Mars Chen Android开发教学视频中XML代码实现的总结

个人总结：

1.制作xml文件时候特别小心回车和Tab键，在解析程序，把他们也当做是有效字符，因此输出结果会跟预期不一样.

2.在从网上下载文件时读入文件流时候，需要添加StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());

要不然下载文件会报错，下载文件失败。这个函数要求在API 9以上才可以使用，因此注意需要在AndroidManifest中配置

<uses-sdk

        android:minSdkVersion="9"

        android:targetSdkVersion="18" />

android:minSdkVersion要在9以上，如果为8，则系统将报错，无法编译。

3. 使笔记本调试Eclipse程序，有时候很多快捷键用不了是因为Eclipse很多快捷键跟笔记本的快捷键冲突，而系统优先系统的快捷键。加入一个外插键盘，eclipse快捷键就都能用了。

（1）AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.xml"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="9"

        android:targetSdkVersion="18" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name="com.example.xml.MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

    

    <uses-permission android:name="android.permission.INTERNET" />

     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

</manifest>

(2)FileUtils.java

package com.example.utils;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import android.os.Environment;

public class FileUtils {

private String SDPATH;

public String getSDPATH() {

return SDPATH;

}

public FileUtils() {

SDPATH = Environment.getExternalStorageDirectory() + "/";

}

public File createSDFile(String fileName) throws IOException {

File file = new File(SDPATH + fileName);

file.createNewFile();

return file;

}

public File createSDDir(String dirName) {

File dir = new File(SDPATH + dirName);

dir.mkdir();

return dir;

}

public boolean isFileExist(String strFileName) {

File file = new File(SDPATH + strFileName);

return file.exists();

}

public File write2SDFromInput(String path, String fileName,

InputStream input) {

File file = null;

OutputStream output = null;

try {

createSDDir(path);

file = createSDFile(path + fileName);

output = new FileOutputStream(file);

byte buffer[] = new byte[4 * 1024];

while ((input.read(buffer)) != -1) {

output.write(buffer);

}

output.flush();

} catch (Exception e) {

e.printStackTrace();

} finally {

try {

output.close();

} catch (Exception e) {

e.printStackTrace();

}

}

return file;

}

}

(3)HttpDownloader.java

package com.example.utils;

import java.io.BufferedReader;

import java.io.File;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import android.os.StrictMode;

public class HttpDownloader {

private URL url = null;

public String download(String strUrl){

StringBuffer sb = new StringBuffer();

String line = null;

BufferedReader buffer = null;

try{

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());

url = new URL(strUrl);

HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();

buffer = new BufferedReader(new InputStreamReader(urlConn.getInputStream()));

while ((line = buffer.readLine()) != null){

sb.append(line);

}

}catch (Exception e){

e.printStackTrace();

}finally{

try{

buffer.close();

}catch (Exception e){

e.printStackTrace();

}

}

return sb.toString();

}

/**

 * 

 * @param strUrl

 * @param strPath

 * @param strFileName

 * @return

 * * -1: error occurs when downloading; 0: downloaded successfully; 1: the downloading file already exists

 */

public int downFile(String strUrl, String strPath, String strFileName){

InputStream inputStream = null;

try{

FileUtils fileUtils = new FileUtils();

if (fileUtils.isFileExist(strPath + strFileName)){

return 1;

} else {

inputStream = getInputStreamFromUrl(strUrl);

File resultFile = fileUtils.write2SDFromInput(strPath, strFileName, inputStream);

if (resultFile == null){

return -1;

}

}

}

catch (Exception e){

e.printStackTrace();

return -1;

}

finally{

try {

inputStream.close();

}

catch (Exception e){

e.printStackTrace();

}

}

return 0;

}

public InputStream getInputStreamFromUrl(String strUrl) throws MalformedURLException, IOException{

StrictMode.setThreadPolicy(new StrictMode.ThreadPolicy.Builder().detectDiskReads().detectDiskWrites().detectNetwork().penaltyLog().build());

url = new URL(strUrl);

HttpURLConnection urlConn = (HttpURLConnection)url.openConnection();

InputStream inputStream = urlConn.getInputStream();

return inputStream;

}

}

(4)MainActivity.java

package com.example.xml;

import java.io.StringReader;

import javax.xml.parsers.SAXParserFactory;

import org.xml.sax.InputSource;

import org.xml.sax.XMLReader;

import android.app.Activity;

import android.os.Bundle;

import android.view.Menu;

import android.view.View;

import android.widget.Button;

import com.example.utils.HttpDownloader;

public class MainActivity extends Activity {

private Button parseXML = null;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        

        parseXML = (Button)findViewById(R.id.parseXML);

        parseXML.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View arg0) {

// TODO Auto-generated method stub

HttpDownloader hd = new HttpDownloader();

String strResult = hd.download("http://10.0.2.2:8080/examples/test.xml");

System.out.println(strResult);

try {

//使用Simple API for XML (SAX) 读取文件

//相对于DOM一次性按节点模式全读入内存，才能进行处理

//该类为边读边处理，读取操作可以随时中断，适合于超大型的xml文件

SAXParserFactory factory = SAXParserFactory.newInstance();

XMLReader reader = factory.newSAXParser().getXMLReader();

reader.setContentHandler(new MyContentHandler());

reader.parse(new InputSource(new StringReader(strResult)));

}

catch (Exception e) {

e.printStackTrace();

}

}

});

    }

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        getMenuInflater().inflate(R.menu.main, menu);

        return true;

    }

    

}

(5)MyContentHandler.java

package com.example.xml;

import org.xml.sax.Attributes;

import org.xml.sax.SAXException;

import org.xml.sax.helpers.DefaultHandler;

//这里没有实现contentHandler接口是因为我们不需要重写所有接口函数

//我们采用继承模式，只需将需要重新的函数实现即可

public class MyContentHandler extends DefaultHandler{

String name1, address1, money1, sex1, status1;

String tagName;

/* (non-Javadoc)

 * @see org.xml.sax.helpers.DefaultHandler#characters(char[], int, int)

 */

@Override

public void characters(char[] ch, int start, int length)

throws SAXException {

// TODO Auto-generated method stub

if (tagName.equals("name")) {

name1 = new String(ch, start, length);

}

if (tagName.equals("sex")) {

sex1 = new String(ch, start, length);

}

if (tagName.equals("status")) {

status1 = new String(ch, start, length);

}

if (tagName.equals("address")) {

address1 = new String(ch, start, length);

}

if (tagName.equals("money")) {

money1 = new String(ch, start, length);

}

}

/* (non-Javadoc)

 * @see org.xml.sax.helpers.DefaultHandler#endDocument()

 */

@Override

public void endDocument() throws SAXException {

// TODO Auto-generated method stub

System.out.println("-----------end----------");

}

/* (non-Javadoc)

 * @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)

 */

@Override

public void endElement(String uri, String localName, String qName)

throws SAXException {

// TODO Auto-generated method stub

if (localName.equals("worker")) {

this.printOut();

}

}

//之所以打印不来这些名称值，是因为在xml中存在"\t"这种符号

//需要对文件重新进行整理

public void printOut() {

System.out.println("name: " + name1);

System.out.println("sex: " + sex1);

System.out.println("status: " + status1);

System.out.println("address: " + address1);

System.out.println("money: " + money1);

}

/* (non-Javadoc)

 * @see org.xml.sax.helpers.DefaultHandler#startDocument()

 */

@Override

public void startDocument() throws SAXException {

// TODO Auto-generated method stub

System.out.println("------------begin-----------------");

}

/* (non-Javadoc)

 * @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String, org.xml.sax.Attributes)

 */

@Override

public void startElement(String uri, String localName, String qName,

Attributes attributes) throws SAXException {

// TODO Auto-generated method stub

tagName = localName;

if (localName.equals("worker")) {

for (int i = 0; i < attributes.getLength(); i++) {

System.out.println(attributes.getLocalName(i) + "=" + attributes.getValue(i));

}

}

}

}