XML overview and sample code for Pull parsing

XMLOverview and Pull parsing details

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AndroidThe most developed ones are json. And parsing xml With Xstream, I have almost forgotten the manual parsing of xml. Generally, the most common ones are demo4j based on dom, and pull parsing based on sax. There is another kind that I have forgotten

Overview:

What is XML?
eXtensible Markup Language (extensible markup language);

Common functions of XML:

1 , used asconfiguration file
2, data format during data transmission
3, resource file in Android

Basic syntax of XML:

1. The statement must be written on the first line

 version : xml的版本号.目前只有1,0版本 encoding: 编码格式

2, there can only be one root tag

3, each tag must be closed

4, cannot Cross-nesting

is in the form of:

  #3F51B5 

5, CDATA area

should be used when special symbols such as "<", ">" are used in the document CDATA area, otherwise it cannot be compiled normally.

Pull to write the XML file.

public class WriteXml { public static void main(String[] args) throws Exception { // 创建xml解析工厂 XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); // 通过工厂创建序列化器(xml生成器) XmlSerializer ser = factory.newSerializer(); // 为序列化器指定输出流(将xml文件写到指定的某个文件中) ser.setOutput(new FileOutputStream("src/b.xml"), "utf-8"); // 开始写xml文件 // 1.xml的声明----------  ser.startDocument("utf-8", true); // 2. 开始标签 ---------- <书库> ser.startTag(null, "书库"); for ( int i = 0; i < 2; i++) { //3.开始标签 ------------- <书> ser.startTag(null, "书"); // 4. 开始标签------------ <书名> ser.startTag(null, "书名"); //4.1为书名标签设置 属性--------- <书名 id = "1001"> ser.attribute(null, "id", "1001"); //4.2标签设置 文本------------ <书名 id = "1001" >百年孤独 ser.text("百年孤独"); // 5,结束标签 ------------  ser.endTag(null, "书名"); // 6.结束标签------------ ser.endTag(null, "书"); } // 7.根标签 结束----------- ser.endTag(null, "书库"); ser.endDocument(); } }

The generated b.xml file is:

 <书库> <书> <书名 id="1001">百年孤独  <书> <书名 id="1002">百年孤独  

Pull parsing xmlpull_1_1_3_4c.jar two jars are parsed.

If there is no build.path, the following error will be reported:

public class XmlParserDemo { /** * @param args * @throws Exception */ public static void main(String[] args) throws Exception { // 创建pull解析器工厂对象 XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); // 创建解析器对象 ArrayList list = null; Book book = null; // 获得解析器 XmlPullParser parser = factory.newPullParser(); // 从指定文件中解析 出xml parser.setInput(new FileInputStream("src/b.xml"), "utf-8"); // 1 . 判断是否是根标签的结束标签 while (parser.getEventType() != XmlPullParser.END_DOCUMENT) { switch (parser.getEventType()) { case XmlPullParser.START_TAG: // 开始标签 if (parser.getName().equalsIgnoreCase("书库")) { // ------------<书库> // 如果是 跟标签时,创建集合存储 对象 list = new ArrayList(); } else if (parser.getName().equalsIgnoreCase("书")) { // ----------<书> // 当标签是对象时. 创建 对象 book = new Book(); } else if (parser.getName().equalsIgnoreCase("书名")) { // ----------<书名> // 获得当前标签中的 属性以及text.并存储到对象中 String id = parser.getAttributeValue(null, "id"); book.setId(id); String name = parser.nextText(); book.setName(name); } break; case XmlPullParser.END_TAG: // 结束标签 // 标签为对象的结束标签时,将对象存储到集合中  if (parser.getName().equalsIgnoreCase("书")) { // ------- // 注意:当时结束标签时不用做处理 list.add(book); } break; } parser.next(); } for (int i = 0; i < list.size(); i++) { System.out.println("---" + list.get(i)); } } }

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2. The return value of the parser.getName() method – The tag name

is in the shape of:

org.xmlpull.v1.XmlPullParserException: caused by: org.xmlpull.v1.XmlPullParserException: resource not found: /META-INF/services/org.xmlpull.v1.XmlPullParserFactory make sure that parser implementing XmlPull API is available

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When parser parses, parser will also move to the tag title text (text). And text has no tag name, so it is null.

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