XML解析之Pull解析方式

XML文件：

<apps>
<app>
<id>1</id>
<name>gogle</name>
<version>1.0</version>
</app>
<app>
<id>2</id>
<name>Chrome</name>
<version>2.0</version>
</app>
<app>
<id>3</id>
<name>gogle PLAY</name>
<version>3.0</version>
</app>
</apps>

总体上的思路是这样的：

先获得一个XmlParser对象，然后从文档开始读到文档结束，然后获取每个标签后面的文本内容。

写代码之前先来介绍下几个函数以及标志。

public interface Xmlparser

int START_TAG       Returned from getEventType(), next(), nextToken() when a start tag was read.（大致意思是，当开始标签被读取由getEventType()，next(), nextToken()函数返回这个值。）

int END_TAG     Returned from getEventType(), next(), or nextToken() when an end tag was read.（当结束标签被读取由getEventType()，next(), nextToken()函数返回这个值。）

int END_DOCUMENT    Logical end of the xml document.（逻辑XML文件结尾）

abstract int    getEventType()
Returns the type of the current event (ST
4000
ART_TAG, END_TAG, TEXT, etc.) （返回当前event类型）

abstract String getName()
For START_TAG or END_TAG events, the (local) name of the current element is returned when namespaces are enabled.
（返回当前元素名）

abstract String nextText()
If current event is START_TAG then if next element is TEXT then element content is returned or if next event is END_TAG then empty string is returned, otherwise exception is thrown.（当前event是 START_TAG，返回后面的文本内容）

private void parseXmlWithPull(String data){
try {
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
XmlPullParser pullParser=factory.newPullParser();
pullParser.setInput(new StringReader(data));
int eventType=pullParser.getEventType();
String id="";
String name="";
String version="";
while (eventType!=XmlPullParser.END_DOCUMENT){
Log.d(TAG,"eventType is: "+eventType);
Log.d(TAG,"event name is: "+pullParser.getName());
switch (eventType){
case XmlPullParser.START_TAG: {
if (pullParser.getName().equals("id")) {
id = pullParser.nextText();
} else if (pullParser.getName().equals("name")) {
name = pullParser.nextText();
} else if (pullParser.getName().equals("version")) {
version = pullParser.nextText();
}
break;
}
case XmlPullParser.END_TAG:{
if (pullParser.getName().equals("app")){
Log.d(TAG, "id is:" + id);
Log.d(TAG, "name is:" + name);
Log.d(TAG, "version is:" + version);
}
}
default:
break;
}

eventType=pullParser.next();
}
}catch (Exception e){
e.printStackTrace();
}
}

输出：

/*0： START_DOCUMENT
1：END_DOCUMENT
2：START_TAG
3：END_TAG
4：TEXT
*/
10-16 08:19:10.910 968-1012/com.example.administrator.testforparse D/Test: eventType is: 0
10-16 08:19:10.910 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.910 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: apps
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: app
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: id
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: name
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.920 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: version
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 3
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: app
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: id is:1
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: name is:gogle
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: version is:1.0
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: app
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: id
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: name
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: version
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 3
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: app
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: id is:2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: name is:Chrome
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: version is:2.0
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: app
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: id
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: name
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 2
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: event name is: version
10-16 08:19:10.930 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: eventType is: 3
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: event name is: app
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: id is:3
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: name is:gogle PLAY
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: version is:3.0
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: eventType is: 4
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: event name is: null
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: eventType is: 3
10-16 08:19:10.950 968-1012/com.example.administrator.testforparse D/Test: event name is: apps

如下图：



所以这里我们姑且可以这么理解：（个人理解，若有错误请帮忙指出，非常感谢）

getEventType获取每个元素的类型，如果是结点开始端（如< app>）的话，就返回 START TAG，当检测到START TAG 就去检测结点的名字，然后获取对应的文本，当检测到节点结尾返回END TAG（如< / app>）当然你也可以用getEventType检测判断是否为文本类型，如果是就获取他的文本内容。