通常的接收mq消息都会根据topic来确定怎么处理该条消息,还有tag用来细分topic消息。在代码中用if else来判断topic和tag然后进行相应的处理。本文将使用java自定义注解来映射相对应的类,处理mq消息,用来代替难看的if else判断,并整合spring
1. 自定义注解
package cn.cxnxs.mq.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target(value=ElementType.TYPE)
@Retention(value = RetentionPolicy.RUNTIME)
public @interface Topic {
String value();
}
package cn.cxnxs.mq.annotation;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target(value=ElementType.METHOD)
@Retention(value = RetentionPolicy.RUNTIME)
public @interface Tag {
String value();
}
用这两个注解分别对应mq消息的topic和tag
2.mq消息处理类
package cn.cxnxs.mq.handler;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import cn.cxnxs.entity.Book;
import cn.cxnxs.mq.annotation.Tag;
import cn.cxnxs.mq.annotation.Topic;
import cn.cxnxs.mq.pojo.MQContext;
import cn.cxnxs.service.BookService;
@Service
@Topic("h1")
public class Handler1{
@Autowired
private BookService bookServiceImpl;
@Tag("a")
public void queryBook(MQContext context) {
System.out.println("Handler1正在处理");
//List<Book> s= bookServiceImpl.findBookById(1);
//System.out.println(s);
}
}
package cn.cxnxs.mq.handler;
import org.springframework.stereotype.Service;
import cn.cxnxs.mq.MQHandler;
import cn.cxnxs.mq.annotation.Tag;
import cn.cxnxs.mq.annotation.Topic;
import cn.cxnxs.mq.pojo.MQContext;
@Service
@Topic("h1")
public class Handler2 implements MQHandler{
@Tag("*")
public void Handler2Message(MQContext context) {
System.out.println("Handler2正在处理");
}
}
这两个处理类分别映射了topic=h1,tag=a这条mq消息,tag支持模糊匹配,Handler2中@Tag(*)代表匹配所有h1的tag.
3.处理类调用类
package cn.cxnxs.mq;
import java.io.File;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;
import org.apache.log4j.Logger;
import org.springframework.web.context.ContextLoader;
import org.springframework.web.context.WebApplicationContext;
import cn.cxnxs.mq.annotation.Tag;
import cn.cxnxs.mq.annotation.Topic;
import cn.cxnxs.mq.pojo.MQContext;
/**
*
*
* <p>
* Title: MQHandlerManager
* </p>
*
* <p>
* Description:
* </p>
*
* @author potatomato
*
* @date 2018年12月17日
*/
public class MQHandlerManager {
private String packageName;
private boolean isShowContent = false;
private WebApplicationContext webApplicationContext = ContextLoader.getCurrentWebApplicationContext();;
private Logger logger=Logger.getLogger(getClass());
/**
* 执行类
*/
public void runHandler(MQContext context) {
logger.info("开始扫描包[" + packageName + "]");
List<String> classNames = getClassName(packageName);
for (String className : classNames) {
logger.info("MQ消息处理类:" + className);
}
if (isShowContent) {
logger.info("消息标签:" + context.toString());
logger.info("消息内容:" + context.getContent());
}
int count = 0;
for (String className : classNames) {
try {
Class<?> handler = (Class<?>) Class.forName(className);
if (handler.isAnnotationPresent(Topic.class)) {
count++;
Topic topic = (Topic) handler.getAnnotation(Topic.class);
String topicVal=topic.value();
if(topicVal.equals(context.getTopic())){
Method[] methods=handler.getMethods();
for (Method method:methods) {
if(method.isAnnotationPresent(Tag.class)){
Tag tag=method.getAnnotation(Tag.class);
String tagStr=tag.value();
String pattern = formatPattern(tagStr);
boolean isMatch = Pattern.matches(pattern, context.getTag());
if (isMatch) {
String handlerName = bgCap2low(handler.getSimpleName());
//从spring容器中获取对象
method.invoke(webApplicationContext.getBean(handlerName),context);
}
}
}
}
}
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (count <= 0) {
logger.info("消息" + context.toString() + "未匹配到处理类");
return;
}
}
/**
* 根据包名获取包下的所有类
*
* @param packageName
* @return
*/
private List<String> getClassName(String packageName) {
String filePath =this.getClass().getResource("/").getPath() + packageName.replace(".", "");
List<String> fileNames = getClassName(filePath, null);
return fileNames;
}
private List<String> getClassName(String filePath, List<String> className) {
List<String> myClassName = new ArrayList<String>();
File file = new File(filePath);
File[] childFiles = file.listFiles();
for (File childFile : childFiles) {
if (childFile.isDirectory()) {
myClassName.addAll(getClassName(childFile.getPath(), myClassName));
} else {
String childFilePath = childFile.getPath();
childFilePath = childFilePath.substring(childFilePath.indexOf("classes") + 9,
childFilePath.lastIndexOf("."));
childFilePath = childFilePath.replace("", ".");
myClassName.add(childFilePath);
}
}
return myClassName;
}
private String formatPattern(String str) {
str = str.replaceAll("*", ".*");
return str;
}
/**
* 把一个字符串的第一个字母小写
*/
private String bgCap2low(String fildeName) throws Exception {
byte[] items = fildeName.getBytes();
items[0] = (byte) ((char) items[0] - 'A' + 'a');
return new String(items);
}
/**
* @return the packageName
*/
public String getPackageName() {
return packageName;
}
/**
* @param packageName
* the packageName to set
*/
public void setPackageName(String packageName) {
this.packageName = packageName;
}
/**
* @return the isShowContent
*/
public boolean isShowContent() {
return isShowContent;
}
/**
* @param isShowContent
* the isShowContent to set
*/
public void setShowContent(boolean isShowContent) {
this.isShowContent = isShowContent;
}
}
将mq消息处理类放在固定的包里,扫描这个包中所有的类,循环判断类中是否用了@Topic注解,再执行这个类中@Tag注解的方法进行处理。
MQ消息封装类
package cn.cxnxs.mq.pojo;
public class MQContext {
private String topic;
private String tag;
private String content;
public MQContext(String topic,String tag,String content) {
this.topic=topic;
this.tag=tag;
this.content=content;
}
/**
* @return the topic
*/
public String getTopic() {
return topic;
}
/**
* @param topic the topic to set
*/
public void setTopic(String topic) {
this.topic = topic;
}
/**
* @return the tag
*/
public String getTag() {
return tag;
}
/**
* @param tag the tag to set
*/
public void setTag(String tag) {
this.tag = tag;
}
@Override
public String toString(){
return "[topic="+topic+",tag="+tag+"]";
}
/**
* @return the content
*/
public String getContent() {
return content;
}
/**
* @param content the content to set
*/
public void setContent(String content) {
this.content = content;
}
}
场景类
package cn.cxnxs.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import cn.cxnxs.entity.Book;
import cn.cxnxs.mq.MQHandlerManager;
import cn.cxnxs.mq.pojo.MQContext;
import cn.cxnxs.service.BookService;
@Controller
public class BookController {
@Autowired
private BookService bookServiceImpl;
@RequestMapping("/handler")
@ResponseBody
public String handler(){
MQHandlerManager manager=new MQHandlerManager();
manager.setPackageName("cn.cxnxs.mq.handler");
manager.setShowContent(true);
String topic="h1";
String tag="a";
String content="{name:'张三',age:20}";
MQContext context=new MQContext(topic, tag, content);
manager.runHandler(context);
return "OK";
}
}
因为反射调用方法的时候用webApplicationContext获取的对象,所以要使用这套代码事先得搭建好springmvc,场景类这里就写了一个controller