spring boot 源码解析24-HealthEndpoint解析

spring boot 源码解析24-HealthEndpoint解析

spring boot 源码解析24-HealthEndpoint解析

一个努力的码农 2018-01-15 15:26:38 16686 收藏 1

分类专栏： spring boot spring boot 源码解析 文章标签： spring 源码 class

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前言

spring boot actuator中的HealthEndPoint涉及的内容比较多, HealthEndPoint是通过HealthIndicator来实现功能的,而HealthIndicator的实现都在org.springframework.boot.actuate.health包下,如图:

整理成类图如下：

本节我们就来分析这部分的内容.

解析

HealthIndicator

public interface HealthIndicator {

// 返回health

Health health();

}

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这里面涉及到了Health, 该类的实现使用了建造者模式,类图如下:

@JsonInclude(Include.NON_EMPTY)

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则如果该类中的所有属性都为空（“”）或者为 NULL则不序列化.

其内部定义了如下字段:

// 状态码

private final String code;

// 描述

private final String description;

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并预定义了4个静态字段,:

// 系统状态未知

public static final Status UNKNOWN = new Status("UNKNOWN");

// 可用

public static final Status UP = new Status("UP");

// 服务挂掉

public static final Status DOWN = new Status("DOWN");

// 服务不可用

public static final Status OUT_OF_SERVICE = new Status("OUT_OF_SERVICE");

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// 状态

private final Status status;

// 详情

private final Map details;

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Builder 则是定义在 Health类中,则定义的字段和Health中的一样.则构造器如下:

public Builder() {

this.status = Status.UNKNOWN;

this.details = new LinkedHashMap();

}

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意味着:默认情况下,构建出来的Health状态为UNKNOWN.

如何使用 Builder 构建Health呢?

可以通过如下的方式进行:

try {

// do some test to determine state of component

return new Health.Builder().up().withDetail("version", "1.1.2").build();

}

catch (Exception ex) {

return new Health.Builder().down(ex).build();

}

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更多的方式,可以参考Builder类的api

AbstractHealthIndicator

public final Health health() {

// 1. 实例化Health$Builder

Health.Builder builder = new Health.Builder();

try {

// 2. 进行状态的检查,如果在检查过程中出现异常,则状态为Status.DOWN

doHealthCheck(builder);

}

catch (Exception ex) {

this.logger.warn("Health check failed", ex);

builder.down(ex);

}

// 3. 构建Health

return builder.build();

}

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实例化Health$Builder

调用抽象方法doHealthCheck–>进行状态的检查,如果在检查过程中出现异常,则状态为Status.DOWN

构建Health

下面我们就依次看一下其各个子类的实现吧

ApplicationHealthIndicator

该类的实现比较简单,通过继承AbstractHealthIndicator,实现其doHealthCheck,在该方法中直接将其设置为up.代码如下:

protected void doHealthCheck(Health.Builder builder) throws Exception {

builder.up();

}

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自动化配置:

在HealthIndicatorAutoConfiguration 进行了配置,代码如下:

@Bean

@ConditionalOnMissingBean(HealthIndicator.class)

public ApplicationHealthIndicator applicationHealthIndicator() {

return new ApplicationHealthIndicator();

}

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@Bean –> 注册1个id为applicationHealthIndicator,类型为ApplicationHealthIndicator的bean

@ConditionalOnMissingBean(HealthIndicator.class) –> 当beanFactory中不存在HealthIndicator类型的bean时生效

CassandraHealthIndicator

CassandraHealthIndicator 持有1个CassandraOperations类型的实例,该实例通过构造器进行注入,代码如下:

private CassandraOperations cassandraOperations;

public CassandraHealthIndicator(CassandraOperations cassandraOperations) {

Assert.notNull(cassandraOperations, "CassandraOperations must not be null");

this.cassandraOperations = cassandraOperations;

}

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doHealthCheck 实现:

protected void doHealthCheck(Health.Builder builder) throws Exception {

try {

Select select = QueryBuilder.select("release_version").from("system",

"local");

ResultSet results = this.cassandraOperations.query(select);

if (results.isExhausted()) {

builder.up();

return;

}

String version = results.one().getString(0);

builder.up().withDetail("version", version);

}

catch (Exception ex) {

builder.down(ex);

}

}

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通过CassandraOperations 查询 在system(keyspace)下的local表中的 release_version 字段

如果执行成功,但是没有返回值,则设置为up,然后return

否则,设置状态为up,并添加key–>version,value–> 结果值到详情中

如果在查询过程中出现异常,则设置为状态为down.

自动化装配:

public abstract class CompositeHealthIndicatorConfiguration

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其中,泛型参数H 代表 HealthIndicator 的类型,泛型参数S代表bean的原始类型(the bean source type).

createHealthIndicator,代码如下:

protected HealthIndicator createHealthIndicator(Map beans) {

if (beans.size() == 1) {

return createHealthIndicator(beans.values().iterator().next());

}

CompositeHealthIndicator composite = new CompositeHealthIndicator(

this.healthAggregator);

for (Map.Entry entry : beans.entrySet()) {

composite.addHealthIndicator(entry.getKey(),

createHealthIndicator(entry.getValue()));

}

return composite;

}

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如果传入的beans的size 为 1,则调用createHealthIndicator 创建HealthIndicator

否则,创建CompositeHealthIndicator,遍历传入的beans,依次创建HealthIndicator,加入到CompositeHealthIndicator中

createHealthIndicator,代码如下:

protected H createHealthIndicator(S source) {

Class[] generics = ResolvableType

.forClass(CompositeHealthIndicatorConfiguration.class, getClass())

.resolveGenerics();

Class indicatorClass = (Class) generics[0];

Class sourceClass = (Class) generics[1];

try {

return indicatorClass.getConstructor(sourceClass).newInstance(source);

}

catch (Exception ex) {

throw new IllegalStateException("Unable to create indicator " + indicatorClass

+ " for source " + sourceClass, ex);

}

}

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获得CompositeHealthIndicatorConfiguration中的泛型参数

@Configuration

@ConditionalOnClass({ CassandraOperations.class, Cluster.class })

@ConditionalOnBean(CassandraOperations.class)

@ConditionalOnEnabledHealthIndicator("cassandra")

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@Configuration –> 配置类

@ConditionalOnClass({ CassandraOperations.class, Cluster.class }) –> 在当前的类路径下存在CassandraOperations.class, Cluster.class时生效

@ConditionalOnBean(CassandraOperations.class)–> 在beanFactory 中存在CassandraOperations类型的bean时生效

@ConditionalOnEnabledHealthIndicator(“cassandra”)–> 如果配置有management.health.cassandra.enabled = true 或者management.health.defaults.enabled = true 则该配置生效.关于此处的实现我们后续有文章进行分析.

因此,默认情况下,该配置(CassandraHealthIndicator) 是不会生效的.

@Bean

@ConditionalOnMissingBean(name = "cassandraHealthIndicator")

public HealthIndicator cassandraHealthIndicator() {

return createHealthIndicator(this.cassandraOperations);

}

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@Bean –> 注册1个id为cassandraHealthIndicator,类型为HealthIndicator的bean

@ConditionalOnMissingBean(name = “cassandraHealthIndicator”) –> 当beanFactory中不存在id为cassandraHealthIndicator 的bean 时生效.

public static class CassandraHealthIndicatorConfiguration extends

CompositeHealthIndicatorConfiguration

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因此,H为 CassandraHealthIndicator,S 为 CassandraOperations.

又由于CassandraHealthIndicatorConfiguration 持有的是Map 集合,因此,在实例化CassandraHealthIndicatorConfiguration的时候,会将BeanFactory中所有类型为CassandraOperations都注入进来,key–>bean的id,value –> bean的实例.

因此,当前创建的HealthIndicator有2种情况:

当前beanFactory中只存在1个CassandraOperations的实例:

public CassandraHealthIndicator(CassandraOperations cassandraOperations) {

Assert.notNull(cassandraOperations, "CassandraOperations must not be null");

this.cassandraOperations = cassandraOperations;

}

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然后进行实例化.

当前beanFactory中存在多个CassandraOperations实例的话,则会创建CompositeHealthIndicator,会遍历CassandraOperations的实例,创建CassandraHealthIndicator,在CompositeHealthIndicator中进行注册,其中,Key为CassandraOperations bean的id,value为 CassandraHealthIndicator

CouchbaseHealthIndicator

CouchbaseHealthIndicator和CassandraHealthIndicator类似,其内部持有CassandraOperations,构造器如下:

private CassandraOperations cassandraOperations;

public CassandraHealthIndicator(CassandraOperations cassandraOperations) {

Assert.notNull(cassandraOperations, "CassandraOperations must not be null");

this.cassandraOperations = cassandraOperations;

}

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doHealthCheck 实现如下:

protected void doHealthCheck(Health.Builder builder) throws Exception {

List versions = this.couchbaseOperations.getCouchbaseClusterInfo()

.getAllVersions();

builder.up().withDetail("versions",

StringUtils.collectionToCommaDelimitedString(versions));

}

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通过couchbaseOperations 获得版本号

如果访问成功的话,则设置状态为up,并设置key–> versions,value–> 版本号,如果有多个的话,会通过,进行拼接

自动装配:

同样和CassandraHealthIndicatorConfiguration 一样,继承自CompositeHealthIndicatorConfiguration,泛型参数分别为CouchbaseHealthIndicator, CouchbaseOperations,代码如下:

public static class CouchbaseHealthIndicatorConfiguration extends

CompositeHealthIndicatorConfiguration

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@Configuration

@ConditionalOnClass({ CouchbaseOperations.class, Bucket.class })

@ConditionalOnBean(CouchbaseOperations.class)

@ConditionalOnEnabledHealthIndicator("couchbase")

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@Configuration –> 配置类

@ConditionalOnClass({ CouchbaseOperations.class, Bucket.class }) –> 在当前类路径下存在CouchbaseOperations.class, Bucket.class时生效

@ConditionalOnBean(CouchbaseOperations.class)–> 在beanFactory中存在CouchbaseOperations类型的bean时生效

@ConditionalOnEnabledHealthIndicator(“couchbase”) –> 如果配置有management.health.couchbase.enabled = true 或者management.health.defaults.enabled = true 则该配置生效.

其@Bean方法如下:

@Bean

@ConditionalOnMissingBean(name = "couchbaseHealthIndicator")

public HealthIndicator couchbaseHealthIndicator() {

return createHealthIndicator(this.couchbaseOperations);

}

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@Bean –> 注册1个id为couchbaseHealthIndicator,类型为HealthIndicator的bean

@ConditionalOnMissingBean(name = “couchbaseHealthIndicator”) –> 当beanFactory中不存在id为couchbaseHealthIndicator 的bean 时生效.

其构建过程和CassandraHealthIndicatorConfiguration一样,这里就不在赘述了

DataSourceHealthIndicator

DataSourceHealthIndicator 中定义了如下字段:

// 默认的测试语句为SELECT 1

private static final String DEFAULT_QUERY = "SELECT 1";

// 数据库资源

private DataSource dataSource;

// 测试语句

private String query;

private JdbcTemplate jdbcTemplate;

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DataSourceHealthIndicator 实现了InitializingBean接口,因此在初始化后会调用afterPropertiesSet方法,代码如下:

public void afterPropertiesSet() throws Exception {

Assert.state(this.dataSource != null,

"DataSource for DataSourceHealthIndicator must be specified");

}

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doHealthCheck 实现:

protected void doHealthCheck(Health.Builder builder) throws Exception {

// 1. 如果DataSource没有配置,则直接返回up,message 为unknown

if (this.dataSource == null) {

builder.up().withDetail("database", "unknown");

}

else {

// 2.

doDataSourceHealthCheck(builder);

}

}

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如果DataSource没有配置,则直接返回up,message 为unknown

否则,调用doDataSourceHealthCheck,代码如下:

private void doDataSourceHealthCheck(Health.Builder builder) throws Exception {

// 1. 获得数据库产商,并添加至builder中

String product = getProduct();

builder.up().withDetail("database", product);

// 2. 获得测试的语句,默认为SELECT 1,然后进行查询,将查询结果放入builder中,key-->hello,value-->结果值

// 如果出现异常,则调用Builder#down

String validationQuery = getValidationQuery(product);

if (StringUtils.hasText(validationQuery)) {

try {

// Avoid calling getObject as it breaks MySQL on Java 7

List