从数据库中为动态列表注入Spring依赖项

Question

I'm new to Spring. My question is how to inject a value loaded from the database(dyanmic list of business units from db) into another bean for some processing.

I'm doing the following from my code.

                               /*** Sample code Starts here ****/

/* Load Business Units from Database using the load method */

public class BusinessUnitDaoImpl implements BusinessUnitDao {

    private JdbcTemplate jdbctemplate;

    public BusinessUnitDaoImpl() {
        super();
    }

    public BusinessUnitDaoImpl(DataSource ds) {
        this.jdbctemplate=new JdbcTemplate(ds);
    }

    @Override
    public List<BusinessUnit> load() {
        String SQL = "select * from business_unit";
        List<BusinessUnit> businessunits = jdbctemplate.query(SQL,
                new BusinessUnitRowMapper());
        return businessunits;
    }
}

/* Business Unit Row Mapper */

public class BusinessUnitRowMapper implements RowMapper<BusinessUnit> {

    public BusinessUnitRowMapper() {
        // TODO Auto-generated constructor stub
    }

    public BusinessUnit mapRow(ResultSet rs, int rowNum) throws SQLException {
          BusinessUnit bunit = new BusinessUnit();
          bunit.setBusinessUnitId(rs.getInt("business_unit_id"));
          bunit.setBusinessUnitDesc(rs.getString("business_unit_desc"));
          bunit.setCurrencyCode(rs.getString("currency_code"));
          return bunit;
       }


}

/* Business Unit VO */

public class BusinessUnit {

    private int businessUnitId;
    private String businessUnitDesc;
    private String currencyCode;


    public BusinessUnit() {
        super();
    }


    public int getBusinessUnitId() {
        return businessUnitId;
    }


    public void setBusinessUnitId(int businessUnitId) {
        this.businessUnitId = businessUnitId;
    }


    public String getBusinessUnitDesc() {
        return businessUnitDesc;
    }


    public void setBusinessUnitDesc(String businessUnitDesc) {
        this.businessUnitDesc = businessUnitDesc;
    }


    public String getCurrencyCode() {
        return currencyCode;
    }


    public void setCurrencyCode(String currencyCode) {
        this.currencyCode = currencyCode;
    }


    @Override
    public String toString() {
        return "BusinessUnit [businessUnitId=" + businessUnitId
                + ", businessUnitDesc=" + businessUnitDesc + ", currencyCode="
                + currencyCode + "]";
    }



}

/* Some Service , which calls the dao to load the business unit*/

public class HarmonyService {

    private BusinessUnitDao budao;
    private RequestDetails requestDetails;

    public HarmonyService(BusinessUnitDao budao,RequestDetails requestDetails) {
        this.budao=budao;
        this.requestDetails=requestDetails;
    }

    public List<BusinessUnit> show() {
        return budao.load();
    }

    public WFRequest getDetail(long requestId) {
        return requestDetails.load(requestId);
    }

}

Spring xml:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:property-placeholder location="file:${databaseConfiguration}"/>

    <bean id="AmericasDataSource" class="dell.harmony.data.HarmonyBasicDataSource" destroy-method="close" >
       <property name="url"><value>${HarmonyAmericasDb.url}</value></property>
       <property name="driverClassName"><value>${HarmonyAmericasDb.driverClassName}</value></property>
       <property name="username"><value>${HarmonyAmericasDb.username}</value></property>
       <property name="password"><value>${HarmonyAmericasDb.password}</value></property>
       <property name="removeAbandoned"><value>${HarmonyAmericasDb.removeAbandoned}</value></property>
       <property name="initialSize"><value>${HarmonyAmericasDb.initialSize}</value></property>
       <property name="maxActive"><value>${HarmonyAmericasDb.maxActive}</value></property>
    </bean>

    <bean id="EMEADataSource" class="dell.harmony.data.HarmonyBasicDataSource" destroy-method="close" >
       <property name="url"><value>${HarmonyEMEADb.url}</value></property>
       <property name="driverClassName"><value>${HarmonyEMEADb.driverClassName}</value></property>
       <property name="username"><value>${HarmonyEMEADb.username}</value></property>
       <property name="password"><value>${HarmonyEMEADb.password}</value></property>
       <property name="removeAbandoned"><value>${HarmonyEMEADb.removeAbandoned}</value></property>
       <property name="initialSize"><value>${HarmonyEMEADb.initialSize}</value></property>
       <property name="maxActive"><value>${HarmonyEMEADb.maxActive}</value></property>
    </bean>

    <bean id="budao" class="test.dao.BusinessUnitDaoImpl">
        <constructor-arg index="0"><ref bean="AmericasDataSource"/></constructor-arg>
     </bean>

     <bean id="requestdao" class="test.dao.RequestDetailImpl">
        <constructor-arg index="0"><ref bean="AmericasDataSource"/></constructor-arg>
     </bean>

    <bean id="service" class="test.service.HarmonyService">
        <constructor-arg index="0"><ref bean="budao"/></constructor-arg>
        <constructor-arg index="1"><ref bean="requestdao"/></constructor-arg>
     </bean>

</beans>

/* Test application for testing the spring */

public class MyApp {

    public static void main(String args[]) {
        ApplicationContext context = 
            new ClassPathXmlApplicationContext("Spring-All-Module.xml");
        HarmonyService hservice = (HarmonyService) context.getBean("service");
        System.out.println(hservice.show());
        System.out.println(hservice.getDetail(13090000000001L));
    }

}

                /*** Sample code ends here ****/

Question:

If suppose, i want to inject the list of business units from the service HarmonyService's load method, how to do that?

Assume i've a processorclass, something like BatchProcessor the below one.

public class BatchProcessor {


          public List<BusinessUnit> proces(List<BusinessUnit> businessUnitList ) {
                 //do some processing here.

           }

}

how to inject the dynamically created businessUnit into the local method variable businessUnitList using spring xml(please explain with java code and spring xml changes).

1. Is it possible to inject into the dynamic list into a local method variable.
2. Give an example on how to inject the value into the instance variable, assuming the above businessUnitList is an instance varaible instead of method local variable.

Regards, Raghu

---

I'll take the above answer.

As i said earlier , i'm very new to spring. I got an idea when i explored Stackoverflow another question.

Lets assume the businessUnitList as an instance variable.

public class BatchProcessor {

    public BatchProcessor(List<BusinessUnit> businessUnitList) {
        this.businessUnitList=businessUnitList;
    }

    private List<BusinessUnit> businessUnitList;

    public List<BusinessUnit> getBusinessUnitList() {
        return businessUnitList;
    }

    public void setBusinessUnitList(List<BusinessUnit> businessUnitList) {
        this.businessUnitList = businessUnitList;
    }

    public List<BusinessUnit> process() {
        System.out.println("Started processing the business Units" + businessUnitList);
        //do some processing
        return this.businessUnitList;
    }

From the MyApp Main program, i can do this.

BatchProcessor bprocess = (BatchProcessor) context.getBean("bprocessor", hservice.show());
System.out.println(bprocess.process());

//context.getBean("bprocessor",hservice.show()); here i'm sending the dynamic list from hservice.show, which connects to database and get the list of business Units.

now again, i'lll call the process method of BatchProcessor.

Is this a good way of doing things?

Basically when we want to dyanmically pass a value, we need to call, contextbean, with the argument.

My Spring xml:

<!-- passing a dummy list to the constructor -->

 <bean id="bprocessor" class="test.rules.BatchProcessor" scope="prototype">
  <constructor-arg type="java.util.List">
        <list>
            <ref bean="bunit"/>
        </list> 
  </constructor-arg>

Am i right?

Answer 1

You can crate BatchProcessor on similar lines as HarmonyService

<bean id="service" class="test.service.BatchProcessor">
    <constructor-arg index="0"><ref bean="budao"/></constructor-arg>
</bean>

then inside BatchProcessor :

public class BatchProcessor {
    private BusinessUnitDao budao;

    public BatchProcessor(BusinessUnitDao dao) {
        this.budao = dao;
    }

    public List<BusinessUnit> process() {
       // process budao.load() list here
    }
}