教你如何利用分布式的思想处理集群的参数配置信息——spring的configurer妙用

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns="http://www.springframework.org/schema/beans" 
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
         http://www.springframework.org/schema/tx
         http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
         http://www.springframework.org/schema/aop
         http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
         http://www.springframework.org/schema/context
         http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <context:component-scan base-package="cn.zxl.core" />
    
    <bean id="jdbcPropertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <array>
                <value>classpath:jdbc.properties</value>
                <value>classpath:security.properties</value>
            </array>
        </property>
    </bean>

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${driverClassName}" />
        <property name="url" value="${url}" />
        <property name="username" value="${username}" />
        <property name="password" value="${password}" />
        <property name="initialSize" value="${initialSize}" />
        <property name="maxActive" value="${maxActive}" />
        <property name="maxIdle" value="${maxIdle}" />
    </bean>
    
    <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="entityInterceptor" ref="entityInterceptor"/>
        <property name="packagesToScan" ref="hibernateDomainPackages" />
        <property name="hibernateProperties">
            <value>
                hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
                hibernate.cache.provider_class=org.hibernate.cache.internal.NoCachingRegionFactory
                hibernate.current_session_context_class=org.springframework.orm.hibernate4.SpringSessionContext
                hibernate.show_sql=true
                hibernate.hbm2ddl.auto=update
            </value>
        </property>
    </bean>
    
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="classpath:mybatis-config.xml"/>
        <property name="mapperLocations" value="classpath*:mybatis/*.xml" />
    </bean>

    <bean id="sqlSessionTemplate" class="org.mybatis.spring.SqlSessionTemplate">
        <constructor-arg index="0" ref="sqlSessionFactory" />
    </bean>
    
</beans>

<?xml version="1.0" encoding="UTF-8"?>
<!-- - Application context containing authentication, channel - security 
    and web URI beans. - - Only used by "filter" artifact. - -->

<b:beans xmlns="http://www.springframework.org/schema/security"
    xmlns:b="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
        http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/security 
        http://www.springframework.org/schema/security/spring-security-3.2.xsd">

    <!-- 不要过滤图片等静态资源 -->
    <http pattern="/**/*.jpg" security="none" />
    <http pattern="/**/*.png" security="none" />
    <http pattern="/**/*.gif" security="none" />
    <http pattern="/**/*.css" security="none" />
    <http pattern="/**/*.js" security="none" />
    <http pattern="/login.jsp*" security="none" />
    <http pattern="/webservice/**/*" security="none" />

    <!-- 这个元素用来在你的应用程序中启用基于安全的注解 -->
    <global-method-security pre-post-annotations="enabled"/>
    
    <!-- 配置页面访问权限 -->
    <http auto-config="true" authentication-manager-ref="authenticationManager">

        <intercept-url pattern="/**" access="${accessRole}" />

        <form-login login-page="${loginPage}" default-target-url="${indexPage}" 
            always-use-default-target="true" authentication-failure-handler-ref="defaultAuthenticationFailureHandler"/>

        <!-- "记住我"功能，采用持久化策略（将用户的登录信息存放在数据库表中） -->
        <remember-me data-source-ref="dataSource"/>
        
        <logout />

        <!-- 只能登陆一次 -->
        <session-management>
            <concurrency-control max-sessions="1" error-if-maximum-exceeded="true" />
        </session-management>
        
        <custom-filter ref="resourceSecurityFilter" before="FILTER_SECURITY_INTERCEPTOR"/>
    </http>
    
    <b:bean id="defaultAuthenticationFailureHandler" class="cn.zxl.core.filter.DefaultAuthenticationFailureHandler">
        <b:property name="loginUrl" value="${loginPage}" />
    </b:bean>
    
    <b:bean id="resourceSecurityFilter" class="cn.zxl.core.filter.ResourceSecurityFilter">  
        <b:property name="authenticationManager" ref="authenticationManager" />  
        <b:property name="accessDecisionManager" ref="resourceAccessDecisionManager" />  
        <b:property name="securityMetadataSource" ref="resourceSecurityMetadataSource" />  
    </b:bean>  

    <!-- 数据中查找用户 -->
    <authentication-manager alias="authenticationManager">
        <authentication-provider user-service-ref="userService">
            <password-encoder hash="md5">
                <salt-source user-property="username"/>
            </password-encoder>
        </authentication-provider>
    </authentication-manager>

</b:beans>

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost/test
username=root
password=123456
initialSize=10
maxActive=50
maxIdle=10

accessRole=ROLE_USER
indexPage=/index.jsp
loginPage=/login.jsp　　

package cn.zxl.core.spring;

import java.io.IOException;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * 从数据库读取配置信息
 * @author zuoxiaolong
 *
 */
public class DatabaseConfigurer extends PropertyPlaceholderConfigurer implements ApplicationContextAware{
    
    private ApplicationContext applicationContext;
    
    private String dataSourceBeanName = "dataSource";
    
    private String querySql = "select * from database_configurer_properties";
    
    public void setApplicationContext(ApplicationContext applicationContext)
            throws BeansException {
        this.applicationContext = applicationContext;
    }
    
    public void setDataSourceBeanName(String dataSourceBeanName) {
        this.dataSourceBeanName = dataSourceBeanName;
    }

    public void setQuerySql(String querySql) {
        this.querySql = querySql;
    }

    protected Properties mergeProperties() throws IOException {
        Properties properties = new Properties();
        //获取数据源
        DataSource dataSource = (DataSource) applicationContext.getBean(dataSourceBeanName);
        Connection connection = null;
        try {
            connection = dataSource.getConnection();
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery(querySql);
            while (resultSet.next()) {
                String key = resultSet.getString(1);
                String value = resultSet.getString(2);
                //存放获取到的配置信息
                properties.put(key, value);
            }
            resultSet.close();
            statement.close();
            connection.close();
        } catch (SQLException e) {
            throw new IOException("load database properties failed.");
        }
        //返回供后续使用
        return properties;
    }

}

<bean id="jdbcPropertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <array>
                <value>classpath:jdbc.properties</value>
                <value>classpath:security.properties</value>
            </array>
        </property>
    </bean>

    <bean id="jdbcPropertyPlaceholderConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="order" value="1"/>
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
        <property name="ignoreResourceNotFound" value="true"/>
        <property name="locations">
            <array>
                <value>classpath:jdbc.properties</value>
            </array>
        </property>
    </bean>
    
    <bean id="databaseConfigurer" class="cn.zxl.core.spring.DatabaseConfigurer">
        <property name="order" value="2"/>
    </bean>

CREATE TABLE database_configurer_properties (
  key varchar(200) NOT NULL,
  value text,
  PRIMARY KEY (key)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;