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 as configuration 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

<?xml version="1.0" encoding="utf-8"?>

    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:

    <?xml version="1.0" encoding="utf-8"?>
    <resources>
        <color name="colorPrimary">#3F51B5</color>
     </resources>

5, CDATA area

    <![CDATA[

    将有特殊符号文本显示
    if( 3< 5 ){
       }

    ]]>

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---------- <?xml version=&#39;1.0&#39; encoding=&#39;utf-8&#39; standalone=&#39;yes&#39; ?>
        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 ------------  </书名>
            ser.endTag(null, "书名");        
            // 6.结束标签------------</书>   
            ser.endTag(null, "书");
         

        }        
        // 7.根标签 结束-----------</书库>
        ser.endTag(null, "书库");
        ser.endDocument();

    }
    }

The generated b.xml file is:

<?xml version=&#39;1.0&#39; encoding=&#39;utf-8&#39; standalone=&#39;yes&#39; ?>
    <书库>
        <书>
            <书名 id="1001">百年孤独</书名>
        </书>
        <书>
            <书名 id="1002">百年孤独</书名>
        </书>
    </书库>

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<Book> 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<Book>();
                } 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 </书>
                if (parser.getName().equalsIgnoreCase("书")) { 
                // -------</书>
                                                            
                                                            
                    // 注意:当时</书名>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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