注解将Java 对象转Apama的event

    项目中需要整合web框架和apama平台，用Apama提供的engineClient互相链接。在交互时将java类封装成event会非常麻烦，目前知道两种办法：

    1、拼接成字符串：将消息拼成字符串

String eventStr = "com.event.TestEvent('field1','field2','field3')";
Event event = new Event(eventStr);

    2、用Event类包装

EventType eventType = new EventType("com.event.TestEvent")
eventType.addField('field1name', StringFieldType.TYPE);
eventType.addField('field2name', StringFieldType.TYPE);
eventType.addField('field3name', StringFieldType.TYPE);

Event event = new Event(eventType);
event.setField('field1name', field1);
event.setField('field2name', field2);
event.setField('field3name', field3);

每一次交互都需要用这样的方法处理一遍，代码容易出错也不易维护，就用了注解方式处理

注解：EventField

package com.test.common.apama;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 用于标记变量在EVENT中的名称及类型
 * @Author: ZH
 * @Date: Created on 16:28 2018/3/13.
 */
@Documented
@Inherited
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.FIELD})//次注解作用于类和字段上
public @interface EventField {
    /**
     * 获取名称
     * @return
     */
    String name() default "";
}

注解处理类ApamaUtils：

package com.test.common.apama;

import com.apama.event.Event;
import com.apama.event.parser.BooleanFieldType;
import com.apama.event.parser.DictionaryFieldType;
import com.apama.event.parser.EventType;
import com.apama.event.parser.FloatFieldType;
import com.apama.event.parser.IntegerFieldType;
import com.apama.event.parser.SequenceFieldType;
import com.apama.event.parser.StringFieldType;
import com.finesys.common.utils.StringUtils;

import java.lang.reflect.Field;

/**
 * APAMA工具类
 *
 * @Author: ZH
 * @Date: Created on 15:59 2018/3/13.
 */
public class ApamaUtils {
    /***
     * 根据类获取EventType-只能处理int、String、double、float、char、int[]、double[]、float[]、string[]、boolean[]、map<string,string>
     * @param packageName
     * @param clazz
     * @return
     */
    public static EventType getEventTypeByClass(String packageName, Class clazz) {
        EventField packageInfo = (EventField) clazz.getAnnotation(EventField.class);
        if (StringUtils.isEmpty(packageName) && packageInfo != null) {
            packageName = packageInfo.name();
        }
        if (StringUtils.isEmpty(packageName)) {
            throw new NullPointerException("未获取packageName");
        }
        EventType eventType = new EventType(packageName);
        Field[] fields = clazz.getDeclaredFields();
        if (fields != null && fields.length > 0) {
            for (Field field : fields) {
                //解析注解
                EventField fieldType = field.getAnnotation(EventField.class);
                if (fieldType == null) {
                    continue;
                }
                //string类型
                String simpleName = field.getType().getSimpleName();
                //获取变量名称
                String name = field.getName();
                if (StringUtils.isNotEmpty(fieldType.name())) {
                    name = fieldType.name();
                }
                if (simpleName.equals("String") || simpleName.equals("char")) {
                    eventType.addField(name, StringFieldType.TYPE);
                    continue;
                }
                //int类型
                if (simpleName.equals("int")) {
                    eventType.addField(name, IntegerFieldType.TYPE);
                    continue;
                }
                //double类型
                if (simpleName.equals("double") || simpleName.equals("float")) {
                    eventType.addField(name, FloatFieldType.TYPE);
                    continue;
                }
                //boolean类型
                if (simpleName.equals("boolean")) {
                    eventType.addField(name, BooleanFieldType.TYPE);
                    continue;
                }
                //String[]类型数组
                if (simpleName.equals("String[]") ) {
                    eventType.addField(name, new SequenceFieldType(StringFieldType.TYPE));
                    continue;
                }
                //int[]类型数组
                if (simpleName.equals("int[]") ) {
                    eventType.addField(name, new SequenceFieldType(IntegerFieldType.TYPE));
                    continue;
                }
                //double[]类型数组或者float[]类型
                if (simpleName.equals("double[]")||simpleName.equals("float[]") ) {
                    eventType.addField(name, new SequenceFieldType(FloatFieldType.TYPE));
                    continue;
                }
                //boolean[]类型数组
                if (simpleName.equals("boolean[]")||simpleName.equals("float[]") ) {
                    eventType.addField(name, new SequenceFieldType(BooleanFieldType.TYPE));
                    continue;
                }
                //map类型，只支持String\String类型
                if (simpleName.equals("Map") ) {
                    eventType.addField(name, new DictionaryFieldType(StringFieldType.TYPE,StringFieldType.TYPE));
                    continue;
                }

            }
        }
        return eventType;
    }

    public static Event getEventByObject(Object object) {
        return getEventByObject(null, object);
    }

    /**
     * 获取指定对象的Event
     * @param packageName
     * @param object
     * @return
     */
    public static Event getEventByObject(String packageName, Object object) {
        Event event = new Event(getEventTypeByClass(packageName,object.getClass()));
        Field[] fields = object.getClass().getDeclaredFields();
        if (fields != null && fields.length > 0) {
            for (Field field : fields) {
                //解析注解
                EventField eventField = field.getAnnotation(EventField.class);
                if (eventField == null) {
                    continue;
                }
                //修改权限
                boolean accessFlag = field.isAccessible();
                field.setAccessible(true);
                Object o;
                try {
                    //获取变量值
                    o = field.get(object);
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                    continue;
                }
                String name = field.getName();
                if (StringUtils.isNotEmpty(eventField.name())) {
                    name = eventField.name();
                }
                if (StringUtils.isNotEmpty(name) && o != null) {
                    event.setField(name, o);
                }
                //还原权限
                field.setAccessible(accessFlag);
            }
        }
        return event;
    }
   @EventField(name = "com.text.Test")
   static class Test {
        @EventField(name = "String")
        public String StringName;
        @EventField
        public int intName;
        @EventField()
        private float floatName;
    }
}

在使用注解时变量声明顺序应该和event中顺序一致，否则赋值会混乱。考虑在注解中加一个排序字段。