责任连模式

设计模式-责任连模式

常见设计模式分三大类:

1. 创建模式:
   工厂方法, 抽象工厂, 建造模式, 原型模式, 单例模式5种.
2. 结构模式:
   适配器模式, 桥梁模式, 代理模式, 装饰模式, 门面模式5种.
3. 行为模式:
   模板模式, 责任连模式, 迭代器模式, 观察者模式, 状态模式, 策略模式6种.

责任连模式

应用场景: 在业务线区分比较明显相对独立的复杂业务逻辑处理中,可以尝试使用责任连模式一环套一环.
意图: 避免请求发送者与接收者耦合在一起，让多个对象都有可能接收请求，将这些对象连接成一条链，并且沿着这条链传递请求，直到有对象处理它为止。

示例一:

1. Handler.java

   package comdata.synch.model;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-12-8.
    */
   public abstract class Handler {
   
       /**
        * 核心思想: 父类的引用指向子类的对象
        */
       private Handler handler;
   
       /**
        * 具体角色实现自己的处理逻辑
        *
        * @param role
        */
       public abstract void doWork(String role);
   
       public Handler getHandler() {
           return handler;
       }
   
       public void setHandler(Handler handler) {
           this.handler = handler;
       }
   }

2. RoleConfig.java

   package comdata.synch.model;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-12-8.
    */
   public class RoleConfig {
   
       public static final String TEACHER = "teacher";
       public static final String STUDENT = "student";
   
   }

3. StudentRequestHandler.java

   package comdata.synch.model;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-12-8.
    */
   public class StudentRequestHandler extends Handler {
   
       @Override
       public void doWork(String role) {
           if (RoleConfig.STUDENT.equals(role)) {
               System.out.println("在这里处理 * 同学 * 的请求");
           } else if (RoleConfig.TEACHER.equals(role) && null != getHandler()) {
               // 继续寻找处理者
               getHandler().doWork(role);
           }
       }
   }

4. TeacherRequestHandler.java

   package comdata.synch.model;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-12-8.
    */
   public class TeacherRequestHandler extends Handler {
   
       @Override
       public void doWork(String role) {
           if (RoleConfig.TEACHER.equals(role)) {
               System.out.println("在这里处理 * 老师 * 的请求");
           } else if (RoleConfig.STUDENT.equals(role) && null != getHandler()) {
               // 继续寻找处理者
               getHandler().doWork(role);
           }
       }
   }

5. AppTest.java

   package comdata.synch;
   
   
   import comdata.synch.model.Handler;
   import comdata.synch.model.RoleConfig;
   import comdata.synch.model.StudentRequestHandler;
   import comdata.synch.model.TeacherRequestHandler;
   import org.junit.Test;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-12-7.
    */
   public class AppTest {
   
       private Logger LOGGER = LoggerFactory.getLogger(AppTest.class);
   
       @Test
       public void testSingleton() {
           Handler teacher = new TeacherRequestHandler(), student = new StudentRequestHandler();
           teacher.setHandler(student);
           teacher.doWork(RoleConfig.TEACHER);
           teacher.doWork(RoleConfig.STUDENT);
       }
   
   }

运行结果:

在这里处理 * 老师 * 的请求
在这里处理 * 同学 * 的请求

Process finished with exit code 0

实例,我是这么处理我们的业务逻辑

说明,这里由于牵着线上业务所以代码只能贴出来一部分,我尽量贴.

1. 主入口, BaseHandler.java

   @Override
       protected String processHandler(Request request) {
           long startTime = System.currentTimeMillis();
   
           BaseHandler paramCheck = new ParamCheckHandler(), pageDetail = new PageDetailHandler(), page = new PageHandler(), doProcess = new DoProcessHandler();
           paramCheck.setDoWorker(pageDetail);
           pageDetail.setDoWorker(page);
           page.setDoWorker(doProcess);
   
           String result = "";
           CommonResult commonResult = new CommonResult();
   //        RequestValues values = new RequestValues(request);
   
           try {
               String requestURI = request.getRequestURI();
               switch (requestURI) {
                   case "/bigdata":
                       paramCheck.handleRequest(request, commonResult);
   //                    commonResult.setInfo(dataAction.getResultData(values));
                       break;
                   case "/bgsn":
                       SyncCassandraService cassandraService = new SyncCassandraService();
                       // 初始化数据
                       cassandraService.initSync();
   //                    cassandraService.findOmsBrandInfo();
                       break;
                   case "/favicon.ico":
                       break;
                   default:
                       paramCheck.handleRequest(request, commonResult);
                       break;
               }
   
           } catch (NumberFormatException e) { //数字格式错误
               commonResult.setCodeAndMessage(ApiMessage.SHU_ZI_GE_SHI_ERROR.code, ApiMessage.SHU_ZI_GE_SHI_ERROR.message);
               logService.printErrorLog(logService.getStackTrace(e));
           } catch (Exception e) {
               commonResult.setCodeAndMessage(ApiMessage.ERROR.code, ApiMessage.ERROR.message);
               logService.printErrorLog(logService.getStackTrace(e));
           } finally {
               long ms = System.currentTimeMillis() - startTime;
   
               if (null != commonResult.getInfo())
                   addRTLog(commonResult.getInfo().toString(), ms);
           }
   
           return responseResult(commonResult);
       }

2. BaseHandler.java

   package com.redstar.data.common.base;
   
   import com.redstar.data.api.dto.CommonResult;
   import org.eclipse.jetty.server.Request;
   
   import java.sql.SQLException;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-11-4.
    */
   public abstract class BaseHandler {
   
       /**
        * 后续责任对象
        */
       protected BaseHandler doWorker;
   
       /**
        * 流程处理
        *
        * @param request
        * @return
        */
       public abstract CommonResult handleRequest(Request request, CommonResult commonResult) throws SQLException;
   
       public void setDoWorker(BaseHandler doWorker) {
           this.doWorker = doWorker;
       }
   }

3. ParamCheckHandler.java

   package com.redstar.data.api.service.handler;
   
   import com.redstar.data.api.dto.CommonResult;
   import com.redstar.data.api.helper.BigDataApiHelper;
   import com.redstar.data.api.helper.WebAppConfig;
   import com.redstar.data.api.model.RequestParam;
   import com.redstar.data.common.base.BaseHandler;
   import com.redstar.data.common.base.BaseLogService;
   import com.redstar.data.common.exception.ApiMessage;
   import org.eclipse.jetty.server.Request;
   import org.eclipse.jetty.util.StringUtil;
   
   import java.sql.SQLException;
   import java.util.Set;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-11-4.
    * 参数检测
    */
   public class ParamCheckHandler extends BaseHandler {
   
       private BaseLogService baseLogService = BaseLogService.getInstance();
   
       /**
        * 参数验证
        *
        * @param request
        * @return
        */
       @Override
       public CommonResult handleRequest(Request request, CommonResult commonResult) throws SQLException {
           // 初始化参数
           RequestParam.newInstance().initParam(request);
   
           // 验证必传参数
           if (paramIsBlank(RequestParam.newInstance().fields, RequestParam.newInstance().owner, RequestParam.newInstance().operation, RequestParam.newInstance().datatypes, RequestParam.newInstance().ids)) {
               commonResult.setCodeAndMessage(ApiMessage.CAN_SHU_ERROR.code, ApiMessage.CAN_SHU_ERROR.message);
               baseLogService.printWarnLog(String.format("必传参数不能为空:%s", RequestParam.newInstance().toString()));
               return commonResult;
           }
   
           // ids长度验证, 防止
           if (WebAppConfig.App.requestIdsMaxLength < RequestParam.newInstance().idsSet.size()) {
               commonResult.setCodeAndMessage(ApiMessage.CAN_SHU_ERROR.code, ApiMessage.CAN_SHU_ERROR.message);
               baseLogService.printWarnLog("ids长度过长,最大支持500个");
               return commonResult;
           }
   
           // 验证参数合法性 - operation
           if (!WebAppConfig.App.checkOperation(RequestParam.newInstance().operation)) {
               commonResult.setCodeAndMessage(ApiMessage.CAN_SHU_ERROR.code, ApiMessage.CAN_SHU_ERROR.message);
               baseLogService.printWarnLog("业务放标识不合法");
               return commonResult;
           }
   
           // dataType验证, 此处区分大小写
           if (!RequestParam.newInstance().datatypesSet.contains(BigDataApiHelper.Datatypes.HISTORY) &&
                   !RequestParam.newInstance().datatypesSet.contains(BigDataApiHelper.Datatypes.NOW)) {
               commonResult.setCodeAndMessage(ApiMessage.CAN_SHU_ERROR.code, ApiMessage.CAN_SHU_ERROR.message);
               baseLogService.printWarnLog("dataType参数不对");
               return commonResult;
           }
   
           // 验证业务方fields
           if (!checkRequestFields()) {
               commonResult.setCodeAndMessage(ApiMessage.CAN_SHU_ERROR.code, ApiMessage.CAN_SHU_ERROR.message);
               baseLogService.printWarnLog("fields参数不对");
               return commonResult;
           }
   
           // fields中id必传
           if (!RequestParam.newInstance().fieldsSet.contains("id")) {
               RequestParam.newInstance().fieldsSet.add("id");
               RequestParam.newInstance().queryFieldsSet.add("id");
               BaseLogService.getInstance().printWarnLog("注意:id属性为请求必传字段请求未携带该字段,系统自动添加.");
           }
   
           commonResult.setOwner(RequestParam.newInstance().owner);
           commonResult.setOperation(RequestParam.newInstance().operation);
   
           return doWorker.handleRequest(request, commonResult);
       }
   
       /**
        * 验证请求属性是否合法
        *
        * @return false:不合法; true:合法
        */
       public boolean checkRequestFields() {
           if (RequestParam.newInstance().fieldsSet.size() > WebAppConfig.App.requestFieldsMaxLength) {
               baseLogService.printWarnLog(String.format("fields字段长度过长, 限制长度:%d ; 实际长度:%d, 实际内容:%s",
                       WebAppConfig.App.requestFieldsMaxLength,
                       RequestParam.newInstance().fieldsSet.size(),
                       RequestParam.newInstance().fields));
               return false;
           }
   
           StringBuilder errorField = new StringBuilder();
           Set<String> fieldsByOperation = WebAppConfig.App.getFieldsByOperation(RequestParam.newInstance().operation);
           for (String field : RequestParam.newInstance().fieldsSet) {
               if (!fieldsByOperation.contains(field))
                   errorField.append(field).append(",");
           }
   
           if (errorField.length() > 0) {
               errorField = errorField.deleteCharAt(errorField.length() - 1);
               baseLogService.printWarnLog(String.format("请求的fields字段中含有系统中没有配置的字段,请求owner为:%s ; 请求operation为:%s ; 非法fields为:%s ",
                       RequestParam.newInstance().owner,
                       RequestParam.newInstance().operation,
                       errorField.toString()));
           }
           return true;
       }
   
       /**
        * 检测必传参数是否为空
        *
        * @param fields    需要返回哪些值
        * @param owner     使用方名称
        * @param operation 调用接口业务类型
        * @param datatypes 需要返回的数据种类,数据种类包含两种（history/now）
        * @param ids       一次需要返回多个id的结果信息，用逗号隔开
        * @return
        */
       public boolean paramIsBlank(String fields, String owner, String operation, String datatypes, String ids) {
           return StringUtil.isBlank(fields) ||
                   StringUtil.isBlank(owner) ||
                   StringUtil.isBlank(operation) ||
                   StringUtil.isBlank(datatypes) ||
                   StringUtil.isBlank(ids);
       }
   }

4. CommonResult.java

   package com.redstar.data.api.dto;
   
   
   import com.redstar.data.common.exception.ApiMessage;
   
   import java.io.Serializable;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-9-8.
    * 通用结果
    */
   public class CommonResult implements Serializable {
   
       /**
        * 状态码
        */
       private int code = ApiMessage.SUCCESS.code;
   
       /**
        * 操作者
        */
       private String owner = null;
   
       /**
        * 业务类型
        */
       private String operation = null;
   
       /**
        * 描述
        */
       private String error = ApiMessage.SUCCESS.message;
   
       /**
        * 时间戳
        */
       private Long ts = System.currentTimeMillis();
   
       /**
        * 响应数据
        */
       private Object info = null;
   
       public CommonResult() {
       }
   
       public void setCodeAndMessage(int code, String error) {
           this.code = code;
           this.error = error;
       }
   
       public CommonResult(int code, String error, String owner, String operation, Object info) {
           this.code = code;
           this.error = error;
           this.owner = owner;
           this.operation = operation;
           this.info = info;
       }
   
       public int getCode() {
           return code;
       }
   
       public void setCode(int code) {
           this.code = code;
       }
   
       public String getOwner() {
           return owner;
       }
   
       public void setOwner(String owner) {
           this.owner = owner;
       }
   
       public String getOperation() {
           return operation;
       }
   
       public void setOperation(String operation) {
           this.operation = operation;
       }
   
       public String getError() {
           return error;
       }
   
       public void setError(String error) {
           this.error = error;
       }
   
       public Long getTs() {
           return ts;
       }
   
       public void setTs(Long ts) {
           this.ts = ts;
       }
   
       public Object getInfo() {
           return info;
       }
   
       public CommonResult setInfo(Object info) {
           this.info = info;
           return this;
       }
   
       @Override
       public String toString() {
           return "CommonResult{" +
                   "code=" + code +
                   ", owner='" + owner + '\'' +
                   ", operation='" + operation + '\'' +
                   ", error='" + error + '\'' +
                   ", ts=" + ts +
                   ", info=" + info +
                   '}';
       }
   }

5. ApiMessage.java

   package com.redstar.data.common.exception;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-8-9.
    */
   public enum ApiMessage {
   
       SUCCESS(ApiStatusCode.SUCCESS, "成功"),
       FAIL(ApiStatusCode.FAIL, "失败"),
       CAN_SHU_ERROR(ApiStatusCode.CAN_SHU_ERROR, "参数错误"),
       ZI_DUAN_WEI_KONG(ApiStatusCode.ZI_DUAN_WEI_KONG, "非空字段为空"),
       SHU_ZI_GE_SHI_ERROR(ApiStatusCode.SHU_ZI_GE_SHI_ERROR, "数字格式错误"),
       YAN_ZHENG_ERROR(ApiStatusCode.FAIL_JIAO_YAN_ERROR, "校验错误"),
       ERROR(ApiStatusCode.FAIL_SYSTEM_ERROR, "server error call admin"),
       GE_SHI_ERROR(ApiStatusCode.FAIL_GE_SHI_ERROR, "请求格式错误"),
       WU_QUAN_FANG_WEN(ApiStatusCode.FAIL_WU_QUAN_FANG_WEN, "无权访问该资源"),
       FAIL_NEED_LOGIN(ApiStatusCode.FAIL_NEED_LOGIN, "需要登录访问"),
       FAIL_ZI_YUAN_BU_CUN_ZAI(ApiStatusCode.FAIL_ZI_YUAN_BU_CUN_ZAI, "资源不存在"),
       WEI_SHOU_QUAN(ApiStatusCode.FAIL_WEI_SHOU_QUAN, "未授权");
   
       public int code;
       public String message;
   
       ApiMessage(int code, String message) {
           this.code = code;
           this.message = message;
       }
   
   
       public String getMessage(int code) {
           for (ApiMessage apiMessage : ApiMessage.values()) {
               if (code == apiMessage.getCode())
                   return message;
           }
           return "";
       }
   
       private int getCode() {
           return code;
       }
   
       private void setCode(int code) {
           this.code = code;
       }
   
       private void setMessage(String message) {
           this.message = message;
       }
   
   
   }

6. BaseLogService.java

   package com.redstar.data.common.base;
   
   import com.google.common.collect.Queues;
   import com.redstar.data.api.helper.PropertiesConfig;
   import org.apache.log4j.Logger;
   import org.apache.log4j.PropertyConfigurator;
   
   import java.util.concurrent.ArrayBlockingQueue;
   import java.util.concurrent.ExecutorService;
   import java.util.concurrent.Executors;
   
   /**
    * Created by xiehui1956(@)gmail.com on 16-11-8.
    * 日志操作
    */
   public class BaseLogService {
   
       /**
        * 创建线程数
        */
       private final static int rt_logTask = 30;
   
       /**
        * 日志队列
        */
       private ArrayBlockingQueue<String> blockingServiceQueue, blockingInfoQueue, blockingWarnQueue, blockingErrorQueue;
       private static BaseLogService logService;
   
       /**
        * 业务相关, 主要用于日志分析等作用
        */
       private Logger log_service = Logger.getLogger("RS_SERVICE");
   
       /**
        * 普通记录,用于记录系统日志
        */
       private Logger log_info = Logger.getLogger("RS_INFO");
   
       /**
        * 用于记录系统警告
        */
       private Logger log_warn = Logger.getLogger("RS_WARN");
   
       /**
        * 用于记录系统错误
        */
       private Logger log_error = Logger.getLogger("RS_ERROR");
   
   
       public static BaseLogService getInstance() {
           if (null == logService)
               logService = new BaseLogService();
           return logService;
       }
   
       private BaseLogService() {
           // 加载日志配置
           PropertyConfigurator.configure(PropertiesConfig.getConfigPath(PropertiesConfig.LOG4J));
           //日志打印
           this.blockingServiceQueue = Queues.newArrayBlockingQueue(15000);
           this.blockingInfoQueue = Queues.newArrayBlockingQueue(15000);
           this.blockingWarnQueue = Queues.newArrayBlockingQueue(15000);
           this.blockingErrorQueue = Queues.newArrayBlockingQueue(15000);
           ExecutorService executors = Executors.newFixedThreadPool(30);
           for (int i = 0; i < rt_logTask; i++) {
               // service
               executors.execute(new Runnable() {
                   @Override
                   public void run() {
                       String service = null;
                       while (true) {
                           try {
                               service = blockingServiceQueue.take();
                           } catch (InterruptedException e) {
                               service = null;
                           }
                           if (service == null) continue;
                           log_service.info(service);
                           service = null;
                       }
                   }
               });
   
               // info
               executors.execute(new Runnable() {
                   @Override
                   public void run() {
                       String info = null;
                       while (true) {
                           try {
                               info = blockingInfoQueue.take();
                           } catch (InterruptedException e) {
                               info = null;
                           }
                           if (info == null) continue;
                           log_info.info(info);
                           info = null;
                       }
                   }
               });
   
               // warn
               executors.execute(new Runnable() {
                   @Override
                   public void run() {
                       String warn = null;
                       while (true) {
                           try {
                               warn = blockingWarnQueue.take();
                           } catch (InterruptedException e) {
                               warn = null;
                           }
                           if (warn == null) continue;
                           log_warn.warn(warn);
                           warn = null;
                       }
                   }
               });
   
               // error
               executors.execute(new Runnable() {
                   @Override
                   public void run() {
                       String error = null;
                       while (true) {
                           try {
                               error = blockingErrorQueue.take();
                           } catch (InterruptedException e) {
                               error = null;
                           }
                           if (error == null) continue;
                           log_error.error(error);
                           error = null;
                       }
                   }
               });
           }
       }
   
       /**
        * 打印日志
        *
        * @param clazz
        * @param log
        */
       public void printServiceLog(Class clazz, String log) {
           StringBuffer logInfo = new StringBuffer();
           logInfo.append(" ").append(clazz.toString()).append(" ").append(log);
           blockingServiceQueue.offer(logInfo.toString());
       }
   
       /**
        * 打印info日志
        *
        * @param log
        */
       public void printInfoLog(String log) {
           blockingInfoQueue.offer(log);
       }
   
       /**
        * 打印warn日志
        *
        * @param log
        */
       public void printWarnLog(String log) {
           blockingWarnQueue.offer(log);
       }
   
       /**
        * 打印error日志
        *
        * @param log
        */
       public void printErrorLog(String log) {
           blockingErrorQueue.offer(log);
       }
   
       /**
        * 异常信息
        *
        * @param ex
        * @return
        */
       public String getStackTrace(Exception ex) {
           String err = "";
           StackTraceElement[] emArr = ex.getStackTrace();
           err += "\n" + ex.toString() + "\n";
           for (int i = 0; i < emArr.length; i++) {
               err += emArr[i].toString() + "\n";
           }
           return err;
       }
   
   }

说明: 这些代码应该可以说明问题了. 责任连的设置在第一个方法中”BaseHandler paramCheck = new ParamCheckHandler()”这里.
以上.