我使用ektorp来连接CouchDB。
构建一个ektorp HttpClient实例的方式是使用构建器模式：
HttpClient httpClient = new StdHttpClient.Builder()
.host("mychouchdbhost")
.port(4455)
.build();
我相对来说对Spring比较新，请给我一些建议，如何配置一个HttpClient在我的上下文中通过Builder创建它。
其中一个方法是使用@Configuration。还有其他选项吗？
您可以尝试实现FactoryBean接口：
public class HttpFactoryBean implements FactoryBean<HttpClient>{
private String host;
private int port;
public HttpClient getObject() throws Exception {
return new StdHttpClient.Builder()
.host(host)
.port(port)
.build();
}
public Class<? extends HttpClient> getObjectType() {
return StdHttpClient.class;
}
public boolean isSingleton() {
return true;
}
public void setHost(String host) {
this.host = host;
}
public void setPort(int port) {
this.port = port;
}}
并将以下 bean 定义添加到配置中：
<beans ...">
<bean name="myHttpClient" class="HttpFactoryBean">
<property name="port" value="8080"/>
<property name="host" value="localhost"/>
</bean>
</beans>
接下来你可以将这个bean注入到其他的beans中，它将会被解析为StdHttpClient实例。
我曾在开发FlexyPool时遇到过同样的问题，这就是我所做的。
基本上，从以下构建器开始：
public final class Configuration<T extends DataSource> extends ConfigurationProperties<T, Metrics, PoolAdapter<T>> {
public static final long DEFAULT_METRIC_LOG_REPORTER_PERIOD = 5;
public static class Builder<T extends DataSource> {
private final String uniqueName;
private final T targetDataSource;
private final PoolAdapterBuilder<T> poolAdapterBuilder;
private final MetricsBuilder metricsBuilder;
private boolean jmxEnabled = true;
private long metricLogReporterPeriod = DEFAULT_METRIC_LOG_REPORTER_PERIOD;
public Builder(String uniqueName, T targetDataSource, MetricsBuilder metricsBuilder, PoolAdapterBuilder<T> poolAdapterBuilder) {
this.uniqueName = uniqueName;
this.targetDataSource = targetDataSource;
this.metricsBuilder = metricsBuilder;
this.poolAdapterBuilder = poolAdapterBuilder;
}
public Builder setJmxEnabled(boolean enableJmx) {
this.jmxEnabled = enableJmx;
return this;
}
public Builder setMetricLogReporterPeriod(long metricLogReporterPeriod) {
this.metricLogReporterPeriod = metricLogReporterPeriod;
return this;
}
public Configuration<T> build() {
Configuration<T> configuration = new Configuration<T>(uniqueName, targetDataSource);
configuration.setJmxEnabled(jmxEnabled);
configuration.setMetricLogReporterPeriod(metricLogReporterPeriod);
configuration.metrics = metricsBuilder.build(configuration);
configuration.poolAdapter = poolAdapterBuilder.build(configuration);
return configuration;
}
}
private final T targetDataSource;
private Metrics metrics;
private PoolAdapter poolAdapter;
private Configuration(String uniqueName, T targetDataSource) {
super(uniqueName);
this.targetDataSource = targetDataSource;
}
public T getTargetDataSource() {
return targetDataSource;
}
public Metrics getMetrics() {
return metrics;
}
public PoolAdapter<T> getPoolAdapter() {
return poolAdapter;
}
}
使用基于Java的配置很简单：
@org.springframework.context.annotation.Configuration
public class FlexyDataSourceConfiguration {
@Bean
public Configuration configuration() {
return new Configuration.Builder(
UUID.randomUUID().toString(),
poolingDataSource,
CodahaleMetrics.BUILDER,
BitronixPoolAdapter.BUILDER
).build();
}
}
<bean id="configurationBuilder" class="com.vladmihalcea.flexypool.config.Configuration$Builder">
<constructor-arg value="uniqueId"/>
<constructor-arg ref="poolingDataSource"/>
<constructor-arg value="#{ T(com.vladmihalcea.flexypool.metric.codahale.CodahaleMetrics).BUILDER }"/>
<constructor-arg value="#{ T(com.vladmihalcea.flexypool.adaptor.BitronixPoolAdapter).BUILDER }"/>
</bean>
<bean id="configuration" factory-bean="configurationBuilder" factory-method="build"/>
虽然对于您的情况没有明确说明，但如果构建器通过标准的bean模式set方法公开属性，则可以进行扩展。例如，如果我们以org.apache.httpcomponents:httpclient HttpClientBuilder为例，我们可以如下操作：
public class HttpClientFactoryBean
extends HttpClientBuilder
implements InitializingBean,
FactoryBean<HttpClient> {
private HttpClient value;
@Override
public void afterPropertiesSet() throws Exception {
this.value = build();
}
@Override
public HttpClient getObject() throws Exception {
return value;
}
@Override
public Class<?> getObjectType() {
return HttpClient.class;
}
@Override
public boolean isSingleton() {
return true;
}
}
HttpClientBuilder 公开的任何方法都可以被您的工厂 bean 访问。现在可以实现以下配置：<beans id="httpClient" class="com.drunkendev.factory.HttpClientFactoryBean">
<beans name="defaultCredentialsProvider" ref="credentialsProvider"/>
<beans name="targetAuthenticationStrategy">
<util:constant static-field="org.apache.http.impl.client.TargetAuthenticationStrategy.INSTANCE"/>
</beans>
</beans>
FactoryBean虽然更清洁，但有一种更快速且简单的方法，即使用SpEL。
这是我刚刚配置Neo4j driver的方式：
<bean id = "neoDriver" class = "org.neo4j.driver.v1.GraphDatabase"
factory-method="driver">
<constructor-arg value = "bolt://127.0.0.1:7687" />
<constructor-arg>
<bean class = "org.neo4j.driver.v1.AuthTokens" factory-method = "basic">
<constructor-arg value = "neo4j" />
<constructor-arg value = "***" />
</bean>
</constructor-arg>
<constructor-arg type="org.neo4j.driver.v1.Config"
value = "#{T(org.neo4j.driver.v1.Config).build ()
.withConnectionAcquisitionTimeout ( 10, T(java.util.concurrent.TimeUnit).SECONDS )
.withConnectionTimeout ( 10, T(java.util.concurrent.TimeUnit).SECONDS )
.toConfig ()
}"
/>
</bean>
从工厂方法的第三个参数可以看出，您可以将构建器及其方法作为SpEL表达式调用，但需要通过完全限定名称指定类。这避免了您编写整个样板FactoryBean的麻烦。
setJmxEnabled或setMetricLogReporterPeriod，只使用了构建器构造函数。 - Krease