Develop Reference

fetching files from SFTP

I want to fetch files from SFTP which are created after a given timestamp(time of last pull) in java. I am using j2ssh as of now. Please let me know if some other API supports such a feature.

Jsch supports the ls command which will bring you back all the attributes of the remote file. You can write a little code to eliminate the files you want to retrieve from there.
Java Doc: http://epaul.github.io/jsch-documentation/javadoc/
This example compares the remote file timestamps to find the oldest file, it wouldn't be much of a stretch to modify it to compare your last run date against the remote file date, then do the download as part of the loop.
Code from Finding file size and last modified of SFTP file using Java
try {
list = Main.chanSftp.ls("*.xml");
if (list.isEmpty()) {
fileFound = false;
}
else {
lsEntry = (ChannelSftp.LsEntry) list.firstElement();
oldestFile = lsEntry.getFilename();
attrs = lsEntry.getAttrs();
currentOldestTime = attrs.getMTime();
for (Object sftpFile : list) {
lsEntry = (ChannelSftp.LsEntry) sftpFile;
nextName = lsEntry.getFilename();
attrs = lsEntry.getAttrs();
nextTime = attrs.getMTime();
if (nextTime < currentOldestTime) {
oldestFile = nextName;
currentOldestTime = nextTime;
}
}

Using SQLite in Codename One Application

I have a working sqlite db which I have place in my /src folder.
I then went onto the Codename One website and followed their doc example
Database db = null;
Cursor cur = null;
try {
db = Display.getInstance().openOrCreate("MyDb.db");
if(query.getText().startsWith("select")) {
cur = db.executeQuery(query.getText());
int columns = cur.getColumnCount();
frmMain.removeAll();
if(columns > 0) {
boolean next = cur.next();
if(next) {
ArrayList<String[]> data = new ArrayList<>();
String[] columnNames = new String[columns];
for(int iter = 0 ; iter < columns ; iter++) {
columnNames[iter] = cur.getColumnName(iter);
}
while(next) {
Row currentRow = cur.getRow();
String[] currentRowArray = new String[columns];
for(int iter = 0 ; iter < columns ; iter++) {
currentRowArray[iter] = currentRow.getString(iter);
}
data.add(currentRowArray);
next = cur.next();
}
Object[][] arr = new Object[data.size()][];
data.toArray(arr);
frmMain.add(BorderLayout.CENTER, new Table(new DefaultTableModel(columnNames, arr)));
} else {
frmMain.add(BorderLayout.CENTER, "Query returned no results");
}
} else {
frmMain.add(BorderLayout.CENTER, "Query returned no results");
}
} else {
db.execute(query.getText());
frmMain.add(BorderLayout.CENTER, "Query completed successfully");
}
frmMain.revalidate();
} catch(IOException err) {
frmMain.removeAll();
frmMain.add(BorderLayout.CENTER, "Error: " + err);
frmMain.revalidate();
} finally {
Util.cleanup(db);
Util.cleanup(cur);
}
However when I run the example and try and execute a simple select query I get this error ...
java.sql.SQLException: [SQLITE_ERROR] SQL error or missing database (no such table: MyTable)
So I have added the DB
I have used the 'openOrCreate' statement
Have I missed a step?
Thanks

Are you shure that you current working directory at execution is ./src ?
Try
db = Display.getInstance().openOrCreate("./src/MyDb.db");
or open with absolute filename:
db = Display.getInstance().openOrCreate("/path/to/src/MyDb.db");

You can try this cn1lib https://github.com/shannah/cn1-data-access-lib
I have used it and it works a charm, except doesn't work for 2 tables in the same query and can't perform delete operations.
Cheers

Thanks for all the input guys.
Unfortunately none of the advice worked for me.
However I did solve it in the end.
It turns out that there is a folder in my home directory called '.cn1/database'. Once I placed the DB into this folder it worked.
Two things:
1] If the db does not exist then it will create it and place it into this directory
2] The db does not show up anywhere in Netbeans (well not that I could see anyway)
Thanks again

From the developer guide:
Some SQLite apps ship with a "ready made" database. We allow you to
replace the DB file by using the code:
String path = Display.getInstance().getDatabasePath(“databaseName”);
You can then use the FileSystemStorage class to write the content of
your DB file into the path. Notice that it must be a valid SQLite
file!
Important: getDatabasePath() is not supported in the Javascript port. It
will always return null.
This is very useful for applications that need to synchronize with a
central server or applications that ship with a large database as part
of their core product.
You are relying on paths that make sense in the simulator, in the device you need to copy a resource into location. Check out the SQL demo where this is implemented: https://www.codenameone.com/blog/sql-demo-revisited.html

Use following code to copy database to Codenameone storage after put the database file in src folder, the database will copy to directory ".cn1/database" after running
String DB_NAME = "DBNAME.db";
Database temp_db = Database.openOrCreate(DB_NAME); //To create an empty file before copy, otherwise Android will throw file not found exception
temp_db.close();
String p = Database.getDatabasePath(DB_NAME);
OutputStream o = FileSystemStorage.getInstance().openOutputStream(p);
InputStream i = Display.getInstance().getResourceAsStream(getClass(), "/" + DB_NAME);
Util.copy(i, o);

This doesn't seem like a complete answer.
I'm going through the demo, and something seems to be missing:
Shouldn't a build task copy this db resource to the correct target folder? Otherwise how can a deployment ever work? (if the db doesnt get packaged up then how will it get deployed?) without it the app cant run

Request.BinaryRead with Java HttpURLConnection.getHeaderFieldKey

I have an ASP application that uploads a PDF file through Request.BinaryRead(Request.TotalBytes). The requests that I make, are made through a java application. The problem is that I have method in Java that iterates through the Header Field Keys of the object HttpURLConnection. When the iteration is made I get in my ASP code an error "cannot call binaryread after using request.form".
Here is my java code:
public String getCookieValue(HttpURLConnection con, String cookieKey) {
String cookieValue = null;
String headerName = null;
for (int i = 1; (headerName = con.getHeaderFieldKey(i)) != null; i++) {
if (headerName.equals("Set-Cookie")) {
String cookie = con.getHeaderField(i);
cookie = cookie.substring(0, cookie.indexOf(";"));
String cookieName = cookie.substring(0, cookie.indexOf("="));
if (cookieName.equals(cookieKey)) {
cookieValue = cookie.substring(cookie.indexOf("=") + 1, cookie.length());
}
}
}
return cookieValue;
}
The exact line of java code that breaks my ASP application is con.getHeaderFieldKey(i). When I upload the file without this Java application, the file is uploaded properly.
What can I do to bypass this issue ?
Thank you

Actually the problem here was that we are using a wrapper for the Session object. When we are trying to retrieve the information regarding the session Id we are using the Request.From method, and this intervenes with the Request.BinaryRead method which generates an error.

Redis java api for inserting multiple values

I have a csv file named abc.csv which contains data as follows :
All,Friday,0:00,315.06,327.92,347.24
All,Friday,1:00,316.03,347.73,370.55
and so on .....
I wish to import the data into Redis. How to do it through the Java API.
Please suggest the steps to do this.
I wish to run the jar and get the data imported into Redis db.
Any help on mass insert would also be helpful in case Java option is not possible.

You can do it by using Jedis(https://github.com/xetorthio/jedis), java client for redis. Just create a class with main method and create a connection, set keys.
void processData(){
List<String> lines = Files.readAllLines(
Paths.get("\Path\abc.csv"), Charset.forName("UTF-8"));
Jedis connection = new Jedis("host", port);
Pipeline p = connection.pipelined();
for(String line: lines){
String key = getKey(line);
String value = getValue(line);
p.set(key,value);
}
p.sync();
}
If the file is big you can create an inputstream out of it and read line by line instead of loading the whole file. You should also than call p.sync() in batches, just keep a counter and do a modulo with batch size.

Redisson allows to organize multiple commands to one. This called Redis pipelining. Here is example:
List<String> lines = ...
RBatch batch = redisson.createBatch();
RList<String> list = batch.getList("yourList");
for(String line: lines){
String key = getKey(line);
batch.getBucket(key).set(line);
}
// send to Redis as single command
batch.execute();

You can use Jedis Lib. Here I have extended my Java Object to get key and Hash to set in the object. In your case, you can have a list of parsed CSV values and keys directly sent as a list.
private static final int BATCH_SIZE = 1000;
public void setRedisHashInBatch(List<? extends RedisHashMaker> Obj) {
try (Jedis jedis = jedisPool.getResource()) {
log.info("Connection IP -{}", jedis.getClient().getSocket().getInetAddress());
Pipeline p = jedis.pipelined();
log.info("Setting Records in Cache. Size: " + Obj.size());
int j = 0;
for (RedisHashMaker obj : Obj) {
p.hmset(obj.getUniqueKey(), obj.getRedisHashStringFromObject());
j++;
if (j == BATCH_SIZE) {
p.sync();
j = 0;
}
}
p.sync();
}
}

Search Box for Jpanel

I am in the middle of creating an app that allows users to apply for job positions and upload their CVs. I`m currently stuck on trying to make a search box for the admin to be able to search for Keywords. The app will than look through all the CVs and if it finds such keywords it will show up a list of Cvs that contain the keyword. I am fairly new to Gui design and app creation so not sure how to go about doing it. I wish to have it done via java and am using the Eclipse Window builder to help me design it. Any help will be greatly appreciated, hints, advice anything. Thank You.

Well, this not right design approach as real time search of words in all files of given folder will be slow and not sustainable in long run. Ideally you should have indexed all CV's for keywords. The search should run on index and then get the associated CV for that index ( think of indexes similar to tags). There are many options for indexing - simples DB indexing or using Apache Lucene or follow these steps to create a index using Maps and refer this index for search.
Create a map Map<String, List<File>> for keeping the association of
keywords to files
iterate through all files, and for each word in
each file, add that file to the list corresponding to that word in
your index map
here is the java code which will work for you but I would still suggest to change your design approach and use indexes.
File dir = new File("Folder for CV's");
if(dir.exists())
{
Pattern p = Pattern.compile("Java");
ArrayList<String> list = new ArrayList<String>(); // list of CV's
for(File f : dir.listFiles())
{
if(!f.isFile()) continue;
try
{
FileInputStream fis = new FileInputStream(f);
byte[] data = new byte[fis.available()];
fis.read(data);
String text = new String(data);
Matcher m = p.matcher(text);
if(m.find())
{
list.add(f.getName()); // add file to found-keyword list.
}
fis.close();
}
catch(Exception e)
{
System.out.print("\n\t Error processing file : "+f.getName());
}
}
System.out.print("\n\t List : "+list); // list of files containing keyword.
} // IF directory exists then only process.
else
{
System.out.print("\n Directory doesn't exist.");
}
Here you get the files list to show now for "Java". As I said use indexes :)

Thanks for taking your time to look into my problem.
I have actually come up with a solution of my own. It is probably very amateur like but it works for me.
JButton btnSearch = new JButton("Search");
btnSearch.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent arg0)
{
list.clear();
String s = SearchBox.getText();
int i = 0,present = 0;
int id;
try
{
Class.forName(driver).newInstance();
Connection conn = DriverManager.getConnection(url+dbName,userName,password);
Statement st = conn.createStatement();
ResultSet res = st.executeQuery("SELECT * FROM javaapp.test");
while(res.next())
{
i = 0;
present = 0;
while(i < 9)
{
String out = res.getString(search[i]);
if(out.toLowerCase().contains(s.toLowerCase()))
{
present = 1;
break;
}
i++;
}
if(tglbtnNormalshortlist.isSelected())
{
if(present == 1 && res.getInt("Shortlist") == 1)
{
id = res.getInt("Candidate");
String print = res.getString("Name");
list.addElement(print+" "+id);
}
}
else
{
if(present == 1 && res.getInt("Shortlist") == 0)
{
id = res.getInt("Candidate");
String print = res.getString("Name");
list.addElement(print+" "+id);
}
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
}
});