springboot项目创建笔记19 之《整合redis》

1、pom文件添加redis启动器

<!--redis启动器-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<!-- 连接池 -->
<dependency>
	<groupId>org.apache.commons</groupId>
	<artifactId>commons-pool2</artifactId>
</dependency>

2、application-dev.yml添加配置

spring:
    redis:
        database: 0
        host: 192.168.102.63
        port: 10079
        password: 123_12345678^_00
        lettuce:
            pool:
                max-active: 16 #连接池最大连接数（使用负值表示没有限制）
                max-idle: 8 #连接池中的最大空闲连接
                max-wait: 100ms #连接池最大阻塞等待时间（使用负值表示没有限制）
                min-idle: 4 #连接池中的最小空闲连接

3、配置RedisTemplate序列化器
RedisTemplate默认使用JdkSerializationRedisSerializer序列化，缺点是：
1）实体类必须实现Serializable接口
2）序列化后存入redis为十六进制字符\x0c这样的，可读性差
3）占用空间特别大
在包com.example.config下，添加RedisTemplateConfig.java

package com.example.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.GenericToStringSerializer;

@Configuration
public class RedisTemplateConfig {
	@Bean
	public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
		RedisTemplate<Object, Object> redisTemplate = new RedisTemplate<>();
		redisTemplate.setConnectionFactory(redisConnectionFactory);
		// 创建一个json的序列化对象
		GenericJackson2JsonRedisSerializer genericJackson2JsonRedisSerializer = new GenericJackson2JsonRedisSerializer();
		// 设置key的序列化方式为String
		redisTemplate.setKeySerializer(new GenericToStringSerializer<>(Object.class));
		// 设置value的序列化方式为json
		redisTemplate.setValueSerializer(genericJackson2JsonRedisSerializer);
		// 设置hashKey的序列化方式为String
		redisTemplate.setHashKeySerializer(new GenericToStringSerializer<>(Object.class));
		// 设置hashValue的序列化方式为json
		redisTemplate.setHashValueSerializer(genericJackson2JsonRedisSerializer);
		// 设置支持事务
		redisTemplate.setEnableTransactionSupport(true);
		redisTemplate.afterPropertiesSet();
		return redisTemplate;
	}
}

4、建立测试Controller
在包com.example.web下，添加RedisController.java

package com.example.web;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.create.entity.TblTeacherInf;
import com.example.service.TeacherService;

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;

@Api(description = "redis测试接口")
@RestController
@RequestMapping("/redis")
public class RedisController {
	
	@Autowired
	TeacherService teacherService;

	@ApiOperation("增加一条记录")
	@GetMapping("/insert")
	public boolean insert(TblTeacherInf teacher) {
		return teacherService.insert(teacher);
	}
	
	@ApiOperation("修改一条记录")
	@GetMapping("/update")
	public boolean update(TblTeacherInf teacher) {
		return teacherService.update(teacher);
	}
	
	@ApiOperation("删除一条记录")
	@GetMapping("/delete")
	public boolean delete(TblTeacherInf teacher) {
		return teacherService.delete(teacher);
	}
	
	@ApiOperation("查找一条记录")
	@GetMapping("/findById")
	public TblTeacherInf findById(Integer id) {
		return teacherService.findById(id);
	}
}

5、建立测试Service
在包com.example.service下，添加TeacherService.java

package com.example.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Service;

import com.create.entity.TblTeacherInf;
import com.create.entity.TblTeacherInfMapper;

@Service
public class TeacherService {

	public static final String CACHE_KEY = "redis-cache:";

	@Autowired
	TblTeacherInfMapper teacherMapper;

	@Autowired
	RedisTemplate<Object, Object> redisTemplate;

	/**
	 * 增加
	 * 
	 * @param teacher
	 * @return
	 */
	public boolean insert(TblTeacherInf teacher) {
		// 先插入数据库
		teacherMapper.insert(teacher);
		// 再查询出插入的对象
		teacher = teacherMapper.selectByPrimaryKey(teacher.getId());
		if (null != teacher) {
			// 再增加redis缓存
			redisTemplate.opsForValue().set(CACHE_KEY + teacher.getId(), teacher);
			return true;
		} else {
			return false;
		}
	}

	/**
	 * 修改
	 * 
	 * @param teacher
	 * @return
	 */
	public boolean update(TblTeacherInf teacher) {
		// 先修改数据库
		teacherMapper.updateByPrimaryKeySelective(teacher);
		// 再查询出修改的对象
		teacher = teacherMapper.selectByPrimaryKey(teacher.getId());
		if (null != teacher) {
			// 再更新redis缓存，更新也是set命令
			redisTemplate.opsForValue().set(CACHE_KEY + teacher.getId(), teacher);
			return true;
		} else {
			return false;
		}
	}

	/**
	 * 删除
	 * 
	 * @param teacher
	 * @return
	 */
	public boolean delete(TblTeacherInf teacher) {
		// 临时保存key
		String tempKey = CACHE_KEY + teacher.getId();
		// 先删除数据库记录
		teacherMapper.deleteByPrimaryKey(teacher.getId());
		// 再查询删除的对象，为空则删除缓存
		teacher = teacherMapper.selectByPrimaryKey(teacher.getId());
		if (null == teacher) {
			// 再删除redis缓存
			redisTemplate.delete(tempKey);
			return true;
		} else {
			return false;
		}
	}

	/**
	 * 查找
	 * 
	 * @param id
	 * @return
	 */
	public TblTeacherInf findById(Integer id) {
		ValueOperations<Object, Object> operation = redisTemplate.opsForValue();
		// 先查找redis缓存
		TblTeacherInf obj = (TblTeacherInf) operation.get(CACHE_KEY + id);
		if (obj == null) {
			// 到数据库查询
			obj = teacherMapper.selectByPrimaryKey(id);
			if (obj != null) {
				// 添加到redis缓存
				operation.set(CACHE_KEY + obj.getId(), obj);
			}
		}
		return obj;
	}
}

6、注意事项
6.1、config里定义redisTemplate类型为RedisTemplate<Object, Object>，注入对象时不能改为RedisTemplate<String, TblTeacherInf>，会报错：

***************************
APPLICATION FAILED TO START
***************************

Description:

Field redisTemplate in com.example.service.TeacherService required a bean of type 'org.springframework.data.redis.core.RedisTemplate' that could not be found.

The injection point has the following annotations:
	- @org.springframework.beans.factory.annotation.Autowired(required=true)

The following candidates were found but could not be injected:
	- Bean method 'redisTemplate' in 'RedisAutoConfiguration' not loaded because @ConditionalOnMissingBean (names: redisTemplate; SearchStrategy: all) found beans named redisTemplate


Action:

Consider revisiting the entries above or defining a bean of type 'org.springframework.data.redis.core.RedisTemplate' in your configuration.

6.2、数据库和缓存之间的操作关系
增加时：
1）先插数据库
2）再查询出插入对象
3）再增加redis缓存
修改时：
1）先修改数据库
2）再查询出修改的对象
3）再更新redis缓存
删除时：
1）先删除数据库记录
2）再查询数据库记录，为空则删除缓存
查询时：
1）先查询redis缓存
2）如果缓存为空，到数据库查询
3）如果数据库有记录，则更新到缓存

7、测试
访问swagger测试页面：http://127.0.0.1:8088/swagger-ui.html

注：最新代码上传至https://github.com/csj50/myboot

springboot项目创建笔记19 之《整合redis》

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