Android开发XML解析与生成

释放双眼,带上耳机,听听看~!

 

本文要解析的test.xml文件如下:

<?xml version="1.0" encoding="utf-8"?>
<test>
<title>testSAX</title>
<content aa="1" bb="2">
<name>hellogv</name>
<url>http://blog.csdn.net/hellogv</url>
</content>
</test>

解析如上XML的结果如下图所示:

使用SAX解析,需要定义SAXParserFactory(使应用程序能够配置和获取基于 SAX 的解析器以解析 XML 文档),SAXParser(从各种输入源解析 XML),XMLReader(使用回调函数读取 XML 文档),其中XMLReader是个关键。XMLReader可以为解析XML定义各种回调函数,“条件符合”的时候触发这些回调函数。

SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
XMLReader reader = parser.getXMLReader();
reader.setContentHandler(handler);
reader.parse(new InputSource(testSAX.this.getResources()
.openRawResource(R.raw.test)));

在这段代码里,XMLReader就调用继承DefaultHandler的SAXHandler。DefaultHandler已实现ContentHandler, DTDHandler, EntityResolver, ErrorHandler等接口,包含常见读取XML的操作,具体请看下面的SAXHandler.java源码。

最终生成XML的结果如下图所示:

上图是读取各节点之后,使用XmlSerializer重新组合并输出XML字符串。

本文的main.xml代码如下:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:layout_height="wrap_content"
android:layout_width="fill_parent" android:id="@+id/btnSAX"
android:text="使用SAX解析XML"></Button>
<Button android:layout_height="wrap_content"
android:layout_width="fill_parent" android:text="生成XML" android:id="@+id/btnOutput"></Button>
<EditText android:text="@+id/EditText01" android:id="@+id/EditText01"
android:layout_width="fill_parent" android:layout_height="fill_parent"></EditText>
</LinearLayout>

SAXHandler.java的源码如下:

package com.testSAX;
import java.util.ArrayList;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
import android.util.Log;
public class SAXHandler extends DefaultHandler{
private ArrayList<String> keys = new ArrayList<String>();//保存字段名称
private ArrayList<Object> values = new ArrayList<Object>();//保存值
@Override
public void startDocument() throws SAXException {
super.startDocument();
}
@Override
public void endDocument() throws SAXException {
super.endDocument();
}
@Override
public void startElement(String uri, String localName, String qName,
Attributes attributes) throws SAXException {
//保存开始标记
keys.add("startTag");
values.add(localName);
Log.e("startTag",localName);
//保存属性值
for ( int i = 0; i < attributes.getLength(); i++ ){
keys.add("Attr");
String[] str=new String[2];
str[0]=attributes.getLocalName(i);
str[1]=attributes.getValue(i);
values.add(str);
Log.e("Attr",str[0]+"="+str[1]);
}
}
@Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
//保存结束标记
keys.add("endTag");
values.add(localName);
Log.e("endTag",localName);
}
@Override
public void characters(char[] ch, int start, int length)
throws SAXException {
String value = new String(ch, start, length);
value = value.trim();
if (value.length() == 0)
return;
keys.add("text");
values.add(value);
Log.e("text",value);
}
public ArrayList<String> GetKeys()
{
return keys;
}
public ArrayList<Object> GetValues()
{
return values;
}
}

testSAX.java的源码如下:

package com.testSAX;
import java.io.StringWriter;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.InputSource;
import org.xml.sax.XMLReader;
import org.xmlpull.v1.XmlSerializer;
import android.app.Activity;
import android.os.Bundle;
import android.util.Xml;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class testSAX extends Activity {
/** Called when the activity is first created. */
Button btnSAX, btnOutput;
EditText memo;
SAXHandler handler = new SAXHandler();
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnSAX = (Button) this.findViewById(R.id.btnSAX);
btnSAX.setOnClickListener(new ClickEvent());
btnOutput = (Button) this.findViewById(R.id.btnOutput);
btnOutput.setOnClickListener(new ClickEvent());
memo = (EditText) this.findViewById(R.id.EditText01);
}
class ClickEvent implements View.OnClickListener {
@Override
public void onClick(View v) {
if (v == btnSAX) {//解析XML,并保存标记,属性等值
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser parser = factory.newSAXParser();
XMLReader reader = parser.getXMLReader();
reader.setContentHandler(handler);
reader.parse(new InputSource(testSAX.this.getResources()
.openRawResource(R.raw.test)));
} catch (Exception ee) {}
}
else if (v == btnOutput) {//生成XML
try {
XmlSerializer serializer = Xml.newSerializer();
StringWriter writer = new StringWriter();
try {
serializer.setOutput(writer);
serializer.startDocument("UTF-8",true);
for(int i=0;i<handler.GetKeys().size();i++)
{
if(handler.GetKeys().get(i).equals("startTag"))
{
serializer.startTag("", (String) handler.GetValues().get(i));
}
else if(handler.GetKeys().get(i).equals("Attr")){
String[] str= (String[]) handler.GetValues().get(i);
serializer.attribute("",str[0],str[1]);
}
else if(handler.GetKeys().get(i).equals("text"))
serializer.text((String)handler.GetValues().get(i));
else if(handler.GetKeys().get(i).equals("endTag"))
{
serializer.endTag("", (String) handler.GetValues().get(i));
}
}
serializer.endDocument();
String text=writer.toString();
text=text.replace("><", ">/r/n<");
memo.setText(text);//输出到文本框
} catch (Exception e) {
throw new RuntimeException(e);
}
} catch (Exception e) {}
}
}
}
}

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