實(shí)現(xiàn)效果

先說(shuō)效果，要實(shí)現(xiàn)方法級(jí)別注解切換當(dāng)前數(shù)據(jù)源，不設(shè)置注解時(shí)走默認(rèn)數(shù)據(jù)源，同時(shí)支持JNDI源。

總體思路

Spring框架中存在一個(gè)抽象類(lèi)AbstractRoutingDataSource，他是一個(gè)可以動(dòng)態(tài)選擇當(dāng)前DataSource的路由類(lèi)，我們就是要從這里入手，重新實(shí)現(xiàn)數(shù)據(jù)源的切換選擇邏輯。然后借助注解和切面，將當(dāng)前需要的數(shù)據(jù)源名稱(chēng)放在ThreadLocal中，需要時(shí)從當(dāng)前線程取得即可完成數(shù)據(jù)源的切換。
注解部分比較簡(jiǎn)單不再詳說(shuō)，看AbstractRoutingDataSource。該類(lèi)文檔寫(xiě)的非常全面，自行翻譯一下就可以看懂。主要看其中的幾個(gè)關(guān)鍵方法。

setTargetDataSources

類(lèi)中存在一個(gè)成員變量targetDataSources，結(jié)合之后的setTargetDataSources方法可知，這里用來(lái)保存目標(biāo)數(shù)據(jù)源。
根據(jù)注釋我們可以知道，targetDataSources的key可以是數(shù)據(jù)源的名字，value是相應(yīng)數(shù)據(jù)源的實(shí)例。
當(dāng)然這里也可是使用其他的保存方式，然后自行改寫(xiě)用來(lái)查找數(shù)據(jù)源的determineCurrentLookupKey方法，默認(rèn)場(chǎng)景就足夠我們使用了。所以我們要構(gòu)建一個(gè)Map出來(lái)，其中key用來(lái)區(qū)分?jǐn)?shù)據(jù)源的名字，value放入對(duì)應(yīng)數(shù)據(jù)源的實(shí)例，有幾個(gè)數(shù)據(jù)源就放幾個(gè)進(jìn)去。

	@Nullable
	private Map<Object, Object> targetDataSources;

	/**
	 * Specify the map of target DataSources, with the lookup key as key.
	 * The mapped value can either be a corresponding {@link javax.sql.DataSource}
	 * instance or a data source name String (to be resolved via a
	 * {@link #setDataSourceLookup DataSourceLookup}).
	 * <p>The key can be of arbitrary type; this class implements the
	 * generic lookup process only. The concrete key representation will
	 * be handled by {@link #resolveSpecifiedLookupKey(Object)} and
	 * {@link #determineCurrentLookupKey()}.
	 */
	public void setTargetDataSources(Map<Object, Object> targetDataSources) {
		this.targetDataSources = targetDataSources;
	}

setDefaultTargetDataSource

上面說(shuō)了如何設(shè)置當(dāng)前數(shù)據(jù)源，那如果在開(kāi)發(fā)的時(shí)候每一個(gè)方法都要聲明一下使用哪個(gè)源就太麻煩了，所以Spring提供了一個(gè)方法用來(lái)設(shè)置默認(rèn)的數(shù)據(jù)源，沒(méi)啥可說(shuō)的，傳入DataSource實(shí)例就好了。

	@Nullable
	private Object defaultTargetDataSource;

	/**
	 * Specify the default target DataSource, if any.
	 * <p>The mapped value can either be a corresponding {@link javax.sql.DataSource}
	 * instance or a data source name String (to be resolved via a
	 * {@link #setDataSourceLookup DataSourceLookup}).
	 * <p>This DataSource will be used as target if none of the keyed
	 * {@link #setTargetDataSources targetDataSources} match the
	 * {@link #determineCurrentLookupKey()} current lookup key.
	 */
	public void setDefaultTargetDataSource(Object defaultTargetDataSource) {
		this.defaultTargetDataSource = defaultTargetDataSource;
	}

determineCurrentLookupKey

在設(shè)置好數(shù)據(jù)源之后，接下來(lái)這幾個(gè)尋路方法則是能實(shí)現(xiàn)動(dòng)態(tài)數(shù)據(jù)源切換的重點(diǎn)。afterPropertiesSet方法對(duì)我們以配置的數(shù)據(jù)源進(jìn)行校驗(yàn)；如果我們?cè)诘谝徊脚渲脭?shù)據(jù)源map的時(shí)候?qū)ey有特殊處理則要自己實(shí)現(xiàn)抽象方法resolveSpecifiedLookupKey，告訴Spring應(yīng)該怎么解析這個(gè)key值；determineTargetDataSource則最終確定要使用哪一個(gè)數(shù)據(jù)源，其中有一個(gè)方法determineCurrentLookupKey需要關(guān)注，這個(gè)方法會(huì)返回當(dāng)前要使用的數(shù)據(jù)源名字，但他是個(gè)抽象方法，所以我們需要給他重寫(xiě)一下，改為從當(dāng)前線程獲取數(shù)據(jù)源名稱(chēng)。

	@Override
	public void afterPropertiesSet() {
		if (this.targetDataSources == null) {
			throw new IllegalArgumentException("Property 'targetDataSources' is required");
		}
		this.resolvedDataSources = CollectionUtils.newHashMap(this.targetDataSources.size());
		this.targetDataSources.forEach((key, value) -> {
			Object lookupKey = resolveSpecifiedLookupKey(key);
			DataSource dataSource = resolveSpecifiedDataSource(value);
			this.resolvedDataSources.put(lookupKey, dataSource);
		});
		if (this.defaultTargetDataSource != null) {
			this.resolvedDefaultDataSource = resolveSpecifiedDataSource(this.defaultTargetDataSource);
		}
	}

	@Override
	public Connection getConnection(String username, String password) throws SQLException {
		return determineTargetDataSource().getConnection(username, password);
	}

	/**
	 * Retrieve the current target DataSource. Determines the
	 * {@link #determineCurrentLookupKey() current lookup key}, performs
	 * a lookup in the {@link #setTargetDataSources targetDataSources} map,
	 * falls back to the specified
	 * {@link #setDefaultTargetDataSource default target DataSource} if necessary.
	 * @see #determineCurrentLookupKey()
	 */
	protected DataSource determineTargetDataSource() {
		Assert.notNull(this.resolvedDataSources, "DataSource router not initialized");
		Object lookupKey = determineCurrentLookupKey();
		DataSource dataSource = this.resolvedDataSources.get(lookupKey);
		if (dataSource == null && (this.lenientFallback || lookupKey == null)) {
			dataSource = this.resolvedDefaultDataSource;
		}
		if (dataSource == null) {
			throw new IllegalStateException("Cannot determine target DataSource for lookup key [" + lookupKey + "]");
		}
		return dataSource;
	}

	/**
	 * Determine the current lookup key. This will typically be
	 * implemented to check a thread-bound transaction context.
	 * <p>Allows for arbitrary keys. The returned key needs
	 * to match the stored lookup key type, as resolved by the
	 * {@link #resolveSpecifiedLookupKey} method.
	 */
	@Nullable
	protected abstract Object determineCurrentLookupKey();

代碼實(shí)現(xiàn)

思路理順了，代碼寫(xiě)起來(lái)就比較快，直接貼最后代碼，部分地方保留了注釋。

數(shù)據(jù)源切換注解

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 數(shù)據(jù)源切換注解，默認(rèn)為primary
 */
@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface TargetDataSource {
    DataSourceEnum value() default DataSourceEnum.PRIMARY;
}

數(shù)據(jù)源切換切面

這里需要特別提醒一下，事務(wù)注解@Transactional默認(rèn)處于切面代理的最后一個(gè)，所以我們需要保證數(shù)據(jù)源切換注解優(yōu)先級(jí)要高于事務(wù)注解。

import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

/**
 * 數(shù)據(jù)源切換切面
 */
@Aspect
@Component
@Order(1)
public class DynamicDataSourceAspect {

    private final static Logger log = LoggerFactory.getLogger(DynamicDataSourceAspect.class);

    @Before(value = "@annotation(targetDataSource)")
    public void beforePointCut(TargetDataSource targetDataSource) {
        log.debug("數(shù)據(jù)源切換為 " + targetDataSource.value().getDataSourceName());
        DynamicDataSourceContextHolder.setDataSource(targetDataSource.value().getDataSourceName());
    }

    @After(value = "@annotation(targetDataSource)")
    public void afterPointCut(TargetDataSource targetDataSource) {
        log.debug("數(shù)據(jù)源恢復(fù)為 " + DataSourceEnum.PRIMARY.getDataSourceName());
        DynamicDataSourceContextHolder.clearDataSource();
    }
}

數(shù)據(jù)源枚舉類(lèi)

/**
 * 數(shù)據(jù)源枚舉類(lèi)
 */
public enum DataSourceEnum {

    PRIMARY("primary"), SECONDARY("secondary");

    private final String dataSourceName;

    public String getDataSourceName() {
        return dataSourceName;
    }

    DataSourceEnum(String dataSourceName) {
        this.dataSourceName = dataSourceName;
    }
}

數(shù)據(jù)源上下文保持類(lèi)

/**
 * 數(shù)據(jù)源上下文線程持有類(lèi)
 */
public class DynamicDataSourceContextHolder {

    /**
     * 存放當(dāng)前線程使用的數(shù)據(jù)源類(lèi)型信息
     */
    private static final ThreadLocal<String> CONTEXT_HOLDER = new ThreadLocal<>();

    public static void setDataSource(String dataSourceType) {
        CONTEXT_HOLDER.set(dataSourceType);
    }

    public static String getDataSource() {
        return CONTEXT_HOLDER.get();
    }

    public static void clearDataSource() {
        CONTEXT_HOLDER.remove();
    }
}

AbstractRoutingDataSource自定義實(shí)現(xiàn)

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

import javax.sql.DataSource;
import java.util.Map;

/**
 * 動(dòng)態(tài)數(shù)據(jù)源切換類(lèi)
 *
 * @author liuenqi
 */
public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceContextHolder.getDataSource();
    }

    public DynamicDataSource(DataSource defaultTargetDataSource, Map<Object, Object> targetDataSources) {
        // 默認(rèn)數(shù)據(jù)源
        super.setDefaultTargetDataSource(defaultTargetDataSource);
        // 所有目標(biāo)數(shù)據(jù)源
        super.setTargetDataSources(targetDataSources);
        // 后處理
        super.afterPropertiesSet();
    }
}

數(shù)據(jù)源注冊(cè)

注意使用jndi源的時(shí)候需要加一個(gè)特定前綴。文章來(lái)源地址http://www.zghlxwxcb.cn/news/detail-481399.html

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

/**
 * 多數(shù)據(jù)源注冊(cè)類(lèi)
 */
public class DynamicDataSourceRegister implements ImportBeanDefinitionRegistrar, EnvironmentAware {

    private DataSource primaryDataSource;
    private DataSource secondaryDataSource;

    @Override
    public void setEnvironment(Environment environment) {
        initPrimaryDataSource(environment);
        initSecondaryDataSource(environment);
    }

    /**
     * 組裝主數(shù)據(jù)源參數(shù)，兼容jdbc-url與jndi
     *
     * @param env Environment
     */
    private void initPrimaryDataSource(Environment env) {
        Map<String, String> paramMap = new HashMap<>(4);
        if (StringUtils.isNotBlank(env.getProperty("spring.datasource.primary.url"))) {
            paramMap.put("url", env.getProperty("spring.datasource.primary.url"));
            paramMap.put("userName", env.getProperty("spring.datasource.primary.username"));
            paramMap.put("password", env.getProperty("spring.datasource.primary.password"));
            paramMap.put("driverClassName", env.getProperty("spring.datasource.primary.driver-class-name"));
        } else {
            paramMap.put("jndi", env.getProperty("spring.datasource.primary.jndi-name"));
        }

        primaryDataSource = buildDataSource(paramMap);
    }

    /**
     * 組裝輔數(shù)據(jù)源參數(shù)，兼容jdbc-url與jndi
     *
     * @param env Environment
     */
    private void initSecondaryDataSource(Environment env) {
        if (StringUtils.isNotBlank(env.getProperty("spring.datasource.secondary.url"))) {
            Map<String, String> paramMap = new HashMap<>(4);
            paramMap.put("url", env.getProperty("spring.datasource.secondary.url"));
            paramMap.put("userName", env.getProperty("spring.datasource.secondary.username"));
            paramMap.put("password", env.getProperty("spring.datasource.secondary.password"));
            paramMap.put("driverClassName", env.getProperty("spring.datasource.secondary.driver-class-name"));
            secondaryDataSource = buildDataSource(paramMap);
        } else if (StringUtils.isNotBlank(env.getProperty("spring.datasource.secondary.jndi-name"))) {
            Map<String, String> paramMap = new HashMap<>(2);
            paramMap.put("jndi", env.getProperty("spring.datasource.secondary.jndi-name"));
            secondaryDataSource = buildDataSource(paramMap);
        }
    }

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        Map<Object, Object> targetDataSource = new HashMap<>(2);
        targetDataSource.put("primary", primaryDataSource);
        if (Objects.nonNull(secondaryDataSource)) {
            targetDataSource.put("secondary", secondaryDataSource);
        }

        // 為DynamicDataSource構(gòu)造參數(shù)，注意參數(shù)順序
        ConstructorArgumentValues constructorArgumentValues = new ConstructorArgumentValues();
        constructorArgumentValues.addGenericArgumentValue(primaryDataSource);
        constructorArgumentValues.addGenericArgumentValue(targetDataSource);

        // 構(gòu)造bean放入IOC
        GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
        beanDefinition.setBeanClass(DynamicDataSource.class);
        beanDefinition.setConstructorArgumentValues(constructorArgumentValues);
        beanDefinition.setSynthetic(true);

        registry.registerBeanDefinition("dataSource", beanDefinition);
    }

    /**
     * 使用HikariDataSource
     *
     * @param paramMap {"url":"JDBC-URL","userName":"數(shù)據(jù)庫(kù)用戶(hù)名","password":"密碼","driverClassName":"驅(qū)動(dòng)名","jndi":"jndi源"}
     * @return HikariDataSource
     */
    private DataSource buildDataSource(Map<String, String> paramMap) {
        HikariConfig hikariConfig = new HikariConfig();
        if (paramMap.containsKey("url")) {
            hikariConfig.setJdbcUrl(paramMap.get("url"));
            hikariConfig.setUsername(paramMap.get("userName"));
            hikariConfig.setPassword(paramMap.get("password"));
            hikariConfig.setDriverClassName(paramMap.get("driverClassName"));
        } else {
            hikariConfig.setDataSourceJNDI("java:comp/env/" + paramMap.get("jndi"));
        }
        return new HikariDataSource(hikariConfig);
    }
}

啟動(dòng)類(lèi)配置

@Import({DynamicDataSourceRegister.class})

application.yml配置

spring:
  datasource:
    primary:
      url: jdbc:mysql://xxxxx
      username: xxxx
      password: xxxxx
      driver-class-name: com.mysql.cj.jdbc.Driver
    secondary: 
      jndi-name: jdbc/db

到了這里，關(guān)于基于注解切換、Hikari實(shí)現(xiàn)的SpringBoot動(dòng)態(tài)數(shù)據(jù)源（支持JNDI）的文章就介紹完了。如果您還想了解更多內(nèi)容，請(qǐng)?jiān)谟疑辖撬阉鱐OY模板網(wǎng)以前的文章或繼續(xù)瀏覽下面的相關(guān)文章，希望大家以后多多支持TOY模板網(wǎng)！