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SNMP4j with snmpv3 response and error is null

I'm using snmp4j 3.4.2 inside my java application (full code below)
I'm trying to execute a snmpget with snmpv3, security DES and auth MD5 and custom OID (python script, which is executed by snmp's extend funtionality). To create better understanding I used SnmpConstants.sysUpTime in the example below.
The SNMP resource has this user configured:
defSecurityName demo
defSecurityLevel authPriv
defAuthType MD5
defPrivType DES
defAuthPassphrase pass
defPrivPassphrase pass
I'm already using this user and resource to successfully perform the snmpget with python (pysnmp) and bash (snmpget), so I can definitely tell that my setup works and the java code is the problem.
I have two java classes (Listener.java and ServerStatusHelper.java)
Listener.java contains main and calls the snmpGet inside ServerStatusHelper.java, other code of Listener is excluded as its not neccessary.
import org.snmp4j.PDU;
import org.snmp4j.ScopedPDU;
import org.snmp4j.Snmp;
import org.snmp4j.Target;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.security.AuthMD5;
import org.snmp4j.security.AuthSHA;
import org.snmp4j.security.PrivAES128;
import org.snmp4j.security.PrivDES;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.VariableBinding;
public class Listener {
public static void main(String[] args) {
ServerStatusHelper agent = new ServerStatusHelper("host.tld", "udp", 161, "demo", "demo",
"pass", "pass", new AuthMD5(), new PrivDES(), true);
try {
agent.startAgent();
ResponseEvent response = agent.snmpGetOperation(SnmpConstants.sysUpTime);
if (response != null) {
System.out.println(
"response null - error: "+ response.getError() +
"peerAddress: " + response.getPeerAddress() +
"source: " + response.getSource().toString() +
"request: " + response.getRequest());
}
} catch (
IOException e) {
e.printStackTrace();
}
}
}
ServerStatusHelper.java
import java.io.IOException;
import org.snmp4j.CommunityTarget;
import org.snmp4j.PDU;
import org.snmp4j.ScopedPDU;
import org.snmp4j.Snmp;
import org.snmp4j.TransportMapping;
import org.snmp4j.UserTarget;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.MPv3;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.security.AuthGeneric;
import org.snmp4j.security.AuthMD5;
import org.snmp4j.security.PrivDES;
import org.snmp4j.security.PrivacyGeneric;
import org.snmp4j.security.SecurityLevel;
import org.snmp4j.security.SecurityModels;
import org.snmp4j.security.SecurityProtocols;
import org.snmp4j.security.USM;
import org.snmp4j.security.UsmUser;
import org.snmp4j.smi.Address;
import org.snmp4j.smi.GenericAddress;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.OctetString;
import org.snmp4j.smi.TransportIpAddress;
import org.snmp4j.smi.VariableBinding;
import org.snmp4j.transport.DefaultTcpTransportMapping;
import org.snmp4j.transport.DefaultUdpTransportMapping;
public class ServerStatusHelper {
private Address nmsIP;
private String user;
private String securityName;
private String privacyPassword;
private String authorizationPassword;
private AuthGeneric authProtocol;
private PrivacyGeneric privacyProtocol;
private String protocol;
private boolean encryption;
private long timeOut = 1000;
private int noOfRetries = 10;
private Snmp snmp;
private UserTarget target;
private CommunityTarget v1target;
ServerStatusHelper(String ip, String protocol, int snmpPort, String username, String securityName,
String privacyPassword, String authPassowrd, AuthGeneric authProtocol, PrivacyGeneric privacyProtocol,
boolean encryption) {
nmsIP = GenericAddress.parse(protocol + ":" + ip + "/" + snmpPort);
System.out.println("NMS IP set : " + nmsIP.toString());
this.protocol = protocol;
this.user = username;
this.securityName = securityName;
this.privacyPassword = privacyPassword;
this.authorizationPassword = authPassowrd;
this.authProtocol = authProtocol;
this.privacyProtocol = privacyProtocol;
this.encryption = encryption;
SecurityProtocols.getInstance().addAuthenticationProtocol(new AuthMD5());
SecurityProtocols.getInstance().addPrivacyProtocol(new PrivDES());
}
public void startAgent() throws IOException {
if (snmp == null) {
TransportMapping<? extends TransportIpAddress> transport = null;
if (protocol.equalsIgnoreCase("udp")) {
System.out.println("UDP Protocol selected.");
transport = new DefaultUdpTransportMapping();
} else {
System.out.println("TCP Protocol selected.");
transport = new DefaultTcpTransportMapping();
}
snmp = new Snmp(transport);
USM usm = new USM(SecurityProtocols.getInstance(), new OctetString(MPv3.createLocalEngineID()), 0);
SecurityModels.getInstance().addSecurityModel(usm);
transport.listen();
snmp.getUSM().addUser(new OctetString(user),
new UsmUser(new OctetString(securityName), authProtocol.getID(),
new OctetString(authorizationPassword), privacyProtocol.getID(),
new OctetString(privacyPassword)));
if (encryption)
target = createUserTarget();
else
v1target = createUserTargetWithoutEncryption();
}
}
public ResponseEvent snmpSetOperation(VariableBinding[] vars) throws IOException {
PDU setPdu = new ScopedPDU();
for (VariableBinding variableBinding : vars) {
setPdu.add(variableBinding);
}
return snmp.send(setPdu, target);
}
public ResponseEvent snmpGetOperation(OID oid) throws IOException {
if (encryption) {
PDU getPdu = new ScopedPDU();
getPdu.add(new VariableBinding(oid));
getPdu.setType(ScopedPDU.GET);
return snmp.get(getPdu, target);
} else {
PDU getPdu = new PDU();
getPdu.add(new VariableBinding(oid));
getPdu.setType(PDU.GET);
return snmp.get(getPdu, v1target);
}
}
private UserTarget createUserTarget() {
UserTarget target = new UserTarget();
target.setAddress(nmsIP);
target.setRetries(noOfRetries);
target.setTimeout(timeOut);
target.setVersion(SnmpConstants.version3);
target.setSecurityLevel(SecurityLevel.AUTH_PRIV);
target.setSecurityName(new OctetString(securityName));
return target;
}
private CommunityTarget createUserTargetWithoutEncryption() {
CommunityTarget target = new CommunityTarget();
target.setCommunity(new OctetString("public"));
target.setAddress(nmsIP);
target.setRetries(noOfRetries);
target.setTimeout(timeOut);
target.setVersion(SnmpConstants.version1);
return target;
}
public long getTimeOut() {
return timeOut;
}
public void setTimeOut(long timeOut) {
this.timeOut = timeOut;
}
public int getNoOfRetries() {
return noOfRetries;
}
public void setNoOfRetries(int noOfRetries) {
this.noOfRetries = noOfRetries;
}
}
The execution of the program exits with
NMS IP set : **IPREMOVED**/161
UDP Protocol selected.
response null - error: nullpeerAddress: **IPREMOVED**/161source: org.snmp4j.Snmp#e580929 request: GET[{contextEngineID=80:00:1f:88:80:5e:2e:49:07:2f:68:44:57:00:00:00:00, contextName=}, requestID=588252045, errorStatus=0, errorIndex=0, VBS[1.3.6.1.2.1.1.3.0 = Null]]
Anyone has an idea what I'm doing wrong?
Edit:
From the servers syslog I can see, that the request arrives at the resource:
Jul 31 11:52:46 loadbalancer snmpd[1219]: Connection from UDP: [IP REMOVED]:54734->[IP REMOVED]:161
Jul 31 11:52:46 loadbalancer snmpd[1219]: Connection from UDP: [IP REMOVED]:54734->[IP REMOVED]:161

#i-shm I think you are doing everything ok.
The only problem in your code could be just the line in which you evaluate the response variable. Your are indicating response != null when it should be actually response == null. I mean:
import org.snmp4j.PDU;
import org.snmp4j.ScopedPDU;
import org.snmp4j.Snmp;
import org.snmp4j.Target;
import org.snmp4j.event.ResponseEvent;
import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.security.AuthMD5;
import org.snmp4j.security.AuthSHA;
import org.snmp4j.security.PrivAES128;
import org.snmp4j.security.PrivDES;
import org.snmp4j.smi.OID;
import org.snmp4j.smi.VariableBinding;
public class Listener {
public static void main(String[] args) {
ServerStatusHelper agent = new ServerStatusHelper("host.tld", "udp", 161, "demo", "demo",
"pass", "pass", new AuthMD5(), new PrivDES(), true);
try {
agent.startAgent();
ResponseEvent event = agent.snmpGetOperation(SnmpConstants.sysUpTime);
final PDU response = event.getResponse();
if (response == null) {
System.out.println(
"response null - error: "+ event.getError() +
"peerAddress: " + event.getPeerAddress() +
"source: " + event.getSource().toString() +
"request: " + event.getRequest());
} else {
System.out.println("Response PDU:" + response.toString());
// Process the response as you need, maybe something like this:
long sysUpTime = response.get(0).getVariable().toLong();
// You can find relevant information in the javadocs of the library:
// https://agentpp.com/doc/snmp4j/index.html?org/snmp4j/package-summary.html
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
This is why you do not receive errors in the java code and your syslog indicates that the requests were actually sent.

calling a java class method in another class

Hi I have below Java Class for Sending Fax from Java
package oracle.apps.print;
import com.softlinx.replixfax.*;
import javax.xml.ws.*;
import org.apache.commons.codec.binary.Base64;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.nio.file.Path;
import java.io.File;
public class Fax {
public void SendFax(String Filepath, String faxno) {
try {
ReplixFaxService service = new ReplixFaxService();
ReplixFaxPort port = service.getReplixFaxPort();
((BindingProvider)port).getRequestContext().put(BindingProvider.USERNAME_PROPERTY, "admin");
// ((BindingProvider) port).getRequestContext().put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY,"https://api.rpxfax.com/softlinx/replixfax/wsapi");
((BindingProvider)port).getRequestContext().put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY,
"https://api.rpxtest.com:9999/softlinx/replixfax/wsapi");
Authentication auth = new Authentication();
auth.setLogin("user");
String password = "pwd";
auth.setPassword(org.apache.commons.codec.binary.Base64.encodeBase64String(password.getBytes()));
auth.setRealm("MTBC");
auth.setPasswordSecurity("base64");
SendFaxInput sendFaxInput = new SendFaxInput();
sendFaxInput.setAuthentication(auth);
FaxRecipient recipient = new FaxRecipient();
recipient.setFaxNumber(faxno.toString());
Attachment attachment = new Attachment();
File f = new File(Filepath.toString());
attachment.setFileName(f.getName());
Path path = Paths.get(Filepath.toString());
byte[] data = Files.readAllBytes(path);
attachment.setAttachmentContent(data);
sendFaxInput.getFaxRecipient().add(recipient);
sendFaxInput.getAttachment().add(attachment);
SendFaxOutput result = port.sendFax(sendFaxInput);
System.out.println("Status Code= " + result.getRequestStatus().getStatusCode());
if (result.getFaxInfo() != null) {
System.out.println("Fax ID = " + result.getFaxInfo().get(0).getFaxId());
}
} catch (Exception ex) {
System.out.println("Exception: " + ex.getMessage());
}
}
}
I am compiling this class like this
javac -cp .;./commons-codec-1.10.jar Fax.java
However Compiling of both classes is fine no error at compile time
when i call the method Fax in another class (XXEmail) like this
package oracle.apps.print;
public class XXEmail implements JavaConcurrentProgram {
public static void main(String[] args) {
try {
Fax mtbcfax = new Fax();
mtbcfax.SendFax("E:\\csv_svb\\3010218.pdf", "173224xxxx");
out.writeln("Fax Sent Successfully");
} catch (Exception i) {
log.writeln("Error while Sending Fax " + i.getMessage(), LogFile.STATEMENT);
} finally {
log.writeln("Error while Sending Fax ");
}
}
}
It always goes to Finally block with out showing any error
How can i call this method so it should return with success code or exception

Try to:
Comment all lines in the SendFax function and add only a log:
public void SendFax(String Filepath, String faxno) {
out.writeln("No problem here");
}
Now start the program and see if the function is correctly called or not.
If It is correctly called, so probably the arguments you send are wrong.

Different Result on DBPedia Spotlight by using the code and DBPedia Spotlight endpoint

This is the main class in which query is being fired
package extractKeyword;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.methods.GetMethod;
import org.dbpedia.spotlight.exceptions.AnnotationException;
import org.dbpedia.spotlight.model.DBpediaResource;
import org.dbpedia.spotlight.model.Text;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.File;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.LinkedList;
import java.util.List;
public class db extends AnnotationClient {
//private final static String API_URL = "http://jodaiber.dyndns.org:2222/";
private static String API_URL = "http://spotlight.dbpedia.org/";
private static double CONFIDENCE = 0.0;
private static int SUPPORT = 0;
// private static String powered_by ="non";
// private static String spotter ="CoOccurrenceBasedSelector";//"LingPipeSpotter"=Annotate all spots
//AtLeastOneNounSelector"=No verbs and adjs.
//"CoOccurrenceBasedSelector" =No 'common words'
//"NESpotter"=Only Per.,Org.,Loc.
//private static String disambiguator ="Default";//Default ;Occurrences=Occurrence-centric;Document=Document-centric
//private static String showScores ="yes";
#SuppressWarnings("static-access")
public void configiration(double CONFIDENCE,int SUPPORT)
//, String powered_by,String spotter,String disambiguator,String showScores)
{
this.CONFIDENCE=CONFIDENCE;
this.SUPPORT=SUPPORT;
// this.powered_by=powered_by;
//this.spotter=spotter;
//this.disambiguator=disambiguator;
//showScores=showScores;
}
public List<DBpediaResource> extract(Text text) throws AnnotationException {
// LOG.info("Querying API.");
String spotlightResponse;
try {
String Query=API_URL + "rest/annotate/?" +
"confidence=" + CONFIDENCE
+ "&support=" + SUPPORT
// + "&spotter=" + spotter
// + "&disambiguator=" + disambiguator
// + "&showScores=" + showScores
// + "&powered_by=" + powered_by
+ "&text=" + URLEncoder.encode(text.text(), "utf-8");
//LOG.info(Query);
GetMethod getMethod = new GetMethod(Query);
getMethod.addRequestHeader(new Header("Accept", "application/json"));
spotlightResponse = request(getMethod);
} catch (UnsupportedEncodingException e) {
throw new AnnotationException("Could not encode text.", e);
}
assert spotlightResponse != null;
JSONObject resultJSON = null;
JSONArray entities = null;
try {
resultJSON = new JSONObject(spotlightResponse);
entities = resultJSON.getJSONArray("Resources");
} catch (JSONException e) {
//throw new AnnotationException("Received invalid response from DBpedia Spotlight API.");
}
LinkedList<DBpediaResource> resources = new LinkedList<DBpediaResource>();
if(entities!=null)
for(int i = 0; i < entities.length(); i++) {
try {
JSONObject entity = entities.getJSONObject(i);
resources.add(
new DBpediaResource(entity.getString("#URI"),
Integer.parseInt(entity.getString("#support"))));
} catch (JSONException e) {
//((Object) LOG).error("JSON exception "+e);
}
}
return resources;
}
}
The extended class
package extractKeyword;
import org.apache.commons.httpclient.DefaultHttpMethodRetryHandler;
import org.apache.commons.httpclient.Header;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.HttpException;
import org.apache.commons.httpclient.HttpMethodBase;
import org.apache.commons.httpclient.HttpStatus;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.params.HttpMethodParams;
import org.dbpedia.spotlight.exceptions.AnnotationException;
import org.dbpedia.spotlight.model.DBpediaResource;
import org.dbpedia.spotlight.model.Text;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.logging.Logger;
import javax.ws.rs.HttpMethod;
/**
* #author pablomendes
*/
public abstract class AnnotationClient {
//public Logger LOG = Logger.getLogger(this.getClass());
private List<String> RES = new ArrayList<String>();
// Create an instance of HttpClient.
private static HttpClient client = new HttpClient();
public List<String> getResu(){
return RES;
}
public String request(GetMethod getMethod) throws AnnotationException {
String response = null;
// Provide custom retry handler is necessary
( getMethod).getParams().setParameter(HttpMethodParams.RETRY_HANDLER,
new DefaultHttpMethodRetryHandler(3, false));
try {
// Execute the method.
int statusCode = client.executeMethod((org.apache.commons.httpclient.HttpMethod) getMethod);
if (statusCode != HttpStatus.SC_OK) {
// LOG.error("Method failed: " + ((HttpMethodBase) method).getStatusLine());
}
// Read the response body.
byte[] responseBody = ((HttpMethodBase) getMethod).getResponseBody(); //TODO Going to buffer response body of large or unknown size. Using getResponseBodyAsStream instead is recommended.
// Deal with the response.
// Use caution: ensure correct character encoding and is not binary data
response = new String(responseBody);
} catch (HttpException e) {
// LOG.error("Fatal protocol violation: " + e.getMessage());
throw new AnnotationException("Protocol error executing HTTP request.",e);
} catch (IOException e) {
//((Object) LOG).error("Fatal transport error: " + e.getMessage());
//((Object) LOG).error(((HttpMethodBase) method).getQueryString());
throw new AnnotationException("Transport error executing HTTP request.",e);
} finally {
// Release the connection.
((HttpMethodBase) getMethod).releaseConnection();
}
return response;
}
protected static String readFileAsString(String filePath) throws java.io.IOException{
return readFileAsString(new File(filePath));
}
protected static String readFileAsString(File file) throws IOException {
byte[] buffer = new byte[(int) file.length()];
#SuppressWarnings("resource")
BufferedInputStream f = new BufferedInputStream(new FileInputStream(file));
f.read(buffer);
return new String(buffer);
}
static abstract class LineParser {
public abstract String parse(String s) throws ParseException;
static class ManualDatasetLineParser extends LineParser {
public String parse(String s) throws ParseException {
return s.trim();
}
}
static class OccTSVLineParser extends LineParser {
public String parse(String s) throws ParseException {
String result = s;
try {
result = s.trim().split("\t")[3];
} catch (ArrayIndexOutOfBoundsException e) {
throw new ParseException(e.getMessage(), 3);
}
return result;
}
}
}
public void saveExtractedEntitiesSet(String Question, LineParser parser, int restartFrom) throws Exception {
String text = Question;
int i=0;
//int correct =0 ; int error = 0;int sum = 0;
for (String snippet: text.split("\n")) {
String s = parser.parse(snippet);
if (s!= null && !s.equals("")) {
i++;
if (i<restartFrom) continue;
List<DBpediaResource> entities = new ArrayList<DBpediaResource>();
try {
entities = extract(new Text(snippet.replaceAll("\\s+"," ")));
System.out.println(entities.get(0).getFullUri());
} catch (AnnotationException e) {
// error++;
//LOG.error(e);
e.printStackTrace();
}
for (DBpediaResource e: entities) {
RES.add(e.uri());
}
}
}
}
public abstract List<DBpediaResource> extract(Text text) throws AnnotationException;
public void evaluate(String Question) throws Exception {
evaluateManual(Question,0);
}
public void evaluateManual(String Question, int restartFrom) throws Exception {
saveExtractedEntitiesSet(Question,new LineParser.ManualDatasetLineParser(), restartFrom);
}
}
The Main Class
package extractKeyword;
public class startAnnonation {
public static void main(String[] args) throws Exception {
String question = "What is the winning chances of BJP in New Delhi elections?";
db c = new db ();
c.configiration(0.25,0);
//, 0, "non", "AtLeastOneNounSelector", "Default", "yes");
c.evaluate(question);
System.out.println("resource : "+c.getResu());
}
}
The main problem is here when I am using DBPedia spotlight using spotlight jar (above code)then i am getting different result as compared to the dbpedia spotlight endpoint(dbpedia-spotlight.github.io/demo/)
Result using the above code:-
Text :-What is the winning chances of BJP in New Delhi elections?
Confidence level:-0.35
resource : [Election]
Result on DBPedia Spotlight endpoint(//dbpedia-spotlight.github.io/demo/)
Text:-What is the winning chances of BJP in New Delhi elections?
Confidence level:-0.35
resource : [Bharatiya_Janata_Party, New_Delhi, Election]
Why also the spotlight now don't have support as a parameter?

Programmatically Fetching Google+ status updates

Is there a way to programmatically fetch Google+ updates for a user's profile? I can't seem to find much in the documentation at https://developers.google.com/+/api/latest/people and http://developer.android.com/reference/com/google/android/gms/plus/model/people/Person.html about fetching statuses. I would like to fetch the data by making an HTTP request or if there is some sort of SDK for Android that will help me, that would work to.

The API you are looking for is plus.activities.list. This will list the Google+ equivalent of Facebook status updates. The referenced page has example code to get you started.
When accessing the API, you should use the Google API client as documented here.

The following code will be useful to retrieve the Http responses.
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Type;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;
import java.util.zip.GZIPInputStream;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
public class GooglePlusStatusHelper {
public GooglePlusStatusHelper() {
}
public static void main(String... args) {
GooglePlusStatusHelper googlePlusStatusHelper = new GooglePlusStatusHelper();
try {
googlePlusStatusHelper.tagsUsed();
} catch (IOException e) {
e.printStackTrace();
}
}
private void tagsUsed() throws IOException {
URL url = createQuery("users");
Type dataType = new TypeToken<Wrapper<Status>>(){}.getType();
Status status = executeQuery(url, dataType);
System.out.println(status);
}
private URL createQuery(String inputParam) throws MalformedURLException {
String baseUrl = "http://api.example.com/" + inputParam ;
System.out.println(baseUrl);
URL url = new URL(baseUrl);
return url;
}
private Status executeQuery(URL url, Type clz) throws IOException {
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.connect();
System.out.println("Response Code:" + conn.getResponseCode());
System.out.println("Response Message:" + conn.getResponseMessage());
System.out.println("TYPE:" + conn.getContentType());
InputStream content = conn.getInputStream();
String encoding = conn.getContentEncoding();
if (encoding != null && encoding.equals("gzip")) {
content = new GZIPInputStream(content);
}
String result = new Scanner(content, "UTF-8").useDelimiter("\\A").next();
content.close();
Gson gson = new Gson();
return gson.fromJson(result, clz);
}
}
Status class :
public class Status {
private int count;
private String status;
......
public String toString() {
String result = "\ncount: " + count +
"\status:" + status;
result = result + "\n------------";
return result;
}
}

How to read MP3 file tags

I want to have a program that reads metadata from an MP3 file. My program should also able to edit these metadata. What can I do?
I got to search out for some open source code. But they have code; but not simplified idea for my job they are going to do.
When I read further I found the metadata is stored in the MP3 file itself. But I am yet not able to make a full idea of my baby program.
Any help will be appreciated; with a program or very idea (like an algorithm). :)

The last 128 bytes of a mp3 file contains meta data about the mp3 file., You can write a program to read the last 128 bytes...
UPDATE:
ID3v1 Implementation
The Information is stored in the last 128 bytes of an MP3. The Tag
has got the following fields, and the offsets given here, are from
0-127.
Field Length Offsets
Tag 3 0-2
Songname 30 3-32
Artist 30 33-62
Album 30 63-92
Year 4 93-96
Comment 30 97-126
Genre 1 127
WARINING- This is just an ugly way of getting metadata and it might not actually be there because the world has moved to id3v2. id3v1 is actually obsolete. Id3v2 is more complex than this, so ideally you should use existing libraries to read id3v2 data from mp3s . Just putting this out there.

You can use apache tika Java API for meta-data parsing from MP3 such as title, album, genre, duraion, composer, artist and etc.. required jars are tika-parsers-1.4, tika-core-1.4.
Sample Program:
package com.parse.mp3;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import org.apache.tika.exception.TikaException;
import org.apache.tika.metadata.Metadata;
import org.apache.tika.parser.ParseContext;
import org.apache.tika.parser.Parser;
import org.apache.tika.parser.mp3.Mp3Parser;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class AudioParser {
/**
* #param args
*/
public static void main(String[] args) {
String fileLocation = "G:/asas/album/song.mp3";
try {
InputStream input = new FileInputStream(new File(fileLocation));
ContentHandler handler = new DefaultHandler();
Metadata metadata = new Metadata();
Parser parser = new Mp3Parser();
ParseContext parseCtx = new ParseContext();
parser.parse(input, handler, metadata, parseCtx);
input.close();
// List all metadata
String[] metadataNames = metadata.names();
for(String name : metadataNames){
System.out.println(name + ": " + metadata.get(name));
}
// Retrieve the necessary info from metadata
// Names - title, xmpDM:artist etc. - mentioned below may differ based
System.out.println("----------------------------------------------");
System.out.println("Title: " + metadata.get("title"));
System.out.println("Artists: " + metadata.get("xmpDM:artist"));
System.out.println("Composer : "+metadata.get("xmpDM:composer"));
System.out.println("Genre : "+metadata.get("xmpDM:genre"));
System.out.println("Album : "+metadata.get("xmpDM:album"));
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (SAXException e) {
e.printStackTrace();
} catch (TikaException e) {
e.printStackTrace();
}
}
}

For J2ME(which is what I was struggling with), here's the code that worked for me..
import java.io.InputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.file.FileConnection;
import javax.microedition.lcdui.*;
import javax.microedition.media.Manager;
import javax.microedition.media.Player;
import javax.microedition.media.control.MetaDataControl;
import javax.microedition.midlet.MIDlet;
public class MetaDataControlMIDlet extends MIDlet implements CommandListener {
private Display display = null;
private List list = new List("Message", List.IMPLICIT);
private Command exitCommand = new Command("Exit", Command.EXIT, 1);
private Alert alert = new Alert("Message");
private Player player = null;
public MetaDataControlMIDlet() {
display = Display.getDisplay(this);
alert.addCommand(exitCommand);
alert.setCommandListener(this);
list.addCommand(exitCommand);
list.setCommandListener(this);
//display.setCurrent(list);
}
public void startApp() {
try {
FileConnection connection = (FileConnection) Connector.open("file:///e:/breathe.mp3");
InputStream is = null;
is = connection.openInputStream();
player = Manager.createPlayer(is, "audio/mp3");
player.prefetch();
player.realize();
} catch (Exception e) {
alert.setString(e.getMessage());
display.setCurrent(alert);
e.printStackTrace();
}
if (player != null) {
MetaDataControl mControl = (MetaDataControl) player.getControl("javax.microedition.media.control.MetaDataControl");
if (mControl == null) {
alert.setString("No Meta Information");
display.setCurrent(alert);
} else {
String[] keys = mControl.getKeys();
for (int i = 0; i < keys.length; i++) {
list.append(keys[i] + " -- " + mControl.getKeyValue(keys[i]), null);
}
display.setCurrent(list);
}
}
}
public void commandAction(Command cmd, Displayable disp) {
if (cmd == exitCommand) {
notifyDestroyed();
}
}
public void pauseApp() {
}
public void destroyApp(boolean unconditional) {
}
}