第三方数据库连接池包

1.dbcp

第一步：导入dbcp包

第二步：通过核心类连接数据库

public void Demo1(){

        BasicDataSource ds=new BasicDataSource();

        ds.setDriverClassName("com.mysql.jdbc.Driver");

        ds.setUrl("jdbc:mysql///contacts?characterEncoding=UTF8");

        ds.setUsername("root");

        ds.setPassword("admin");

        ds.setMaxActive(5);//设置最多有几个连接

        ds.setInitialSize(2);//设置在开始时创建几个连接

    }

第三步：创建一个资源文件

driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql://127.0.0.1:3306/contacts?useUnicode=true&characterEncoding=UTF8

username=root

password=admin

maxActive=3

Properties p=new Properties();

        p.load(Demo1pool.class.getResourceAsStream("jdbc.properties"));

        DataSource ds=new BasicDataSourceFactory().createDataSource(p);

使用连接池

在一个项目中，就只能拥有一个DataSource的实例。在这个dataqSource3中有多个Connectioin。声明一个工厂类，创建维护唯一的一个DataSource

 

package javaee.utils;



import java.sql.Connection;

import java.sql.SQLException;

import java.util.Properties;



import javax.sql.DataSource;



import org.apache.commons.dbcp.BasicDataSourceFactory;



public class DataSourceUtils {

    private DataSourceUtils() {

    }



    private static DataSource ds;

    static {

        try {

            Properties p = new Properties();

            p.load(DataSourceUtils.class.getClassLoader().getResourceAsStream(

                    "jdbc.properties"));

            ds = new BasicDataSourceFactory().createDataSource(p);

        } catch (Exception e) {

        }

    }

    // 返回一个唯一的连接

    public static Connection getCon() {

        Connection con = null;

        try {

            con = ds.getConnection();

        } catch (SQLException e) {

            e.printStackTrace();

        }

        return con;

    }



    // 提供一个方法返回DataSource

    public static DataSource getDs() {

        return ds;

    }

}

第三方操作数据库包专门接收DataSource-dbutils

Dbutils

操作数据第三方包。依赖数据源DataSource（DBCP|C3p0）。

QueryRunner – 接收DataSource｜Connection，查询数据删除修改操作。返回结果。

ResultSetHandler – 结果集句柄，将结果数据封装成程序所需要的数据类型Map,List,Bean。

package cn.demo;



import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

import java.util.Map;



import javax.sql.DataSource;



import org.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.ResultSetHandler;

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;

import org.junit.Test;



import cn.domain.Contact;

import cn.domain.User;

import static cn.dbutils.DataSourceUtils.*;



public class Demo1 {

    @Test

    public void query1() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from users";

        Object[] o = run.query(sql, new ArrayHandler());

        for (Object s : o) {

            System.err.println(s);

        }



    }



    @Test

    public void query2() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from users";

        List<Object[]> o = run.query(sql, new ArrayListHandler());

        for (Object[] s : o) {

            for (Object os : s) {

                System.err.println(os);

            }

        }

    }



    @Test

    public void queryBean() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from users ";

        User user = run.query(sql, new BeanHandler<User>(User.class));

        System.err.println(user);



    }



    @Test

    public void queryBean1() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from users where id=?";

        User user = run.query(sql, new BeanHandler<User>(User.class), "U003");

        System.err.println(user);



    }



    @Test

    public void queryBeanList() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from users ";

        List<User> user = run.query(sql, new BeanListHandler<User>(User.class));

        for (User u : user) {

            System.err.println(u);

        }



    }



    @Test

    public void queryColumnList() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select name from users ";

        List<Object> obj = run.query(sql, new ColumnListHandler());

        for (Object o : obj) {

            System.err.println(o);

        }



    }



    @Test

    public void querykeyed() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from users";

        Map<Object, Map<String, Object>> mm = run.query(sql, new KeyedHandler(

                "id"));

        System.err.println(mm);

        Iterator it = mm.keySet().iterator();

        while (it.hasNext()) {

            Map m1 = mm.get(it.next());

            System.err.println(m1.get("id") + "," + m1.get("name") + ","

                    + m1.get("pwd"));

        }



    }

    @Test

    public void queryMap() throws Exception{

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "SELECT u.name as uname,c.name as cname"+

                     " FROM users u INNER JOIN contacts c ON u.id=c.uid where u.id='U001'";

        System.err.println(sql);

        Map<String,Object> mm = run.query(sql,new MapHandler());

        System.err.println(mm);

    }

    

    

    @Test

    public void queryMapList() throws Exception{

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "SELECT u.name as uname,c.name as cname"+

                     " FROM users u INNER JOIN contacts c ON u.id=c.uid where u.id='U001'";

        System.err.println(sql);

        List<Map<String, Object>> mm = run.query(sql,new MapListHandler());

        System.err.println(mm);

    }



    @Test

    public void queryScalar() throws Exception{

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select count(*) from users ";

        System.err.println(sql);

        Object mm = run.query(sql,new ScalarHandler());

        System.err.println(mm);

    }

    

    @Test

    public void queryValidBean() throws Exception{

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select id as cid,name as cname,sex from contacts";

        List<Contact> cs = run.query(sql,new BeanListHandler<Contact>(Contact.class));

        System.err.println(cs);

    }

    //手工封装

    @Test

    public void queryValidBean1() throws Exception{

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "select * from contacts";

        List<Contact> cs =

                run.query(sql, 

                new ResultSetHandler<List<Contact>>(){

                    @Override

                    public List<Contact> handle(ResultSet rs)

                            throws SQLException {

                        List<Contact> list = new ArrayList<Contact>();

                        while(rs.next()){

                            Contact c = new Contact();

                            c.setCid(rs.getString("name"));

                            c.setCname(rs.getString("id"));

                            c.setSex(rs.getString("sex"));

                            list.add(c);

                        }

                        return list;

                    }

                });

        System.err.println(">>>:"+cs);

    }

    @Test

    public void Insert1() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        run.update("insert into users values('U003','张三','888')");

    }



    @Test

    public void Insert2() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        run.update("insert into users values(?,?,?)", "u004", "王武", "999");

    }



    @Test

    public void del() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "delete from users where name ='王武'";

        int len = run.update(sql);

        System.err.println(len);

    }



    @Test

    public void update() throws Exception {

        QueryRunner run = new QueryRunner(getDataSource());

        String sql = "update users set name='李四' where id='U003'";

        int len = run.update(sql);

        System.err.println(len);

    }

}

driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql://127.0.0.1:3306/contacts?useUnicode=true&characterEncoding=UTF8&useOldAliasMetadataBehavior=true

username=root

password=admin

maxActive=5

package cn.domain;



public class Contact {

    private String cid;

    private String cname;

    private String sex;

    public String getCid() {

        return cid;

    }

    public void setCid(String cid) {

        this.cid = cid;

    }

    public String getCname() {

        return cname;

    }

    public void setCname(String cname) {

        this.cname = cname;

    }

    public String getSex() {

        return sex;

    }

    public void setSex(String sex) {

        this.sex = sex;

    }

    public String toString(){

        return "Contect[id='"+cid+"'  name='"+cname+"'  sex='"+sex+"']";

    }

}

package cn.domain;



public class User {



    private String id;

    private String name;

    private String pwd;

    public String getId() {

        return id;

    }

    public void setId(String id) {

        this.id = id;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

    public String getPwd() {

        return pwd;

    }

    public void setPwd(String pwd) {

        this.pwd = pwd;

    }

    @Override

    public String toString(){

        return "User[id='"+id+"',name='"+name+"',pwd='"+pwd+"']";

    }

    

}