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Spring多数据源解决方案

2014-12-23 23:06 253 查看

Figure 2 多数据源的选择逻辑渗透至客户端

解决方案

Figure 3 采用Proxy模式来封转数据源选择逻辑

通过采用Proxy模式我们在方案实现中实现一个虚拟的数据源.并且通过它来封装数据源选择逻辑,这样就可以有效地将数据源选择逻辑从Client中分离出来.Client提供选择所需的上下文(因为这是Client所知道的),有虚拟的DataSource根据Client提供的上下文来实现数据源的选择.Spring2.x的版本中提供了实现这种方式的基本框架.虚拟的DataSource仅需要继承AbstractRoutingDataSource实现determineCurrentLookupKey()在其中封装数据源选择逻辑.

实例:

public class DynamicDataSource extends AbstractRoutingDataSource{

static Logger log=Logger.getLogger("DynamicDataSource");

@Override

protected Object determineCurrentLookupKey(){

String userId=(String)DbContextHolder.getContext();

Integer dataSourceId=getDataSourceIdByUserId(userId);

return dataSourceId;

}

}

实例中通过UserId来决定数据存放在哪个数据库中。

配置文件示例：

下面是个人在项目中用过的配置方法(以后公布)：

程序中的控制代码

public class DbContextHolder{

private static final ThreadLocal contextHolder = new ThreadLocal();

public static void setDbType(String dbType)

{

contextHolder.set(dbType);

}

public static String getDbType()

{

String str=(String) contextHolder.get();

if(null==str || "".equals(str))

str="1";

return str;

}

public static void clearDbType()

{

contextHolder.remove();

}

}

在程序中通过设置DbContextHolder.setDbType(String dbType);来控制数据库的选取,其中key配置目标数据源的键值.

MySQL中group_concat函数

@author Bob 2012/08/07

本文通过实例介绍了MySQL中的group_concat函数的使用方法，比如select group_concat(name) 。

MySQL中group_concat函数

完整的语法如下：

group_concat([DISTINCT] 要连接的字段 [Order BY ASC/DESC 排序字段] [Separator '分隔符'])

基本查询

mysql> select * from aa;

+------+------+

| id| name |

+------+------+

|1 | 10|

|1 | 20|

|1 | 20|

|2 | 20|

|3 | 200 |

|3 | 500 |

+------+------+

6 rows in set (0.00 sec)

以id分组，把name字段的值打印在一行，逗号分隔(默认)

mysql> select id,group_concat(name) from aa group by id;

+------+--------------------+

| id| group_concat(name) |

+------+--------------------+

|1 | 10,20,20|

|2 | 20 |

|3 | 200,500|

+------+--------------------+

3 rows in set (0.00 sec)

以id分组，把name字段的值打印在一行，分号分隔

mysql> select id,group_concat(name separator ';') from aa group by id;

+------+----------------------------------+

| id| group_concat(name separator ';') |

+------+----------------------------------+

|1 | 10;20;20 |

|2 | 20|

|3 | 200;500 |

+------+----------------------------------+

3 rows in set (0.00 sec)

以id分组，把去冗余的name字段的值打印在一行，

逗号分隔

mysql> select id,group_concat(distinct name) from aa group by id;

+------+-----------------------------+

| id| group_concat(distinct name) |

+------+-----------------------------+

|1 | 10,20|

|2 | 20 |

|3 | 200,500 |

+------+-----------------------------+

3 rows in set (0.00 sec)

以id分组，把name字段的值打印在一行，逗号分隔，以name排倒序

mysql> select id,group_concat(name order by name desc) from aa group by id;

+------+---------------------------------------+

| id| group_concat(name order by name desc) |

+------+---------------------------------------+

|1 | 20,20,10 |

|2 | 20|

|3 | 500,200|

+------+---------------------------------------+

3 rows in set (0.00 sec)

本人在做用户有哪些角色动态显示是用到.可以提高代码简洁性与程序的效率,不用对比用户角色关联表与用户角色与用户表.

JavaScript 动态实现树形菜单(使用dtree控件)

@author Bob 2012/08/09

动态生成树型菜单

数据库脚本：

use master

go

if exists (select * from sysdatabases where name = 'tree')

drop database tree

go

create database tree

on

(

Name = 'tree_data', --主数据文件的逻辑名称

FileName = 'D:/tree_data.mdf', --数据文件的物理名称

Size = 5Mb, -- 主数据文件的初始大小

FileGrowth = 20% --主数据文件增长率

)

log on

(

Name = 'tree_log',

FileName = 'd:/tree_log.ldf',

Size = 3Mb,

FileGrowth = 10%

)

go

if exists (select * from sysobjects where name = 'dtree')

drop table dtree

go

use tree

go

/*--- 创建节点表 ---*/

create table dtree

(

id varchar(20) , --节点编号

pid varchar(20) , --父节点

[name] varchar(20), --节点名称

url varchar(20), --连接地址

title varchar(20), --节点描述

target varchar(20), --Target

icon varchar(20), --图标

iconOpen varchar(20), --展开状态下的图标路径

[open] varchar(20) --是否展开

)

/*--- 初始化测试数据 ---*/

insert into dtree values('0','-1','T16班','index.jsp','blank','','','','')

insert into dtree values('1','0','教师','index.jsp','blank','','','','')

insert into dtree values('2','0','班干部','index.jsp','blank','','','','')

insert into dtree values('3','0','组长','index.jsp','blank','','','','')

insert into dtree values('4','0','学员','index.jsp','blank','','','','')

insert into dtree values('5','1','班主任','index.jsp','blank','','','','')

insert into dtree values('6','1','教员','index.jsp','blank','','','','')

insert into dtree values('7','2','班长','index.jsp','blank','','','','')

insert into dtree values('8','2','学委','index.jsp','blank','','','','')

insert into dtree values('9','4','学员1','index.jsp','blank','','','','')

insert into dtree values('10','4','学员2','index.jsp','blank','','','','')

insert into dtree values('11','4','学员3','index.jsp','blank','','','','')

insert into dtree values('12','4','学员4','index.jsp','blank','','','','')

insert into dtree values('13','4','学员5','index.jsp','blank','','','','')

insert into dtree values('14','4','学员6','index.jsp','blank','','','','')

insert into dtree values('15','4','学员7','index.jsp','blank','','','','')

insert into dtree values('16','4','学员8','index.jsp','blank','','','','')

insert into dtree values('17','4','学员9','index.jsp','blank','','','','')

insert into dtree values('18','4','学员10','index.jsp','blank','','','','')

insert into dtree values('19','4','学员11','index.jsp','blank','','','','')

insert into dtree values('20','4','学员12','index.jsp','blank','','','','')

insert into dtree values('21','4','学员13','index.jsp','blank','','','','')

insert into dtree values('22','4','学员14','index.jsp','blank','','','','')

insert into dtree values('23','4','学员15','index.jsp','blank','','','','')

select id,pid,[name],url,title,target,icon,iconOpen,[open] from dtree

客户端代码 index.jsp：

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<%@page import="com.zsw.biz.TreeNodeBiz;"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>树形菜单</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">

<link rel="StyleSheet" href="dtree.css" type="text/css" />

<script type="text/javascript" src="dtree.js"></script>

</head>

<body>

<div>

<%

TreeNodeBiz tnb = new TreeNodeBiz();

%>

<script type="text/javascript">

d = <%= tnb.getList("dtree") %>

document.write(d);

</script>

</div>

</body>

</html>

转换成节点数据转换成js文件关键代码：

if(list==null || list.size() == 0){

System.out.println("没有节点");

return "";

}

StringBuffer contents = new StringBuffer();

contents.append("dtree = new dTree('"+dtree+"');");

for(TreeNode tn : list){

contents.append("/n");

contents.append(dtree+".add('");

contents.append(tn.getId());

contents.append("','");

contents.append(tn.getPid());

contents.append("','");

contents.append(tn.getName());

contents.append("','");

contents.append(tn.getUrl());

contents.append("','");

contents.append(tn.getTitle());

contents.append("','");

contents.append(tn.getTarget());

contents.append("','");

contents.append(tn.getIcon());

contents.append("','");

contents.append(tn.getIconOpen());

contents.append("','");

contents.append(tn.getOpen());

contents.append("');");

contents.append("/n");

}

客户端的代码：

需要导入：dtree.js 和dtree.css

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>

<%@page import="com.zsw.biz.TreeNodeBiz;"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>树形菜单</title>

<meta http-equiv="pragma" content="no-cache">

<meta http-equiv="cache-control" content="no-cache">

<meta http-equiv="expires" content="0">

<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">

<meta http-equiv="description" content="This is my page">

<link rel="StyleSheet" href="dtree.css" type="text/css" />

<script type="text/javascript" src="dtree.js"></script>

</head>

<body>

<p><a href="javascript: d.openAll();">全部展开</a> |

<a href="javascript: d.closeAll();">全部关闭</a>

</p>

<div>

<%

TreeNodeBiz tnb = new TreeNodeBiz();

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