前言
上一篇文章介紹了SpringBoot的PropertySourceLoader，自定義了Json格式的配置文件加載。這里再介紹下EndPoint，并通過自定EndPoint來介紹實(shí)現(xiàn)原理。
Endpoint
SpringBoot的Endpoint主要是用來監(jiān)控應(yīng)用服務(wù)的運(yùn)行狀況，并集成在Mvc中提供查看接口。內(nèi)置的Endpoint比如HealthEndpoint會(huì)監(jiān)控dist和db的狀況，MetricsEndpoint則會(huì)監(jiān)控內(nèi)存和gc的狀況。
Endpoint的接口如下，其中invoke()是主要的方法，用于返回監(jiān)控的內(nèi)容，isSensitive()用于權(quán)限控制。
public interface Endpoint<T> {
String getId();
boolean isEnabled();
boolean isSensitive();
T invoke();
}
Endpoint的加載還是依靠spring.factories實(shí)現(xiàn)的。spring-boot-actuator包下的META-INF/spring.factories配置了EndpointAutoConfiguration。
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
...
org.springframework.boot.actuate.autoconfigure.EndpointAutoConfiguration,\
...
EndpointAutoConfiguration就會(huì)注入必要的Endpoint。有些Endpoint需要外部的收集類，比如TraceEndpoint。
@Bean
@ConditionalOnMissingBean
public TraceEndpoint traceEndpoint() {
return new TraceEndpoint(this.traceRepository);
}
TraceEndpoint會(huì)記錄每次請(qǐng)求的Request和Response的狀態(tài)，需要嵌入到Request的流程中，這里就主要用到了3個(gè)類。
- TraceRepository用于保存和獲取Request和Response的狀態(tài)。
public interface TraceRepository {
List<Trace> findAll();
void add(Map<String, Object> traceInfo);
}
- WebRequestTraceFilter用于嵌入web request，收集請(qǐng)求的狀態(tài)并保存在TraceRepository中。
- TraceEndpoint，invoke()方法直接調(diào)用TraceRepository保存的數(shù)據(jù)。
public class TraceEndpoint extends AbstractEndpoint<List<Trace>> {
private final TraceRepository repository;
public TraceEndpoint(TraceRepository repository) {
super("trace");
Assert.notNull(repository, "Repository must not be null");
this.repository = repository;
}
public List<Trace> invoke() {
return this.repository.findAll();
}
}
Endpoint的Mvc接口主要是通過EndpointWebMvcManagementContextConfiguration實(shí)現(xiàn)的，這個(gè)類的配置也放在spring.factories中。
...
org.springframework.boot.actuate.autoconfigure.ManagementContextConfiguration=\
org.springframework.boot.actuate.autoconfigure.EndpointWebMvcManagementContextConfiguration,\
org.springframework.boot.actuate.autoconfigure.EndpointWebMvcHypermediaManagementContextConfiguration
EndpointWebMvcManagementContextConfiguration注入EndpointHandlerMapping來實(shí)現(xiàn)Endpoint的Mvc接口。
@Bean
@ConditionalOnMissingBean
public EndpointHandlerMapping endpointHandlerMapping() {
Set<? extends MvcEndpoint> endpoints = mvcEndpoints().getEndpoints();
CorsConfiguration corsConfiguration = getCorsConfiguration(this.corsProperties);
EndpointHandlerMapping mapping = new EndpointHandlerMapping(endpoints,corsConfiguration);
boolean disabled = this.managementServerProperties.getPort() != null && this.managementServerProperties.getPort() == -1;
mapping.setDisabled(disabled);
if (!disabled) {
mapping.setPrefix(this.managementServerProperties.getContextPath());
}
if (this.mappingCustomizers != null) {
for (EndpointHandlerMappingCustomizer customizer : this.mappingCustomizers) {
customizer.customize(mapping);
}
}
return mapping;
}
自定義Endpoint
自定義Endpoint也是類似的原理。這里自定義Endpoint實(shí)現(xiàn)應(yīng)用內(nèi)存的定時(shí)收集。完整的代碼放在Github上了。
- 收集內(nèi)存，MemStatus是內(nèi)存的存儲(chǔ)結(jié)構(gòu)，MemCollector是內(nèi)存的收集類，使用Spring內(nèi)置的定時(shí)功能，每5秒收集當(dāng)前內(nèi)存。
public static class MemStatus {
public MemStatus(Date date, Map<String, Object> status) {
this.date = date;
this.status = status;
}
private Date date;
private Map<String, Object> status;
public Date getDate() {
return date;
}
public Map<String, Object> getStatus() {
return status;
}
}
public static class MemCollector {
private int maxSize = 5;
private List<MemStatus> status;
public MemCollector(List<MemStatus> status) {
this.status = status;
}
@Scheduled(cron = "0/5 * * * * ? ")
public void collect() {
Runtime runtime = Runtime.getRuntime();
Long maxMemory = runtime.maxMemory();
Long totalMemory = runtime.totalMemory();
Map<String, Object> memoryMap = new HashMap<String, Object>(2, 1);
Date date = Calendar.getInstance().getTime();
memoryMap.put("maxMemory", maxMemory);
memoryMap.put("totalMemory", totalMemory);
if (status.size() > maxSize) {
status.remove(0);
status.add(new MemStatus(date, memoryMap));
} else {
status.add(new MemStatus(date, memoryMap));
}
}
}
- 自定義Endpoint，getId是EndPoint的唯一標(biāo)識(shí)，也是Mvc接口對(duì)外暴露的路徑。invoke方法，取出maxMemory和totalMemory和對(duì)應(yīng)的時(shí)間。
public static class MyEndPoint implements Endpoint {
private List<MemStatus> status;
public MyEndPoint(List<MemStatus> status) {
this.status = status;
}
public String getId() {
return "my";
}
public boolean isEnabled() {
return true;
}
public boolean isSensitive() {
return false;
}
public Object invoke() {
if (status == null || status.isEmpty()) {
return "hello world";
}
Map<String, List<Map<String, Object>>> result = new HashMap<String, List<Map<String, Object>>>();
for (MemStatus memStatus : status) {
for (Map.Entry<String, Object> entry : memStatus.status.entrySet()) {
List<Map<String, Object>> collectList = result.get(entry.getKey());
if (collectList == null) {
collectList = new LinkedList<Map<String, Object>>();
result.put(entry.getKey(), collectList);
}
Map<String, Object> soloCollect = new HashMap<String, Object>();
soloCollect.put("date", memStatus.getDate());
soloCollect.put(entry.getKey(), entry.getValue());
collectList.add(soloCollect);
}
}
return result;
}
}
- AutoConfig，注入了MyEndPoint，和MemCollector。
public static class EndPointAutoConfig {
private List<MemStatus> status = new ArrayList<MemStatus>();
@Bean
public MyEndPoint myEndPoint() {
return new MyEndPoint(status);
}
@Bean
public MemCollector memCollector() {
return new MemCollector(status);
}
}
- 程序入口，運(yùn)行后訪問http://localhost:8080/my 就可以看到了。
@Configuration
@EnableAutoConfiguration
public class CustomizeEndPoint {
public static void main(String[] args) {
SpringApplication application = new SpringApplication(CustomizeEndPoint.class);
application.run(args);
}
}
結(jié)語
Endpoint也是通過spring.factories實(shí)現(xiàn)擴(kuò)展功能，注入了對(duì)應(yīng)的Bean來實(shí)現(xiàn)應(yīng)用監(jiān)控的功能。
