spring boot 源码解析53-AbstractNamedMvcEndpoint

2023年8月18日 473次阅读 来源: Spring Boot

前言

本文来介绍AbstractNamedMvcEndpoint的一系列的子类:

  • AuditEventsMvcEndpoint
  • HeapdumpMvcEndpoint
  • LogFileMvcEndpoint

其他的实现:

  • DocsMvcEndpoint
  • HalJsonMvcEndpoint
  • JolokiaMvcEndpoint

我们后续的文章进行分析

解析

AuditEventsMvcEndpoint

AuditEventsMvcEndpoint–> 继承自AbstractNamedMvcEndpoint

  1. 字段,构造器如下:

    private final AuditEventRepository auditEventRepository;

public AuditEventsMvcEndpoint(AuditEventRepository auditEventRepository) {
    super("auditevents", "/auditevents", true);
    Assert.notNull(auditEventRepository, "AuditEventRepository must not be null");
    this.auditEventRepository = auditEventRepository;
}

    此时注册的路径为/auditevents

  2. 其只声明了1个方法:

    @ActuatorGetMapping
@ResponseBody
public ResponseEntity<?> findByPrincipalAndAfterAndType(
        @RequestParam(required = false) String principal,
        @RequestParam(required = false) @DateTimeFormat(pattern = "yyyy-MM-dd'T'HH:mm:ssZ") Date after,
        @RequestParam(required = false) String type) {
    if (!isEnabled()) {
        return DISABLED_RESPONSE;
    }
    Map<Object, Object> result = new LinkedHashMap<Object, Object>();
    result.put("events", this.auditEventRepository.find(principal, after, type));
    return ResponseEntity.ok(result);
}
    1. 如果不可用的话,则返回默认的失败相应
    2. 否则,查询AuditEventRepository构造响应结果.响应状态码为200

    关于AuditEventRepository的内容,可以查看 spring boot 源码解析31-AuthenticationAuditListener,AuthorizationAuditListener

  3. 属性配置:

    因为该类声明了@ConfigurationProperties(prefix = “endpoints.auditevents”)注解,因此可以通过如下属性配置:

    endpoints.auditevents.enabled= # Enable the endpoint.
endpoints.auditevents.path= # Endpoint path.
endpoints.auditevents.sensitive=false # Enable security on the endpoint.

  4. 自动装配:

    声明在EndpointWebMvcManagementContextConfiguration中,代码如下:

    @Bean
@ConditionalOnMissingBean
@ConditionalOnBean(AuditEventRepository.class)
@ConditionalOnEnabledEndpoint("auditevents")
public AuditEventsMvcEndpoint auditEventMvcEndpoint(
        AuditEventRepository auditEventRepository) {
    return new AuditEventsMvcEndpoint(auditEventRepository);
}
    • @Bean –> 注册1个id为auditEventMvcEndpoint,类型为AuditEventsMvcEndpoint的bean
    • @ConditionalOnMissingBean –> BeanFactory中不存在AuditEventsMvcEndpoint类型的bean时生效
    • @ConditionalOnBean(AuditEventRepository.class) –> BeanFactory中存在AuditEventRepository类型的bean时生效
    • @ConditionalOnEnabledEndpoint(“auditevents”) –> 如果配置有endpoints. auditevents.enabled = true 或者endpoints.enabled= true 则该配置生效.如果没有配置的话,默认返回true

HeapdumpMvcEndpoint

HeapdumpMvcEndpoint–>继承自AbstractNamedMvcEndpoint

  1. 字段,构造器如下:

    private final long timeout;

private final Lock lock = new ReentrantLock();

private HeapDumper heapDumper;

public HeapdumpMvcEndpoint() {
    this(TimeUnit.SECONDS.toMillis(10));
}

protected HeapdumpMvcEndpoint(long timeout) {
    super("heapdump", "/heapdump", true);
    this.timeout = timeout;
}

    这里有必要说明一下HeapDumper–> dump 堆内存到文件中的策略接口,其声明了1个方法,如下:

    void dumpHeap(File file, boolean live) throws IOException, InterruptedException;

    其只有1个实现类–>HotSpotDiagnosticMXBeanHeapDumper–>使用HotSpotDiagnosticMXBean来进行dump.

    1. 字段,构造器如下:

      // HotSpotDiagnosticMXBean对象
private Object diagnosticMXBean;

// HotSpotDiagnosticMXBean中的dumpHeap所对应的Method对象
private Method dumpHeapMethod;

@SuppressWarnings("unchecked")
protected HotSpotDiagnosticMXBeanHeapDumper() {
    try {
        // 1. 获得HotSpotDiagnosticMXBean.class
        Class<?> diagnosticMXBeanClass = ClassUtils.resolveClassName(
                "com.sun.management.HotSpotDiagnosticMXBean", null);
        // 2. 获得HotSpotDiagnosticMXBean
        this.diagnosticMXBean = ManagementFactory.getPlatformMXBean(
                (Class<PlatformManagedObject>) diagnosticMXBeanClass);
        // 3. 获得HotSpotDiagnosticMXBean中的dumpHeap所对应的Method对象
        this.dumpHeapMethod = ReflectionUtils.findMethod(diagnosticMXBeanClass,
                "dumpHeap", String.class, Boolean.TYPE);
    }
    catch (Throwable ex) {
        throw new HeapDumperUnavailableException(
                "Unable to locate HotSpotDiagnosticMXBean", ex);
    }
}

      如果在初始化的过程中出现错误,则抛出HeapDumperUnavailableException.代码如下:

      @ResponseStatus(HttpStatus.SERVICE_UNAVAILABLE)
protected static class HeapDumperUnavailableException extends RuntimeException {
    public HeapDumperUnavailableException(String message, Throwable cause) {
        super(message, cause);
    }
}

      最终返回的状态码为503

    2. dumpHeap–>通过反射的方式dump.代码如下:

      public void dumpHeap(File file, boolean live) {
    // 1. 通过反射的方式dump
    ReflectionUtils.invokeMethod(this.dumpHeapMethod, this.diagnosticMXBean,
            file.getAbsolutePath(), live);
}

  2. 其声明了1个方法,代码如下:

    @RequestMapping(method = RequestMethod.GET, produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
public void invoke(@RequestParam(defaultValue = "true") boolean live,
        HttpServletRequest request, HttpServletResponse response)
                throws IOException, ServletException {
    // 1. 如果不可用的话,返回404
    if (!isEnabled()) {
        response.setStatus(HttpStatus.NOT_FOUND.value());
        return;
    }
    try {
        // 2. 尝试获得锁,默认等待10毫秒
        if (this.lock.tryLock(this.timeout, TimeUnit.MILLISECONDS)) {
            try {
                // 3. 
                dumpHeap(live, request, response);
                return;
            }
            finally {
                // 4. 释放锁
                this.lock.unlock();
            }
        }
    }
    catch (InterruptedException ex) {
        Thread.currentThread().interrupt();
    }
    // 5. 如果锁获取失败,则返回429
    response.setStatus(HttpStatus.TOO_MANY_REQUESTS.value());
}
    1. 如果不可用的话,返回404
    2. 尝试获得锁,默认等待10毫秒

    3. dump文件.代码如下:

      private void dumpHeap(boolean live, HttpServletRequest request,
        HttpServletResponse response)
                throws IOException, ServletException, InterruptedException {
    // 1. 如果heapDumper等于null,则进行实例化.第一次访问该接口时创建
    if (this.heapDumper == null) {
        this.heapDumper = createHeapDumper();
    }
    // 2. 创建临时文件
    File file = createTempFile(live);
    try {
        // 3. 将当前的堆内存信息dump到临时文件中
        this.heapDumper.dumpHeap(file, live);
        // 4. 输出到响应流中
        handle(file, request, response);
    }
    finally {
        file.delete();
    }
}

      1. 如果heapDumper等于null,则进行实例化.第一次访问该接口时创建.代码如下:

        protected HeapDumper createHeapDumper() throws HeapDumperUnavailableException {
    return new HotSpotDiagnosticMXBeanHeapDumper();
}

      2. 创建临时文件.代码如下:

        private File createTempFile(boolean live) throws IOException {
    String date = new SimpleDateFormat("yyyy-MM-dd-HH-mm").format(new Date());
    File file = File.createTempFile("heapdump" + date + (live ? "-live" : ""),
            ".hprof");
    file.delete();
    return file;
}

        在临时目录下创建heapdumpyyyy-MM-dd-HH-mm-live.hprof 的文件.对于笔者来说,临时目录为/var/folders/n9/7jzwh0z507xdrb0ld109vwkh0000gn/T

      3. 将当前的堆内存信息dump到临时文件中

      4. 输出到响应流中.代码如下:

        protected void handle(File heapDumpFile, HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
    // 1. 设置ContentType,响应头
    response.setContentType("application/octet-stream");
    response.setHeader("Content-Disposition",
            "attachment; filename=\"" + (heapDumpFile.getName() + ".gz") + "\"");
    try {
        // 2. 通过GZIPOutputStream将文件中的内容进行压缩,然后输出的response的输出流中
        InputStream in = new FileInputStream(heapDumpFile);
        try {
            GZIPOutputStream out = new GZIPOutputStream(response.getOutputStream());
            StreamUtils.copy(in, out);
            out.finish();
        }
        catch (NullPointerException ex) {
        }
        finally {
            try {
                in.close();
            }
            catch (Throwable ex) {
            }
        }
    }
    catch (FileNotFoundException ex) {
    }
}
        1. 设置ContentType,响应头
        2. 通过GZIPOutputStream将文件中的内容进行压缩,然后输出的response的输出流中
    4. 释放锁
    5. 果锁获取失败,则返回429

    下载的文件可以通过MAT打开

  3. 属性配置:

    由于该类声明了@ConfigurationProperties(prefix = “endpoints.heapdump”)注解,因此可以通过如下属性配置:

    endpoints.heapdump.enabled= # Enable the endpoint.
endpoints.heapdump.path= # Endpoint path.
endpoints.heapdump.sensitive= # Mark if the endpoint exposes sensitive information.

  4. 自动装配:

    在EndpointWebMvcManagementContextConfiguration中进行了声明,代码如下:

    @Bean
@ConditionalOnMissingBean
@ConditionalOnEnabledEndpoint("heapdump")
public HeapdumpMvcEndpoint heapdumpMvcEndpoint() {
    return new HeapdumpMvcEndpoint();
}
    • @Bean –> 注册1个id为heapdumpMvcEndpoint,类型为HeapdumpMvcEndpoint的bean
    • @ConditionalOnMissingBean–> BeanFactory中不存在HeapdumpMvcEndpoint类型的bean时生效
    • @ConditionalOnEnabledEndpoint(“heapdump”)–> 如果配置有endpoints. heapdump.enabled = true 或者endpoints.enabled= true 则该配置生效.如果没有配置的话,默认返回true

LogFileMvcEndpoint

LogFileMvcEndpoint–> 继承自AbstractNamedMvcEndpoint

  1. 字段,构造器如下:

    private static final Log logger = LogFactory.getLog(LogFileMvcEndpoint.class);

// 一般情况下,为null
private File externalFile;

public LogFileMvcEndpoint() {
    super("logfile", "/logfile", true);
}

  2. 方法如下:

    @RequestMapping(method = { RequestMethod.GET, RequestMethod.HEAD })
public void invoke(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    // 1. 如果不可用的话,则返回404
    if (!isEnabled()) {
        response.setStatus(HttpStatus.NOT_FOUND.value());
        return;
    }
    // 2. 获得LogFile,如果不存在的话,则将Resource置为null
    Resource resource = getLogFileResource();
    if (resource != null && !resource.exists()) {
        if (logger.isDebugEnabled()) {
            logger.debug("Log file '" + resource + "' does not exist");
        }
        resource = null;
    }
    // 3. 实例化Handler
    Handler handler = new Handler(resource, request.getServletContext());
    handler.handleRequest(request, response);
}
    1. 如果不可用的话,则返回404

    2. 获得LogFile,如果不存在的话,则将Resource置为null.代码如下:

      private Resource getLogFileResource() {
    if (this.externalFile != null) {
        return new FileSystemResource(this.externalFile);
    }
    LogFile logFile = LogFile.get(getEnvironment());
    if (logFile == null) {
        logger.debug("Missing 'logging.file' or 'logging.path' properties");
        return null;
    }
    return new FileSystemResource(logFile.toString());
}

    3. 实例化Handler处理请求.Handler–>继承自ResourceHttpRequestHandler.

      1. 构造器如下:

        Handler(Resource resource, ServletContext servletContext) {
    this.resource = resource;
    getLocations().add(resource);
    try {
        setServletContext(servletContext);
        afterPropertiesSet();
    }
    catch (Exception ex) {
        throw new IllegalStateException(ex);
    }
}

        将logfile对应的文件添加到ResourceHttpRequestHandler的Locations

      2. getResource–> 直接返回logfile对应的文件.代码如下:

        protected Resource getResource(HttpServletRequest request) throws IOException {
    return this.resource;
}

      3. getMediaType–> 设置了响应类型为text/plain.代码如下:

        protected MediaType getMediaType(Resource resource) {
    return MediaType.TEXT_PLAIN;
}

      这样一来,我们访问/logfile时就会将logFile对应的日志内容渲染到浏览器中.如下:

      2018-02-01 01:07:26.635  INFO 3132 --- [main] com.example.demo.DemoApplication         : Starting DemoApplication on localhost with PID 3132 (/Users/hejiarui/Documents/spring-boot-source/demo/target/classes started by hejiarui in /Users/hejiarui/Documents/spring-boot-source/demo)
2018-02-01 01:07:26.638  INFO 3132 --- [main] com.example.demo.DemoApplication         : The following profiles are active: test
2018-02-01 01:07:26.894  INFO 3132 --- [main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@7d1cfb8b: startup date [Thu Feb 01 01:07:26 CST 2018]; root of context hierarchy
2018-02-01 01:07:27.619  INFO 3132 ---

  3. 属性配置:

    由于该类声明了@ConfigurationProperties(prefix = “endpoints.logfile”),因此可以通过如下注解进行配置:

    endpoints.logfile.enabled=true # Enable the endpoint.
endpoints.logfile.external-file= # External Logfile to be accessed.
endpoints.logfile.path=/logfile # Endpoint URL path.
endpoints.logfile.sensitive=true # Enable security on the endpoint.

  4. 自动装配:

    声明在EndpointWebMvcManagementContextConfiguration中,代码如下:

    @Bean
@ConditionalOnMissingBean
@ConditionalOnEnabledEndpoint("logfile")
@Conditional(LogFileCondition.class)
public LogFileMvcEndpoint logfileMvcEndpoint() {
    return new LogFileMvcEndpoint();
}
    • @Bean –> 注册1个id为 logfileMvcEndpoint,类型为LogFileMvcEndpoint的bean
    • @ConditionalOnMissingBean–>BeanFactory中不存在LogFileMvcEndpoint类型的bean时生效
    • @ConditionalOnEnabledEndpoint(“logfile”) –> 如果配置有endpoints. logfile.enabled = true 或者endpoints.enabled= true 则该配置生效.如果没有配置的话,默认返回true
    • @Conditional(LogFileCondition.class) –> 配置有logging.file,logging.path,endpoints.logfile.external-file 中的任意一个时生效
    原文作者：Spring Boot
    原文地址: https://blog.csdn.net/qq_26000415/article/details/79223630
    本文转自网络文章，转载此文章仅为分享知识，如有侵权，请联系博主进行删除。
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