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:
- 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);
}
}
}
- 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));
}
}
- 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。