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

2020-08-26 10:05:56 浏览数 (1)

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：

Departmen t.java

代码语言：javascript复制
package com.gong.spring.jdbc;

public class Department {

    private Integer id;
    private String name;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

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

}

Employee.java

代码语言：javascript复制
package com.gong.spring.jdbc;

public class Employee {
    
    private Integer id;
    private String lastName;
    private String email;
    
    private Integer dpetId;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getDpetId() {
        return dpetId;
    }

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

    @Override
    public String toString() {
        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

代码语言：javascript复制
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

代码语言：javascript复制
<?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="${jdbc.user}"></property>
        <property name="password" value="${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>
    
</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。

代码语言：javascript复制
package com.gong.spring.jdbc;

import java.sql.SQLException;

import javax.sql.DataSource;

import org.junit.jupiter.api.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;


class JDBCTest {
    
    private ApplicationContext ctx = null;
    {
        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");    
    }
    
    @Test
    void test() throws SQLException {
        DataSource dataSource = ctx.getBean(DataSource.class);
        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

代码语言：javascript复制
　　<context:component-scan base-package="com.gong.spring"></context:component-scan>
    
　　<!-- 配置 Spirng 的 JdbcTemplate -->
    <bean id="jdbcTemplate" 
        class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"></property>
    </bean>

然后在JDBCTest.java中测试相应的操作：

代码语言：javascript复制
package com.gong.spring.jdbc;

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;

class JDBCTest {
    
    private ApplicationContext ctx = null;
    private JdbcTemplate jdbcTemplate;
    {
        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate");
    }
    
    //执行更新
    @Test
    public void 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
    @Test
    public void testBatchUpdate() {
        String sql = "INSERT INTO employees(last_name,email,dept_id) VALUES (?,?,?)";
        List<Object[]> batchArgs = new ArrayList<>();
        batchArgs.add(new Object[]{"jack","jack@qq.com",1});
        batchArgs.add(new Object[]{"bob","bob@qq.com",2});
        batchArgs.add(new Object[]{"mike","mike@qq.com",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
    public void testQueryForObject(){
        String sql = "SELECT id, last_name lastName, email, dept_id as "department.id" FROM employees WHERE id = ?";
        RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);
        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
     */
    @Test
    public void testQueryForList(){
        String sql = "SELECT id, last_name lastName, email FROM employees WHERE id > ?";
        RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);
        List<Employee> employees = jdbcTemplate.query(sql, rowMapper,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) 
     */
    @Test
    public void testQueryForObject2(){
        String sql = "SELECT count(id) FROM employees";
        long count = jdbcTemplate.queryForObject(sql, Long.class);
        
        System.out.println(count);
    }
    @Test
    void test() throws SQLException {
        DataSource dataSource = ctx.getBean(DataSource.class);
        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

代码语言：javascript复制
package com.gong.spring.jdbc;

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

@Repository
public class EmployeeDao {
    
    @Autowired
    private JdbcTemplate jdbcTemplate;
    
    public Employee get(Integer id){
        String sql = "SELECT id, last_name lastName, email FROM employees WHERE id = ?";
        RowMapper<Employee> rowMapper = new BeanPropertyRowMapper<>(Employee.class);
        Employee employee = jdbcTemplate.queryForObject(sql, rowMapper, id);
        
        return employee;
    }
}

在JDBCTest.java中进行测试

代码语言：javascript复制
    private ApplicationContext ctx = null;
    private JdbcTemplate jdbcTemplate;
    private EmployeeDao employeeDao;
    private DepartmentDao departmentDao;
    {
        ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        jdbcTemplate = (JdbcTemplate) ctx.getBean("jdbcTemplate");
        employeeDao = ctx.getBean(EmployeeDao.class);
        departmentDao = ctx.getBean(DepartmentDao.class);
    }
    @Test
    public void testEmployeeDao(){
        System.out.println(employeeDao.get(1));
    }

输出：

对于另外一种：

DepartmentDao.java

代码语言：javascript复制
package com.gong.spring.jdbc;

import javax.sql.DataSource;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.RowMapper;
import org.springframework.jdbc.core.support.JdbcDaoSupport;
import org.springframework.stereotype.Repository;

@Repository
public class DepartmentDao extends JdbcDaoSupport{
    //使用这种方法需要注入DataSource
    @Autowired
    public void setDataSource2(DataSource dataSource){
        setDataSource(dataSource);
    }

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

在JDBCTest.java中进行测试：

代码语言：javascript复制
    @Test
    public void testDepartmentDao(){
        System.out.println(departmentDao.get(1));
    }

输出：

一般推荐使用JdbcTemplate

java 数据库 sql jdbc xml

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