设计模式-创建者模式总结

class DefaultHttpClientFactory {
    private static PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
    private static RequestConfig defaultRequestConfig = RequestConfig.custom().build();

    private static int mgrMaxTotal = DEFAULT_MAX_TOTAL;  //全局最大连接数
    private static int mgrDefaultMaxPerRoute = DEFAULT_MAX_PER_ROUTE; //每个主机最大连接数
    private static int connReqTimeout = DEFAULT_CONN_REQ_TIMEOUT;   //从连接池获取连接超时时间
    private static int connTimout = DEFAULT_CONN_TIMEOUT;   //发起连接超时时间
    private static int connSocketTimeout = DEFAULT_CONN_SOCKET_TIMEOUT;    //连接套接字等待时间

    public static class Builder {
        private int mgrMaxTotal = DEFAULT_MAX_TOTAL;  //全局最大连接数
        private int mgrDefaultMaxPerRoute = DEFAULT_MAX_PER_ROUTE; //每个主机最大连接数
        private int connReqTimeout = DEFAULT_CONN_REQ_TIMEOUT;   //从连接池获取连接超时时间
        private int connTimout = DEFAULT_CONN_TIMEOUT;   //发起连接超时时间
        private int connSocketTimeout = DEFAULT_CONN_SOCKET_TIMEOUT;    //连接套接字等待时间

        Builder() {
        }

        public Builder maxTotal(int maxTotal) {
            this.mgrMaxTotal = maxTotal;
            return this;
        }

        public Builder maxPerRoute(int maxPerRoute) {
            this.mgrDefaultMaxPerRoute = maxPerRoute;
            return this;
        }

        public Builder connReqTimeout(int connReqTimeout) {
            this.connReqTimeout = connReqTimeout;
            return this;
        }

        public Builder connTimout(int connTimout) {
            this.connTimout = connTimout;
            return this;
        }

        public Builder connSocketTimeout(int connSocketTimeout) {
            this.connSocketTimeout = connSocketTimeout;
            return this;
        }

        public DefaultHttpClientFactory build() {
            return new DefaultHttpClientFactory(this);
        }
    }

    private DefaultHttpClientFactory(Builder builder) {
        mgrMaxTotal = builder.mgrMaxTotal;
        mgrDefaultMaxPerRoute = builder.mgrDefaultMaxPerRoute;
        connReqTimeout = builder.connReqTimeout;
        connTimout = builder.connTimout;
        connSocketTimeout = builder.connSocketTimeout;
    }

    public static DefaultHttpClientFactory.Builder custom() {
        return new DefaultHttpClientFactory.Builder();
    }

    public CloseableHttpClient getClient() {
        cm.setMaxTotal(mgrMaxTotal); // 设置最大连接数
        cm.setDefaultMaxPerRoute(mgrDefaultMaxPerRoute); // 设置每个路由最大连接数，每个独立的host为1个路由
        RequestConfig requestConfig = RequestConfig.copy(defaultRequestConfig)
                .setConnectionRequestTimeout(connReqTimeout)//从连接池获取连接超时时间
                .setConnectTimeout(connTimout)//发起连接超时时间
                .setSocketTimeout(connSocketTimeout)//连接套接字等待时间
                .setRedirectsEnabled(false)
                .build();

        HttpClientBuilder httpClientBuilder = HttpClientBuilder.create();
        httpClientBuilder.setConnectionManager(cm);
        httpClientBuilder.setDefaultRequestConfig(requestConfig);

        httpClientBuilder.setRetryHandler(new DefaultHttpRequestRetryHandler(0, false)); // 去掉默认的3次重试
        CloseableHttpClient httpClient = httpClientBuilder.build();
        return httpClient;
    }
}