The primary key annotation

import java.lang.annotation.Retention; import java.lang.annotation.Target; import static java.lang.annotation.ElementType.FIELD; import static java.lang.annotation.ElementType.METHOD; import static java.lang.annotation.RetentionPolicy.RUNTIME; @Target({ METHOD, FIELD }) @Retention(RUNTIME) public @interface Id { Class<? > strategy() default UUIDGenerator.class; }Copy the code
public interface IdGenerator {

	public Serializable generator();
}
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import ObjectId;

import java.io.Serializable;


public class UUIDGenerator implements IdGenerator {

    @Override
    public Serializable generator() {
        returnnew ObjectId().toString(); }}Copy the code

Annotations parsing

import java.io.Serializable; import java.beans.IntrospectionException; import java.beans.PropertyDescriptor; import java.lang.reflect.Field; import java.lang.reflect.Method; import java.util.HashSet; import java.util.Set; public class PropertySet { private Set<ProPertyStrategyMapper> propertys = new HashSet<ProPertyStrategyMapper>(); private Class<? > entity; @SuppressWarnings("unused")
	private PropertySet() { } public PropertySet(Class<? > entity) { this.entity = entity; this.build(); } public Set<ProPertyStrategyMapper>getPropertys() {
		return propertys;
	}

	public void setPropertys(Set<ProPertyStrategyMapper> propertys) {
		this.propertys = propertys;
	}

	public PropertySet build() {
		Field[] fields = entity.getDeclaredFields();
		for (Field field : fields) {
			if ("serialVersionUID".equals(field.getName()))
				continue; // Annotations on attributesif(field.isAnnotationPresent(Id.class)){
				Id id = field.getAnnotation(Id.class);
				if (id.strategy() == null) {
					continue; } Class<? > generator = id.strategy(); Object object = null; try { object = generator.newInstance(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); }if(! (object instanceof IdGenerator)) {continue;
				}
				IdGenerator idGenerator = (IdGenerator) object;
				ProPertyStrategyMapper proPertyStrategyMapper = new ProPertyStrategyMapper(field.getName(),
						idGenerator);
				propertys.add(proPertyStrategyMapper);
				break; } // Annotations on methods PropertyDescriptor PropertyDescriptor = null; try { propertyDescriptor = new PropertyDescriptor(field.getName(), entity); } catch (IntrospectionException e) { e.printStackTrace(); }if (propertyDescriptor == null)
				continue; / / class for the get Method Method Method = propertyDescriptor. GetReadMethod ();if (method == null) {
				continue;
			}
			if (method.isAnnotationPresent(Id.class)) {
				Id id = method.getAnnotation(Id.class);
				if (id.strategy() == null) {
					continue; } Class<? > generator = id.strategy(); Object object = null; try { object = generator.newInstance(); } catch (InstantiationException e) { e.printStackTrace(); } catch (IllegalAccessException e) { e.printStackTrace(); }if(! (object instanceof IdGenerator)) {continue;
				}
				IdGenerator idGenerator = (IdGenerator) object;
				ProPertyStrategyMapper proPertyStrategyMapper = new ProPertyStrategyMapper(field.getName(),
						idGenerator);
				propertys.add(proPertyStrategyMapper);
				break; }}returnthis; }}Copy the code

Strategy map

public class ProPertyStrategyMapper {

	private String propertyName;
	private IdGenerator generator;

	public ProPertyStrategyMapper(String propertyName, IdGenerator generator) {
		super();
		this.propertyName = propertyName;
		this.setGenerator(generator);
	}

	public String getPropertyName() {
		return propertyName;
	}

	public void setPropertyName(String propertyName) {
		this.propertyName = propertyName;
	}

	public IdGenerator getGenerator() {
		return generator;
	}

	public void setGenerator(IdGenerator generator) { this.generator = generator; }}Copy the code

The interceptor

import ProPertyStrategyMapper;
import PropertySet;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.*;
import org.springframework.util.ReflectionUtils;

import java.lang.reflect.Field;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

@Intercepts({ @Signature(type = Executor.class, method = "update", args = { MappedStatement.class, Object.class }) })
public class UUIDInterceptor implements Interceptor {

	@Override
	public Object intercept(Invocation invocation) throws Throwable {

		Object[] args = invocation.getArgs();
		if(args == null || args.length ! = 2 | |! (args[0] instanceof MappedStatement)) {return invocation.proceed();
		}
		MappedStatement mappedStatement = (MappedStatement) args[0];
		SqlCommandType sqlCommandType = mappedStatement.getSqlCommandType();
		if(! SqlCommandType.INSERT.equals(sqlCommandType)) {return invocation.proceed();
		}
		setDefultProperty(args[1]);
		return invocation.proceed();
	}

	public void setDefultProperty(Object obj) {// Batch insertif (obj instanceof Map) {
			Map<String, Object> map = (Map<String, Object>) obj;
			Set<String> keys = map.keySet();
			for (String key : keys) {
				List<Object> list = (List<Object>) map.get(key);
				for (Object object : list) {
					setObjectProperty(object);
				}
				break;
			}
			return;
		}
		setObjectProperty(obj);
	}

	@Override
	public Object plugin(Object target) {
		return Plugin.wrap(target, this);
	}

	@Override
	public void setProperties(Properties properties) {
		System.out.println("init UUIDInterceptor");
	}

	private void setObjectProperty(Object obj) {
		PropertySet propertySet = new PropertySet(obj.getClass());
		Set<ProPertyStrategyMapper> propers = propertySet.getPropertys();
		if (propers == null || propers.isEmpty())
			return;
		for (ProPertyStrategyMapper pro : propers)
			try {
				Field findField = ReflectionUtils.findField(obj.getClass(), pro.getPropertyName());
				findField.setAccessible(true); //findField.set(obj, pro.getGenerator().generator()); ReflectionUtils.setField(findField, obj, pro.getGenerator().generator()); } catch (Exception e) { e.printStackTrace(); }}}Copy the code