DbUtils框架

DbUtils框架

一.DbUtils框架概述

1.DbUtils

• 为了更加简单且高效地使用JDBC，Apache组织提供了数据库操作工具类commons-dbutils，该工具可以自动完成：创建连接、封装结果、释放资源。
• DbUtils对JDBC进行了封装，可简化JDBC的编码工作量（例：DbUtils在查询数据时可把结果转换成List，Array，Set等集合）。

2.DbUtils下载官网

• http://commons.apache.org/proper/commons-dbutils/download_dbutils.cgi

3.DbUtils三大核心

（1）DbUtils工具类

• 该类主要用于关闭连接、装载JDBC驱动程序等

（2）ResultSetHandler接口

• 该接口及其实现类主要用于处理结果集

（3）QueryRunner类

• 该类主要用于增，删，改，查

二.DbUtils相关jar包

• mysql-connector-java-5.0.8-bin.jar
• commons-dbutils-1.4.jar
• c3p0-0.9.1.2.jar

三.DbUtils三大核心方法

1.DbUtils工具类

方法	方法描述
public static boolean loadDriver(java.lang.String driverClassName)	该方法用于方装载并注册JDBC驱动程序，如果成功就返回true。使用该方法，不需要捕捉ClassNotFoundException
public static void close(Connection conn,Statement stmt, ResultSet rs) throws java.sql.SQLException	该类方法用于关闭Connection、Statement和ResultSe
public static void closeQuietly(Connection conn,Statement stmt, ResultSet rs):	该类方法不仅能在Connection、Statement和ResultSet为NULL情况下避免关闭，还能隐藏一些在程序中抛出的SQLEeception
public static void commitAndCloseQuietly(Connection conn)	该方法用于提交事务并关闭连接，而且在关闭连接时不抛出SQL异常。
public static void rollbackAndCloseQuietly(Connection conn)	该方法用于回滚事务并关闭连接，而且在关闭连接时不抛出SQL异常。

2.ResultSetHandler接口

实现类	实现类描述
BeanHandler	将结果集中的第一行数据封装到一个对应的JavaBean实例中。
BeanListHandler	将结果集中的每一行数据都封装到一个对应的JavaBean实例中，再存放到List里
ArrayHandler	把结果集中的第一行数据转成对象数组
ArrayListHandler	把结果集中的每一行数据都转成一个数组存放到List中
ColumnListHandler	将结果集中某一列的数据存放到List中
KeyedHandler(name)	将结果集中的每一行数据都封装到一个Map<列名,列值>里，再把这些map再存到一个map里，其key为指定的key
MapHandler	将结果集中的第一行数据封装到一个Map里，key是列名，value就是对应的值
MapListHandler	将结果集中的每一行数据都封装到一个Map里，然后再存放到List
ScalarHandler	将结果集中某一条记录的其中某一列的数据存储成Object对象；常用于获取聚合函数的值

3.QueryRunner类

方法	方法描述
QueryRunner()	采用该方法创建QueryRunner时数据库的事务可由我们自己手动控制。 正因为该构造方法无参，所以在调用该对象的query、update、等方法时需要传入参数Connection。 利用QueryRunner的无参构造函数即QueryRunner( )创建QueryRunner执行数据库操作后需要手动关闭数据库连接Connection
public Object query(Connection conn, String sql, Object[] params, ResultSetHandler rsh) throws SQLException	该方法用于执行查询，在该查询中Object数组里的每个值被用来作为查询语句的置换参数。该方法会自行处理PreparedStatement和ResultSet的创建和关闭。
public Object query(String sql, Object[] params, ResultSetHandler rsh) throws SQLException	该方法与上面的这个方法基本一样；不同的是它不用传入参数Connection
public Object query(Connection conn, String sql, ResultSetHandler rsh) throws SQLException	该方法与上面的两个方法基本一样，它用于执行一个不需要置换参数的查询操作。
public int update(Connection conn, String sql, Object[] params) throws SQLException	该方法用于执行更新操作(例如：增加、删除、更新)，在该查询中Object数组里的每个元素值被用来作为更新语句的置换参数
public int update(Connection conn, String sql) throws SQLException	该方法与上面的方法基本一样，用来执行一个不需要置换参数的更新操作。
public int update(String sql) throws SQLException	该方法与上面的方法基本一样，用来执行一个不需要置换参数和不指定Connection的更新操作。

四.DbUtils简单封装

package cn.com.demo06;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;

import org.apache.commons.dbutils.DbUtils;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DBUtils {
	
    //创建数据库连接池
    private static DataSource dataSource = new ComboPooledDataSource();
  	
    //获取数据库连接池
  	public static DataSource getDataSource() {
  		return dataSource;
  	}

    //创建连接
    public static Connection getConnection(){
        try {
            return dataSource.getConnection();
        } catch (SQLException e) {
            throw new RuntimeException("获取数据库连接失败");
        }
    }

    //释放连接
    public static void releaseConnection(Connection connection, Statement statement, ResultSet resultSet) {
        DbUtils.closeQuietly(connection, statement, resultSet);
    }
}

五.DbUtils简单使用示例

1.创建表

-- 若存在数据库mydb则删除
DROP DATABASE IF EXISTS mydb;
-- 创建数据库mydb
CREATE DATABASE mydb;
-- 选择数据库mydb
USE mydb;

-- 创建表
CREATE TABLE membershipcard (
    id int primary key auto_increment, 
    username varchar(40),
    password varchar(40), 
    email varchar(40), 
    birthday date 
);

-- 插入数据
INSERT INTO membershipcard (username,password,email,birthday) VALUES ("lili","lili123","[email protected]","1999-08-14");
INSERT INTO membershipcard (username,password,email,birthday) VALUES ("fafa","fafa456","[email protected]","1998-07-15");
INSERT INTO membershipcard (username,password,email,birthday) VALUES ("guigui","guigui333","[email protected]","1997-06-16");
INSERT INTO membershipcard (username,password,email,birthday) VALUES ("bing","bing666","[email protected]","1996-05-17");

2.实体类

package cn.com.demo06;

import java.util.Date;

public class MembershipCard {
	private int id;
	private String username;
	private String password;
	private String email;
	private Date birthday;
	public MembershipCard() {
		
	}
	public MembershipCard(int id, String username, String password, String email, Date birthday) {
		this.id = id;
		this.username = username;
		this.password = password;
		this.email = email;
		this.birthday = birthday;
	}
	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 getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public Date getBirthday() {
		return birthday;
	}
	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}
	@Override
	public String toString() {
		return "MembershipCard [id=" + id + ", username=" + username + ", password=" + password + ", email=" + email
				+ ", birthday=" + birthday + "]";
	}
	
}

3.DbUtils实现增删改查

package cn.com.demo06;

import java.sql.Date;
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;

public class TestDBUtils1 {

	public static void main(String[] args) {
		try {
			TestDBUtils1 demo = new TestDBUtils1();
			demo.testSelectAll();
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
+
	// 插入数据
	public void testInsert() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		Date birthday = Date.valueOf("1997-07-01");
		String sql = "insert into membershipcard(username,password,email,birthday) values(?,?,?,?)";
		Object params[] = { "huhu", "huhu777", "[email protected]", birthday };
		qr.update(sql, params);
	}

	// 更新数据
	public void testUpdate() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "update membershipcard set password=? where username=?";
		Object params[] = { "888888", "huhu" };
		qr.update(sql, params);
	}

	// 删除数据
	public void testDelete() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "delete from membershipcard where username=?";
		Object params[] = { "huhu" };
		qr.update(sql, params);
	}

	// 查询单个数据
	public void testSelect() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "select * from membershipcard where username=?";
		Object params[] = { "lili" };
		BeanHandler beanHandler=new BeanHandler<>(MembershipCard.class);
		MembershipCard membershipCard=qr.query(sql, beanHandler, params);
		System.out.println(membershipCard);
	}

	// 查询所有数据
	public void testSelectAll() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql="select * from membershipcard";
		BeanListHandler beanListHandler = new BeanListHandler(MembershipCard.class);
		List list = qr.query(sql, beanListHandler);
		for (MembershipCard membershipCard : list) {
			System.out.println(membershipCard);
		}
	}

}

4.DbUtils实现查询

package cn.com.demo06;

import java.sql.SQLException;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayHandler;
import org.apache.commons.dbutils.handlers.ArrayListHandler;
import org.apache.commons.dbutils.handlers.BeanHandler;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ColumnListHandler;
import org.apache.commons.dbutils.handlers.KeyedHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;

public class TestDBUtils2 {

	public static void main(String[] args) {
		try {
			TestDBUtils2 demo = new TestDBUtils2();
			demo.testBeanListHandler();
		} catch (Exception e) {
			e.printStackTrace();
		}
		
	}

	//BeanHandler
	public void testBeanHandler() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "select * from membershipcard where username=?";
		Object params[] = { "lili" };
		BeanHandler beanHandler = new BeanHandler<>(MembershipCard.class);
		MembershipCard membershipCard = qr.query(sql, beanHandler, params);
		System.out.println(membershipCard);
	}

	//BeanListHandler
	public void testBeanListHandler() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "select * from membershipcard";
		BeanListHandler beanListHandler = new BeanListHandler(MembershipCard.class);
		List list = qr.query(sql, beanListHandler);
		for (MembershipCard membershipCard : list) {
			System.out.println(membershipCard);
		}
	}
	
	//ArrayHandler
	public void testArrayHandler() throws SQLException{
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "select * from membershipcard";
		ArrayHandler arrayHandler=new ArrayHandler();
		Object[] resultArray = qr.query(sql, arrayHandler);
		for(Object o:resultArray) {
			System.out.println(o);
		}
		System.out.println(Arrays.asList(resultArray));
	}
	
	//ArrayListHandler
	public void testArrayListHandler() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "select * from membershipcard";
		ArrayListHandler arrayListHandler=new ArrayListHandler();
		List list=qr.query(sql, arrayListHandler);
		for(Object[] obj:list) {
			System.out.println(Arrays.asList(obj));
		}
	}
	
	//ColumnListHandler
	public void testColumnListHandler() throws SQLException {
		QueryRunner qr = new QueryRunner(DBUtils.getDataSource());
		String sql = "select * from membershipcard";
		ColumnListHandler columnListHandler=new ColumnListHandler("username");
		List