Saas Spring动态加载、编辑数据源

最近有一个项目需求，要求实现SAAS服务，最终结果大致如上图，当然这只是其中的一部分。这个项目有一个很明确的需求：所有站点用的是一套代码，有一个主站，多个子站，所有子站的数据结构是一致的，A登录时访问子站一，B登录时访问子站二，子站一与子站二的数据分别位于不同的数据库中，数据内容互不影响。

网上查了一些资料，总结并实践后得出此文。

我项目中用的是Spring JPA Data，忽略大部分配置，主要配置如下所示：

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<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jee="http://www.springframework.org/schema/jee"

xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"

xmlns:p="http://www.springframework.org/schema/p" xmlns:util="http://www.springframework.org/schema/util"

xmlns:cache="http://www.springframework.org/schema/cache" xmlns:jpa="http://www.springframework.org/schema/data/jpa"

xmlns:tool="http://www.springframework.org/schema/tool" xmlns:context="http://www.springframework.org/schema/context"

xmlns:jdbc="http://www.springframework.org/schema/jdbc"

xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.1.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.1.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache-3.1.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.1.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.1.xsd http://www.springframework.org/schema/tool http://www.springframework.org/schema/tool/spring-tool.xsd"
default-lazy-init="true" default-autowire="byName">

<bean id="dataSource" class="${datasource.driver}">

<property name="user" value="${datasource.username}" />

<property name="password" value="${datasource.password}" />

<property name="URL" value="${datasource.url}" />

</bean>

<bean id="dynamicDataSource" class="com.gsoft.induasso.datasource.DynamicDataSource">

<property name="targetDataSources">

<map>

</map>

</property>

<property name="defaultTargetDataSource" ref="dataSource" />

</bean>

</beans>

配置中引用了properties文件配置的值，具体如何实现不在此处描述。

DynamicDataSource类的代码如下所示：

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/**

*

* @author Geloin

* @date Jan 16, 2014 6:08:27 PM

*/

package com.gsoft.induasso.datasource;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.Map;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSource;

import org.apache.log4j.Logger;

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

import org.springframework.jdbc.datasource.lookup.JndiDataSourceLookup;

import com.gsoft.crystal.framework.core.util.Utils;

import com.gsoft.induasso.constant.Constants;

/**

*

* @author Geloin

* @date Jan 16, 2014 6:08:27 PM

*/

public class DynamicDataSource extends AbstractRoutingDataSource {

private Logger log = Logger.getLogger(this.getClass());

private Map<Object, Object> _targetDataSources;

/**

* @see org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource#determineCurrentLookupKey()

* @describe 数据源为空或者为0时，自动切换至默认数据源，即在配置文件中定义的dataSource数据源

*/

@Override

protected Object determineCurrentLookupKey() {

String dataSourceName = DbContextHolder.getDBType();

if (dataSourceName == null) {

dataSourceName = Constants.DEFAULT_DATA_SOURCE_NAME;

} else {

this.selectDataSource(dataSourceName);

}

log.debug("--------> use datasource " + dataSourceName);

return dataSourceName;

}

/**

* 到数据库中查找名称为dataSourceName的数据源

*

* @author Geloin

* @date Jan 20, 2014 12:15:41 PM

* @param dataSourceName

*/

private void selectDataSource(String dataSourceName) {

Object sid = DbContextHolder.getDBType();

if (Utils.isEmpty(dataSourceName)

|| dataSourceName.trim().equals("dataSource")) {

DbContextHolder.setDBType("dataSource");

return;

}

Object obj = this._targetDataSources.get(dataSourceName);

if (obj != null && sid.equals(dataSourceName)) {

return;

} else {

DataSource dataSource = this.getDataSource(dataSourceName);

if (null != dataSource) {

this.setDataSource(dataSourceName, dataSource);

}

}

}

@Override

public void setTargetDataSources(Map<Object, Object> targetDataSources) {

this._targetDataSources = targetDataSources;

super.setTargetDataSources(this._targetDataSources);

afterPropertiesSet();

}

private void addTargetDataSource(String key, DataSource dataSource) {

this._targetDataSources.put(key, dataSource);

this.setTargetDataSources(this._targetDataSources);

}

private DataSource createDataSource(String driverClassName, String url,

String username, String password) {

BasicDataSource dataSource = new BasicDataSource();

dataSource.setDriverClassName(driverClassName);

dataSource.setUrl(url);

dataSource.setUsername(username);

dataSource.setPassword(password);

return dataSource;

}

/**

* 到数据库中查询名称为dataSourceName的数据源

*

* @author Geloin

* @date Jan 20, 2014 12:18:12 PM

* @param dataSourceName

* @return

*/

private DataSource getDataSource(String dataSourceName) {

this.selectDataSource(Constants.DEFAULT_DATA_SOURCE_NAME);

this.determineCurrentLookupKey();

Connection conn = null;

try {

conn = this.getConnection();

StringBuilder builder = new StringBuilder();

builder.append("SELECT C_NAME,C_TYPE,C_URL,C_USER_NAME,");

builder.append("C_PASSWORD,C_JNDI_NAME,C_DRIVER_CLASS_NAME ");

builder.append("FROM IA_DATA_SOURCE WHERE c_name = ?");

PreparedStatement ps = conn.prepareStatement(builder.toString());

ps.setString(1, dataSourceName);

ResultSet rs = ps.executeQuery();

if (rs.next()) {

Integer type = rs.getInt("C_TYPE");

if (Utils.isNotEmpty(type)

&& type.intValue() == Constants.DataSourceType.DB

.intValue()) {

// DB

String url = rs.getString("C_URL");

String userName = rs.getString("C_USER_NAME");

String password = rs.getString("C_PASSWORD");

String driverClassName = rs

.getString("C_DRIVER_CLASS_NAME");

DataSource dataSource = this.createDataSource(

driverClassName, url, userName, password);

return dataSource;

} else {

// JNDI

String jndiName = rs.getString("C_JNDI_NAME");

JndiDataSourceLookup jndiLookUp = new JndiDataSourceLookup();

DataSource dataSource = jndiLookUp.getDataSource(jndiName);

return dataSource;

}

}

rs.close();

ps.close();

} catch (SQLException e) {

log.error(e);

} finally {

try {

conn.close();

} catch (SQLException e) {

log.error(e);

}

}

return null;

}

/**

* 将已存在的数据源存储到内存中

*

* @author Geloin

* @date Jan 20, 2014 12:24:13 PM

* @param dataSourceName

* @param dataSource

*/

private void setDataSource(String dataSourceName, DataSource dataSource) {

this.addTargetDataSource(dataSourceName, dataSource);

DbContextHolder.setDBType(dataSourceName);

}

}

其中使用的DbContextHolder类的内容如下所示：

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/**

*

* @author Geloin

* @date Jan 16, 2014 6:08:47 PM

*/

package com.gsoft.induasso.datasource;

/**

*

* @author Geloin

* @date Jan 16, 2014 6:08:47 PM

*/

public class DbContextHolder {

private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();

public static void setDBType(String dbType) {

contextHolder.set(dbType);

}

public static String getDBType() {

return (String) contextHolder.get();

}

public static void clearDBType() {

contextHolder.remove();

}

}

文中还涉及到一个Entity类，如下所示：

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/**

*

* @author Geloin

* @date Jan 17, 2014 10:17:32 AM

*/

package com.gsoft.induasso.entity;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.GenerationType;

import javax.persistence.Id;

import javax.persistence.SequenceGenerator;

import javax.persistence.Table;

import com.gsoft.induasso.constant.Constants;

/**

*

* @author Geloin

* @date Jan 17, 2014 10:17:32 AM

*/

@Entity

@Table(name = "IA_DATA_SOURCE")

public class GsoftDataSource {

@Id

@SequenceGenerator(name = "IA_DATA_SOURCE_SEQ", sequenceName = "IA_DATA_SOURCE_SEQ", allocationSize = 1)

@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "IA_DATA_SOURCE_SEQ")

private Long id;

/**

* data source name

*/

@Column(name = "C_NAME", unique = true)

private String name;

/**

* data source type, default is database<br />

* {@link Constants.DataSourceType}

*/

@Column(name = "C_TYPE")

private Integer type = Constants.DataSourceType.DB.intValue();

/**

* 数据库类型，目前只支持MySql和Oracle<br />

* {@link Constants.DataType}

*/

@Column(name = "C_DATA_TYPE")

private Integer dataType = Constants.DataType.ORACLE.intValue();

@Column(name = "C_URL")

private String url;

@Column(name = "C_USER_NAME")

private String userName;

@Column(name = "C_PASSWORD")

private String password;

@Column(name = "C_JNDI_NAME")

private String jndiName;

@Column(name = "C_DRIVER_CLASS_NAME")

private String driverClassName;

public Long getId() {

return id;

}

public void setId(Long id) {

this.id = id;

}

public Integer getType() {

return type;

}

public void setType(Integer type) {

this.type = type;

}

public String getUrl() {

return url;

}

public void setUrl(String url) {

this.url = url;

}

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 getJndiName() {

return jndiName;

}

public void setJndiName(String jndiName) {

this.jndiName = jndiName;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getDriverClassName() {

return driverClassName;

}

public void setDriverClassName(String driverClassName) {

this.driverClassName = driverClassName;

}

public Integer getDataType() {

return dataType;

}

public void setDataType(Integer dataType) {

this.dataType = dataType;

}

}

常量类可忽略。

在实际的场景中，IA_Data_Source表中保存了多条数据源记录（可以通过增删改查维护），在操作子站点数据时，只需要在每个Service方法中加上以下代码即可：

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DbContextHolder.setDBType("IA_DATA_SOURCE中某个数据源的name属性的值");

网上有较多类似文章，仅供参考，以及自己的备份。