I'm using spring jdbc and I want my application to connect to different DBMS as oracle,mySQL, SAS etc.
the application should work on different systems, so the connection properties are not priorly known.
Ideally, the user will be able to select connection type from a list and then set the connection properties (username,password...)
Can you please help me :)
Have a look at this post: http://examples.javacodegeeks.com/enterprise-java/spring/jdbc/spring-jdbctemplate-example/
There you can see the normal jdbctemplate use. As you can see the dao has got the datasource injected: you can basically do the same, but you need not to set the org.springframework.jdbc.datasource.DriverManagerDataSource properties in the applicationContext.xml. You will do it at runtime according to user choice. That basically means all the daos have to get the datasource needed params in input.
Hope this helps.
Related
I got to know Java spring JPA a couple days ago and there is one question which really makes me confused.
As I create a repository and use 'save()' method to save some objects into it. How does it know what type of database I am using and which local location to save.
I know I can config database (h2) like:
spring.datasource.url=jdbc:h2:mem/mydb
Then JPA will know: ok you are using h2 database and url is "jdbc:h2:mem/mydb"
However, some people said this config is not mandatory. If without this config, how does JPA knows which database I gonna use?
From the spring-boot documentation:
You should at least specify the URL by setting the spring.datasource.url property. Otherwise, Spring Boot tries to auto-configure an embedded database.
The following class is responsible for providing default settings for embedded DB: org.springframework.boot.autoconfigure.jdbc.DataSourceProperties
public String determineDatabaseName() {
...
if (this.embeddedDatabaseConnection != EmbeddedDatabaseConnection.NONE) {
return "testdb";
}
...
}
This answer can also be helpful: Where does the default datasource url for h2 come from on Spring Boot?
I want to configure the properties of the Tomcat JDBC Pool with custom parameter values. The pool is bootstrapped by the spring-cloud (Spring Cloud Connector) environment (Cloud Foundry) and connected to a PostgreSQL database. In particular, I want to set the minIdle, maxIdle and initialSize properties for the given pool.
In a "spring-vanilla" environment (non-cloud) the properties can be easily set by using
application.properties / .yaml files with environment properties,
#ConfigurationProperties annotation.
However, this approach doesn't transfer to my Cloud environment, where the URL (and other parameters) are injected from the environment variable VCAP_SERVICES (via the ServiceInfo instances). I don't want to re-implement the logic which Spring Cloud already did with its connectors.
After some searching I also stumbled over some tutorials / guides, which suggest to make use of the PoolConfig object (e.g. http://cloud.spring.io/spring-cloud-connectors/spring-cloud-spring-service-connector.html#_relational_database_db2_mysql_oracle_postgresql_sql_server). However, that way one cannot set the properties I need but merely the following three:
minPoolSize,
maxPoolSize,
maxWaitTime.
Note that I don't want to set connection-related properties (such as charset), but the properties are associated with the pool itself.
In essence, I would like to do the configuration similarly to https://www.baeldung.com/spring-boot-tomcat-connection-pool (using spring.datasource.tomcat.* properties). The problem with that approach is that the properties are not considered if the datasource was created by Spring Cloud. The article https://dzone.com/articles/binding-data-services-spring, section "Using a CloudFactory to create a DataSource", claims that the following code snippet makes it so that the configuration "can be tweaked using application.properties via spring.datasource.* properties":
#Bean
#ConfigurationProperties(DataSourceProperties.PREFIX)
public DataSource dataSource() {
return cloud().getSingletonServiceConnector(DataSource.class, null);
}
However, my own local test (with spring-cloud:Greenwich.RELEASE and spring-boot-starter-parent:2.1.3.RELEASE) showed that those property values are simply ignored.
I found an ugly way to solve my problem but I think it's not appropriate:
Let spring-cloud create the DataSource, which is not the pooled DataSource directly,
check that the reference is a descendant of a DelegatingDataSource,
resolve the delegate, which is then the pool itself,
change the properties programmatically directly at the pool itself.
I do not believe that this is the right way as I am using internal knowledge (on the layering of datasources). Additionally, this approach does not work for the property initialSize, which is only considered when the pool is created.
Can I dynamically refresh properties that are used by Spring Boot's auto configuration setup?
For example, I have the following properties set (via cloud config) to auto configure a dataSource:
spring.datasource.username=user1
spring.datasource.password=test
Now if I change the password prop on the config server, and hit the /refresh endpoint, I can see that the updated prop is retrieved but the DataSource is not refreshed.
I know I can manually configure the DataSource beans and make sure they fall under a RefreshScope, but I was hoping to find a way to mark the auto configured properties as "refreshable". I have some use cases where I'd want to refresh props used by Spring Boot for other beans besides DataSources, and setting up some of those beans manually could be a pain.
I think I spoke too soon, at least as far as my DataSource example goes. A new db connection was being created with the updated props.
Which makes sense especially when looking at the docs here
This didn't re-connect some of my spring.cloud.stream.bindings properties I had, but in that case I can probably solve the issue with #RefreshScope.
There's a configuration property to set in case of the Autoconfigured bean is immutable (don't change the properties after initialized)
You can put a list (set) of classes that you need to be refreshed and you don't have control over the source code, you can put them under the property: spring.cloud.refresh.extra-refreshable
e.g.:
spring
cloud
refresh
extra-refreshable:
- org.springframework.mail.javamail.JavaMailSenderImpl
see: https://cloud.spring.io/spring-cloud-static/Greenwich.SR1/single/spring-cloud.html#refresh-scope
I am working now with oracle and spring jdbc but I don't want to use the schema in my sql statements:
Example: Select * from SCHEMA.table
Is there any way to set default schema in application.properties or application.yml?
Assuming you define your database connections using spring datasources, you can set the default schema when defining the datasource configuration:
spring.datasource.schema = #value for your default schema to use in database
You can find more info here: Spring Boot Reference Guide. Appendix A. Common application properties
After doing some research, looks like Oracle driver doesn't let you set a default schema to work with, as noted here:
Default Schema in Oracle Connection URL
From that post, you have two options:
Execute this statement before executing your statements:
ALTER SESSION SET CURRENT_SCHEMA=yourSchema
Create synonyms for your tables/views/etc (which I find really cumbersome if we're talking about lots of elements in your database).
I would advice using the first option. From what I see, Spring boot doesn't offer a simple way to execute a statement when retrieving the connection, so the best bet will be to use an aspect around the getConnection method (or the method that retrieves the connection from the data source) and execute the statement there.
From your comment, an easier way to solve it is by using a script in spring.datasource.schema:
spring.datasource.schema = schema.sql
And then a file squema.sql with the following:
ALTER SESSION SET CURRENT_SCHEMA=mySchema
In spring boot, I've found another way of doing it,
#Bean
#ConfigurationProperties(prefix="spring.datasource")
public DataSource dataSource(#Value("${spring.datasource.schema}") String schema) {
DataSource datasource = DataSourceBuilder.create().build();
if(!schema.isEmpty() && datasource instanceof org.apache.tomcat.jdbc.pool.DataSource){
((org.apache.tomcat.jdbc.pool.DataSource) datasource).setInitSQL("ALTER SESSION SET CURRENT_SCHEMA=" + schema);
}
return datasource;
}
I found another way to get around this by updating entity class with
#Table(schema = "SCHEMA_NAME" ,name = "TABLE_NAME")
If you are using hikari, use spring.datasource.hikari.schema=YOUR_SCHEMA.
Works for me with SpringBoot + tomcat using Oracle.
I was having issues with the currently accepted answer; specifically, the schema would only be changed from the initial connection. If your app uses a connection pool, you need to configure the pool to apply SQL for each connection.
For instance, using the default jdbc pool in Spring Boot 1.5.x (Tomcat):
spring.datasource.tomcat.init-s-q-l = ALTER SESSION SET CURRENT_SCHEMA=mySchema
Connecting to the database as your user, you can create a trigger that will change the schema each time you login:
CREATE OR REPLACE TRIGGER LOGON_TRG
AFTER LOGON ON SCHEMA
BEGIN
EXECUTE IMMEDIATE 'ALTER SESSION SET CURRENT_SCHEMA = foo';
EXCEPTION
when others
then null;
END;
/
Another option is to create a datasource wrapper. Create the datasource as normal and then create the wrapper that forwards all methods except for the getConnection methods. For those I just added SQL to set the schema. We have multiple datasources and this allowed us to specify a different schema for each datasource. If anyone knows if there's an issue with this I'd love comments. Or if there's an alternative that uses the properties.
I am working on an engine that is doing the following:
gets data provider info from DB (that tells me to what database & schema details to connect to get my data)
use that info to connect to the database and get my data, that later I use to build some XML content.
The standard setup to handle and isolate database connection management would be to create a DataSource bean (I'm using Spring to wire my components) and inject that in my ProviderConfigDao (loads connection config) and ContentDao (loads data using connection details loaded previously). This would nicely isolate the handling of the connections from the actual code, thus the DAO classes not needing to know how and when a connection is created/opened/closed etc.
This setup doesn't work unfortunately, as when I create my connection, I need to be able to specify the database schema. I don't know all the different schemas from the beginning, so I can't create a set of DataSource objects to cover all of them, thus the DataSource object must be created at runtime and it's creation hidden from the users.
The only solution I can think of is:
Have another class/interface (DataSourceProvider) having one method:
//Gets the connection URL as parameter (which includes the schema name).
DataSource getDataSource(String url);
Add a bean in Spring config to provide a custom implementation for it that manages creation of DataSource objects for each schema.
Inject that object to my DAO classes instead of the DataSource object.
It's not a bad solution, but I was wondering if there is maybe support for something like this already in some open source package ... I'd rather use something already done and tested then reinvent the wheel.
Cheers,
Stef.
there's a JDBC Utils to get all the metada from a database org.springframework.jdbc.support.JdbcUtils
parameters:
DataSource
Implementation of org.springframework.jdbc.support.DatabaseMetaDataCallback