要求一：加入C3P0数据源
——C3P0
——数据库驱动的jar包
1.首先在src目录下创建c3p0的配置文件c3p0-config.xml
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root
password
com.mysql.cj.jdbc.Driver
jdbc:mysql://localhost:3306/yang
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2.创建一个JdbcUtil类，创建一个c3p0连接池，并且创建连接，销毁连接。
public class JdbcUtils {
/**
* 释放Connection连接
* @param connection
*/
public static void releaseConnection(Connection connection){
if (connection!=null){
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
private static DataSource dataSource = null;
static{
dataSource = new ComboPooledDataSource("mysql");
}
public static Connection getConnection() throws SQLException {
return dataSource.getConnection();
}
}
3.可以创建一个测试类来测试，第一个测试是否可以获取一个连接。
@Test
public void testGetConnection() throws SQLException {
Connection connection = JdbcUtils.getConnection();
System.out.println(connection);
}
要求二：编写DAO、DBUtils工具栏和CustomerDAO接口
提供CustomerDAO接口的实现类：CustomerDAOImpl
1.实体类：
package com.mvcapp.entity;
import java.io.Serializable;
public class Customer implements Serializable {
private Integer id;
private String name;
private String password;
public Customer(Integer id, String name, String password) {
this.id = id;
this.name = name;
this.password = password;
}
public Customer(String name, String password) {
this.name = name;
this.password = password;
}
public Customer() {
}
@Override
public String toString() {
return "Customer{" +
"id=" + id +
", name='" + name + '\'' +
", password='" + password + '\'' +
'}';
}
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;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
2.DAO
package com.mvcapp.dao;
import com.mvcapp.db.JdbcUtils;
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.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Types;
import java.util.List;
/**
* 封装了基本的CRUD的方法，以供子类继承使用
* 当前DAO直接在方法中获取数据库连接
* 整个DAO采取DBUtils解决方案
* @param :当前DAO处理的实体类的类型是什么？
*
*/
public class DAO {
private QueryRunner queryRunner = new QueryRunner();
private Class clazz;
public DAO(){
//获得运行时类的超类的类型
Type superClass = getClass().getGenericSuperclass();
if (superClass instanceof ParameterizedType){
ParameterizedType parameterizedType = (ParameterizedType) superClass;
Type [] typeArgs = parameterizedType.getActualTypeArguments();
if (typeArgs !=null && typeArgs.length >0){
if (typeArgs[0] instanceof Class ){
clazz = (Class) typeArgs[0];
}
}
}
}
/**
* 获取一条记录
* @param sql
* @param args
* @return
*/
public T get(String sql,Object ...args){
Connection connection = null;
try {
connection = JdbcUtils.getConnection();
return queryRunner.query(connection,sql,new BeanHandler<>(clazz),args);
} catch (SQLException e) {
e.printStackTrace();
}finally {
JdbcUtils.releaseConnection(connection);
}
return null;
}
/**
* 获取一组值
* @param sql
* @param args
* @return
*/
public List getForList(String sql,Object ...args){
Connection connection = null;
try {
connection = JdbcUtils.getConnection();
return queryRunner.query(connection,sql,new BeanListHandler<>(clazz));
} catch (SQLException e) {
e.printStackTrace();
}finally {
JdbcUtils.releaseConnection(connection);
}
return null;
}
/**
* 返回某一个字段的值，例如返回某一条记录的customerName，或返回数据表中国有多少条记录
* @param sql
* @param args
* @param
* @return
*/
public E getForValue(String sql,Object ...args){
Connection connection = null;
try {
connection = JdbcUtils.getConnection();
return (E) queryRunner.query(connection,sql,new ScalarHandler(),args);
} catch (SQLException e) {
e.printStackTrace();
}finally {
JdbcUtils.releaseConnection(connection);
}
return null;
}
/**
* 该方法封装了INSERT、DELETE、UPDATE操作
* @param sql：SQL语句
* @param args：填充SQL语句的占位符
*/
public void update(String sql,Object ...args){
Connection connection = null;
try {
connection = JdbcUtils.getConnection();
queryRunner.update(connection,sql,args);
} catch (SQLException e) {
e.printStackTrace();
}finally {
JdbcUtils.releaseConnection(connection);
}
}
}
3.CustomerDAO接口
package com.mvcapp.dao;
import com.mvcapp.entity.Customer;
import java.util.List;
public interface CustomerDAO {
public List getAll();
public void save(Customer customer);
public Customer get(Integer id);
public void delete(Integer id);
/**
* 返回和name相等的记录
* @param name
* @return
*/
public long getCountWithName(String name);
}
4.CustomerDAOImpl实现类：
package com.mvcapp.daoimpl;
import com.mvcapp.dao.CustomerDAO;
import com.mvcapp.dao.DAO;
import com.mvcapp.entity.Customer;
import java.util.List;
public class CustomerDAOImpl extends DAO implements CustomerDAO {
@Override
public List getAll() {
String sql = "SELECT * FROM CUSTOMER";
return getForList(sql);
}
@Override
public void save(Customer customer) {
String sql = "insert into customer(name,password) values(?,?)";
update(sql,customer.getName(),customer.getPassword());
}
@Override
public Customer get(Integer id) {
String sql = "select * from customer where id=?";
return get(sql,id);
}
@Override
public void delete(Integer id) {
String sql ="delete from customer where id=?";
update(sql,id);
}
@Override
public long getCountWithName(String name) {
String sql = "Select count(id) from customer where name=?";
return getForValue(sql,name);
}
}
5.CustomerDAOImplTest测试类：
package com.mvcapp.test;
import com.mvcapp.dao.CustomerDAO;
import com.mvcapp.daoimpl.CustomerDAOImpl;
import com.mvcapp.entity.Customer;
import org.junit.jupiter.api.Test;
import java.util.List;
public class CustomerDAOImplTest {
private CustomerDAO customerDAO = new CustomerDAOImpl();
@Test
public void testGet(){
Customer customer = customerDAO.get(1);
System.out.println(customer);
}
@Test
public void testSave(){
Customer customer = new Customer("Wang","222");
customerDAO.save(customer);
}
@Test
public void testdelete(){
int id = 4;
customerDAO.delete(id);
}
@Test
public void testlist(){
List list = customerDAO.getAll();
System.out.println(list);
}
@Test
public void testcount(){
long i = customerDAO.getCountWithName("SEN");
System.out.println(i);
}
}