spring之操作数据库之使用JdbcTemplate和JdbcDaoSupport

首先将以下依赖包添加到build path：

基本文件目录：

注意打开MysqL服务，并在数据库中新建两个表：employees和departments，目录如下：

@H_404_21@

Departmen t.java

package com.gong.spring.jdbc;

public class Department {

    private Integer id;
     String name;

    public Integer getId() {
        return id;
    }

    void setId(Integer id) {
        this.id = String getName() {
         name;
    }

     setName(String name) {
        this.name = name;
    }

    @Override
     String toString() {
        return "Department [id=" + id + ",name=" + name + "]";
    }

}

Employee.java

 Employee {
    
     String lastName;
     String email;
    
     Integer dpetId;

     String getLastName() {
         lastName;
    }

     setLastName(String lastName) {
        this.lastName = String getEmail() {
         email;
    }

     setEmail(String email) {
        this.email = Integer getDpetId() {
         dpetId;
    }

     setDpetId(Integer dpetId) {
        this.dpetId = dpetId;
    }

    @Override
    return "Employee [id=" + id + ",lastName=" + lastName + ",email="
                + email + ",dpetId=" + dpetId + "]";
    }

    
}

一、数据库连接配置

首先是配置数据源：spring是数据库的名字，root是数据库账号，123456是数据库密码

db.properties

jdbc.user=root
jdbc.password=123456
jdbc.driverClass=com.MysqL.jdbc.Driver
jdbc.jdbcUrl=jdbc:MysqL:///spring
jdbc.initPoolSize=5
jdbc.maxPoolSize=10

在applicationContext.xml中配置数据库连接

<?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"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.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"/>
    
     配置 C3P0 数据源 bean id="dataSource"
        class="com.mchange.v2.c3p0.ComboPooledDataSource">
        property name="user" value="${jdbc.user}"></property="password"="${jdbc.password}"="jdbcUrl"="${jdbc.jdbcUrl}"="driverClass"="${jdbc.driverClass}">

        ="initialPoolSize"="${jdbc.initPoolSize}"="maxPoolSize"="${jdbc.maxPoolSize}">
    </bean>
    
beans>

新建一个JUnit Test Case文件：JDBCTest.java。在里面测试数据库是否连接成功。

import java.sql.sqlException;

 javax.sql.DataSource;

 org.junit.jupiter.api.Test;
 org.springframework.context.ApplicationContext;
 org.springframework.context.support.ClasspathXmlApplicationContext;


 JDBCTest {
    
    private ApplicationContext ctx = null;
    {
        ctx = new ClasspathXmlApplicationContext("applicationContext.xml");    
    }
    
    @Test
    void test() throws sqlException {
        DataSource dataSource = ctx.getBean(DataSource.);
        System.out.println(dataSource.getConnection());
    }

}

鼠标右键点击test()方法，选择run as JUnit-Test，若输出为：

则表明连接成功。

二、JdbcTemplate 配置

在applicationContext.xml中进行配置

　　context:component-scan base-package="com.gong.spring"context:component-scan>
    
　　 配置 Spirng 的 JdbcTemplate ="jdbcTemplate" 
        class="org.springframework.jdbc.core.JdbcTemplate" ref="dataSource">

然后在JDBCTest.java中测试相应的操作：

 java.sql.sqlException;
 java.util.ArrayList;
 java.util.List;

 org.springframework.context.support.ClasspathXmlApplicationContext;
 org.springframework.jdbc.core.BeanPropertyRowMapper;
 org.springframework.jdbc.core.JdbcTemplate;
 org.springframework.jdbc.core.RowMapper;

;
     JdbcTemplate jdbcTemplate;
    {
        ctx = );
        jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate");
    }
    
    执行更新
    @Test
     testUpdate() {
        String sql = "UPDATE employees SET last_name = ? where id = ?";
        jdbcTemplate.update(sql,"tom",2);
    }
    执行批量更新
    最后一个参数是Object []的List类型
 testBatchUpdate() {
        String sql = "INSERT INTO employees(last_name,email,dept_id) VALUES (?,?,?)";
        List<Object[]> batchArgs = new ArrayList<>();
        batchArgs.add(new Object[]{"jack","[email protected]",1});
        batchArgs.add(new Object[]{"bob","[email protected]",1)">new Object[]{"mike","[email protected]",3});
        jdbcTemplate.batchUpdate(sql,batchArgs);
    }
    /**
     * 从数据库中获取一条记录,实际得到对应的一个对象
     * 注意不是调用 queryForObject(String sql,Class<Employee> requiredType,Object... args) 方法!
     * 而需要调用 queryForObject(String sql,RowMapper<Employee> rowMapper,Object... args)
     * 1. 其中的 RowMapper 指定如何去映射结果集的行,常用的实现类为 BeanPropertyRowMapper
     * 2. 使用 sql 中列的别名完成列名和类的属性名的映射. 例如 last_name lastName
     * 3. 不支持级联属性. JdbcTemplate 到底是一个 JDBC 的小工具,而不是 ORM 框架
     */
    @Test
     testQueryForObject(){
        String sql = "SELECT id,last_name lastName,dept_id as \"department.id\" FROM employees WHERE id = ?";
        RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.);
        Employee employee = jdbcTemplate.queryForObject(sql,rowMapper,1)">);    
        System.out.println(employee);
    }
    
     * 查到实体类的集合
     * 注意调用的不是 queryForList 方法
      testQueryForList(){
        String sql = "SELECT id,email FROM employees WHERE id > ?");
        List<Employee> employees = jdbcTemplate.query(sql,5);
        
        System.out.println(employees);
    }
    
    
     * 获取单个列的值,或做统计查询
     * 使用 queryForObject(String sql,Class<Long> requiredType) 
      testQueryForObject2(){
        String sql = "SELECT count(id) FROM employees";
        long count = jdbcTemplate.queryForObject(sql,Long.);
        
        System.out.println(count);
    }
    @Test
    );
        System.out.println(dataSource.getConnection());
    }

}

三、利用JdbcTemplate操作实际的类（使用基于注解的方式配置bean）

EmployeeDao.java

 org.springframework.beans.factory.annotation.Autowired;
 org.springframework.jdbc.core.RowMapper;
 org.springframework.stereotype.Repository;

@Repository
 EmployeeDao {
    
    @Autowired
     JdbcTemplate jdbcTemplate;
    
     Employee get(Integer id){
        String sql = "SELECT id,email FROM employees WHERE id = ?");
        Employee employee = jdbcTemplate.queryForObject(sql,id);
        
         employee;
    }
}

在JDBCTest.java中进行测试

     JdbcTemplate jdbcTemplate;
     EmployeeDao employeeDao;
     DepartmentDao departmentDao;
    {
        ctx = );
        employeeDao = ctx.getBean(EmployeeDao.);
        departmentDao = ctx.getBean(DepartmentDao.);
    }
    @Test
     testemployeeDao(){
        System.out.println(employeeDao.get(1));
    }

输出：

对于另外一种：

DepartmentDao.java

 org.springframework.jdbc.core.support.JdbcDaoSupport;
class DepartmentDao extends JdbcDaoSupport{
    //使用这种方法需要注入DataSource
    @Autowired
     setDataSource2(DataSource dataSource){
        setDataSource(dataSource);
    }

     Department get(Integer id){
        String sql = "SELECT id,dept_name name FROM departments WHERE id = ?";
        RowMapper<Department> rowMapper = new BeanPropertyRowMapper<>(Department.);
         getJdbcTemplate().queryForObject(sql,id);
    }
    
}

在JDBCTest.java中进行测试：

 testDepartmentDao(){
        System.out.println(departmentDao.get(1));
    }

输出：

一般推荐使用JdbcTemplate

spring之操作数据库之使用JdbcTemplate和JdbcDaoSupport

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