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SpringBoot实现MapperScan添加动态配置(占位符)

 更新时间：2022年01月10日 10:03:14   作者：BUse  
这篇文章主要介绍了SpringBoot实现MapperScan添加动态配置(占位符)，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教。

MapperScan添加动态配置(占位符)

在对Mybatis自动扫描配置中，使用注解配置时，@MapperScan中的配置，通常配置如下：

@MapperScan(basePackages = {"com.aa.**.mapper","com.bb.**.mapper"}, sqlSessionFactoryRef = "sqlSessionFactory")

不支持在yml或properties文件中动态配置。因为MapperScan注解功能的实现类MapperScannerRegistrar实现的是ImportBeanDefinitionRegistrar。在对@Configuration注解标记的类配置时，实现占位符功能的PropertyPlaceholderAutoConfiguration还没有开始加载。

MapperScannerRegistrard的核心代码如下

List<String> basePackages = new ArrayList();
        basePackages.addAll((Collection)Arrays.stream(annoAttrs.getStringArray("value")).filter(StringUtils::hasText).collect(Collectors.toList()));
        basePackages.addAll((Collection)Arrays.stream(annoAttrs.getStringArray("basePackages")).filter(StringUtils::hasText).collect(Collectors.toList()));
        basePackages.addAll((Collection)Arrays.stream(annoAttrs.getClassArray("basePackageClasses")).map(ClassUtils::getPackageName).collect(Collectors.toList()));
        scanner.registerFilters();
        scanner.doScan(StringUtils.toStringArray(basePackages));

从上面代码中可以看出

为了拓展支持占位符动态配置，只需把basePackages的加载改写即可。

1、参考MapperScannerRegistrard，实现 ImportBeanDefinitionRegistrar和ResourceLoaderAware两个接口

2、为了动态读取配置文件信息，需要引入Environment，所以实现EnvironmentAware接口

3、代码

MapperScannerRegistrar.java

import org.mybatis.spring.mapper.ClassPathMapperScanner;
import org.mybatis.spring.mapper.MapperFactoryBean;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.env.Environment;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils; 
import java.lang.annotation.Annotation;
import java.util.*;
import java.util.stream.Collectors;
 
public class MapperScannerRegistrar implements ImportBeanDefinitionRegistrar, ResourceLoaderAware,EnvironmentAware {
    private Environment environment;
    private ResourceLoader resourceLoader;
    private  static  final Logger logger = LoggerFactory.getLogger(MapperScannerRegistrar. class);
 
    @Override
    public void setEnvironment(Environment environment) {
        this.environment = environment;
    }
 
    @Override
    public void setResourceLoader(ResourceLoader resourceLoader) {
        this.resourceLoader = resourceLoader;
    }
 
    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) { 
        AnnotationAttributes mapperScanAttrs = AnnotationAttributes.fromMap(importingClassMetadata.getAnnotationAttributes(MapperScanner.class.getName()));
        if (mapperScanAttrs != null) {
            this.registerBeanDefinitions(mapperScanAttrs, registry);
        }
    }
 
    void registerBeanDefinitions(AnnotationAttributes annoAttrs, BeanDefinitionRegistry registry) {
        ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
        Optional var10000 = Optional.ofNullable(this.resourceLoader);
        Objects.requireNonNull(scanner);
        Class<? extends Annotation> annotationClass = annoAttrs.getClass("annotationClass");
        if (!Annotation.class.equals(annotationClass)) {
            scanner.setAnnotationClass(annotationClass);
        }
 
        Class<?> markerInterface = annoAttrs.getClass("markerInterface");
        if (!Class.class.equals(markerInterface)) {
            scanner.setMarkerInterface(markerInterface);
        }
 
        Class<? extends BeanNameGenerator> generatorClass = annoAttrs.getClass("nameGenerator");
        if (!BeanNameGenerator.class.equals(generatorClass)) {
            scanner.setBeanNameGenerator((BeanNameGenerator) BeanUtils.instantiateClass(generatorClass));
        }
 
        Class<? extends MapperFactoryBean> mapperFactoryBeanClass = annoAttrs.getClass("factoryBean");
        if (!MapperFactoryBean.class.equals(mapperFactoryBeanClass)) {
            scanner.setMapperFactoryBeanClass(mapperFactoryBeanClass);
        }
 
        scanner.setSqlSessionTemplateBeanName(annoAttrs.getString("sqlSessionTemplateRef"));
        scanner.setSqlSessionFactoryBeanName(annoAttrs.getString("sqlSessionFactoryRef"));
        List<String> basePackages = new ArrayList<String>();
        basePackages.addAll(Arrays.stream(annoAttrs.getStringArray("value")).filter(StringUtils::hasText).collect(Collectors.toList()));
        for (String pkg : annoAttrs.getStringArray("basePackages")) {
            if (StringUtils.hasText(pkg)) {
                String value = parsePlaceHolder(pkg);
                if(StringUtils.hasText(value)){
                    List<String> valueList = Arrays.asList(value.split(","));
                    for(String base : valueList){
                        basePackages.add(base);
                    }
                }
            }
        }
        basePackages.addAll(Arrays.stream(annoAttrs.getClassArray("basePackageClasses")).map(ClassUtils::getPackageName).collect(Collectors.toList()));
        scanner.registerFilters();
        scanner.doScan(StringUtils.toStringArray(basePackages));
    }
 
    private String parsePlaceHolder(String pro) {
        if (StringUtils.hasText(pro) && pro.contains(PropertySourcesPlaceholderConfigurer.DEFAULT_PLACEHOLDER_PREFIX)) {
            String value = environment.getProperty(pro.substring(2, pro.length() - 1));
 
            if (logger.isDebugEnabled()) {
                logger.debug("find placeholder value " + value + " for key " + pro);
            }
 
            if (null == value) {
                throw new IllegalArgumentException("property " + pro + " can not find!!!");
            }
            return value;
        }
        return pro;
    }
}

MapperScanner.java

import org.mybatis.spring.mapper.MapperFactoryBean;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.context.annotation.Import; 
import java.lang.annotation.*;
 
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@Documented
@Import({MapperScannerRegistrar.class})
public @interface MapperScanner {
    String[] value() default {}; 
    String[] basePackages() default {}; 
    Class<?>[] basePackageClasses() default {}; 
    Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class; 
    Class<? extends Annotation> annotationClass() default Annotation.class; 
    Class<?> markerInterface() default Class.class; 
    String sqlSessionTemplateRef() default ""; 
    String sqlSessionFactoryRef() default ""; 
    Class<? extends MapperFactoryBean> factoryBean() default MapperFactoryBean.class;
}

4、使用MapperScanner，占位符扫描配置

@MapperScanner(basePackages = { "${mybatis.mapperScanner.basePackage}" }, sqlSessionFactoryRef = "sqlSessionFactory")
mybatis:
  mapperScanner:
    basePackage: com.aa.**.mapper,com.bb.**.mapper

关于@MapperScan配置

问题

org.apache.ibatis.binding.BindingException: Invalid bound statement (not found): top.yangzefeng.usercenter.user.service.UserService.getById

解决方案

常用配置：

@MapperScan("top.yangzefeng.usercenter.**.mapper")
  • @MapperScan("com.demo.mapper")：扫描指定包中的接口
  • @MapperScan("com.demo.*.mapper")：一个代表任意字符串，但只代表一级包，比如可以扫到com.demo.aaa.mapper，不能扫到com.demo.aaa.bbb.mapper
  • @MapperScan("com.demo.**.mapper")：两个代表任意个包，比如可以扫到com.demo.aaa.mapper，也可以扫到com.demo.aaa.bbb.mapper

以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。

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