使用c3p0连接数据库实现增删改查

时间：2020-11-14 11:20:28|栏目：JAVA代码|点击：次

学习spring之前，视频中先给我们一个任务就是用c3p0连接数据库来完成增删改查

一、准备

JAR包：

既然是连接数据库第一个最重要的就是数据库的驱动包mysql-connection-java-5.1.44-bin.jar

接着就是C3P0-0.9.2.1.jar以及mchange-commons-java-0.2.3.4.jar

然后还少不了dbutils 使用的是commons-dbutils-1.7.jar

一共是4个JAR包

二、配置

配置数据库连接:

创建c3p0-config.xml的配置文件，里面包含连接数据库的信息

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
 <default-config>
 <property name="driverClass">com.mysql.jdbc.Driver</property>
 <property name="jdbcUrl">jdbc:mysql://localhost:3306/mybatis</property>
 <property name="user">root</property>
 <property name="password">123</property>
 <property name="acquireIncrement">5</property>
 <property name="initialPoolSize">10</property>
 <property name="minPoolSize">5</property>
 <property name="maxPoolSize">20</property>
 </default-config>
</c3p0-config>

创建C3P0Util.java 使用ComboPooledDataSource的对象获取数据库连接

package util;
 
import java.sql.Connection;
import java.sql.SQLException;
 
import javax.sql.DataSource;
 
import com.mchange.v2.c3p0.ComboPooledDataSource;
 
public class C3P0Util {
 
 private static ComboPooledDataSource ds=new ComboPooledDataSource();
 
 //获取数据源
 public static DataSource getDataSource(){
 return ds;
 }
 //获取一个连接
 public static Connection getConnection() throws SQLException{
 return ds.getConnection();
 }
}

由于没有使用Mybatis的逆向工程，这里需要手动创建Customer.java 用于获取数据库表的所有列

package domain;
 
import java.io.Serializable;
 
public class Customer implements Serializable{
 
 private int cust_id;
 private String cust_name;
 private String cust_source;
 private String cust_industry;
 private String cust_level;
 private String cust_address;
 private String cust_phone;
 public int getCust_id() {
  return cust_id;
 }
 public void setCust_id(int cust_id) {
  this.cust_id = cust_id;
 }
 public String getCust_name() {
  return cust_name;
 }
 public void setCust_name(String cust_name) {
  this.cust_name = cust_name;
 }
 public String getCust_source() {
  return cust_source;
 }
 public void setCust_source(String cust_source) {
  this.cust_source = cust_source;
 }
 public String getCust_industry() {
  return cust_industry;
 }
 public void setCust_industry(String cust_industry) {
  this.cust_industry = cust_industry;
 }
 public String getCust_level() {
  return cust_level;
 }
 public void setCust_level(String cust_level) {
  this.cust_level = cust_level;
 }
 public String getCust_address() {
  return cust_address;
 }
 public void setCust_address(String cust_address) {
  this.cust_address = cust_address;
 }
 public String getCust_phone() {
  return cust_phone;
 }
 public void setCust_phone(String cust_phone) {
  this.cust_phone = cust_phone;
 }
 @Override
 public String toString() {
  return "Customer [cust_id=" + cust_id + ", cust_name=" + cust_name
   + ", cust_source=" + cust_source + ", cust_industry="
   + cust_industry + ", cust_level=" + cust_level
   + ", cust_address=" + cust_address + ", cust_phone="
   + cust_phone + "]";
 } 
}

三、接口

上面的配置文件和数据库表信息文件都已经写好了，现在需要写两个接口提供所有的增删改查的方法

创建ICustomerDao.java 持久层接口，也就是最底层和数据库连接的接口类

package dao;
 
import java.util.List; 
import domain.Customer; 
public interface ICustomerDao {
 
 List<Customer> findAllCustomer(); 
 void saveCustomer(Customer customer); 
 void updateCustomer(Customer customer); 
 void deleteCustomer(int custId); 
 Customer findCustomerById(int custId);
 
}

创建ICustomerService.java 业务层接口，用于持久层和客户端连接的接口类，和Dao的方法一样

package service;
 
import java.util.List;
 
import domain.Customer;
 
public interface ICustomerService {
 
 //查询所有客户
 List<Customer> findAllCustomer();
 //保存客户信息
 void saveCustomer(Customer customer);
 //更改客户信息
 void updateCustomer(Customer customer);
 //根据Id删除对象
 void deleteCustomer(int cust_id);
 //根据ID查询用户，返回用户信息
 Customer findCustomerById(int cust_id);
}

四、实现类

创建CustomerDao.java 实现Dao接口，利用C3P0里的QueryRunner类获取到数据库连接信息连接数据库

并将SQL语句传给数据库然后得到SQL的返回值。

package dao.impl;
 
import java.sql.SQLException;
import java.util.List;
 
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
 
import dao.ICustomerDao;
import domain.Customer;
import util.C3P0Util;
 
//客户的持久层实现类
public class CustomerDao implements ICustomerDao {
 
 private QueryRunner runner=new QueryRunner(C3P0Util.getDataSource());
 @Override
 public List<Customer> findAllCustomer() {
 try {
  return runner.query("select * from cst_customer", new BeanListHandler<Customer>(Customer.class));
 } catch (SQLException e) {
  throw new RuntimeException(e);
 }
 }
 
 @Override
 public void saveCustomer(Customer customer) {
 try {
  runner.update("insert into cst_customer(cust_name,cust_source,cust_industry,cust_level,cust_address,cust_phone)values(?,?,?,?,?,?)",
   customer.getCust_name(),customer.getCust_source(),customer.getCust_industry(),
   customer.getCust_level(),customer.getCust_address(),customer.getCust_phone());
 } catch (SQLException e) {
  throw new RuntimeException(e);
 }
 
 }
 
 @Override
 public void updateCustomer(Customer customer) {
 try {
  runner.update("update cst_customer set cust_name=?,cust_source=?,cust_industry=?,cust_level=?,cust_address=?,cust_phone=? where cust_id=?",
   customer.getCust_name(),customer.getCust_source(),customer.getCust_industry(),
   customer.getCust_level(),customer.getCust_address(),customer.getCust_phone(),customer.getCust_id());
 } catch (SQLException e) {
  throw new RuntimeException(e);
 }
 }
 
 @Override
 public void deleteCustomer(int custId) {
 try {
  runner.update("delete from cst_customer where cust_id=?",custId);
 } catch (SQLException e) {
  throw new RuntimeException(e);
 }
 }
 
 @Override
 public Customer findCustomerById(int custId) {
 try {
  return runner.query("select * from cst_customer where cust_id=?", new BeanHandler<Customer>(Customer.class),custId);
 } catch (SQLException e) {
  throw new RuntimeException(e);
 }
 }
 
}

创建CustomerService.java 实现业务层，将需要查询的数据传给Dao层，并得到Dao层的返回值。

package service;
 
import java.util.List;
 
import dao.ICustomerDao;
import dao.impl.CustomerDao;
import domain.Customer;
 
//客户的业务层实现类
public class CustomerServiceImpl implements ICustomerService {
 
 private ICustomerDao customerDao=new CustomerDao();
 @Override
 public List<Customer> findAllCustomer() {
 // TODO Auto-generated method stub
 return customerDao.findAllCustomer();
 }
 
 @Override
 public void saveCustomer(Customer customer) {
 customerDao.saveCustomer(customer);
 
 }
 
 @Override
 public void updateCustomer(Customer customer) {
 customerDao.updateCustomer(customer);
 
 }
 
 @Override
 public void deleteCustomer(int custId) {
 customerDao.deleteCustomer(custId);
 }
 
 @Override
 public Customer findCustomerById(int custId) {
 // TODO Auto-generated method stub
 return customerDao.findCustomerById(custId);
 }
 
}

五、测试类

创建CustomerServiceTest.java 获取CustomerServiceImpl所有方法的测试方法

该类中在方法里创建CustomerServiceImpl对象获取原始方法，将参数传入Customer中，通过CustomerService获取到返回值并打印。

package test;
 
import static org.junit.Assert.fail;
 
import java.util.List;
 
import org.junit.Test;
 
import domain.Customer;
import service.CustomerServiceImpl;
import service.ICustomerService;
 
public class CustomerServicerTest {
 
 @Test
 public void testFindAllCustomer() {
 ICustomerService cs=new CustomerServiceImpl();
 List<Customer> list=cs.findAllCustomer();
 for(Customer c: list){
  System.out.println(c);
 }
 }
 
 @Test
 public void testSaveCustomer() {
 ICustomerService cs=new CustomerServiceImpl();
 Customer c=new Customer();
 c.setCust_name("滴滴");
 c.setCust_source("dache");
 
 cs.saveCustomer(c);
 }
 
 @Test
 public void testUpdateCustomer() {
 fail("Not yet implemented");
 }
 
 @Test
 public void testDeleteCustomer() {
 fail("Not yet implemented");
 }
 
 @Test
 public void testFindCustomerById() {
 ICustomerService cs=new CustomerServiceImpl();
 Customer c=cs.findCustomerById(2);
 System.out.println(c);
 }
 
}

至此C3P0连接数据库进行单表增删改查功能完结。附上结构图

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