Develop Reference

AWS Lambda Java, connect to MySQL RDS

I need to develop an AWS Lambda Java function to retrieve some records from RDS MySQL database.
Should I use JDBC? Should I use the standard JDBC example:
try {
String url = "jdbc:msql://200.210.220.1:1114/Demo";
Connection conn = DriverManager.getConnection(url,"","");
Statement stmt = conn.createStatement();
ResultSet rs;
rs = stmt.executeQuery("SELECT Lname FROM Customers WHERE Snum = 2001");
while ( rs.next() ) {
String lastName = rs.getString("Lname");
System.out.println(lastName);
}
conn.close();
} catch (Exception e) {
System.err.println("Got an exception! ");
System.err.println(e.getMessage());
}

Step 1:
login IAM console
roles -> create new roles
role name :lambda-vpc-execution-role
AWS service roles ->
a) Select aws lambda
b) Attach policy "AWSLambdaFullAccess"
Step 2:
Get code from https://github.com/vinayselvaraj/lambda-jdbc-sample (note this is maven project)
Right click on project select Run as --->5.maven build...
for goal provide name package shade:shade
Go to project folder and target/lamda-0.0.1-SNAPSHOT-shaded.jar
Step 3:
Login to lambda console(skip blueprint)
Create new lambda
name: time-test
a) runtime-java
b) upload .zip(.jar) file (target/lamda-0.0.1-SNAPSHOT-shaded.jar)
Provide package.class-name::myhandler -> Handler
Role -> lambda-vpc-exceution-role
vpc provide rds-vpc details (this should work in same vpc group)
Create function
In the Action drop down list select configure test event
result will shown down like this "Execution result: succeeded (logs)"

Yes, you need to use standard JDBC code in your lambda function class. The code you provided looks okay. There are a few more things you need to do when accessing RDS or any other RDBMS through a Lamda function -
Create a jar or a zip file for your Lambda function
Your zip file needs to have a lib folder in which your JDBC driver file goes. The Lambda function doc says this is one of the two standard ways, but it didn't work for me.
You can create a jar file in which the driver classes are put in. This works. The best way to do it is through the Maven Shade plugin, which extracts the JDBC drivers and packs the classes in one single jar file.
Setup the handler function and specify it at the time of Lambda deployment
Define execution role and VPC as needed.
Upload and publish your jar or zip file.
You can test the Lambda function through the console, and see the actual output in the CloudWatch logs.

You could use this kinda implementation:
public static DataSource getDataSource(){
Utils._logger.log("Get data source");
MysqlDataSource mysqlDs = null;
try{
mysqlDs = new MysqlDataSource();
mysqlDs.setURL('jdbc:msql://'+'url');
mysqlDs.setUser('user');
mysqlDs.setPassword('pwd');
Utils._logger.log("Object "+mysqlDs.getUrl()+" "+mysqlDs.getUser()+" ");
return mysqlDs;
}
catch(Exception e) {
Utils._logger.log("No se pudo abrir el archivo de properties");
e.printStackTrace();
}
return mysqlDs;
}

One thing I am particularly noticing in your codebase is that even when you use this Lambda function for connecting to the specific RDS you have, the hostname may not be the correct one for Amazon RDS.
It needs to be the endpoint of the RDS you are trying to connect to and your complete connection url would look something like this below -
//jdbc:mysql://hostname (endpoint of RDS):port/databasename
String url = "jdbc:mysql://"+dbHost+":3306/"+dbName;
Since those endpoints can change for different databases and servers, you can make them as environment variables within Lambda and refer using
String dbHost = System.getenv("dbHost");
String dbName = System.getenv("dbName");
for a much cleaner and stateless design that Lambda supports.

Connection to oracle database

Hi I am new enough to java and I am trying to create a connection from it to my sql database. using Netbeans I managed to set up a connection easily enough. The issue is when I try to connect using my code I get driver not found. Is there something wrong with what I have?
//function to execute the insert update delete query
public void theQuery(String query){
Connection con = null;
Statement st = null;
try{
con = DriverManager.getConnection("jdbc:oracle:thin:#redwood.ict.ad.dit.ie:1521:pdb12c.ict.ad.dit.ie", "eocribin","");
st = con.createStatement();
st.executeUpdate(query);
JOptionPane.showMessageDialog(null,"Query Executed");
}catch(Exception ex){
JOptionPane.showMessageDialog(null,ex.getMessage());
}
}

you have to add oracle thin driver into your projects library and then restart the IDE to take notice of changes. Make sure that oracle's server is running when you run this code. Also check the username and password.
Java Persistence in netbeans is a much better option then using Oracle thin driver in your code. Because it saves much of your time typing and harcoding. JPA(Java Persistence API) allows you to easily add the oracle's thin driver from its menu and reduces much of your time. It is used in enterprise applications . You should try this and watch its tutorials on the following site.
These are called JPA tutorials.
http://www.programming-simplified.com

Using Multiple Oracle JDBC drivers in one Java application?

I want to connect to two different Oracle databases (one 8.0.5.0.0 and one 12c) via JDBC. I do have both JDBC drivers that can individually and successfully connect to the corresponding DB via simple "hello world" applications. Below, I have put both of them together into one Java application, which unfortunately does not work anymore (with both drivers being loaded).
I have read this post: Handle multiple JDBC drivers from the SAME VENDOR . The option 1 mentioned there might be the way to go, but there seems to be one major problem:
It seems that OracleDataSource does not yet exist in the old version 8 driver and only has been introduced at later versions (in the 12c version driver it exists).
Any hints, on how to connect to these two Oracle databases with one single Java application and two JDBC drivers?
import java.sql.*;
class db {
public static void main (String args []) throws SQLException {
// Oracle 8 connection
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
Connection c1 = DriverManager.getConnection(
"jdbc:oracle:thin:#some-oracle-8-server:port:sid",
"my-user",
"my-password");
Statement s1 = c1.createStatement ();
ResultSet r1 = s1.executeQuery ("SELECT banner FROM V$VERSION WHERE banner LIKE 'Oracle%'");
while (r1.next ()) {
System.out.println(r1.getString (1));
}
c1.close();
// Oracle 12 connection
Connection c2 = DriverManager.getConnection(
"jdbc:oracle:thin:#some-oracle-12-server:port:sid",
"my-user",
"my-password");
Statement s2 = c2.createStatement ();
ResultSet r2 = s2.executeQuery ("SELECT banner FROM V$VERSION WHERE banner LIKE 'Oracle%'");
while (r2.next ()) {
System.out.println(r2.getString (1));
}
c2.close();
}
}
Thanks in adavnce!

If you don't register the drivers you avoid them being loaded by the same classloader.
Then you can create connections using the two different drivers by loading them through separate classloaders:
// Oracle 8 connection
File jar = new File("/path/to/oracle8.jar");
URL[] cp = new URL[1];
cp[0] = jar.toURI().toURL();
URLClassLoader ora8loader = new URLClassLoader(cp, ClassLoader.getSystemClassLoader());
Class drvClass = ora8loader.loadClass("oracle.jdbc.driver.OracleDriver");
Driver ora8driver = (Driver)drvClass.newInstance();
Properties props = new Properties();
// "user" instead of "username"
props.setProperty("user", "my-user");
props.setProperty("password", "my-password");
Connection ora8conn = ora8driver.connect("jdbc:oracle:thin:#some-oracle-8-server:port:sid",props);
Then do the same for the Oracle 12 driver.
You might also be able to still use the "other" driver through DriverManager, but I'm not sure about that.
There are some corner cases where accessing Oracle specific classes gets a bit complicated, but in general you can use the connections created through this without any problems.

I see two different solutions for different constellations.
(Using same (?) classes with different versions normally would be an idealh use case for OSGi, or if your application is a NetBeans RCP, their modular system. This works using class loaders that separate the software into modules, so one in different modules may load different jars with different versions of the same product.)
(Alternatively one might a different application with its own Oracle jar that is accessed using RMI.)
You might use the same technique: either write your own delegating ClassLoader that loads the right jar, or use the conceptually simpler RMI that however requires managing system resources.
So
Do not use imports from the vendors; that is contrary to the vendor indepence of JDBC.
Ensure that javax.sql interfaces come from a java-ee jar.
Picking the ClassLoader solution:
It would be best to make your own delegating Driver say with a protocol jdbc:myswitch:8: .... It could then use two different class loader instances. For instance using an URLClassLoader with a file:/... path.
One could make two separate instances of the custom delegating driver, so one can use the Delegate pattern.
public static class MySwitchDriver implements Driver {
private final String oraURIPrefix;
private final Driver delegateDriver;
public MySwitchDriver(String oraURIPrefix) {
this.oraURIPrefix = oraURIPrefix; // "8:" or "12:"
String jarFileURI = oraURIPrefi.equals("8")
? "file:/... .jar" : "file:/... .jar";
URLClassLoader classLoader = new URLClassLoader(...);
delegateDriver = classLoader.loadClass(
"oracle.jdbc.driver.OracleDriver", true);
DriverManager.registerDriver(this);
}
private String delegateURL(String url) {
// Something safer than this:
return "jdbc:" + url.substring(
"jdbc:myswitch".length
+ oraURIPrefix.length);
}
#Override
public Connection connect(String url, Properties info)
throws SQLException {
String url2 = delegateURL(url);
Properties info2 = info;
return delegateDriver.connect(url2, info2);
}
#Override
public boolean acceptsURL(String url) throws SQLException {
return url.startsWith("jdbc:myswitch:" + oraURIPrefix)
&& delegateDriver.acceptsURL(delegateURL(url));
}
...
}

You can use Factory design pattern in order to get which connection you would like to have, then, store it some Singleton which is making your connection to each databse.
So, each of your database connections are Singletons, and being instansated by the Factory with the given ENUM you put him as a parameter.

Use Database in java application

I am beginner in Java application programming.
I've created a database application in Java. I use an MS access database with the JDBC-ODBC driver. My application's create-connection code is below:
private void connection() {
try {
String driverurl = "jdbc:odbc:dharti_data";
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
con = DriverManager.getConnection(driverurl,"","");
} catch (SQLException e) {
JOptionPane.showMessageDialog(frm,e.getSQLState(),"Database Access Error",JOptionPane.ERROR_MESSAGE);
} catch (Exception e) {
JOptionPane.showMessageDialog(null,e.getMessage(),"Database Access Error",JOptionPane.ERROR_MESSAGE);
}
}
This code works perfectly, but this code uses a datasource name I declared in Control Panel > Administrative Tools > Data Sources (ODBC) > System DSN > Add Data Source, with a Microsoft Access Driver (*.mdb).
But when I run the application on another PC, it can't run and instead it generates a database error.
I know that I can declare a driver in Data Sources (ODBC) > System DSN, and then it will run. But I don't want to do this on every machine I run my application on. My application should be able to pick up the database connection automatically. How can I make my application not require a data-source name?

String filename = "C:/Lab/northwind.mdb"; // this the path to mdb file
String database = "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=";
database+= filename.trim() + ";DriverID=22;READONLY=true}"; // add on to the end
// now we can get the connection from the DriverManager
Connection con = DriverManager.getConnection( database ,"","");

Im not sure if I got this, but are you shipping the jdbc driver along with your application? It has to be in your classpath and needs to be deployed with your application.

You will have to programmatically modify these registry sections:
HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI and
HKEY_LOCAL_MACHINE\SOFTWARE\ODBC\ODBC.INI\ODBC
Ice Engineering offer a public domain api that allows you to do that. Beside jars it has a DLL that you have to ship with your application. It is fairly straight forward and will work.
In order to get a better idea of what you have to do, use regedit in order to see the values before installing anything, then install an ODBC database manually, finally compare the new values with the old.

I used the sun.jdbc.odbc.JdbcOdbcDriver to connect to a MS Access database. Have that in the same directory as the class file and it should work. Although it should come already installed in the Java SDK.
This is a sample of a practice program I made a while ago.
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
System.out.println("Driver loaded");
// Establish a connection
Connection connection = DriverManager.getConnection
("jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=(MS ACCESS DATABASE DIRECTORY)");
System.out.println("Database connected");
// Create a statement
Statement statement = connection.createStatement();
// Execute a statement
ResultSet resultSet = statement.executeQuery
("select f_name, l_name from Test where f_name = 'Luke'"); // For example
// Iterate through the result and print the results
while (resultSet.next())
System.out.println(resultSet.getString(1) + "\t" + resultSet.getString(2) );

integrate ms access and mysql in java

I have a problem connecting to MS Access and MySQL using Java. My problem is that I cannot find the driver for MySQL. Here is my code:
<%# page import="java.sql.*" %>
<%
Connection odbcconn = null;
Connection jdbcconn = null;
PreparedStatement readsms = null;
PreparedStatement updsms = null;
ResultSet rsread = null;
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); //load database driver
odbcconn = DriverManager.getConnection("jdbc:odbc:SMS"); //connect to database
readsms = odbcconn.prepareStatement("select * from inbox where Status='New'");
rsread = readsms.executeQuery();
while(rsread.next()){
Class.forName("com.mysql.jdbc.Driver");
jdbcconn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bakme", "root", ""); //connect to database
updsms = jdbcconn.prepareStatement("insert into inbox(sms,phone) values (?,?)");
updsms.setString(1, rsread.getString("Message"));
updsms.setString(2, rsread.getString("Phone"));
updsms.executeUpdate();
}
%>

Thus, you get a ClassNotFoundException on the MySQL JDBC driver class? Then you need to put the MySQL JDBC driver JAR file containing that class in the classpath. In case of a JSP/Servlet application, the classpath covers under each the webapplication's /WEB-INF/lib folder. Just drop the JAR file in there. Its JDBC driver is also known as Connector/J. You can download it here.
That said, that's really not the way how to use JDBC and JSP together. This doesn't belong in a JSP file. You should be doing this in a real Java class. The JDBC code should also be more robust written, now it's leaking resources.

BalusC is spot on: this is not the way you should write something like this.
Connection, Statement, and ResultSet all represent finite resources. They are not like memory allocation; the garbage collector does not clean them up. You have to do that in your code, like this:
// Inside a method
Connection connection = null;
Statement statement = null;
ResultSet rs = null;
try
{
// interact with the database using connection, statement, and rs
}
finally
{
// clean up resources in a finally block using static methods,
// called in reverse order of creation, that don't throw exceptions
close(rs);
close(statement);
close(connection);
}
But if you do decide to move this to a server-side component, you're bound to have huge problems with code like this:
while(rsread.next())
{
Class.forName("com.mysql.jdbc.Driver");
jdbcconn = DriverManager.getConnection("jdbc:mysql://localhost:3306/bakme", "root", ""); //connect to database
updsms = jdbcconn.prepareStatement("insert into inbox(sms,phone) values (?,?)");
updsms.setString(1, rsread.getString("Message"));
updsms.setString(2, rsread.getString("Phone"));
updsms.executeUpdate();
}
Registering the driver, creating a connection, without closing it, and repeatedly preparing a statement inside a loop for every row that you get out of Access shows a serious misunderstanding of relational databases and JDBC.
You should register the driver and create connections once, do what needs to be done, and clean up all the resources you've used.
If you absolutely MUST do this in a JSP, I'd recommend using JNDI data sources for both databases so you don't have to set up connections inside the page. You should not be writing scriptlet code - better to learn JSTL and use its <sql> tags.

You can use this link to download the MySql Driver. Once you download it, you need to make sure it is on the class path for the web server that you are using. The particulars of configuring JDBC drivers for a server vary from server to server. You may want to edit your question to include more details to get a better answer.