需求：Trigger代码里面，肯定是不建议写具体的逻辑代码，那么我们就需要一个TriggerHander的示例

下面是一个所有Object都可以继承的TriggerHander的接口代码

public interface TriggerHandler {
    void beforeInsert(List<SObject> newRecords);
    void beforeUpdate(List<SObject> oldRecords, List<SObject> newRecords, Map<ID, SObject> oldRecordMap, Map<ID, SObject> newRecordMap);
    void beforeDelete(List<SObject> oldRecords, Map<ID, SObject> oldRecordMap);
    void afterInsert(List<SObject> newRecords, Map<ID, SObject> newRecordMap);
    void afterUpdate(List<SObject> oldRecords, List<SObject> newRecords, Map<ID, SObject> oldRecordMap, Map<ID, SObject> newRecordMap);
    void afterDelete(List<SObject> oldRecords, Map<ID, SObject> oldRecordMap);
    void afterUndelete(List<SObject> newRecords, Map<ID, SObject> newRecordMap);
}

下面是一个Account的TriggerHandler继承TriggerHandler 

在下面的示例代码里面，大家可能注意到了AccountTriggerHelper的存在。

这个我们后面会讲到，我们把具体的逻辑代码，可以全部放到这个AccountTriggerHelper 里面。

public without sharing class AccountTriggerHandler implements TriggerHandler {
    private boolean triggerIsExecuting;
    private integer triggerSize;
    public AccountTriggerHelper helper;
    public AccountTriggerHandler(boolean triggerIsExecuting, integer triggerSize) {
        this.triggerIsExecuting = triggerIsExecuting;
        this.triggerSize = triggerSize;
        this.helper = new AccountTriggerHelper();
    }
    public void beforeInsert(List<Account> newAccounts) {
        // helper.doTask1();
        // helper.doTask2();
    }
    public void beforeUpdate(List<Account> oldAccounts, List<Account> newAccounts, Map<ID, SObject> oldAccountMap, Map<ID, SObject> newAccountMap) {
        // helper.doTask3();
        // helper.doTask4();
    }
    public void beforeDelete(List<Account> oldAccounts, Map<ID, SObject> oldAccountMap) {
        // helper.doTask5();
        // helper.doTask1();
    }
    public void afterInsert(List<Account> newAccounts, Map<ID, SObject> newAccountMap) {
        // helper.doTask2();
        // helper.doTask3();
    }
    public void afterUpdate(List<Account> oldAccounts, List<Account> newAccounts, Map<ID, SObject> oldAccountMap, Map<ID, SObject> newAccountMap) {
        // helper.doTask4();
        // helper.doTask5();
    }
    public void afterDelete(List<Account> oldAccounts, Map<ID, SObject> oldAccountMap) {
        // helper.doTask3();
        // helper.doTask1();
    }
    public void afterUndelete(List<Account> newAccounts, Map<ID, SObject> newAccountMap) {
        // helper.doTask4();
        // helper.doTask2();
    }
}

这里就是Helper的示例代码。我们可以把所有的任务都拆分开，分别写在不同的方法里面。方便AccountTriggerHandler调用。

public without sharing class AccountTriggerHelper {
    public AccountTriggerHelper() {
        System.debug('Inside AccountTriggerHelper Constructor');
    }
    public void doTask1() {
        System.debug('Inside Task 1');
    }
    public void doTask2() {
        System.debug('Inside Task 2');
    }
    public void doTask3() {
        System.debug('Inside Task 3');
    }
    public void doTask4() {
        System.debug('Inside Task 4');
    }
    public void doTask5() {
        System.debug('Inside Task 5');
    }
}

本文参考到了下面的链接文章。

 https://www.salesforceben.com/the-salesforce-trigger-handler-framework/