jdbc connectvity如何在Spring MVC中工作

Question

Below is the way, i am using jdbc connectivity for my spring mvc. I have some technical doubts, which follows-

1.

As i have invoked datasource object in every bean that requires db connectivity. Is it the right way of doing it? What if i don't want a particular repository object to be instantiated when the application starts up (because I'm not sure when user will invoke the object, so why instantiate it at the very beginning)?

<bean 
        class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
            <property name="location">
                <value>classpath:jdbc.properties</value>
            </property>
    </bean>

    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
        destroy-method="close">
        <property name="driverClass" value="${jdbc.driverClassName}" />
        <property name="jdbcUrl" value="${jdbc.url}" />
        <property name="user" value="${jdbc.username}" />
        <property name="password" value="${jdbc.password}" />
        <property name="maxPoolSize" value="${jdbc.maxPoolSize}" />
        <property name="minPoolSize" value="${jdbc.minPoolSize}" />
        <property name="maxStatements" value="${jdbc.maxStatements}" />
        <property name="testConnectionOnCheckout" value="${jdbc.testConnection}" />
    </bean>

<bean id="ustestuthenticationRepository" 
                class="com.test.repository.impl.UstestuthenticationRepositoryImpl">

        <property name="dataSource" ref="dataSource" />
</bean>
<bean id="someclass" 
                class="com.test.repository.impl.someclass">

        <property name="dataSource" ref="dataSource" />
</bean>

2.

@Qualifier("dbDataSource")
    private static DataSource dataSource;

    public void setDataSource(DataSource dataSource) {
        this.dataSource = dataSource;
    }

and then creating

JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);

I'm not sure if this is the right way of invoking datasource.If each and every Repository object creates separate jdbctemplate, is it something appropriate?

In every repository class, i am invoking datasource in the folowing way-

Modified Code

<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <constructor-arg  ref="dataSource" />
    </bean>

<bean id="someclass" class="com.era.repository.impl.someclass">
    <property name="jdbcTemplate" ref="jdbcTemplate" />
</bean>

and implementation in someclass is -

private JdbcTemplate jdbcTemplate;

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

then only accessing jdbcTemplate variable wherever is required. Am i doing it correctly now? Please advise.

Answer 1

What you done is not an error. It is possible to work that way. However. It means you will simply work with JDBC directly. It means, you need handle transactions "manually". It is hard and a lot of code.

You better use spring data and hibernate. Or spring data and JPA. Anyway, spring data will help you to manage all resources and will simplify data access for you.

If you already on spring MVC, take also spring data. Why bother? Official spring data example: https://spring.io/guides/gs/accessing-data-jpa/