springboot 自定义自动配置

springboot 自动配置

springboot 核心就在自动配置 搞明白自动配置就搞定了springboot 一半
下面一图是依赖注入的核心


主要就在这spring-auto-autoconfigure 这边
下面示范下 自动注入 以httpclient 为例

1 加注解

  		<dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.10</version>
       </dependency>

2 写自动注入类的属性配置 (可以在application.yml 配置的属性)

package com.xyhua.autoconfig;

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "spring.httpclient")
public class HttpClientProperties {


    private Integer connectTimeOut = 1000;

    private Integer socketTimeOut = 10000;

    private String agent = "agent";
    private Integer maxConnPerRoute = 10;
    private Integer maxConnTotaol   = 50;

    public Integer getConnectTimeOut() {
        return connectTimeOut;
    }

    public void setConnectTimeOut(Integer connectTimeOut) {
        this.connectTimeOut = connectTimeOut;
    }

    public Integer getSocketTimeOut() {
        return socketTimeOut;
    }

    public void setSocketTimeOut(Integer socketTimeOut) {
        this.socketTimeOut = socketTimeOut;
    }

    public String getAgent() {
        return agent;
    }

    public void setAgent(String agent) {
        this.agent = agent;
    }

    public Integer getMaxConnPerRoute() {
        return maxConnPerRoute;
    }

    public void setMaxConnPerRoute(Integer maxConnPerRoute) {
        this.maxConnPerRoute = maxConnPerRoute;
    }

    public Integer getMaxConnTotaol() {
        return maxConnTotaol;
    }

    public void setMaxConnTotaol(Integer maxConnTotaol) {
        this.maxConnTotaol = maxConnTotaol;
    }
}

3 写自动注入类

package com.xyhua.autoconfig;

import org.apache.http.client.HttpClient;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.impl.NoConnectionReuseStrategy;
import org.apache.http.impl.client.HttpClientBuilder;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@ConditionalOnClass({HttpClient.class})
@EnableConfigurationProperties({HttpClientProperties.class})
public class HttpClientAutoConfiguration {

    private final HttpClientProperties properties;

    public HttpClientAutoConfiguration(HttpClientProperties properties) {
        this.properties = properties;
    }

    @Bean
    @ConditionalOnMissingBean({HttpClient.class})
    public HttpClient mHttpClient() {
        RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(properties.getConnectTimeOut())
                .setSocketTimeout(properties.getSocketTimeOut()).build();//构建requestConfig
        HttpClient client = HttpClientBuilder.create().setDefaultRequestConfig(requestConfig).setUserAgent(properties.getAgent())
                .setMaxConnPerRoute(properties.getMaxConnPerRoute()).setConnectionReuseStrategy(new NoConnectionReuseStrategy()).build();
        return client;
    }
}

很简单的三步就搞定了 自动注入

需要注意一个细节

上面的类需要和springbootapplication 在同一根目录下

不在更目录下 可以使用下面的方式

第一种 使用MET-INF

1 MET-INF 下 spring.factories
 *         # Auto Configure
 *         org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
 *         com.xyhua.autoconfig.HttpClientAutoConfiguration(主入类的全路径)

第二种 加注解

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Import(HttpClientAutoConfiguration.class)
public @interface EnableHttpClient {
}

需要在启动类种加入@EnableHttpClient

两种选一种