一、Druid连接池在程序初始化时，预先创建指定数量的数据库连接对象存储在池中。
当需要连接数据库时，从连接池中取出现有连接；
使用完毕后, 也不会进行关闭，而是放回池中，实现复用，节省资源。
1.1 Druid连接池使用步骤创建 database.properties 配置文件。
引入druid-1.1.5.jar文件。
1.1.1database.properties 配置文件#连接设置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/companydb?useUnicode=true&characterEncoding=utf
username=root
password=root
#
initialSize=10
#最大连接数量
maxActive=50
#
minldle=5
# 放回池中
connection.close();//调用的是DruidPooledConnection实现类里的close()方法
}
}
}
二、Apache的DbUtils使用Commons DbUtils是Apache组织提供的一个对JDBC逬行简单封装的开源工具类库，使用它能够简化JDBC应用程序的开发！同时，不会影响程序的性能。
2.1 DbUtils 简介DbUtils是Java编程中数据库操作实用小工具，小巧、简单、实用对于数据表的查询操作，可以把结果转换为List、Array、Set等集合。便于操作。
对于数据表的DML操作，也变得很简单(只需要写SQL语句)。
2.1.1DbUtils主要包含ResultSetHandler接口：转换类型接口BeanHandler类：实现类，把一条记录转换成对象 (查询单个)
BeanListHandler类：实现类，把多条记录转换成List集合。 (查询所有)
ScalarHandler类：实现类，适合获取一行一列的数据。
QueryRunner: 执行sql语句的类增、删、改：update();
查询：query();
2.2DbUtils的使用步骤导入jar包mysql连接驱动jar包 mysql-connector-java-5.1.28-bin.jar
druid-1.1.5.jar
database.properties配置文件
commons-dbutils-1.6,jar
2.2.1 DbUtils 工具类package com.ziming.chapter1_JDBC.demo05_jdbcfinal.utils;
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
public class DbUtils {
//声明连接池对象
private static DruidDataSource ds;
static {
Properties properties = new Properties();
InputStream is = DbUtils.class.getResourceAsStream("/database.properties");
try {
properties.load(is);
//创建连接池
ds = (DruidDataSource)DruidDataSourceFactory.createDataSource(properties);
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public static Connection getConnection(){
try {
return ds.getConnection();//通过连接池获得 连接对象
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
public static DataSource getDataSource(){ //获得 DataSource 连接池对象
return ds;
}
}
2.2.2 UserDaoImpl数据访问对象package com.ziming.chapter1_JDBC.demo05_jdbcfinal.entity;
public class User {
private int id;
private String username;
private String password;
private String phone;
public User() {}
public User(int id, String username, String password, String phone) {
this.id = id;
this.username = username;
this.password = password;
this.phone = phone;
}
@Override
public String toString() {
return "user{" +
"id=" + id +
", username='" + username + '\'' +
", password='" + password + '\'' +
", phone='" + phone + '\'' +
'}';
}
public int getId() { return id; }
public void setId(int id) { this.id = id; }
public String getUsername() { return username; }
public void setUsername(String username) { this.username = username; }
public String getPassword() { return password; }
public void setPassword(String password) { this.password = password; }
public String getPhone() { return phone; }
public void setPhone(String phone) { this.phone = phone; }
}
package com.ziming.chapter1_JDBC.demo05_jdbcfinal.dao;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.entity.User;
import java.util.List;
public interface UserDao {
public int insert(User user);
public int update(User user);
public int delete(int id);
public User select(int id);
public List selectAll();
//查看目前多少条记录(用户数量)
public long selectUserNums();
}
package com.ziming.chapter1_JDBC.demo05_jdbcfinal.dao.impl;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.dao.UserDao;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.entity.User;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.utils.DbUtils;
import mons.dbutils.QueryRunner;
import mons.dbutils.handlers.BeanHandler;
import mons.dbutils.handlers.BeanListHandler;
import mons.dbutils.handlers.ScalarHandler;
import javax.swing.*;
import java.sql.SQLException;
import java.util.List;
public class UserDaoImpl implements UserDao {
private QueryRunner queryRunner = new QueryRunner(DbUtils.getDataSource());
@Override
public int insert(User user) {
String sql = "insert into user(username,password,phone) values (?,?,?);";
try {
return queryRunner.update(sql,user.getUsername(),user.getPassword(),user.getPhone());
} catch (SQLException e) {
e.printStackTrace();
}
return 0;
}
@Override
public int update(User user) {
String sql = "update user set username=?,password=?,phone=? where id=?;";
try {
return queryRunner.update(sql,user.getUsername(),user.getPassword(),user.getPhone(),user.getId());
} catch (SQLException e) {
e.printStackTrace();
}
return 0;
}
@Override
public int delete(int id) {
String sql = "delete from user where id=?;";
try {
return queryRunner.update(sql,id);
} catch (SQLException e) {
e.printStackTrace();
}
return 0;
}
@Override
public User select(int id) {
String sql = "select * from user where id=?;";
try {
User user = queryRunner.query(sql, new BeanHandler(User.class), id);
return user;
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
@Override
public List selectAll() {
String sql = "select * from user;";
try {
List list = queryRunner.query(sql, new BeanListHandler(User.class));
return list;
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
@Override
public long selectUserNums() {
String sql = "select count(*) from user";
try {
long count = queryRunner.query(sql, new ScalarHandler<>());
return count;
} catch (SQLException e) {
e.printStackTrace();
}
return 0;
}
}
package com.ziming.chapter1_JDBC.demo05_jdbcfinal.test;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.dao.UserDao;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.dao.impl.UserDaoImpl;
import com.ziming.chapter1_JDBC.demo05_jdbcfinal.entity.User;
import java.util.List;
public class TestDbUtils {
public static void main(String[] args) {
UserDao userDao = new UserDaoImpl();
//User user = new User(3,"xiaoli","123456","1234569874");
//int result = userDao.insert(user); //新增
//User user = new User(3,"xiaoli","123","1234569874");
//int result = userDao.update(user); //修改
//int result = userDao.delete(3);//删除
//System.out.println(result);
//查单个
// User user = userDao.select(1);
// System.out.println(user);
//查所有
//List list = userDao.selectAll();
//list.forEach(System.out::println);
long count = userDao.selectUserNums();
System.out.println("一共有："+count);
}
}
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