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Section 7 Data Dictionary: hash followed by Daewoo redis ------- directory post

2022-07-24 17:46:00 【51CTO】

One 、 Heart method

Redis hash It's a string Type of field and value Mapping table , Of course, here it is string Type refers to the string after data serialization .

Common business scenarios are to cache key value pairs . Let me give you an example , There are thirty students in one class , Every student has a unique student number , Then you can use Redis Of hash For storage . Class as a sign of these students a common (key), In other words, you can find this group of students through this class . In this group of students , Every student (value) There is also a unique logo , For example, student ID (field) To distinguish them .

data structure ： key class ------ field Student number ----- value Specific students

therefore , Immediately think of using Hash Cached mental method ： There is an identifier that can filter out a set of data key. In this group of filtered data , Each data itself has a unique identifier field, To identify it value. Data with such characteristics , have access to Redis Of hash As caching .

Common business scenarios

（ One ） Cache dictionary table . A simple dictionary table , Refer to the following figure .type Field as key, code Field as field, The corresponding records serve as value.

（ Two ） Cache normal tables . Table name (key) Used to filter a set of data （ All the data in this table ）, The primary key of the record ID(field) As each data (value) Unique identifier of .

Two 、 Use Hash Example

Pages often have key value pairs similar to drop-down boxes . such as , Color 、 Gender . These data will be stored in the dictionary table of the system .

I consider when the system goes online , Load all the data of the dictionary table into Redis The cache . And every time you operate the dictionary , Update cache .

Section 7 The data dictionary ：Hash Hash Follow Daewoo Redis-------- Catalogue post _redis

For example, there is the dictionary table above . Suppose there is a management page , Add a record , If the operation of the dictionary table is successful , Then query all the data in this dictionary table , Add it to Redis The cache . for example color As type, Can identify the color category .sex As type, Can express the gender category .

The data structure is as follows ：

Key ----------------- field --------------------- value

Custom constant type Field Multiple records of corresponding types List<Parameter>

       
       public 
       
       Integer 
       
       addParameter(
       
       Parameter 
       
       parameter) {
       
       parameter.
       
       setId(
       
       null);
       
       mapper.
       
       insertSelective(
       
       parameter);
       
       if (
       
       parameter.
       
       getId() 
       
       > 
       
       0) {
       
       // Real time synchronous cache 
       
       cacheAllConfig();
       
        }
       
       return 
       
       parameter.
       
       getId();
       
    }
       
       private 
       
       void 
       
       cacheAllConfig() {
       
       // Clear the last cache 
       
       redisTemplate.
       
       delete(
       
       Constant.
       
       MAP_KEY);
       
       HashOperations
       
       <
       
       String, 
       
       String, 
       
       List
       
       <
       
       Parameter
       
       >> 
       
       hashOperations 
       
       = 
       
       this.
       
       getHashOperations();
       
       // Get all the data of the dictionary table 
       
       List
       
       <
       
       Parameter
       
       > 
       
       parameters 
       
       = 
       
       mapper.
       
       getAll();
       
       // Dictionary of type As a unique identifier , Identify a set of data 
       
       for (
       
       Parameter 
       
       parameter : 
       
       parameters) {
       
       // Corresponding API command  Hget key field
       
       List
       
       <
       
       Parameter
       
       > 
       
       parametersList 
       
       = 
       
       hashOperations.
       
       get(
       
       Constant.
       
       MAP_KEY, 
       
       parameter.
       
       getType());
       
       if (
       
       parametersList 
       
       == 
       
       null 
       
       || 
       
       parametersList.
       
       isEmpty()) {
       
       // If the added category parameter is not in the cache , Then create a List
       
       parametersList 
       
       = 
       
       new 
       
       ArrayList
       
       <>();
       
            }
       
       parametersList.
       
       add(
       
       parameter);
       
       hashOperations.
       
       put(
       
       Constant.
       
       MAP_KEY, 
       
       parameter.
       
       getType(), 
       
       parametersList);
       
        }
       
    }
       
       private 
       
       HashOperations 
       
       getHashOperations() {
       
       return 
       
       redisTemplate.
       
       opsForHash();
       
    }
      
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How to get it ？

       
       public 
       
       Map
       
       <
       
       String, 
       
       List
       
       <
       
       Parameter
       
       >> 
       
       getParameter() {
       
       HashOperations
       
       <
       
       String, 
       
       String, 
       
       List
       
       <
       
       Parameter
       
       >> 
       
       hashOperations 
       
       = 
       
       getHashOperations();
       
       //Hash Of entries command , obtain key All the corresponding  field - value
       
       // there field Namely  type, value Namely type Corresponding multiple records 
       
       Map
       
       <
       
       String, 
       
       List
       
       <
       
       Parameter
       
       >> 
       
       result 
       
       = 
       
       hashOperations.
       
       entries(
       
       Constant.
       
       MAP_KEY);
       
       return 
       
       result;
       
    }
       
       public 
       
       List
       
       <
       
       Parameter
       
       > 
       
       getParameterByType(
       
       final 
       
       String 
       
       type) {
       
       HashOperations
       
       <
       
       String, 
       
       String, 
       
       List
       
       <
       
       Parameter
       
       >> 
       
       hashOperations 
       
       = 
       
       getHashOperations();
       
       // The basis of get command  hget key filed 
       
       List
       
       <
       
       Parameter
       
       > 
       
       result 
       
       = 
       
       hashOperations.
       
       get(
       
       Constant.
       
       MAP_KEY, 
       
       type);
       
       return 
       
       result;
       
    }
       
       private 
       
       HashOperations 
       
       getHashOperations() {
       
       return 
       
       redisTemplate.
       
       opsForHash();
       
    }
      
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I'll add a dictionary table data first , Trigger the above load cache operation , According to type, Load in Redis In cache .

Section 7 The data dictionary ：Hash Hash Follow Daewoo Redis-------- Catalogue post _ cache _02

Then request all dictionary table data on the page , Of course, all these data come from Redis in , Can avoid and DB Interact .

Section 7 The data dictionary ：Hash Hash Follow Daewoo Redis-------- Catalogue post _redis_03

Final test , according to type To get the specified dictionary table data .

Section 7 The data dictionary ：Hash Hash Follow Daewoo Redis-------- Catalogue post _ cache _04

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当前位置：网站首页>Section 7 Data Dictionary: hash followed by Daewoo redis ------- directory post

Section 7 Data Dictionary: hash followed by Daewoo redis ------- directory post

One 、 Heart method

Two 、 Use Hash Example

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