Spring SimpleJdbcTemplate查询示例 - Spring教程

这里有几个例子来说明如何使用SimpleJdbcTemplate query()方法来查询或从数据库中提取数据。在 JdbcTemplate query() 方法，需要手动转换返回的结果转换为一个目标对象类型，并传递一个对象数组作为参数。在SimpleJdbcTemplate类，它是更加人性化和简单。jdbctemplate VS simplejdbctemplate 请比较 JdbcTemplate类的示例和SimpleJdbcTemplate类的示例。

1.查询单行

这里有向你展示了如何查询或从数据库中提取单行的两种方式，并将其转换成一个模型类。

1.1 自定义RowMapper

在一般情况下，它总是建议来实现 RowMapper 接口来创建自定义的RowMapper，以满足您的需求。

package com.yiibai.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

在SimpleJdbcTemplate类，需要使用“ParameterizedBeanPropertyRowMapper' 代替 '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，查询多行

从数据库查询或提取多行记录，并将其转换成一个列表。

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.查询单值

查询或提取数据库中的单个列的值。

3.1单列名

它显示了如何查询单个列名作为字符串。

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、行总数

它展示了如何从数据库中查询行的总数。

public int findTotalCustomer(){

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

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

    return total;
}

运行它

package com.yiibai.common;

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

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.yiibai.customer.dao.CustomerDAO;
import com.yiibai.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);

    }
}

总结

SimpleJdbcTemplate 是不能代替 JdbcTemplate 的，它只是一个Java5的友好补充它。下载代码 – http://pan.baidu.com/s/1eRisz6M