Android入门教程(三十)------之XML解析与生成

本文来自http://blog.csdn.net/hellogv/ ，引用必须注明出处！

       本文使用SAX来解析XML，在Android里面可以使用SAX和DOM，DOM需要把整个XML文件读入内存再解析，比较消耗内存，而SAX基于事件驱动的处理方式，可以在各节点触发回调函数，不过SAX适合节点结构简单的XML文档，复杂的XML文档在后期的节点深度处理会有点麻烦。

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>

<?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：

 

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)));

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。

生成XML的结果如下：

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>

<?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;
        }


}

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) {}
            }

        }

    }
}