java通过注解实现分表详解

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface DynamicTable {
    /**
     * 需要分割的表名
     * @return
     */
    String tableName();

    /**
     * 后缀key
     * @return
     */
    String separateKey();
}

@Aspect
@Component
@Slf4j
public class DynamicTableAspect {

    /**
     * 用于SpEL表达式解析.
     */
    private SpelExpressionParser parser = new SpelExpressionParser();
    /**
     * 用于获取方法参数定义名字.
     */
    private DefaultParameterNameDiscoverer nameDiscoverer = new DefaultParameterNameDiscoverer();

    private static final String TABLE_NAME = "tableName";
    private static final String TABLE_SUFFIX = "tableSuffix";

    /**
     * 以注解为切点
     */
    @Pointcut("@annotation(com.leoli04.DynamicTable)")
    public void dynamicTable() {
    }

    @Around("dynamicTable()")
    public Object doAround(ProceedingJoinPoint joinPoint) throws Throwable {
        MethodSignature methodSignature = (MethodSignature)joinPoint.getSignature();
        Method method = methodSignature.getMethod();
        if(method.isAnnotationPresent(DynamicTable.class)){
            DynamicTable dynamicTable =  (DynamicTable) method.getAnnotation(DynamicTable.class);
            String key = dynamicTable.separateKey();
            // 获取参数
            Object[] args = joinPoint.getArgs();

            Expression expression = parser.parseExpression(key);
            // 使用spring的DefaultParameterNameDiscoverer获取方法形参名数组
            String[] paramNames = nameDiscoverer.getParameterNames(method);
            // spring的表达式上下文对象
            EvaluationContext context = new StandardEvaluationContext();
            // 给上下文赋值
            for (int i = 0; i < args.length; i++) {
                context.setVariable(paramNames[i], args[i]);
            }

            RequestDataHelper.setRequestData(new HashMap<String, Object>() {{
                put(TABLE_NAME, dynamicTable.tableName());
                put(TABLE_SUFFIX, expression.getValue(context));
            }});
            Object proceed = joinPoint.proceed();
            RequestDataHelper.removeRequestData();
            return proceed;
        }else{
            Object proceed = joinPoint.proceed();
            return proceed;
        }
    }

}

RequestDataHelper.setRequestData(new HashMap<String, Object>() {{
                put(TABLE_NAME, dynamicTable.tableName());
                put(TABLE_SUFFIX, expression.getValue(context));
            }});
            
Object proceed = joinPoint.proceed();

RequestDataHelper.removeRequestData();

@Configuration
@Slf4j
public class MyBatisPlusConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor(){
        MybatisPlusInterceptor mybatisPlusInterceptor = new MybatisPlusInterceptor();
        // 添加分页插件
        mybatisPlusInterceptor.addInnerInterceptor(new PaginationInnerInterceptor());

        // 动态表名插件
        DynamicTableNameInnerInterceptor dynamicTableNameInnerInterceptor = new DynamicTableNameInnerInterceptor();
        dynamicTableNameInnerInterceptor.setTableNameHandler((sql, tableName) -> {
            // 获取参数方法
            Map<String, Object> paramMap = RequestDataHelper.getRequestData();
            if (CollectionUtils.isNotEmpty(paramMap)) {
                var tableNameParam = (String) paramMap.get("tableName");
                paramMap.forEach((k, v) -> log.info(k + "----" + v));
                if(tableNameParam.equals(tableName)){
                    // 获取传递的参数
                    String tableSuffix = (String) paramMap.get("tableSuffix");
                    if(StringUtils.isBlank(tableSuffix)){
                        return tableName;
                    }else{
                        // 组装动态表名
                        return tableName + "_" + tableSuffix;
                    }
                }
            }
            return tableName;
        });
        mybatisPlusInterceptor.addInnerInterceptor(dynamicTableNameInnerInterceptor);
        return mybatisPlusInterceptor;
    }
}