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代码

import cn.hutool.core.util.StrUtil;
import com.alibaba.csp.sentinel.datasource.ReadableDataSource;
import com.alibaba.csp.sentinel.datasource.zookeeper.ZookeeperDataSource;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.zookeeper.ZookeeperProperties;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.List;

@Component
public class ZkDataSourceConfig {

    @Value("${spring.application.name}")
    private String appname;

    @Value("${spring.profiles.active}")
    private String profile;

    @Resource
    private ZookeeperProperties zookeeperProperties;

    @PostConstruct
    public void init() {
        loadRules(zookeeperProperties.getConnectString());
    }


    private void loadRules(String remoteAddress) {

        // 规则会持久化到zk的/groupId/flowDataId节点
        // groupId和和flowDataId可以用/开头也可以不用
        // 建议不用以/开头，目的是为了如果从Zookeeper切换到Nacos的话，只需要改数据源类名就可以
        String groupId = StrUtil.format("sentinel/{}:{}", appname, profile);
        
        ReadableDataSource<String, List<FlowRule>> flowRuleDataSource = new ZookeeperDataSource<>(remoteAddress, groupId, "FlowRule",
                // source 就是从 zookeeper 中读出来的字符串
                source -> JSON.parseObject(source, new TypeReference<List<FlowRule>>() {
                }));
        //限流
        FlowRuleManager.register2Property(flowRuleDataSource.getProperty());

        ReadableDataSource<String, List<DegradeRule>> degradeRuleDataSource = new ZookeeperDataSource<>(remoteAddress, groupId, "DegradeRule",
                // source 就是从 zookeeper 中读出来的字符串
                source -> JSON.parseObject(source, new TypeReference<List<DegradeRule>>() {
                }));
        //降级
        DegradeRuleManager.register2Property(degradeRuleDataSource.getProperty());
    }
}

ZK配置参考

/sentinel/应用名:环境=FlowRule=[{"resource": "资源1", "limitApp": "default", "grade": 1, "count": 40.0, "strategy": 0, "controlBehavior": 2, "maxQueueingTimeMs": 100000 }, {"resource": "资源2", "limitApp": "default", "grade": 1, "count": 40.0, "strategy": 0, "controlBehavior": 2, "maxQueueingTimeMs": 100000 }, {"resource": "资源3", "limitApp": "default", "grade": 1, "count": 10.0, "strategy": 0, "controlBehavior": 2, "maxQueueingTimeMs": 100000 } ]

使用

public class demo {
    public static void main(String[] args) {
        // 定义规则
        initFlowRules();
        //用SphU.entry()的形式定义资源
        while (true) {
            try (Entry entry = SphU.entry("myResource")) {//与规则定义中的rule.setResource("myResource")一致
                // 被保护的业务逻辑...
                System.out.println("业务资源访问成功！");
            } catch (BlockException ex) {
                // 处理被流控的逻辑：限流或降级...
                System.out.println("资源访问失败！！！");
            } finally {
            	if (entry != null) {
            		entry.exit();//必须退出资源调用
                }
            }
        }
        
        
        //用SphO.entry()的形式定义资源
        while (true) {
            if(SphO.entry("myResource")){//与规则定义中的rule.setResource("myResource")一致
                try{
                    // 被保护的业务逻辑...
                    System.out.println("业务资源访问成功！");
                } catch (BlockException ex) {
                    // 处理被流控的逻辑：限流或降级...
                    System.out.println("资源访问失败！！！");
                }finally{
                    SphO.exit();//必须退出资源调用
                }
            }
        }
        
        //上面两种方式对代码侵入性很高，可用注解的方式定义资源
        while(true){
            getUserById("111");
        }
    }
	
	//文章开始通过zk加载配置，此处通过代码定义规则	
    //定义规则 
    private static void initFlowRules(){
        List<FlowRule> rules = new ArrayList<>();// 存储规则 FlowRule
        FlowRule rule = new FlowRule();
        rule.setResource("myResource");	// 指定限流规则作用于哪个资源上，资源名为字符串，可为任意有标识意义的方法名/接口名/其他字符串，此处资源名为"myResource"
        rule.setGrade(RuleConstant.FLOW_GRADE_QPS);	// 限流类型为QPS模式：限制QPS
        rule.setCount(10);	   // QPS不得超出10
        rule.setLimitApp("default");	// 针对的调用来源，default代表不区分来源
        rules.add(rule);
        FlowRuleManager.loadRules(rules);// 加载规则
	}
	
	
	//定义"myResource"资源，并设置违背sentinel流控规则时的处理方法handlerException()
	@SentinelResource(value="myResource",blockHandler="handlerException")
	public User getUserById(String id){
	    return new User("数据库用户")；
	}
	//注意：此处理方法的参数必须和定义资源的方法getUserById参数一致（）同时加上【BlockException exception】参数
	public User handlerException(String id,BlockException exception){
	    return new User("流控用户");
	}
}

Entry entry = null;
try {
	entry = SphU.entry("myResource"); //此处说明资源
	// 被保护的业务逻辑
	...
} catch (BlockException e1) {
	// 资源访问阻止，被限流或被降级,进行相应的处理操作
	...
} finally {
	if (entry != null) {
		entry.exit();
    }
}