Spring SimpleJdbcTemplate Querying examples

Here are few examples to show how to use

SimpleJdbcTemplate

query()

methods to query or extract data from database. In

JdbcTemplate

query()

, you need to manually cast the returned result to desire object type, and pass an

Object

array as parameters. In

SimpleJdbcTemplate

, it is more user friendly and simple.

jdbctemplate

vesus

simplejdbctemplate

Please compare this

SimpleJdbcTemplate

example with this

JdbcTemplate

example.

1. Querying for Single Row

Here’s two ways to show you how to query or extract a single row from database, and convert it into a model class.

1.1 Custom

RowMapper

In general, It’s always recommend to implement the

RowMapper

interface to create a custom

RowMapper

to suit your needs.

package com.mkyong.customer.model;

import java.sql.ResultSet;
import java.sql.SQLException;

import org.springframework.jdbc.core.RowMapper;

public class CustomerRowMapper implements RowMapper
{
public Object mapRow(ResultSet rs, int rowNum) throws SQLException {
Customer customer = new Customer();
customer.setCustId(rs.getInt("CUST_ID"));
customer.setName(rs.getString("NAME"));
customer.setAge(rs.getInt("AGE"));
return customer;
}

}

public Customer findByCustomerId(int custId){

String sql = "SELECT * FROM CUSTOMER WHERE CUST_ID = ?";

Customer customer = getSimpleJdbcTemplate().queryForObject(
sql,  new CustomerParameterizedRowMapper(), custId);

return customer;
}

1.2 BeanPropertyRowMapper

In SimpleJdbcTemplate, you need to use ‘ParameterizedBeanPropertyRowMapper’ instead of ‘BeanPropertyRowMapper’.

public Customer findByCustomerId2(int custId){

String sql = "SELECT * FROM CUSTOMER WHERE CUST_ID = ?";

Customer customer = getSimpleJdbcTemplate().queryForObject(sql,
ParameterizedBeanPropertyRowMapper.newInstance(Customer.class), custId);

return customer;
}

2. Querying for Multiple Rows

Query or extract multiple rows from database, and convert it into a

List

.

2.1

ParameterizedBeanPropertyRowMapper

public List<Customer> findAll(){

String sql = "SELECT * FROM CUSTOMER";

List<Customer> customers =
getSimpleJdbcTemplate().query(sql,
ParameterizedBeanPropertyRowMapper.newInstance(Customer.class));

return customers;
}

3. Querying for a Single Value

Query or extract a single column value from database.

3.1 Single column name

It shows how to query a single column name as

String

.

public String findCustomerNameById(int custId){

String sql = "SELECT NAME FROM CUSTOMER WHERE CUST_ID = ?";

String name = getSimpleJdbcTemplate().queryForObject(
sql, String.class, custId);

return name;

}

3.2 Total number of rows

It shows how to query a total number of rows from database.

public int findTotalCustomer(){

String sql = "SELECT COUNT(*) FROM CUSTOMER";

int total = getSimpleJdbcTemplate().queryForInt(sql);

return total;
}

Run it

package com.mkyong.common;

import java.util.ArrayList;
import java.util.List;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.mkyong.customer.dao.CustomerDAO;
import com.mkyong.customer.model.Customer;

public class SimpleJdbcTemplateApp
{
public static void main( String[] args )
{
ApplicationContext context =
new ClassPathXmlApplicationContext("Spring-Customer.xml");

CustomerDAO customerSimpleDAO =
(CustomerDAO) context.getBean("customerSimpleDAO");

Customer customerA = customerSimpleDAO.findByCustomerId(1);
System.out.println("Customer A : " + customerA);

Customer customerB = customerSimpleDAO.findByCustomerId2(1);
System.out.println("Customer B : " + customerB);

List<Customer> customerAs = customerSimpleDAO.findAll();
for(Customer cust: customerAs){
System.out.println("Customer As : " + customerAs);
}

List<Customer> customerBs = customerSimpleDAO.findAll2();
for(Customer cust: customerBs){
System.out.println("Customer Bs : " + customerBs);
}

String customerName = customerSimpleDAO.findCustomerNameById(1);
System.out.println("Customer Name : " + customerName);

int total = customerSimpleDAO.findTotalCustomer();
System.out.println("Total : " + total);

}
}

Conclusion

The

SimpleJdbcTemplate

isn’t a replacement for

JdbcTemplate

, it’s just a java5-friendly supplement to it.