增加了@UseDataSource取值动态处理逻辑支持处理器

1：DataSourceProcessor 为处理器接口
2：DelegatingDataSourceProcessor 为DataSourceProcessor的委托类，目的增强扩大 DataSourceProcessor类或对象的结构
3：ParamIndexDataSourceProcessor 简单参数所以读取的支持处理器
4：SpelExpressionDataSourceProcessor 支持SPEL 表达式的处理器类

mybatis-flex-core/src/main/java/com/mybatisflex/core/datasource/DataSourceKey.java

@@ -78,6 +78,12 @@ public class DataSourceKey {
         lookup = threadLocal;
     }
 
+    public static String processDataSourceKey(String dataSourceKey, Object mapper, Method method, Object[] arguments) {
+        String dsKey = DataSourceManager.processDataSourceKey(dataSourceKey, mapper, method, arguments);
+        return dsKey != null ? dsKey : dataSourceKey;
+    }
+
+
     public static String getShardingDsKey(String dataSource, Object mapper, Method method, Object[] args) {
         String shardingDsKey = DataSourceManager.getShardingDsKey(dataSource, mapper, method, args);
         return shardingDsKey != null ? shardingDsKey : dataSource;
@@ -89,18 +95,22 @@ public class DataSourceKey {
     public static String getByManual() {
         throw new UnsupportedOperationException("使用 DataSource.get() 代替。");
     }
+
     @Deprecated
     public static String getByAnnotation() {
         throw new UnsupportedOperationException("使用 DataSource.get() 代替。");
     }
+
     @Deprecated
     public static void useWithAnnotation(String dataSourceKey) {
         throw new UnsupportedOperationException("使用 DataSource.use(String) 代替。");
     }
+
     @Deprecated
     public static void setAnnotationKeyThreadLocal(ThreadLocal<String> annotationKeyThreadLocal) {
         throw new UnsupportedOperationException("使用 DataSource.setThreadLocal(ThreadLocal<Deque<String>>) 代替。");
     }
+
     @Deprecated
     public static void setManualKeyThreadLocal(ThreadLocal<String> manualKeyThreadLocal) {
         throw new UnsupportedOperationException("使用 DataSource.setThreadLocal(ThreadLocal<Deque<String>>) 代替。");

mybatis-flex-core/src/main/java/com/mybatisflex/core/datasource/DataSourceManager.java

@@ -15,6 +15,7 @@
  */
 package com.mybatisflex.core.datasource;
 
+import com.mybatisflex.core.datasource.processor.DataSourceProcessor;
 import com.mybatisflex.core.exception.FlexExceptions;
 import com.mybatisflex.core.util.ClassUtil;
 import org.apache.ibatis.logging.LogFactory;
@@ -37,6 +38,19 @@ public class DataSourceManager {
         DataSourceManager.decipher = decipher;
     }
 
+    /**
+     * 动态数据源key取值处理
+     */
+    private static DataSourceProcessor dataSourceProcessor;
+
+    public static DataSourceProcessor getDataSourceProcessor() {
+        return dataSourceProcessor;
+    }
+
+    public static void setDataSourceProcessor(DataSourceProcessor dataSourceProcessor) {
+        DataSourceManager.dataSourceProcessor = dataSourceProcessor;
+    }
+
     private static DataSourceShardingStrategy dataSourceShardingStrategy;
 
     public static DataSourceShardingStrategy getDataSourceShardingStrategy() {
@@ -95,6 +109,11 @@ public class DataSourceManager {
         return null;
     }
 
+    static String processDataSourceKey(String dataSourceKey, Object mapper, Method method, Object[] arguments) {
+        // 如果没有配置 DataSourceProcessor 实例,则不做处理,返回原始值
+        return dataSourceProcessor == null ? dataSourceKey : dataSourceProcessor.process(dataSourceKey, mapper, method, arguments);
+    }
+
 
     static String getShardingDsKey(String dataSource, Object mapper, Method method, Object[] args) {
         return dataSourceShardingStrategy != null ? dataSourceShardingStrategy.doSharding(dataSource, mapper, method, args) : null;

mybatis-flex-core/src/main/java/com/mybatisflex/core/datasource/processor/DataSourceProcessor.java

@@ -0,0 +1,25 @@
+package com.mybatisflex.core.datasource.processor;
+
+import java.lang.reflect.Method;
+
+/**
+ * 动态数据源 @UseDataSource key 解析处理器,使用时推荐注入 DelegatingDataSourceProcessor{@link DelegatingDataSourceProcessor} 类
+ * 对动态数据源注解@UseDataSource 增强处理{@link com.mybatisflex.annotation.UseDataSource}
+ *
+ * @author Alay
+ * @since 2024-12-07 15:34
+ */
+public interface DataSourceProcessor {
+
+    /**
+     * 数据源key解析扩展
+     *
+     * @param dataSourceKey 注解UseDataSource的value 值,调用process时不会为null,可能会空字符串
+     * @param mapper        Mapper对象(代理对象)
+     * @param method        Mapper当前执行的方法函数
+     * @param arguments     Mapper当前执行的函数参数
+     * @return 数据源名称（可能为null 为 null 时表示不符合当前处理器的处理,传递到下一个处理器进行处理）
+     */
+    String process(String dataSourceKey, Object mapper, Method method, Object[] arguments);
+
+}

mybatis-flex-core/src/main/java/com/mybatisflex/core/datasource/processor/DelegatingDataSourceProcessor.java

@@ -0,0 +1,54 @@
+package com.mybatisflex.core.datasource.processor;
+
+import com.mybatisflex.core.exception.FlexAssert;
+
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * DataSourceProcessor 委托扩展类,对 DataSourceProcessor 结构进行扩大和增强
+ *
+ * @author Alay
+ * @since 2024-12-07 15:38
+ */
+public class DelegatingDataSourceProcessor implements DataSourceProcessor {
+
+    private final List<DataSourceProcessor> delegates;
+
+
+    private DelegatingDataSourceProcessor(List<DataSourceProcessor> delegates) {
+        this.delegates = delegates;
+    }
+
+    /**
+     * @param processors 使用时请注意 DataSourceProcessor 的顺序
+     */
+    public static DelegatingDataSourceProcessor with(DataSourceProcessor... processors) {
+        FlexAssert.notEmpty(processors, "datasource processors");
+        List<DataSourceProcessor> dataSourceProcessors = new ArrayList<>(Arrays.asList(processors));
+        return new DelegatingDataSourceProcessor(dataSourceProcessors);
+    }
+
+    /**
+     * @param processors 使用时请注意 DataSourceProcessor 的顺序
+     */
+    public static DelegatingDataSourceProcessor with(List<DataSourceProcessor> processors) {
+        FlexAssert.notEmpty(processors, "datasource processors");
+        return new DelegatingDataSourceProcessor(processors);
+    }
+
+
+    @Override
+    public String process(String dataSourceKey, Object mapper, Method method, Object[] arguments) {
+        for (DataSourceProcessor delegate : delegates) {
+            // 使用时请注意 DataSourceProcessor 的顺序,一旦匹配到处理器将进行中断处理并返回处理结果
+            String returnKey = delegate.process(dataSourceKey, mapper, method, arguments);
+            if (null != returnKey) return returnKey;
+        }
+        // 无可用的处理器策略,返回原始值
+        return dataSourceKey;
+    }
+
+}

mybatis-flex-core/src/main/java/com/mybatisflex/core/datasource/processor/ParamIndexDataSourceProcessor.java

@@ -0,0 +1,58 @@
+package com.mybatisflex.core.datasource.processor;
+
+import com.mybatisflex.processor.util.StrUtil;
+
+import java.lang.reflect.Method;
+
+/**
+ * 参数索引中取出数据源名称(针对简单类型参数快速解析读取)
+ *
+ * @author Alay
+ * @since 2024-12-07 15:43
+ */
+public class ParamIndexDataSourceProcessor implements DataSourceProcessor {
+    private static final String NULL_STR = "null";
+    private static final String DYNAMIC_PREFIX = "#";
+    private static final String INDEX_FIRST = "#first";
+    private static final String INDEX_LAST = "#last";
+    private static final String PARAM_INDEX = "#index";
+
+    /**
+     * 若不符合处理逻辑将返回 null 值
+     */
+    @Override
+    public String process(String dataSourceKey, Object mapper, Method method, Object[] arguments) {
+        if (StrUtil.isBlank(dataSourceKey)) return null;
+        if (!dataSourceKey.startsWith(DYNAMIC_PREFIX)) return null;
+        // 无效的参数
+        if (arguments.length == 0) return null;
+
+        Integer index = null;
+        if (INDEX_FIRST.equals(dataSourceKey)) index = 0;
+        if (INDEX_LAST.equals(dataSourceKey)) index = arguments.length - 1;
+        if (dataSourceKey.startsWith(PARAM_INDEX)) index = parseIndex(dataSourceKey);
+
+        // 没有符合约定的格式输入,则会返回 null
+        if (null == index) return null;
+        // 参数输入不合法(索引参数大于参数索引数)
+        if (index >= arguments.length) return null;
+
+        // 参数中按照索引取出数值
+        String value = String.valueOf(arguments[index]);
+        if (StrUtil.isBlank(value) || NULL_STR.equals(value)) return null;
+
+        return value;
+    }
+
+    private static Integer parseIndex(String dsKey) {
+        // 参数索引
+        String indexStr = dsKey.substring(PARAM_INDEX.length());
+        if (indexStr.isEmpty()) return null;
+        try {
+            return Integer.parseInt(indexStr);
+        } catch (NumberFormatException ex) {
+            return null;
+        }
+    }
+
+}

mybatis-flex-core/src/main/java/com/mybatisflex/core/datasource/processor/package-info.java

@@ -0,0 +1,20 @@
+/*
+ *  Copyright (c) 2022-2025, Mybatis-Flex (fuhai999@gmail.com).
+ *  <p>
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  <p>
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *  <p>
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/**
+ * 动态数据源注解@UseDataSource 的扩展
+ */
+package com.mybatisflex.core.datasource.processor;

mybatis-flex-core/src/main/java/com/mybatisflex/core/mybatis/binding/FlexMapperProxy.java

@@ -26,6 +26,7 @@ import com.mybatisflex.core.row.RowMapper;
 import com.mybatisflex.core.table.TableInfo;
 import com.mybatisflex.core.table.TableInfoFactory;
 import com.mybatisflex.core.util.StringUtil;
+import com.mybatisflex.processor.util.StrUtil;
 import org.apache.ibatis.reflection.ExceptionUtil;
 import org.apache.ibatis.session.SqlSession;
 
@@ -61,7 +62,12 @@ public class FlexMapperProxy<T> extends MybatisMapperProxy<T> {
                 finalDsKey = getMethodDsKey(method, proxy);
             }
 
-            //通过自定义分配策略去获取最终的数据源
+            // 对数据源取值进行动态取值处理(#)
+            if (!StrUtil.isBlank(finalDsKey)) {
+                finalDsKey = DataSourceKey.processDataSourceKey(finalDsKey, proxy, method, args);
+            }
+
+            // 通过自定义分配策略去获取最终的数据源
             finalDsKey = DataSourceKey.getShardingDsKey(finalDsKey, proxy, method, args);
 
             if (StringUtil.hasText(finalDsKey) && !finalDsKey.equals(userDsKey)) {

mybatis-flex-spring/src/main/java/com/mybatisflex/spring/datasource/processor/SpelExpressionDataSourceProcessor.java

@@ -0,0 +1,106 @@
+package com.mybatisflex.spring.datasource.processor;
+
+import com.mybatisflex.core.datasource.processor.DataSourceProcessor;
+import com.mybatisflex.processor.util.StrUtil;
+import org.springframework.context.expression.MethodBasedEvaluationContext;
+import org.springframework.core.DefaultParameterNameDiscoverer;
+import org.springframework.core.ParameterNameDiscoverer;
+import org.springframework.expression.BeanResolver;
+import org.springframework.expression.ExpressionParser;
+import org.springframework.expression.ParserContext;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.expression.spel.support.StandardEvaluationContext;
+
+import java.lang.reflect.Method;
+
+/**
+ * SpEL表达式支持处理器
+ *
+ * @author Alay
+ * @since 2024-12-07 15:48
+ */
+public class SpelExpressionDataSourceProcessor implements DataSourceProcessor {
+    /**
+     * 动态表达式前缀
+     */
+    private static final String DYNAMIC_PREFIX = "#";
+    /**
+     * 参数发现器
+     */
+    private static final ParameterNameDiscoverer NAME_DISCOVERER = new DefaultParameterNameDiscoverer();
+    /**
+     * Express语法解析器
+     */
+    private static final ExpressionParser PARSER = new SpelExpressionParser();
+
+    private BeanResolver beanResolver;
+    /**
+     * 解析上下文的模板 对于默认不设置的情况下,从参数中取值的方式 #param1
+     * 设置指定模板 ParserContext. TEMPLATE_EXPRESSION{@link ParserContext#TEMPLATE_EXPRESSION} 后的取值方式: #{#param1}
+     */
+    private ParserContext parserContext = new ParserContext() {
+
+        @Override
+        public boolean isTemplate() {
+            return false;
+        }
+
+        @Override
+        public String getExpressionPrefix() {
+            return null;
+        }
+
+        @Override
+        public String getExpressionSuffix() {
+            return null;
+        }
+    };
+
+
+    @Override
+    public String process(String dataSourceKey, Object mapper, Method method, Object[] arguments) {
+        if (StrUtil.isBlank(dataSourceKey)) return null;
+        if (!dataSourceKey.startsWith(DYNAMIC_PREFIX)) return null;
+        if (arguments.length == 0) return null;
+
+        RootObject rootObject = new RootObject(method, arguments, mapper);
+        StandardEvaluationContext context = new MethodBasedEvaluationContext(rootObject, method, arguments, NAME_DISCOVERER);
+        context.setBeanResolver(beanResolver);
+        final Object value = PARSER.parseExpression(dataSourceKey, parserContext).getValue(context);
+        return value == null ? null : value.toString();
+    }
+
+
+    public void setBeanResolver(BeanResolver beanResolver) {
+        this.beanResolver = beanResolver;
+    }
+
+    public void setParserContext(ParserContext parserContext) {
+        this.parserContext = parserContext;
+    }
+
+    public static class RootObject {
+        private final Method method;
+        private final Object[] args;
+        private final Object target;
+
+        public RootObject(Method method, Object[] args, Object target) {
+            this.method = method;
+            this.args = args;
+            this.target = target;
+        }
+
+        public Method getMethod() {
+            return method;
+        }
+
+        public Object[] getArgs() {
+            return args;
+        }
+
+        public Object getTarget() {
+            return target;
+        }
+    }
+
+}

mybatis-flex-spring/src/main/java/com/mybatisflex/spring/datasource/processor/package-info.java

@@ -0,0 +1,20 @@
+/*
+ *  Copyright (c) 2022-2025, Mybatis-Flex (fuhai999@gmail.com).
+ *  <p>
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *  <p>
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *  <p>
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/**
+ * 动态数据源注解@UseDataSource 的扩展
+ */
+package com.mybatisflex.spring.datasource.processor;