JavaWeb购物系统（十一）购物系统-连接数据库（Mysql、sqlServer、Access的匹配方案）
我们推荐使用的是连接
Mysql，因为我的购物系统就是在Mysql环境下测试的。当然在最后，我也对sqlServer和Access的连接做了一些测试，但可能得修改业务相关的sql语句，因为不同的数据库管理系统厂商对sql支持不同。
至于为什么要做不同数据库的匹配：当然是有的学校必须得用sqlServer和Access
正文
Mysql
使用德鲁伊数据库连接池和apache.dbutils工具类
JdbcUtil
package com.myUtil;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JdbcUtil {
private static ThreadLocal<Connection> threadLocalConn = new ThreadLocal<>();
private static DataSource ds;
static {
Properties properties = new Properties();
try {
properties.load(JdbcUtil.class.getClassLoader().getResourceAsStream("jdbc.properties"));
ds = DruidDataSourceFactory.createDataSource(properties);
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection() {
Connection connection = threadLocalConn.get();
if (connection==null){
try {
// 得到连接
connection = ds.getConnection();
// 关闭自动提交
connection.setAutoCommit(false);
threadLocalConn.set(connection);
} catch (SQLException e) {
e.printStackTrace();
}
}
return connection;
}
/**
* 事务的提交
*/
public static void commit(){
Connection connection = threadLocalConn.get();
if (connection != null){
try {
connection.commit();
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
try {
connection.close(); // 关闭连接
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
// 提交之后将connection从ThreadLocal清除掉
threadLocalConn.remove();
}
/**
* 回滚/撤销connection管理的dml等操作
*/
public static void rollback(){
Connection connection = threadLocalConn.get();
if (connection!=null){
try {
connection.rollback();
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
threadLocalConn.remove();
}
public static void close(Connection connection, Statement statement, ResultSet resultSet){
if (resultSet != null){
try {
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if (connection!=null){
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if (statement != null){
try {
statement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
}
BasicDao
package com.dao;
import com.myUtil.JdbcUtil;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
public class BasicDao<T> {
private QueryRunner qr = new QueryRunner();
public Boolean dmlData(String sql,Object... parameters){
Connection connection = null;
try {
connection = JdbcUtil.getConnection();
int update = qr.update(connection, sql, parameters);
if (update>0){
return true;
}else {
return false;
}
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
JdbcUtil.close(null,null,null);
}
}
public List<T> queryMulti(String sql, Class<T> clazz, Object... parameters){
Connection connection = null;
try {
connection = JdbcUtil.getConnection();
List<T> query = qr.query(connection, sql, new BeanListHandler<>(clazz), parameters);
return query;
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
JdbcUtil.close(null,null,null);
}
}
/**
*
* @param sql
* @param clazz
* @param parameters
* @return 一行数据
*/
public T querySingle(String sql, Class<T> clazz,Object... parameters){
Connection connection = null;
try {
connection = JdbcUtil.getConnection();
return qr.query(connection, sql, new BeanHandler<>(clazz), parameters);
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
JdbcUtil.close(null,null,null);
}
}
/**
*
* @param sql
* @param parameters
* @return 单行单列
**/
public T rowColumn(String sql,Object... parameters){
Connection connection = null;
try {
connection = JdbcUtil.getConnection();
T query = (T) qr.query(connection, sql, new ScalarHandler(), parameters);
return query;
} catch (SQLException e) {
throw new RuntimeException(e);
} finally {
JdbcUtil.close(null,null,null);
}
}
}
properties配置文件
#Mysql
driverClassNam=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/数据库名?serverTimezone=UTC
username=用户名
password=密码
注意：我这里的驱动是 Mysql8.0 版本的。
Mysql5.7版本的请用 com.mysql.jdbc.Driver
SqlServer
经过测试，通过 SqlServer 也可以用德鲁伊数据连接池和apache.dbutils工具类
前置条件
- 德鲁伊数据库连接池下载地址
- dbutils下载地址
- SqlService驱动下载地址
JdbcUtil
这个类和Mysql的一样
BasicDao
这个类和Mysql的一样
properties配置文件
#sqlSqerver
driverClassNam=com.microsoft.sqlserver.jdbc.SQLServerDriver
url=jdbc:sqlserver://localhost:1433;DatabaseName=数据库名;encrypt=false
username=用户名
password=密码
sqlServer得改我代码里边的相关sql语句
例如：select * from `user` 改为 select * from [user]
Access
Access就像在文件存储数据。查资料后，连接方式有种ODBC桥接的方式，但得要求JDK版本为8.0以下。所以我们采用另外一种，使用驱动的方式。
前置条件：
- Access驱动
- 德鲁伊数据库连接池下载地址
- dbutils下载地址
但这个驱动还有个限制：查询50次限制、查询结果1000条限制、插入500次限制
JdbcUtil
package com.myUtil;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
public class JdbcUtil {
private static ThreadLocal<Connection> threadLocalConn = new ThreadLocal<>();
public static Connection getConnection() {
Connection connection = threadLocalConn.get();
if (connection==null){
try {
// 得到连接
Class<?> aClass = Class.forName("com.hxtt.sql.access.AccessDriver");
String url = "jdbc:Access:///D://Access数据库文件/Database2.accdb";
connection = DriverManager.getConnection(url);
// 关闭自动提交
connection.setAutoCommit(false);
threadLocalConn.set(connection);
} catch (SQLException e) {
e.printStackTrace();
}
}
return connection;
}
/**
* 事务的提交
*/
public static void commit(){
Connection connection = threadLocalConn.get();
if (connection != null){
try {
connection.commit();
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
try {
connection.close(); // 关闭连接
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
// 提交之后将connection从ThreadLocal清除掉
threadLocalConn.remove();
}
/**
* 回滚/撤销connection管理的dml等操作
*/
public static void rollback(){
Connection connection = threadLocalConn.get();
if (connection!=null){
try {
connection.rollback();
} catch (SQLException throwables) {
throwables.printStackTrace();
}finally {
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
threadLocalConn.remove();
}
public static void close(Connection connection, Statement statement, ResultSet resultSet){
if (resultSet != null){
try {
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if (connection!=null){
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
if (statement != null){
try {
statement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
}
BasicDao
和Mysql和SqlServer一样。
不使用 apache.dbutils工具类
我们只需将上边BasicDao改为我这里自己写的，自动封装对象的代码。
package com.dao;
import com.myUtil.JdbcUtil;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;
public class BasicDao<T> {
// 查询单行
public T querySingle(String sql, Class<T> clazz){
T object = null;
Connection connection = null;
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
try {
object = clazz.newInstance();
connection = JdbcUtil.getConnection();
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
if (!resultSet.next()){
return null;
}
Field[] declaredFields = clazz.getDeclaredFields();
for (Field file : declaredFields) {
String name = file.getName();
file.setAccessible(true);
Object res = resultSet.getObject(name);
file.set(object,res);
}
return object;
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
JdbcUtil.close(null,preparedStatement,resultSet);
}
}
// 添加/删除/修改数据
public boolean dmlData(String sql){
Connection connection = null;
PreparedStatement preparedStatement = null;
try {
connection = JdbcUtil.getConnection();
preparedStatement = connection.prepareStatement(sql);
int result = preparedStatement.executeUpdate();
if (result > 0){
return true;
}
} catch (SQLException e) {
throw new RuntimeException(e);
}finally {
JdbcUtil.close(null,preparedStatement,null);
}
return false;
}
// 查询多行数据
public List<T> queryMulti(String sql, Class<T> clazz) {
Connection connection = null;
List<T> list = new ArrayList<>();
PreparedStatement preparedStatement = null;
ResultSet resultSet = null;
T object = null;
try {
connection = JdbcUtil.getConnection();
preparedStatement = connection.prepareStatement(sql);
resultSet = preparedStatement.executeQuery();
Field[] declaredFields = clazz.getDeclaredFields();
while (resultSet.next()){
object = clazz.newInstance();
for (Field file : declaredFields) {
String name = file.getName();
file.setAccessible(true);
Object res = resultSet.getObject(name);
file.set(object,res);
}
list.add(object);
}
} catch (Exception e) {
throw new RuntimeException(e); //将编译异常->运行异常 ,抛出
} finally {
JdbcUtil.close(null, preparedStatement, resultSet);
}
if (list.size() == 0){
return null;
}else {
return list;
}
}
}
至此购物系统的全部模块都讲解完毕。因为是初次做，所以有些地方还考虑的还不是很完善。整个购物系统方面，没有添加太多的功能。有什么问题，还有改进的地方，还望大家提出宝贵意见。
最后希望大家多多关注 ^_^，你们的关注是我不断前进的动力！！！
感谢感谢~~~