Spring_使用(JDBC)

Spring_对JDBC的支持

使用JdbcTemplate更新数据库

导入jar包

创建applicationcontext.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-4.0.xsd">

 <!-- 导入资源文件 -->
   <context:property-placeholder location="classpath:db.properties"></context:property-placeholder>

   <!-- 配置C3p0数据源 -->
   <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
     <property name="user" value="${jdbc.user}"></property>
     <property name="password" value="${jdbc.password}"></property>
     <property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>
     <property name="driverClass" value="${jdbc.driverClass}"></property>

     <property name="initialPoolSize" value="${jdbc.initPoolSize}"></property>
     <property name="maxPoolSize" value="${jdbc.maxPoolSize}"></property>
   </bean>

   <!-- 配置Spring的jdbcTemplate -->
   <bean id="jdbcTemplate"
   class="org.springframework.jdbc.core.JdbcTemplate">
       <property name="dataSource" ref="dataSource"></property>
   </bean>
</beans>

创建db.properties文件

jdbc.user=root
jdbc.password=password
jdbc.driverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/spring4?serverTimezone=GMT%2B8

jdbc.initPoolSize=5
jdbc.maxPoolSize=10

创建测试类

package com.tanlei.pojo.jdbc;

import static org.junit.jupiter.api.Assertions.*;

import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import javax.sql.DataSource;

import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;

import junit.framework.TestListener;

public class JDBCTest {

 private ApplicationContext ctx=null;
    private  JdbcTemplate jdbcTemplate;
    {
        ctx=new ClassPathXmlApplicationContext("applicationcontext.xml");
        jdbcTemplate=(JdbcTemplate) ctx.getBean("jdbcTemplate");

    }

/**
     *
     *tanlei
     *2018年12月26日
     *执行INSERT UPDATE DELETE
     */
    //单独修改一条语句
    //update
    @Test
    public void testUpdate() {
        String sql="update  employee  set EMP_NAME=?  where EMP_ID=?";
        jdbcTemplate.update(sql,"tanlei",769);
    }

    //批量增加数据,修改,删除
    //batchUpdate
    @Test
    public  void testAlladd() {
        String sql="insert into  DEPARTMENT(DEPT_ID,DEPT_NAME,DEPT_NO) values (?,?,?)";
        List<Object[]> batchArgs=new ArrayList<>();
        batchArgs.add(new Object[] {1,"AA","D1"});
        batchArgs.add(new Object[] {2,"BB","D2"});
        jdbcTemplate.batchUpdate(sql, batchArgs);
    }

    //从数据库获取一条记录,实际上得到一个对象
    //queryForObject   使用sql中的列的 别名完成列名和属性名的映射
    //jdbcTemplate是一个jdbc的小工具,不是orm框架
    @Test
    public void testemployee() {
        String sql="select EMP_ID as id,EMP_NAME as empname,EMP_NO as empno,JOB as job  from  employee  where EMP_ID=?";
        RowMapper<Employee> rowMapper=new BeanPropertyRowMapper<>(Employee.class);
        Employee employee=jdbcTemplate.queryForObject(sql, rowMapper,769);
        System.out.println(employee);
    }

    //查到实体类的集合
    @Test
    public void TestList() {
        String sql="select EMP_ID as id,EMP_NAME as empname,EMP_NO as empno,JOB as job  from  employee  where EMP_ID>?";
        RowMapper<Employee> rowMapper=new BeanPropertyRowMapper<>(Employee.class);
        List<Employee> employees=jdbcTemplate.query(sql, rowMapper,769);
        System.out.println(employees);
    }

    //获取某一个属性值,或做统计查询
    @Test
    public void testListForObject() {
        String sql="select count(EMP_ID) as id  from  employee  ";
        long count=jdbcTemplate.queryForObject(sql, Long.class);
        System.out.println(count);
    }

@Test
    public void testDataSource() throws SQLException {
        DataSource dataSource=ctx.getBean(DataSource.class);
        System.out.println(dataSource.getConnection());
    }

}

1.查询单行数据

1.1 自定义RowMapper

public class RowMapper implements org.springframework.jdbc.core.RowMapper {
    @Override
    public Object mapRow(ResultSet resultSet, int i) throws SQLException {
        Customer customer=new Customer();
        customer.setCustid(resultSet.getInt("cus_id"));
        customer.setName(resultSet.getString("name"));
        customer.setAge(resultSet.getInt("age"));
        return null;
    }
}

它传递给 queryForObject()方法，返回的结果将调用自定义 mapRow()方法的值匹配到属性

public Customer findByCustomerId(int custId){

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

    Customer customer = (Customer)getJdbcTemplate().queryForObject(
            sql, new Object[] { custId }, new CustomerRowMapper());

    return customer;
}

1.2 BeanPropertyRowMapper

在Spring2.5中，带有一个方便 RowMapper 实现所谓“BeanPropertyRowMapper”，它可以通过匹配行的名字的列值映射到一个属性。只要确保这两个属性和列具有相同的名称，如属性“CUSTID'将匹配到列名为：”CUSTID'或下划线“CUST_ID”。

public Customer findByCustomerId2(int custId){

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

    Customer customer = (Customer)getJdbcTemplate().queryForObject(
            sql, new Object[] { custId },
            new BeanPropertyRowMapper(Customer.class));

    return customer;
}

2，查询多行

现在，查询或从数据库中提取多行，并且将它转换成一个列表。

2.1手动映射它

返回多行，RowMapper 不支持 queryForList()方法，需要手动映射它。 

public List<Customer> findAll(){

    String sql = "SELECT * FROM CUSTOMER";

    List<Customer> customers = new ArrayList<Customer>();

    List<Map> rows = getJdbcTemplate().queryForList(sql);
    for (Map row : rows) {
        Customer customer = new Customer();
        customer.setCustId((Long)(row.get("CUST_ID")));
        customer.setName((String)row.get("NAME"));
        customer.setAge((Integer)row.get("AGE"));
        customers.add(customer);
    }

    return customers;
}

2.2 BeanPropertyRowMapper

最简单的解决方案是使用 BeanPropertyRowMapper 类。 

public List<Customer> findAll(){

    String sql = "SELECT * FROM CUSTOMER";

    List<Customer> customers  = getJdbcTemplate().query(sql,
            new BeanPropertyRowMapper(Customer.class));

    return customers;
}

继承JdbcDaoSupport(不推荐使用,而推进直接使用

jdbcTemplate

)