guava缓存使用

guava在springboot中使用

1.pom中引入包

<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.company</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <url>http://maven.apache.org</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.google.guava</groupId>
            <artifactId>guava</artifactId>
            <version>23.0</version>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>1.5.9.RELEASE</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

2.springboot项目

2.1 启动类

package com.company.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Hello world!
 *
 */
@SpringBootApplication
public class App {
    public static void main(String[] args) {
        // System.out.println( "Hello World!" );

        System.out.println("启动中...");

        SpringApplication.run(App.class, args);

        System.out.println("启动成功");
    }
}

2.2 controller类中使用cache

package com.company.demo.controller;

import java.util.Date;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

@RestController
@RequestMapping("/cache")
public class CacheController {


    static final Cache<String, String> cache = CacheBuilder.newBuilder().maximumSize(1000)
            .expireAfterWrite(3, TimeUnit.SECONDS).build();

    @RequestMapping("/test")
    public void Index() {

        
    
        String cacheKey = "time";

        // 使用方式1
        // 获取如果为空赋值
        String time = cache.getIfPresent(cacheKey);
        if (time == null) {
            time = new Date().toString();
            cache.put(cacheKey, time);
        }

        System.out.println("time:" + time);

        // 强制过期
        cache.invalidate(cacheKey);

        // 使用方式2
        String time2 = cache.get(cacheKey, new Callable<String>() {
            @Override
            public String call() throws Exception {
                String time = new Date().toString();
                return time;
            }
        });

        System.out.println("time:" + time2);

    }
}