这篇博客介绍了XML的基本知识，包括start document和end document的概念，以及XML节点的结构和属性。重点讲解了Pull解析的工作原理，它是如何逐行扫描XML文件，将内容拆分为字符数组进行解析，并在节点开始和结束时触发相应事件，允许精确控制解析过程。
xml知识补充：
在xml文件中，<?xml version= ....?> 称为 start document ，即xml起始位置，最末尾为 end document ，即为xml结束，每一个<>都是一个节点，称之为tag, <person>为starttag，而</person>为endtag 每个节点都可以有属性，<person id="1">，则id为attribute name，而1 为attribute value 节点也可以包含内容， <name>Tom</name>, Tom就是内容，即text
pull解析：就是对xml文件的逐行扫描，pull解析器会将文件内容拆分为char[]，逐字符读取，在调用其方法时，以每个节点为一次完整的读取来确定如恶化完成具体的解析工作
PULL一共有5种事件类型：
* START_DOCUMENT：文档的开始，解析器尚未读取任何输入。
* START_TAG：开始标签的解析。
* TEXT：标签内元素的内容解析。
* END_TAG：结束标签的解析。
* END_DOCUMENT：文档的结束。
主要用的是4个，他们与XML文件相应内容是这么对应的（他们在XML文件中的位置是这样）
简单总结就是：
- 文档的开头和结束分别有文档开始和文档结束事件
- 文档中的每个节点，无论是根节点还是叶子节点，都在节点开始和节点结束的地方有事件
具体使用的建议：
- 文档开始和文档结束事件是有固定位置的，你只要在这个位置做你要做的事情就好了，比如初始化一些资源
- 节点开始和节点结束的事件在很多位置都可能发生，为了精确控制，你可以使用【获取他们的节点名称(name)进行判断】这一方法
代码：
data.xml,在assets目录下
<span style="font-size:14px;"><?xml version="1.0" encoding="utf-8"?>
<objects>
<students>
<student id="2222" type="23">
<name>王大</name>
<sex>男</sex>
<age>12</age>
<grade>3</grade>
</student>
</students>
<teachers>
<teacher id="110" type="22">
<name>张老师</name>
<sex>男</sex>
<age>12</age>
<grade>3</grade>
</teacher>
</teachers>
</objects></span>这不是最常见的简单的xml，因为他里面包含了2个元素，students 和 teachers
一个简单的布局文件 activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context="${relativePackage}.${activityClass}" >
<LinearLayout
android:id="@+id/line_s"
android:layout_width="match_parent"
android:layout_height="250dp"
android:layout_alignParentTop="true"
android:orientation="vertical" >
<ScrollView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="6" >
<TextView
android:id="@+id/tv_result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
</ScrollView>
<EditText
android:id="@+id/et_delete"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="#7f7f7f" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:gravity="bottom"
android:orientation="vertical" >
<Button
android:id="@+id/btn_add_node_to_xml"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="add node to xml" />
<Button
android:id="@+id/btn_delete_from_xml"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="delete from xml" />
<Button
android:id="@+id/btn_in_db"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="writer to db" />
<Button
android:id="@+id/btn_writer_xml"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="writer to xml" />
<Button
android:id="@+id/btn_pull_analysis"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="analysis" />
</LinearLayout>
</LinearLayout>Teacher.class
@Column行可以无视删除，是因为这里用到这个倒数据库，Student.class 跟这个一样写就可以了
package com.example.pullanalysis;
import org.xutils.db.annotation.Column;
public class Teacher {
@Column(name = "name")
String name;
@Column(name = "sex")
String sex;
@Column(name = "age")
String age;
@Column(name = "grade")
String grade;
@Column(name = "id")
String id;
@Column(name = "type")
String type;
@Column(name = "code")
String code;
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 String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getGrade() {
return grade;
}
public void setGrade(String grade) {
this.grade = grade;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
@Override
public String toString() {
return "Teacher [name=" + name
+ ", sex=" + sex
+ ", age=" + age
+ ", grade=" + grade
+ ", id=" + id
+ ", type="+ type
+ ", code=" + code
+ "]";
}
}
MainActivity.class
<pre name="code" class="java">package com.example.pullanalysis;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;
import org.xutils.common.util.LogUtil;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.support.v4.content.LocalBroadcastManager;
import android.util.Log;
import android.util.Xml;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements OnClickListener {
/**
* 对xml文件的pull解析 生成xml文件 对xml文件的增加，删除
*/
private TextView mtvResult;
private Button mbtnAnalysis;
private Button mbtnWriter;
private Button mbtnWriterdb;
private Button mbtnDelete;
private Button mbtnAdd;
private EditText metdelete;
private List<Student> mStudentlist;
private List<Teacher> mTeacherlist;
Map<String, Object> mListMap;
private String path;
private File file;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
initData();
}
private void initData() {
// TODO Auto-generated method stub
path = Environment.getExternalStorageDirectory().getAbsolutePath();
file = new File(path, "Astudent.xml");
}
private void initView() {
// TODO Auto-generated method stub
mtvResult = (TextView) findViewById(R.id.tv_result);
mbtnAnalysis = (Button) findViewById(R.id.btn_pull_analysis);
mbtnWriter = (Button) findViewById(R.id.btn_writer_xml);
mbtnWriterdb = (Button) findViewById(R.id.btn_in_db);
mbtnDelete = (Button) findViewById(R.id.btn_delete_from_xml);
metdelete = (EditText) findViewById(R.id.et_delete);
mbtnAdd = (Button) findViewById(R.id.btn_add_node_to_xml);
mListMap = new HashMap<String, Object>();
mbtnAnalysis.setOnClickListener(this);
mbtnWriter.setOnClickListener(this);
mbtnWriterdb.setOnClickListener(this);
mbtnDelete.setOnClickListener(this);
mbtnAdd.setOnClickListener(this);
metdelete.requestFocus();
metdelete.setText("测试数据");
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.btn_pull_analysis:
readxml();
break;
case R.id.btn_writer_xml:
writertoxml(mListMap);
break;
case R.id.btn_in_db:
writertodb();
break;
case R.id.btn_delete_from_xml:
delete("teacher", "id", "0");
break;
case R.id.btn_add_node_to_xml:
Map<String, String> map = new LinkedHashMap<String, String>();
map.put("name", "白雪公主");
map.put("sex", "man");
map.put("age", "7");
map.put("grade", "2");
add("books", "book", "123", map);
break;
default:
break;
}
}
/**
* 将对象写入数据库
*/
private void writertodb() {
TStudent tstu = new TStudent(MainActivity.this);
Student stu = mStudentlist.get(0);
boolean d = true;
int n = 1;
long btime = System.currentTimeMillis();
long etime = 0;
while (d) {
tstu.insert(stu);
if (n < 1000) {
n++;
} else {
d = false;
etime = System.currentTimeMillis();
mtvResult.setText(String.valueOf(etime - btime));
}
}
}
/**
* pull 解析读取xml文件
*/
private void readxml() {
try {
InputStream ips = getAssets().open("data.xml");// 打开assets下的文件
XmlPullParser parser = Xml.newPullParser();
parser.setInput(ips, "utf-8");
int eventtype = parser.getEventType();// 产生第一个事件
Student student = null;
Teacher teacher = null;
StringBuffer str1 = new StringBuffer();
StringBuffer str2 = new StringBuffer();
while (eventtype != XmlPullParser.END_DOCUMENT) {
switch (eventtype) {
case XmlPullParser.START_DOCUMENT:// 判断当前事件是否为文档开始事件
break;
case XmlPullParser.START_TAG:// 判断当前事件是否为标签元素开始事件
String name = parser.getName();
if (name.equals("students")) {
mStudentlist = new ArrayList<Student>();
}
if (name.equals("student")) { // 判断开始标签元素是否是student
student = new Student();
student.setCode("student");
student.setId(parser.getAttributeValue(0));
student.setType(parser.getAttributeValue(1));
}
if (student != null) {
if (name.equals("name")) {
student.setName(parser.nextText());
} else if (name.equals("sex")) {
student.setSex(parser.nextText());
} else if (name.equals("age")) {
student.setAge(parser.nextText());
} else if (name.equals("grade")) {
student.setGrade(parser.nextText());
}
}
if (name.equals("teachers")) {
mTeacherlist = new ArrayList<Teacher>();
}
if (name.equals("teacher")) {
teacher = new Teacher();
teacher.setCode("teacher");
teacher.setId(parser.getAttributeValue(0));
teacher.setType(parser.getAttributeValue(1));
}
if (teacher != null) {
if (name.equals("name")) {
teacher.setName(parser.nextText());
} else if (name.equals("sex")) {
teacher.setSex(parser.nextText());
} else if (name.equals("age")) {
teacher.setAge(parser.nextText());
} else if (name.equals("grade")) {
teacher.setGrade(parser.nextText());
}
}
break;
case XmlPullParser.END_TAG:// 判断当前事件是否为标签元素结束事件
// 当读到student的时候，表示一个student对象读完了，这时候就可以把这个对象加入到list里了
// 当然，在读到student前还会读到</name></sex>等的end_tag 直接无视就好了
if (parser.getName().equals("student")) {
mStudentlist.add(student);
student = null;
}
if (parser.getName().equals("teacher")) {
mTeacherlist.add(teacher);
teacher = null;
}
// 读到＜/students>表示，students读完了
if (parser.getName().equals("students")) {
mListMap.put("students", mStudentlist);
}
if (parser.getName().equals("teachers")) {
mListMap.put("teachers", mTeacherlist);
}
break;
default:
break;
}
eventtype = parser.next();// 不断的去更新，持续的解析XML文件直到文件的尾部。
}
if (mStudentlist != null && mStudentlist.size() != 0) {
for (int i = 0; i < mStudentlist.size(); i++) {
str1.append("name:" + mStudentlist.get(i).getName())
.append(" sex:" + mStudentlist.get(i).getSex())
.append(" age:" + mStudentlist.get(i).getAge())
.append(" grade:" + mStudentlist.get(i).getGrade()).append("\n\n");
}
Toast.makeText(MainActivity.this, "解析成功", Toast.LENGTH_LONG).show();
}
if (mTeacherlist != null && mTeacherlist.size() != 0) {
for (int i = 0; i < mTeacherlist.size(); i++) {
str2.append("name:" + mTeacherlist.get(i).getName())
.append(" sex:" + mTeacherlist.get(i).getSex())
.append(" age:" + mTeacherlist.get(i).getAge())
.append(" grade:" + mTeacherlist.get(i).getGrade()).append("\n\n");
}
Toast.makeText(MainActivity.this, "解析成功", Toast.LENGTH_SHORT).show();
}
mtvResult.setText(str1.toString() + "" + str2);
} catch (IOException e) {
LogUtil.d("IOException", e);
} catch (XmlPullParserException e) {
LogUtil.d("XmlPullParserException", e);
}
}
/**
* 将对象的list写入xml文件
*
* @param list
*/
private void writertoxml(Map<String, Object> listmap) {
if (listmap != null && listmap.size() > 0) {
FileOutputStream out = null;
XmlSerializer xsl = Xml.newSerializer();
List<Student> stlist = (List<Student>) listmap.get("students");
List<Teacher> tealist = (List<Teacher>) listmap.get("teachers");
int a = stlist.size();
try {
out = new FileOutputStream(file);
xsl.setOutput(out, "utf-8");
xsl.startDocument("utf-8", true);
xsl.startTag("", "Object");
xsl.attribute("", "path", "http://xxxx.yyyy.cc.v");
xsl.attribute("", "time", "23:23:23");
if (stlist != null && stlist.size() > 0) {
xsl.startTag("", "students");
int i = 0;
for (Student stu : stlist) {
String node = "student" + (i++);
xsl.startTag("", "student");
xsl.attribute("", "id", String.valueOf(i));
xsl.attribute("", "type", stu.getType());
xsl.startTag("", "name");
xsl.text(stu.getName());
xsl.endTag("", "name");
xsl.startTag("", "sex");
xsl.text(stu.getSex());
xsl.endTag("", "sex");
xsl.startTag("", "age");
xsl.text(stu.getAge());
xsl.endTag("", "age");
xsl.startTag("", "grade");
xsl.text(stu.getGrade());
xsl.endTag("", "grade");
xsl.endTag("", "student");
}
xsl.endTag("", "students");
}
if (tealist != null && tealist.size() > 0) {
xsl.startTag("", "teachers");
int j = 0;
for (Teacher teacher : tealist) {
String node = "teacher" + (j++);
xsl.startTag("", "teacher");
xsl.attribute("", "id", String.valueOf(j));
xsl.attribute("", "type", teacher.getType());
xsl.startTag("", "name");
xsl.text(teacher.getName());
xsl.endTag("", "name");
xsl.startTag("", "sex");
xsl.text(teacher.getSex());
xsl.endTag("", "sex");
xsl.startTag("", "age");
xsl.text(teacher.getAge());
xsl.endTag("", "age");
xsl.startTag("", "grade");
xsl.text(teacher.getGrade());
xsl.endTag("", "grade");
xsl.endTag("", "teacher");
}
xsl.endTag("", "teachers");
}
xsl.endTag("", "Object");
xsl.endDocument();
out.close();
Toast.makeText(MainActivity.this, "写入成功", Toast.LENGTH_LONG).show();
} catch (IllegalArgumentException e) {
LogUtil.d("IllegalArgumentException", e);
} catch (IllegalStateException e) {
LogUtil.d("IllegalStateException", e);
} catch (IOException e) {
LogUtil.d("IOException", e);
}
}
}
/**
* 根据节点code以及对于的属性值删除对应的节点
*
* @param code
* @param property
* @param value
*/
private void delete(String code, String property, String value) {// code,子节点，子节点的值
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder bulider = factory.newDocumentBuilder();
Document doc = bulider.parse(file);
doc.normalize();
Element root = doc.getDocumentElement();// 得到根节点
NodeList listnode = doc.getElementsByTagName(code);
for (int i = 0; i < listnode.getLength(); i++) {
Element elink = (Element) listnode.item(i);
String prop = elink.getAttribute(property);
if (prop.equals(value)) {
if(listnode.getLength()==1){
//如果只有一条数据，那么这条数据删除之后，大节点也应该被删除
root.removeChild(elink.getParentNode());
}else{
elink.getParentNode().removeChild(elink);
}
Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_LONG).show();
}
}
TransformerFactory tfactory = TransformerFactory.newInstance();
Transformer trans = tfactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(file);
trans.transform(source, result);// 将原文件覆盖
} catch (Exception e) {
LogUtil.d("ParserConfigurationException", e);
}
}
private int getMaxId(String code, String idnum) {
int num = 0;
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder bulider = factory.newDocumentBuilder();
Document doc = bulider.parse(file);
doc.normalize();
NodeList listnode = doc.getElementsByTagName(code);
for (int i = 0; i < listnode.getLength(); i++) {
Element elink = (Element) listnode.item(i);
String id = elink.getAttribute(idnum);
if (Integer.valueOf(id) > num) {
num = Integer.valueOf(id);
}
}
return num;
} catch (ParserConfigurationException e) {
LogUtil.d("ParserConfigurationException", e);
return num;
} catch (SAXException e) {
LogUtil.d("SAXException", e);
return num;
} catch (IOException e) {
LogUtil.d("IOException", e);
return num;
}
}
/**
* 添加节点尚不存在的对象
*/
private void addtoxml(String bigcode, String code, String type, Map<String, String> map) {
FileOutputStream out = null;
XmlSerializer xsl = Xml.newSerializer();
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder bulider = factory.newDocumentBuilder();// 1.通过DocumentBuilder工厂得到对应的xml解析器
Document doc = bulider.parse(file);// 2.通过解析器得到Document对象
doc.normalize();
Element root = doc.getDocumentElement();// 得到根节点
Element bigNode = doc.createElement(bigcode);
Element codeNode = doc.createElement(code);
codeNode.setAttributeNS("", "id", String.valueOf(getMaxId(code, "id") + 1));
codeNode.setAttributeNS("", "type", type);
for (String key : map.keySet()) {
Node node = codeNode.appendChild(doc.createElement(key)).appendChild(doc.createTextNode(map.get(key)));
}
bigNode.appendChild(codeNode);
root.appendChild(bigNode);
TransformerFactory tfactory = TransformerFactory.newInstance();
Transformer trans = tfactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(file);
trans.transform(source, result);
Toast.makeText(MainActivity.this, "增加成功", Toast.LENGTH_SHORT).show();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
Log.d("www", e + "");
}
}
/**
* 添加已存在节点的对象
*
* @param code
*/
private void add(String bigCode, String code, String type, Map<String, String> map) {
try {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder bulider = factory.newDocumentBuilder();// 1.通过DocumentBuilder工厂得到对应的xml解析器
Document doc = bulider.parse(file);// 2.通过解析器得到Document对象
doc.normalize();
Element root = doc.getDocumentElement();// 得到根节点
NodeList employees = root.getChildNodes();
// 判断是节点是否存在
if (employees != null) {
int flag = 0;
for (int i = 0; i < employees.getLength(); i++) {
Node mycode = employees.item(i);
if (mycode.getNodeName().equals(bigCode)) {
flag++;
}
}
if (flag == 0) {
addtoxml(bigCode, code, type, map);
return;
}
}
Element per = (Element) selectSingleNode("/Object/" + bigCode, root);
Element codeNode = doc.createElement(code);
codeNode.setAttributeNS("", "id", String.valueOf(getMaxId(code, "id") + 1));
codeNode.setAttributeNS("", "type", type);
for (String key : map.keySet()) {
Node node = codeNode.appendChild(doc.createElement(key)).appendChild(doc.createTextNode(map.get(key)));
}
per.appendChild(codeNode);
TransformerFactory tfactory = TransformerFactory.newInstance();
Transformer trans = tfactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(file);
trans.transform(source, result);
Toast.makeText(MainActivity.this, "增加成功", Toast.LENGTH_LONG).show();
} catch (ParserConfigurationException e) {
LogUtil.d("ParserConfigurationException", e);
} catch (SAXException e) {
LogUtil.d("SAXException", e);
} catch (IOException e) {
LogUtil.d("IOException", e);
} catch (TransformerConfigurationException e) {
LogUtil.d("TransformerConfigurationException", e);
} catch (TransformerException e) {
LogUtil.d("TransformerException", e);
}
}
/**
* 选择具体某一结点
*
*
*/
public static Node selectSingleNode(String express, Element source) {
Node result = null;
XPathFactory xpathFactory = XPathFactory.newInstance();
XPath xpath = xpathFactory.newXPath();
try {
result = (Node) xpath.evaluate(express, source, XPathConstants.NODE);
} catch (XPathExpressionException e) {
e.printStackTrace();
}
return result;
}
}
注： 1.运行的时候先点解析，在生成，增加，删除
2. 关于数据库的直接注释掉就可以了
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