spring 动态创建bean

spring中可用java代码动态创建bean，具体应用场景：可以用于spring项目启动时加载数据源DataSource和jdbcTemplate：

spring具体的创建的代码如下

1、BeanUtil 的代码如下

import java.util.Iterator;import java.util.List;import java.util.Map;import org.springframework.beans.factory.support.BeanDefinitionBuilder;import org.springframework.beans.factory.support.DefaultListableBeanFactory;import org.springframework.context.ApplicationContext;/** * 管理bean类 */public class BeanUtil {    // Spring Bean 工厂    public static DefaultListableBeanFactory beanFactory;    //注意在spring初始化刷新后要调用这个init方法来获得新的beanFactory对象    public static void init(ApplicationContext applicationContext) {        beanFactory = (DefaultListableBeanFactory) applicationContext.getAutowireCapableBeanFactory();    }    /**     * 动态增加bean     *      * @param className     * @param beanKey     * @param propertyMap     * @param referenceMap     * @return     */    public static boolean addBean(            String className, String beanKey, Map<String, Object> propertyMap,            Map<String, String> referenceMap, List<Object> propertyConstrList,            List<String> referenceConstrList, String destroyMethod) {        // 判断Spring容器中是否存在该Bean        if (beanFactory.containsBeanDefinition(className)) {            return true;        }        BeanDefinitionBuilder bdb = BeanDefinitionBuilder.rootBeanDefinition(className);        bdb.getBeanDefinition().setAttribute("id", beanKey);        // 设置bean参数属性        if (propertyMap != null && !propertyMap.isEmpty()) {            Iterator<String> propertyKeys = propertyMap.keySet().iterator();            while (propertyKeys.hasNext()) {                String keyString = propertyKeys.next();                bdb.addPropertyValue(keyString, propertyMap.get(keyString));            }        }        // 设置bean参数引用        if (referenceMap != null && !referenceMap.isEmpty()) {            Iterator<String> referenceKeys = referenceMap.keySet().iterator();            while (referenceKeys.hasNext()) {                String keyString = referenceKeys.next();                bdb.addPropertyReference(keyString, referenceMap.get(keyString));            }        }        // 设置bean构造参数属性        if (propertyConstrList != null && !propertyConstrList.isEmpty()) {            for (int i = 0; i < propertyConstrList.size(); i++) {                bdb.addConstructorArgValue(propertyConstrList.get(i));            }        }        // 设置bean构造参数引用        if (referenceConstrList != null && !referenceConstrList.isEmpty()) {            for (int i = 0; i < referenceConstrList.size(); i++) {                bdb.addConstructorArgReference(referenceConstrList.get(i));            }        }        if (destroyMethod != null && !destroyMethod.isEmpty()) {            bdb.setDestroyMethodName(destroyMethod);        }        beanFactory.registerBeanDefinition(beanKey, bdb.getBeanDefinition());        return true;    }    /**     * 获取Bean     *      * @param requiredType     * @return     */    public static <T> T getBean(Class<T> requiredType) {        return beanFactory.getBean(requiredType);    }    /**     * 获取bean     * @param beanName     * @param requiredType     * @return     */    public static <T> T getBean(String beanName,Class<T> requiredType) {        return  beanFactory.getBean(beanName,requiredType);    }}

2、DataSourceUtil 类的代码如下

import java.io.File;import java.io.FileInputStream;import java.io.FilenameFilter;import java.io.InputStreamReader;import java.io.Reader;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Properties;import org.springframework.context.ApplicationContext;import org.springframework.jdbc.core.JdbcTemplate;import com.test.BaseConfigUtil;/** * 加载数据源类，将${catalina.home}/ybg/conf下面的所有数据源文件加入到bean工厂中 */public class DataSourceUtil {    /**     * 初始化     *      * @param applicationContext     */    public static void init(ApplicationContext applicationContext) {            File dataDirectory = new File(System.getProperty("catalina.home") + File.separator + "test" + File.separator + "conf");    // 数据源文件必定要是properties类型。     //过滤的文件名称以db开头，以properties结尾        File[] dataFiles = dataDirectory.listFiles(new FilenameFilter() {            @Override            public boolean accept(File dir, String name) {                String fileName = name.toLowerCase();                if (fileName.endsWith(".properties")) {                    if(fileName.startsWith("db")) {                        return true;                    }                }                return false;            }        });    try (Reader reader = new InputStreamReader(new FileInputStream(dataFiles[i]), "UTF-8")) {                Properties properties = new Properties();                properties.load(reader);//读取数据库的.properties配置文件                if (!properties.isEmpty()) {                    // 建立数据源的bean                    Map<String, Object> propertyMap = new HashMap<String, Object>();                    propertyMap.put("driverClassName",properties.getProperty("sqlDriver"));                    propertyMap.put("url",properties.getProperty("sqlUrl"));                    propertyMap.put("username",properties.getProperty("sqlUsername"));                    propertyMap.put("password", properties.getProperty("sqlPassword"));                    propertyMap.put("initialSize",properties.getProperty("sqlInitialSize"));                    propertyMap.put("maxTotal",properties.getProperty("sqlMaxTotal"));                    propertyMap.put("maxIdle",properties.getProperty("sqlMaxIdle"));                    propertyMap.put("maxWaitMillis",properties.getProperty("sqlMaxWaitMillis"));                    BeanUtil.addBean( "org.apache.commons.dbcp2.BasicDataSource", name + "_dataSource", propertyMap, null, null, null, "close");                    // 建立jdbcTemplate的bean                    List<String> referenceConstrList = new ArrayList<String>();                    referenceConstrList.add(name + "_dataSource");                    BeanUtil.addBean( "org.springframework.jdbc.core.JdbcTemplate", name + "_jdbcTemplate", null, null, null, referenceConstrList, null);                    LogUtil.info("load datasource file {} success!", dataFiles[i].getAbsolutePath());                }            } catch (Exception e) {                LogUtil.error("load datasource file {} fail!", dataFiles[i].getAbsolutePath());            }        }}    /**     * 获取数据源     * @param datasourceFileName 数据源配置文件名     * @return     */    public static JdbcTemplate getJdbcTemplate(String datasourceFileName) {        String id = datasourceFileName + "_jdbcTemplate";        return BeanUtil.getBean(id, JdbcTemplate.class);    }}

动态创建bean的代码位置如下图

3、类比如下用xml加载dataSource和jdbcTemplate的方法

    <!-- 数据源配置 -->    <bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource" destroy-method="close">        <property name="driverClassName" value="${sqlDriver}" />        <property name="url"             value="${sqlUrl}" />        <property name="username"        value="${sqlUsername}" />        <property name="password"        value="${sqlPassword}" />        <property name="initialSize"     value="${sqlInitialSize}"/>          <!-- 连接池启动时创建的连接数 -->        <!-- 连接池最大连接数 -->        <property name="maxIdle"         value="${sqlMaxIdle}"/>              <!-- 连接池最大空闲连接数。推荐与 maxTotal 的值一致。 -->        <!-- 等待获取连接的时间.毫秒 -->    </bean>     <!-- 配置Spring对数据库事务的支持   -->    <bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" c:dataSource-ref="dataSource"/>    <!-- 开启注解事务的支持 -->    <tx:annotation-driven transaction-manager="txManager"/>    <!-- 配置Template -->    <bean id="Template" class="org.springframework.jdbc.core.JdbcTemplate" c:dataSource-ref="dataSource"/>