equals(elementName)) {
                        count++;
                    }
                }
            }
            System.out.printf("---> %s count: %d \n", elementName, count);
            return count;
        }

2) 统计多个元素的方法

public Map xpathForCountByEN(String xpath, List<String> elementNames) throws FileNotFoundException, XMLStreamException {
            File file = new File(xpath);
            Map<String, Integer> result = new HashMap<>();
    
            InputStream is = new FileInputStream(file);
            XMLStreamReader streamReader = inputFactory.createXMLStreamReader(is);
    
            while (streamReader.hasNext()) {
                streamReader.next();
                if (streamReader.getEventType() == XMLStreamReader.START_ELEMENT) {
                    for(String elementName: elementNames) {
                        if (streamReader.getLocalName().equals(elementName)) {
                            if (result.containsKey(elementName)) {
                                result.put(elementName, result.get(elementName) + 1);
                            } else {
                                result.put(elementName, 1);
                            }
                        }
                    }
                }
            }
            System.out.printf("---> %s result: %s \n", file.getName(), result);
            return result;
        }

[https_blog.csdn.net_luoww1_article_details_49736559]: https://blog.csdn.net/luoww1/article/details/49736559