自定义MyBatis iterate处理器

在 MyBatis 中，你可以通过实现 org.apache.ibatis.reflection.invoker.Invoker 接口来自定义一个 iterate 处理器。这个接口包含了两个方法：getGetterType() 和 invoke(Object target, Object[] args)。

以下是一个简单的自定义 iterate 处理器示例：

1. 首先，创建一个自定义的 iterate 处理器类，实现 org.apache.ibatis.reflection.invoker.Invoker 接口：

import org.apache.ibatis.reflection.invoker.Invoker;
import java.lang.reflect.InvocationTargetException;
import java.util.Collection;

public class CustomIterateInvoker implements Invoker {
    private final Invoker invoker;

    public CustomIterateInvoker(Invoker invoker) {
        this.invoker = invoker;
    }

    @Override
    public Class<?> getGetterType() {
        return invoker.getGetterType();
    }

    @Override
    public Object invoke(Object target, Object[] args) throws IllegalAccessException, InvocationTargetException {
        // 在这里添加自定义逻辑
        if (target instanceof Collection) {
            Collection<?> collection = (Collection<?>) target;
            for (Object item : collection) {
                invoker.invoke(item, args);
            }
            return null;
        } else {
            return invoker.invoke(target, args);
        }
    }
}

2. 然后，创建一个自定义的 org.apache.ibatis.reflection.wrapper.Wrapper 类，用于包装目标对象并返回自定义的 iterate 处理器：

import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.SystemMetaObject;
import org.apache.ibatis.reflection.wrapper.ObjectWrapper;
import org.apache.ibatis.reflection.wrapper.Wrapper;

public class CustomWrapper implements Wrapper {
    private final MetaObject metaObject;

    public CustomWrapper(Object object) {
        this.metaObject = SystemMetaObject.forObject(object);
    }

    @Override
    public Object get(PropertyTokenizer prop) {
        return metaObject.getValue(prop.getName());
    }

    @Override
    public void set(PropertyTokenizer prop, Object value) {
        metaObject.setValue(prop.getName(), value);
    }

    @Override
    public String findProperty(String name, boolean useCamelCaseMapping) {
        return metaObject.findProperty(name, useCamelCaseMapping);
    }

    @Override
    public String[] getGetterNames() {
        return metaObject.getGetterNames();
    }

    @Override
    public String[] getSetterNames() {
        return metaObject.getSetterNames();
    }

    @Override
    public Class<?> getSetterType(String name) {
        return metaObject.getSetterType(name);
    }

    @Override
    public Class<?> getGetterType(String name) {
        return metaObject.getGetterType(name);
    }

    @Override
    public boolean hasSetter(String name) {
        return metaObject.hasSetter(name);
    }

    @Override
    public boolean hasGetter(String name) {
        return metaObject.hasGetter(name);
    }

    @Override
    public MetaObject instantiatePropertyValue(String name, PropertyTokenizer prop, ObjectFactory objectFactory) {
        return metaObject.instantiatePropertyValue(name, prop, objectFactory);
    }

    @Override
    public boolean isCollection() {
        return metaObject.isCollection();
    }

    @Override
    public void add(Object element) {
        metaObject.add(element);
    }

    @Override
    public <T> T addNew(Class<T> type) {
        return metaObject.addNew(type);
    }

    @Override
    public Iterator<Object> iterator() {
        return metaObject.iterator();
    }

    @Override
    public boolean hasNext() {
        return metaObject.hasNext();
    }

    @Override
    public Object next() {
        return metaObject.next();
    }

    @Override
    public void remove() {
        metaObject.remove();
    }

    @Override
    public ObjectWrapper getWrapper() {
        return new CustomWrapper(metaObject.getOriginalObject());
    }

    @Override
    public Object getWrappedInstance() {
        return metaObject.getOriginalObject();
    }

    @Override
    public Object get(String name) {
        return metaObject.getValue(name);
    }

    @Override
    public void set(String name, Object value) {
        metaObject.setValue(name, value);
    }

    @Override
    public Object invoke(String name, Object[] args) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        return metaObject.invokeMethod(name, args);
    }

    @Override
    public Object invoke(String name, Object[] args, Class<?>[] parameterTypes) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        return metaObject.invokeMethod(name, args, parameterTypes);
    }

    @Override
    public Object invoke(String name, Object[] args, Class<?>[] parameterTypes, Invoker invoker) throws NoSuchMethodException, InvocationTargetException, IllegalAccessException {
        return metaObject.invokeMethod(name, args, parameterTypes, new CustomIterateInvoker(invoker));
    }
}

3. 最后，在 MyBatis 配置文件中注册自定义的 CustomWrapper 类：

    <!-- ... -->
   <objectFactory type="com.example.CustomObjectFactory"/>
    <!-- ... -->
</configuration>

现在，当你在 MyBatis 的 XML 映射文件中使用自定义的 iterate 处理器时，它将按照你在 CustomIterateInvoker 类中定义的逻辑进行处理。