Read/write to external XML file in Android

Question

I'm trying to learn more about reading/writing to an XML-file (as a kind of database) in Android. I can't seem to find anything about this so I guess I don't know what terms to look for.

My goal is to write usernames and passwords from two editText-fields into the file, then read them (and hopefully succeed validating them) later on when I am going to make a login function for my app.

The file I wish to read/write to is located on a server, so this makes it a bit complex for me.

If someone could help me find a tutorial about reading/writing to XML-files I would be very happy.

Thank you.

Answer 1

To create new file in /storage/sdcard0/your_app_name/ use following:

File file = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + "/" + "your_app_name" + "/" + xmlFile);
        file.createNewFile();
        FileOutputStream fileos = new FileOutputStream(file);

Answer 2

public class SkillsParser implements AssyncXmlReader {

private String ns = "";
@Override
public Object parse(InputStream in) throws XmlPullParserException,
        IOException {
    try {
        XmlPullParser parser = Xml.newPullParser();
        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
        parser.setInput(in, null);
        parser.nextTag();
        return readSkills(parser);
    } finally {
        in.close();
    }
}

private Object readSkills(XmlPullParser parser) throws XmlPullParserException, IOException {
    parser.require(XmlPullParser.START_TAG, ns, "skills");
    List<ESkill> skills = new ArrayList<ESkill>();

    while (parser.next() != XmlPullParser.END_TAG) {
        if (parser.getEventType() != XmlPullParser.START_TAG) {
            continue;
        }
        String name = parser.getName();
        // Starts by looking for the entry tag
        if (name.equals("skill")) {
            skills.add(readSkill(parser));
        } else {
            skip(parser);
        }
    }  
    return skills;
}

private ESkill readSkill(XmlPullParser parser) throws XmlPullParserException, IOException {
    /*
    <skill>
        <name>Software Engineering</name>

    </skill>
    */
    String skill_name = "";

    while (parser.next() != XmlPullParser.END_TAG) {
        if (parser.getEventType() != XmlPullParser.START_TAG) {
            continue;
        }
        String name = parser.getName();
        if ("name".equals(name)) {
            skill_name = readName(parser);
        } else {
            skip(parser);
        }
    }

    return new ESkill().setSkill(skill_name);
}

// Processes title tags in the feed.
private String readName(XmlPullParser parser) throws IOException, XmlPullParserException {
    parser.require(XmlPullParser.START_TAG, ns, "name");
    String description = readText(parser);
    parser.require(XmlPullParser.END_TAG, ns, "name");
    return description;
}

// For the tags title and summary, extracts their text values.
private String readText(XmlPullParser parser) throws IOException, XmlPullParserException {
    String result = "";
    if (parser.next() == XmlPullParser.TEXT) {
        result = parser.getText();
        parser.nextTag();
    }
    return result;
}

private void skip(XmlPullParser parser) throws XmlPullParserException, IOException {
    if (parser.getEventType() != XmlPullParser.START_TAG) {
        throw new IllegalStateException();
    }
    int depth = 1;
    while (depth != 0) {
        switch (parser.next()) {
        case XmlPullParser.END_TAG:
            depth--;
            break;
        case XmlPullParser.START_TAG:
            depth++;
            break;
        }
    }
 }

}

Answer 3

Here is the code to write to XML file:

final String xmlFile = "userData";
String userNAme = "username";
String password = "password";
try {
    FileOutputStream fos = new  FileOutputStream("userData.xml");
    FileOutputStream fileos= getApplicationContext().openFileOutput(xmlFile, Context.MODE_PRIVATE);
    XmlSerializer xmlSerializer = Xml.newSerializer();              
    StringWriter writer = new StringWriter();
    xmlSerializer.setOutput(writer);
    xmlSerializer.startDocument("UTF-8", true);
    xmlSerializer.startTag(null, "userData");
    xmlSerializer.startTag(null, "userName");
    xmlSerializer.text(username_String_Here);
    xmlSerializer.endTag(null, "userName");
    xmlSerializer.startTag(null,"password");
    xmlSerializer.text(password_String);
    xmlSerializer.endTag(null, "password");             
    xmlSerializer.endTag(null, "userData");
    xmlSerializer.endDocument();
    xmlSerializer.flush();
    String dataWrite = writer.toString();
    fileos.write(dataWrite.getBytes());
    fileos.close();
}
catch (FileNotFoundException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
catch (IllegalArgumentException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
catch (IllegalStateException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

and to read data from XML File the do as below:

final String xmlFile = "userData";
ArrayList<String> userData = new ArrayList<String>();
try {
    fis = getApplicationContext().openFileInput(xmlFile);
    isr = new InputStreamReader(fis);
    inputBuffer = new char[fis.available()];
    isr.read(inputBuffer);
    data = new String(inputBuffer);
    isr.close();
    fis.close();
}
catch (FileNotFoundException e3) {
    // TODO Auto-generated catch block
    e3.printStackTrace();
}
catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
XmlPullParserFactory factory = null;
try {
    factory = XmlPullParserFactory.newInstance();
}
catch (XmlPullParserException e2) {
    // TODO Auto-generated catch block
    e2.printStackTrace();
}
factory.setNamespaceAware(true);
XmlPullParser xpp = null;
try {
    xpp = factory.newPullParser();
}
catch (XmlPullParserException e2) {
    // TODO Auto-generated catch block
    e2.printStackTrace();
}
try {
    xpp.setInput(new StringReader(data));
}
catch (XmlPullParserException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}
int eventType = 0;
try {
    eventType = xpp.getEventType();
}
catch (XmlPullParserException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}
while (eventType != XmlPullParser.END_DOCUMENT){
    if (eventType == XmlPullParser.START_DOCUMENT) {
        System.out.println("Start document");
    }
    else if (eventType == XmlPullParser.START_TAG) {
        System.out.println("Start tag "+xpp.getName());
    }
    else if (eventType == XmlPullParser.END_TAG) {
        System.out.println("End tag "+xpp.getName());
    }
    else if(eventType == XmlPullParser.TEXT) {
        userData.add(xpp.getText());
    }
    try {
        eventType = xpp.next();
    }
    catch (XmlPullParserException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}
String userName = userData.get(0);
String password = userData.get(1);