XML解析之PULL

Posted 2020-09-13 余磊

在android中极力推荐的xmlpull方式解析xml。

为什么 STAX 解析方式 效率 好于 SAX ？

1、SAX 无选择性的，所有事件都会处理 解析方式，Stax 由用户控制需要处理事件类型

2、在使用Stax进行数据解析时，随时终止解析

        环境：        

    xmlpull_1_1_3_4c.jar

http://www.xmlpull.org/    xmlpull

XML文件:

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <student id="1" group="1">
        <name>张三</name>
        <sex>男</sex>
        <age>18</age>
        <email>[e-mail]</email>
        <birthday>1987-06-08</birthday>
        <memo>好学生</memo>
    </student>
    <student id="2" group="2">
        <name>李四</name>
        <sex>女</sex>
        <age>18</age>
        <email>[e-mail]</email>
        <birthday>1987-06-08</birthday>
        <memo>好学生</memo>
    </student>
    <student id="3" group="3">
        <name>小王</name>
        <sex>男</sex>
        <age>18</age>
        <email>[e-mail]</email>
        <birthday>1987-06-08</birthday>
        <memo>好学生</memo>
    </student>
    <student id="4" group="4">
        <name>小张</name>
        <sex>男</sex>
        <age>18</age>
        <email>[e-mail]</email>
        <birthday>1987-06-08</birthday>
        <memo>好学生</memo>
    </student>
    <student id="5" group="5">
        <name>小明</name>
        <sex>男</sex>
        <age>18</age>
        <email>[e-mail]</email>
        <birthday>1987-06-08</birthday>
        <memo>好学生</memo>
    </student>
</root>

XML对应的实体文件:

public class Student {
    
    private int id;
    private int group;
    private String name;
    private String sex;
    private int age;
    private String email;
    private String memo;
    private String birthday;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public int getGroup() {
        return group;
    }
    public void setGroup(int group) {
        this.group = group;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getMemo() {
        return memo;
    }
    public void setMemo(String memo) {
        this.memo = memo;
    }
    public String getBirthday() {
        return birthday;
    }
    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }
    
}

Pull解析代码

public class PullParseXml {
    
    
    public List<Student> PullParseXML(){
        
        List<Student> list=null;
        Student student = null;
        
        //构建XmlPullParserFactory
        try {
            XmlPullParserFactory pullParserFactory=XmlPullParserFactory.newInstance();
            //获取XmlPullParser的实例
            XmlPullParser xmlPullParser=pullParserFactory.newPullParser();
            //设置输入流  xml文件
            xmlPullParser.setInput(Thread.currentThread().getContextClassLoader().getResourceAsStream("Student.xml"), "UTF-8");
            
            //开始
            int eventType=xmlPullParser.getEventType();
            
            try {
                while(eventType!=XmlPullParser.END_DOCUMENT){
                    String nodeName=xmlPullParser.getName();
                    switch (eventType) {
                    //文档开始
                    case XmlPullParser.START_DOCUMENT:
                        list=new ArrayList<Student>();
                        break;
                    //开始节点
                    case XmlPullParser.START_TAG:
                        //判断如果其实节点为student
                        if("student".equals(nodeName)){
                            //实例化student对象
                            student=new Student();
                            //设置Id属性
                            student.setId(Integer.parseInt(xmlPullParser.getAttributeValue(0)));
                            //设置Group属性
                            student.setGroup(Integer.parseInt(xmlPullParser.getAttributeValue(1)));
                        }else if("name".equals(nodeName)){
                            //设置name
                            student.setName(xmlPullParser.nextText());
                        }else if("sex".equals(nodeName)){
                            //设置sex
                            student.setSex(xmlPullParser.nextText());
                        }else if("age".equals(nodeName)){
                            //设置age
                            student.setAge(Integer.parseInt(xmlPullParser.nextText()));
                        }else if("email".equals(nodeName)){
                            //设置email
                            student.setEmail(xmlPullParser.nextText());
                        }else if("birthday".equals(nodeName)){
                            //设置birthday
                            student.setBirthday(xmlPullParser.nextText());
                        }else if("memo".equals(nodeName)){
                            //设置memo属性
                            student.setMemo(xmlPullParser.nextText());
                        }
                        break;
                    //结束节点
                    case XmlPullParser.END_TAG:
                        if("student".equals(nodeName)){
                            list.add(student);
                            student=null;
                        }
                        break;
                    default:
                        break;
                    }
                    eventType=xmlPullParser.next();
                }
            } catch (NumberFormatException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        } catch (XmlPullParserException e) {
            e.printStackTrace();
        }

        return list;
    }
    
    public static void main(String[] args) {
        List<Student> list=new PullParseXml().PullParseXML();
        for(Student student:list){
            System.out.println("id:"+student.getId()+"\\tgroup:"+student.getGroup()+"\\tname:"+student.getName()+"\\tsex:"+student.getSex()+"\\tage:"+student.getAge()+"\\temail:"+student.getEmail()+"\\tbirthday:"+student.getBirthday()+"\\tmemo:"+student.getMemo());
        }
    }
    
}

Event_Type事件返回的事件代码：

public static final java.lang.String NO_NAMESPACE = "";
  
  public static final int START_DOCUMENT = 0;
  
  public static final int END_DOCUMENT = 1;
  
  public static final int START_TAG = 2;
  
  public static final int END_TAG = 3;
  
  public static final int TEXT = 4;
  
  public static final int CDSECT = 5;
  
  public static final int ENTITY_REF = 6;
  
  public static final int IGNORABLE_WHITESPACE = 7;
  
  public static final int PROCESSING_INSTRUCTION = 8;
  
  public static final int COMMENT = 9;
  
  public static final int DOCDECL = 10;

对XML数据通过PULL解析器进行CURD示意图：