java学习笔记—第三方操作数据库包专门接收DataSource-dbutils （30）

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。

第一步：创建一个新的java项目

第二步：导入包

Mysql.jar

Dbcp.jar – 连接池的包。

Dbtutil.jar

第三步：创建dataSource数据源

driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql:///db909?characterEncoding=UTf8

username=root

password=1234

maxActive=5

工厂类创建一个唯一的dataSorce
package cn.itcast.utils;
import java.io.InputStream;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSourceFactory;
public class DataSourceUtils {
    private static DataSource ds;
    static{
        try{
            //读取资源文件
            InputStream in = DataSourceUtils.class
                                .getClassLoader().getResourceAsStream("dbcp.properties");
            //读取资源对象
            Properties prop = new Properties();
            prop.load(in);
            //创建ds
            ds = new BasicDataSourceFactory().createDataSource(prop);
        }catch(Exception e){
            throw new RuntimeException(e.getMessage(),e);
        }
    }
    //返回整个池对象
    public static DataSource getDatasSource(){
        return ds;
    }
}

第四步：开始测试dbutils的使用

Queryrunner.query　只可以执行select语句。

Queryrunner.update只可以接收update,delte,insert语句。

保存数据：

@Test
    public void insert1() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "insert into users values('U002','李四','888')";
        run.update(sql);
    }
    //接收?
    @Test
    public void insert2() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "insert into users values(?,?,?)";
        run.update(sql,"U003","王五","");
    }
    //删除
    @Test
    public void del1() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "delete from users where name=?";
        int len = run.update(sql,"李四");
        System.err.println(len);
    }
    @Test
    public void udpate1() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "update users set name=? where id=?";
        run.update(sql,"赵'七","U001");
    }

查询：

查询时除了使用queryrunner还要使用别一个核心类resultsethandler：结果集的句本周　封装结果到List,Map,Bean。

ArrayHandler,　　－　用于查询一行唯一的数据。Object[]

QueryRunner run = new QueryRunner(getDatasSource());

       String sql = "select * from users";

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

       for(Object o:os){

           System.err.println(o);

       }

结果是：

U001

赵'七

123

ArrayListHandler,  - 将所有的结果封装成List<Object[]>
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "select * from users";
        List<Object[]> list = run.query(sql,new ArrayListHandler());
        for(Object[] os:list){
            for(Object o:os){
                System.err.print(o+"\t");
            }
            System.err.println("\n=====");
        }

返回的是：

U001   赵'七   123

=====

U002   AaA 44

=====

U003   88  777

=====

 BeanHandler,  　－　返回一个 Bean，结果封装到Bean。只查询第一行。适合根据id查询唯一的一行。
@Test
    public void query2() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "select * from users where id=?";
        User user =
                run.query(sql,new BeanHandler<User>(User.class),"U003");
        System.err.println(user);
    }

BeanListHandler , 　－　返回List<Bean>所有行，都封装到List，适合于查询多个结果
@Test
    public void query3() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "select * from users";
        List<User> us =
                run.query(sql,new BeanListHandler<User>(User.class));
        for(User u:us){
            System.err.println(u);
        }

    }

结果是：

User [id=U001, name=赵'七, pwd=123]

User [id=U002, name=AaA, pwd=44]

User [id=U003, name=88, pwd=777]

ColumnListHandler,　－　查询一个字段时就可以使用这种方式 select name from table;
QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "select * from users";
        List<Object> list = run.query(sql, new ColumnListHandler("pwd"));
        for(Object o:list){
            System.err.println(o);
        }

 KeyedHandler --
QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "select * from users";
        Map<Object,Map<String,Object>> mm =
                run.query(sql, new KeyedHandler("id"));
        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"));
        }

结果是：

800x600

Normal
0

7.8 磅
0
2

false
false
false

EN-US
ZH-CN
X-NONE

MicrosoftInternetExplorer4

/* Style Definitions */
table.MsoNormalTable
{mso-style-name:普通表格;
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin:0cm;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:10.0pt;
font-family:"Times New Roman","serif";}

{U001={id=U001, pwd=123, name=赵'七}, U002={id=U002, pwd=44, name=AaA}, U003={id=U003, pwd=777, name=88}}

, MapHandler ,　　与 BeanHandler应，只返回第一行，封装成Map类型　－　也适合于查询一个结果集的
    适合于关联查询，且没有匹配的Bean。

MapListHandler , 　－　
List<Map>
@Test
    public void query6() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "SELECT u.name as uname,c.name as cname"+
                     " FROM users u INNER JOIN contacts c ON u.id=c.uid";
        System.err.println(sql);
        List<Map<String,Object>> mm = run.query(sql,new MapListHandler());
        System.err.println(mm);
    }
SELECT u.name as uname,c.name as cname FROM users u INNER JOIN contacts c ON u.id=c.uid
[{uname=Jack, cname=Rose}, {uname=Jack, cname=李四}, {uname=Jack, cname=王五}, {uname=张三, cname=马六}, {uname=张三, cname=赵七}]

ScalarHandler – 标量- 用于select count()|sum|avg|max …一些聚合函数
@Test
    public void query7() throws Exception{
        QueryRunner run = new QueryRunner(getDatasSource());
        String sql = "select count(*) from contacts";
        Object o = run.query(sql,new ScalarHandler());
        Integer ss = Integer.valueOf(o.toString());
        System.err.println(ss);
    }

800x600

Normal
0

7.8 磅
0
2

false
false
false

EN-US
ZH-CN
X-NONE

MicrosoftInternetExplorer4

/* Style Definitions */
table.MsoNormalTable
{mso-style-name:普通表格;
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin:0cm;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:10.0pt;
font-family:"Times New Roman","serif";}

总结：

１：包装HttpServletRequest。是对getParaqmgermap增强。

２：用dbcp连接数据库，并在一个项目中维护一个唯一的dataSource。

工厂类，一个datasource的成员静态。

　　Static代码块中读取配置文件连接数据库。创建datasource。

　　　　提供一个工厂方法返回整个池对象。

3：dbutils的所有查询方法

所有ResultSetHandler的子类做一次。

MapHandler

MapListHandler

BeanHandler

BeanListHandler

ScalerHandler

---

800x600

Normal
0

7.8 磅
0
2

false
false
false

EN-US
ZH-CN
X-NONE

MicrosoftInternetExplorer4

/* Style Definitions */
table.MsoNormalTable
{mso-style-name:普通表格;
mso-tstyle-rowband-size:0;
mso-tstyle-colband-size:0;
mso-style-noshow:yes;
mso-style-priority:99;
mso-style-parent:"";
mso-padding-alt:0cm 5.4pt 0cm 5.4pt;
mso-para-margin:0cm;
mso-para-margin-bottom:.0001pt;
mso-pagination:widow-orphan;
font-size:10.0pt;
font-family:"Times New Roman","serif";}