if else 代码优化实战

前言
介绍几种方法，不使用if else语句也能做条件判断。

一：使用枚举

首先定义一个公用接口 RoleOperation，表示不同角色所能做的操作

package com.gavin.enums;

public interface RoleOperation {

    //定义一个方法来表示某个角色，有哪些op（操作）权限
    String op();
}

接下来我们将不同角色的情况全部交由枚举类来做，定义一个不同角色有不同权限的枚举类

package com.gavin.enums;

public enum RoleEnum implements RoleOperation{

    //定义一个超级管理员的操作权限（有AAA的操作权限）
    ROLE_ROOT_ADMIN {
        @Override
        public String op() {
            return "ROLE_ROOT_ADMIN:has AAA permission";
        }
    },

    //定义一个订单管理员的操作权限（有BBB的操作权限）
    ROLE_ORDER_ADMIN {
        @Override
        public String op() {
            return "ROLE_ORDER_ADMIN:has BBB permission";
        }
    },

    //定义一个普通用户的操作权限（有CCC的操作权限）
    ROLE_NORMAL {
        @Override
        public String op() {
            return "ROLE_NORMAL:has CCC permission";
        }
    };
}

一行代码,if/else也灰飞烟灭了

package com.gavin.enums;

public class JudgeRole {

    public static void main(String[] args) {
        String roleName = "ROLE_ROOT_ADMIN";
        String operation = RoleEnum.valueOf(roleName).op();
        System.out.println("操作权限：" + operation);
    }
}

以后扩充条件，只需要去枚举类中加代码即可
。

二：使用工厂模式

不同分支做不同的事情，很明显就提供了使用工厂模式的契机，我们只需要将不同情况单独定义好，然后去工厂类里面聚合即可。

首先，针对不同的角色，单独定义其业务类：

package com.gavin.factory;

import com.gavin.enums.RoleOperation;

public class RootAdminRole implements RoleOperation {

    //定义属性值
    private String roleName;

    //有参构造方法
    public RootAdminRole (String roleName) {
        this.roleName = roleName;
    }

    //实现RoleOperation接口，然后重写接口方法
    @Override
    public String op() {
        return roleName + " has AAA permission";
    }
}

package com.gavin.factory;

import com.gavin.enums.RoleOperation;

public class OrderAdminRole implements RoleOperation {

    //定义属性值
    private String roleName;

    //有参构造方法
    public OrderAdminRole(String roleName) {
        this.roleName = roleName;
    }

    //实现RoleOperation接口，然后重写接口方法
    @Override
    public String op() {
        return roleName + " has BBB permission";
    }
}

package com.gavin.factory;

import com.gavin.enums.RoleOperation;

public class NormalRole implements RoleOperation {

    //定义属性值
    private String roleName;

    //有参构造方法
    public NormalRole(String roleName) {
        this.roleName = roleName;
    }

    //实现RoleOperation接口，然后重写接口方法
    @Override
    public String op() {
        return roleName + " has CCC permission";
    }
}

接下来再写一个工厂类 RoleFactory对上面不同角色进行聚合：

package com.gavin.factory;

import com.gavin.enums.RoleOperation;

import java.util.HashMap;
import java.util.Map;

public class RoleFactory {

    //定义一个Map集合，使用static修饰后会与类一起加载进堆中
    //加载顺序早于没有用static修饰的常量、变量和方法
    static Map<String, RoleOperation> map = new HashMap<>();

    //定义一个静态方法进行初始化
    static {
        map.put("ROLE_ROOT_ADMIN", new RootAdminRole("ROLE_ROOT_ADMIN"));
        map.put("ROLE_ORDER_ADMIN", new OrderAdminRole("ROLE_ORDER_ADMIN"));
        map.put("ROLE_NORMAL", new NormalRole("ROLE_NORMAL"));
    }

    //定义一个获取操作权限的静态方法，提供给其它方法调用
    public static RoleOperation getOp(String roleName) {
        return map.get(roleName);
    }
}

接下来借助上面这个工厂，业务代码调用也只需一行代码：

package com.gavin.factory;

public class JudgeRole02 {

    public static void main(String[] args) {
        /**
         * 使用工厂模式实现思路，先调用RoleFactory类中的getOp方法，找到对应的角色对象中的权限
         * 再调用该对象中的op()方法获取角色的权限信息
         */
        String roleName = "ROLE_ROOT_ADMIN";
        String operation = RoleFactory.getOp(roleName).op();
        System.out.println("操作权限：" + operation);
    }
}

扩展条件也很容易，只需要增加新代码，而不需要动以前的业务代码，非常符合“开闭原则”。

三：使用策略模式

策略模式和工厂模式写起来其实区别也不大！

在上面工厂模式代码的基础上，按照策略模式的指导思想，我们也来创建一个所谓的策略上下文类，这里命名为 RoleContext：

package com.gavin.strategy;

import com.gavin.enums.RoleOperation;

public class RoleContext {

    //定义可更换的策略，传入不同的策略对象，业务即相应变化
    private RoleOperation roleOperation;

    public RoleContext(RoleOperation roleOperation) {
        this.roleOperation = roleOperation;
    }

    //定义获取角色权限的方法
    public String execute() {
        return roleOperation.op();
    }
}

很明显上面传入的参数 operation就是表示不同的“策略”。我们在业务代码里传入不同的角色，即可得到不同的操作结果：

package com.gavin.strategy;

import com.gavin.enums.RoleOperation;
import com.gavin.factory.NormalRole;
import com.gavin.factory.OrderAdminRole;
import com.gavin.factory.RootAdminRole;

public class JudgeRole03 {

    public static void main(String[] args) {
        JudgeRole03 judgeRole03 = new JudgeRole03();
        String operation = judgeRole03.judge(new RootAdminRole("ROLE_ROOT_ADMIN"));
        System.out.println("operation=" + operation);
        String operation2 = judgeRole03.judge(new OrderAdminRole("ROLE_ORDER_ADMIN"));
        System.out.println("operation2=" + operation2);
        String operation3 = judgeRole03.judge(new NormalRole("ROLE_NORMAL"));
        System.out.println("operation3=" + operation3);
    }

    //定义一个方法来调用RoleContext对象中获取角色权限的execute()方法
    public String judge(RoleOperation roleOperation) {
        RoleContext roleContext = new RoleContext(roleOperation);
        return roleContext.execute();
    }
}

几种常用的if else语句的优化方法，写代码前还是得多思考一番，考虑是否有更具可扩展性的写法！

四：实战应用

用枚举扩展实战

public class PublicEvent extends ProcessPubicListener {


    /**
     * 全局流程监听事件
     * @param eventName
     * @param taskInstance
     * @param processExecutionContext
     */
    @Override
    public void call(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        PublicOperationEnum.valueOf(eventName).pOperation(eventName,taskInstance,processExecutionContext);
        System.out.println("操作流程是：" + "------======------   ------======------");
    }

}

定义接口:

public interface ProcessOperation {

    //定义一个方法来表示某个流程，有哪些（操作）
    void pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext);
}

定义枚举:

public enum PublicOperationEnum implements ProcessOperation {

    PROCESS_BEFORE_RESTART{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processBeforeRestart(eventName,processExecutionContext);
        }
    },

    TASK_DELEGATE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.taskDelegate(eventName,taskInstance,processExecutionContext);
        }
    },

    TASK_READ{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.taskRead(eventName,taskInstance);
        }
    },

    PROCESS_CREATE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processCreate(eventName,processExecutionContext);
        }
    },

    TASK_CREATE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.taskCreate(eventName,taskInstance,processExecutionContext);
        }
    },

    PROCESS_BEFORE_DELETE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processBeforeDelete(eventName,taskInstance,processExecutionContext);
        }
    },

    TASK_DELETE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.taskDelete(eventName,taskInstance,processExecutionContext);
        }
    },

    PROCESS_DELETE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processDelete(eventName,taskInstance,processExecutionContext);
        }
    },

    PROCESS_REMIND{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processRemind(eventName,taskInstance,processExecutionContext);
        }
    },

    PROCESS_UPDATE{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processUpdate(eventName,taskInstance);
        }
    },

    PROCESS_RESTART{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processRestart(eventName,taskInstance,processExecutionContext);
        }
    },

    PROCESS_EVENT_END{
        @Override
        public void  pOperation(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
            ProcessTask.processEventEnd(eventName,taskInstance,processExecutionContext);
        }
    };

}

定义流程任务：

public class ProcessTask {


    public static void  processEventEnd(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到[" + eventName + "]" + taskInstance);
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--[" + eventName + "]" +"，结束！");
    }

    public   static void  processRestart(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到：流程重置事件[" + eventName + "]" + taskInstance);
        System.out.println("此时，任务实例是空的！");
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--流程重置，结束！");
    }

    public  static void processUpdate(String eventName, TaskInstance taskInstance) {
        System.out.println("--我监听到：流程修改事件[" + eventName + "]" + taskInstance);
        System.out.println("此时，任务实例，流程实例都是是空的！");
        System.out.println("--流程修改，结束！");
    }

    public  static void processRemind(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到：流程催办[" + eventName + "]" + taskInstance);
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--流程催办，结束！");
    }

    public  static void processDelete(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到：流程实例删除后[" + eventName + "]" + taskInstance);
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--流程实例删除后，结束！");
    }

    public  static void taskDelete(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到：任务删除[" + eventName + "]" + taskInstance);
        if(taskInstance==null){//当任务实例为空的时候是真删除，像流程撤销、流程实例删除
            List<HistoryTaskInstance> deleteTaskList = (List<HistoryTaskInstance> )processExecutionContext.getParameter("taskList");
            System.out.println("输出TASK_DELETE删除的已办任务实例(此处获取的删除任务列表是流程撤消前和流程删除前获取的总和)");
            for(TaskInstance htask:deleteTaskList){
                System.out.println("删除taskInstID为::"+htask.getId());
            }
            System.out.println("此时是真删除，像流程撤销、流程实例删除，流程实例、任务实例都是空的！");
        }else{//当任务实例是非空，那么就是假删除，像流程提交
            String processInstID = processExecutionContext.getProcessInstance().getId();
            String processState = processExecutionContext.getProcessInstance().getControlState();
            String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
            System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
            System.out.println("此时是假删除，像流程提交，流程实例、任务实例都是空的！");
        }
        System.out.println("--任务删除，结束！");
    }

    public  static void processBeforeDelete(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到：流程实例删除前[" + eventName + "]" + taskInstance);
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        List<TaskInstance> tasks = SDK.getTaskQueryAPI().processInstId(processInstID).list();
        System.out.println("输出删除前要删除的任务实例：");
        for(TaskInstance task:tasks){
            System.out.println("删除taskInstID为::"+task.getId());
        }
        List<HistoryTaskInstance> Historytasks  = SDK.getHistoryTaskQueryAPI().processInstId(processInstID).list();
        System.out.println("输出删除前要删除的已办任务实例");
        for(TaskInstance htask:Historytasks){
            System.out.println("删除taskInstID为::"+htask.getId());
        }
        System.out.println("流程实例：："+processInstID+"::状态："+processState);
        System.out.println("--流程实例删除前,结束！");
    }

    public  static void taskCreate(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到:任务实例创建[" + eventName + "]" + taskInstance);
        System.out.println("任务节点信息为："+taskInstance.getActivityDefId());
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--任务实例创建，结束！");
    }

    public  static void processCreate(String eventName, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到流程实例创建[" + eventName + "]" );
        System.out.println("此时，任务实例是空的！");
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--流程实例创建，结束！");
    }

    public  static void taskRead(String eventName, TaskInstance taskInstance) {
        System.out.println("--我监听到：任务阅读[" + eventName + "]" + taskInstance);
        System.out.println("--任务阅读，结束！");
    }

    public  static void taskDelegate(String eventName, TaskInstance taskInstance, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到:任务转办[" + eventName + "]" + taskInstance);
        System.out.println("转办人："+taskInstance.getOwner());
        String processInstID = processExecutionContext.getProcessInstance().getId();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        Map<String,Object> parameters = processExecutionContext.getParameters();
        if(parameters.containsKey("OLD_TASKINST")){
            //获取转办前的执行人
            TaskInstance oldtaskinst = (TaskInstance) parameters.get("OLD_TASKINST");
            System.out.println("接收人："+oldtaskinst.getTarget());
        }
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--任务转办，结束！");
    }

    public static void processBeforeRestart(String eventName, ProcessExecutionContext processExecutionContext) {
        System.out.println("--我监听到：流程撤销前[" + eventName + "]");
        System.out.println("此时，任务实例是空的！");
        String processInstID = processExecutionContext.getProcessInstance().getId();
        System.out.println("流程实例ID为["+processInstID+"]");
        processExecutionContext.getProcessInstance().getControlState();
        String processState = processExecutionContext.getProcessInstance().getControlState();
        List<TaskInstance> tasks = SDK.getTaskQueryAPI().processInstId(processInstID).list();
        System.out.println("输出撤消前要删除的待办任务实例");
        for(TaskInstance task:tasks){
            System.out.println("删除taskInstID为::"+task.getId());
        }
        List<HistoryTaskInstance> Historytasks  = SDK.getHistoryTaskQueryAPI().processInstId(processInstID).list();
        System.out.println("输出撤消前要删除的已办任务实例");
        for(TaskInstance htask:Historytasks){
            System.out.println("删除taskInstID为::"+htask.getId());
        }
        String processTitle=processInstID+processExecutionContext.getProcessInstance().getTitle();
        System.out.println("流程实例：："+processTitle+"["+processInstID+"]::状态："+processState);
        System.out.println("--流程撤销前，结束！");
    }
    
 
}