FactoryBean是如何运用在我们程序中的

       我们在项目中可能都会用到redis,es，或者数据库，比如我们项目中需要连接多个es分片的时候，我们的配置文件最开始可能是下面的形式 ,ConnectionConfig是连接信息类，TransportUtils是工具类，下面是列举了2个业务分片，假如有10多个业务分片的时候需要十多个链接信息类和TransportUtils，显然是不合理的。

<bean id="connectionConfig11" class="com.kk.list.search.es.ConnectionConfig">
<property name="transportAddresses" value="127.0.0.1:9300"/>
<property name="clusterName" value="elastic"/>
<property name="clientTransportSniff" value="false"/>
</bean>

<bean id="connectionConfig12" class="com.kk.list.search.es.ConnectionConfig">
<property name="transportAddresses" value="127.0.0.1:9200"/>
<property name="clusterName" value="elastic"/>
<property name="clientTransportSniff" value="false"/>
</bean>

<bean id="transportUtils11" class="com.kk.list.search.es.TransportUtils">
<property name="connectionConfig"  value="connectionConfig11"/>
</bean>

<bean id="transportUtils12" class="com.kk.list.search.es.TransportUtils">
<property name="connectionConfig" value="connectionConfig12"/>
</bean>

​​​这个时候我们想到用FactoryBean来解决这个场景的问题，FactoryBean 通常是用来创建比较复杂的bean，一般的bean 直接用xml配置即可，但如果一个bean的创建过程中涉及到很多其他的bean 和复杂的逻辑，用xml配置比较困难，这时可以考虑用FactoryBean，我们直接看代码修改后的结果

1先看配置文件，在配置文件传递参数，通过ElasticsearchTransportClientFactoryBean类来生成TransportUtils实例对象

 <bean id="transportUtils11" class="com.kk.list.search.es.ElasticsearchTransportClientFactoryBean">
        <property name="transportAddresses" value="127.0.0.1:9300"/>
        <property name="clusterName" value="elastic"/>
        <property name="clientTransportSniff" value="false"/>
    </bean>

    <bean id="transportUtils12" class="com.kk.list.search.es.ElasticsearchTransportClientFactoryBean">
        <property name="transportAddresses" value="127.0.0.1:9200"/>
        <property name="clusterName" value="elastic"/>
        <property name="clientTransportSniff" value="false"/>
    </bean>

2再看这个ElasticsearchTransportClientFactoryBean类，实现了FacetoryBean的三个方法，还实现DisposableBean接口

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.FactoryBean;



public class ElasticsearchTransportClientFactoryBean implements FactoryBean,DisposableBean {
    protected final Log logger = LogFactory.getLog(getClass());
    private TransportUtils transportUtils;
    private ConnectionConfig connectionConfig = new ConnectionConfig();

    public void setTransportAddresses(String transportAddresses) {
        connectionConfig.setTransportAddresses(transportAddresses);
    }

    public Object getObject() throws Exception {

        TransportUtils transportUtils = new TransportUtils(connectionConfig);
        return transportUtils;
    }

    public void setClusterName(String clusterName) {
        connectionConfig.setClusterName(clusterName);
    }

    public void setClientTransportSniff(boolean clientTransportSniff) {
        connectionConfig.setClientTransportSniff(clientTransportSniff);
    }

    public Class getObjectType() {
        return TransportUtils.class;
    }

    public boolean isSingleton() {
        return true;
    }

    public void destroy() throws Exception {
        transportUtils.destroy();
    }

    public void afterPropertiesSet() throws Exception {
        logger.info("begin to link to server");
        getObject();
        logger.info("link to the server");
    }
}

3我们看看ConnectionConfig类，就是一个POJO类，来传递参数用的

import org.apache.commons.lang.StringUtils;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.util.ArrayList;
import java.util.List;


public class ConnectionConfig {

    protected final Log logger = LogFactory.getLog(getClass());

    /**
     * es集群地址配置串
     * address1:port,address2:port
     */
    private String transportAddresses;

    /**
     * es地址
     * address
     */
    private String addresses;

    /**
     * port
     */
    private int port;

    /**
     * 集群名称
     */
    private String clusterName;


    /**
     * 是否探测服务器集群
     */
    private Boolean clientTransportSniff =false;

    private List<ConnectionConfig> connectionConfigList;


    public String getTransportAddresses() {
        return transportAddresses;
    }

    public void setTransportAddresses(String transportAddresses) {
        this.transportAddresses = transportAddresses;
        if (StringUtils.isNotBlank(transportAddresses)) {
            String[] ads = transportAddresses.split(";");
            if (null != ads && ads.length > 0) {
                List<ConnectionConfig> connectionConfigList = new ArrayList<ConnectionConfig>();
                for (int i = 0; i < ads.length; i++) {
                    String address = ads[i];
                    if (StringUtils.isNotBlank(address)) {
                        String[] urls = address.split(":");
                        if (urls.length == 2) {
                            ConnectionConfig connectionConfig = new ConnectionConfig();
                            connectionConfig.setAddresses(urls[0]);
                            connectionConfig.setPort(Integer.valueOf(urls[1]));
                            connectionConfigList.add(connectionConfig);
                        } else {
                            throw new ExceptionInInitializerError(ads[i] + "  parameter is format error,please check spring config file!");
                        }
                    }
                    setConnectionConfigList(connectionConfigList);
                }
            } else {
                throw new ExceptionInInitializerError("transportAddresses  parameter is format error,please check spring config file!");
            }

        } else {
            throw new ExceptionInInitializerError("transportAddresses init parameter is empty,please check spring config file!");
        }
    }

    public String getAddresses() {
        return addresses;
    }

    public void setAddresses(String addresses) {
        this.addresses = addresses;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public List<ConnectionConfig> getConnectionConfigList() {
        return connectionConfigList;
    }

    public void setConnectionConfigList(List<ConnectionConfig> connectionConfigList) {
        this.connectionConfigList = connectionConfigList;
    }

    public String getClusterName() {
        return clusterName;
    }

    public void setClusterName(String clusterName) {
        this.clusterName = clusterName;
    }

    public Boolean getClientTransportSniff() {
        return clientTransportSniff;
    }

    public void setClientTransportSniff(Boolean clientTransportSniff) {
        this.clientTransportSniff = clientTransportSniff;
    }
}

4接着看TransportUtils工具类，这个才是ElasticsearchTransportClientFactoryBean最后实例化生成的类

import com.carrotsearch.hppc.ObjectContainer;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.elasticsearch.action.admin.indices.alias.get.GetAliasesRequest;
import org.elasticsearch.action.admin.indices.alias.get.GetAliasesResponse;
import org.elasticsearch.action.bulk.BulkProcessor;
import org.elasticsearch.action.bulk.BulkRequest;
import org.elasticsearch.action.bulk.BulkResponse;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.cluster.metadata.AliasMetaData;
import org.elasticsearch.common.collect.ImmutableOpenMap;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.transport.InetSocketTransportAddress;
import org.elasticsearch.common.unit.ByteSizeUnit;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.QueryBuilders;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;


public class TransportUtils {
    TransportClient client = null;
    private ConnectionConfig connectionConfig;
    protected final Log logger = LogFactory.getLog(getClass());
    private BulkProcessor staticBulkProcessor = null;


    public TransportClient getClient() {
        return client;
    }

    public TransportUtils(ConnectionConfig config) throws UnknownHostException {
        this.connectionConfig = config;
        init();
    }
    public void destroy() throws Exception {
        client.close();
    }

    private void init() throws UnknownHostException {
        List<ConnectionConfig> configList = connectionConfig.getConnectionConfigList();
        if (null != configList && !configList.isEmpty()) {
            Settings settings = Settings.settingsBuilder().put("client.transport.ping_timeout", "10s").put("cluster.name", connectionConfig.getClusterName()).put("client.transport.sniff", connectionConfig.getClientTransportSniff()).build();
            logger.info("clusterName:" + connectionConfig.getClusterName() + "clientTransportSniff:" + connectionConfig.getClientTransportSniff());
            for (ConnectionConfig config : configList) {
                if (null != config.getAddresses()) {
                    if (logger.isInfoEnabled()) {
                        logger.info("Adding transport address: " + config.getAddresses() + " port: " + config.getPort());
                    }
                    if (null ==client){
                        client = TransportClient.builder().settings(settings).build();
                    }

                    client.addTransportAddress(new InetSocketTransportAddress(InetAddress.getByName(config.getAddresses()), config.getPort()));
                }
            }
        } else {
            throw new ExceptionInInitializerError("transportAddresses init parameter is empty,please check spring config file!");
        }
        staticBulkProcessor= getBulkProcessor(client);
        logger.info("transport init  succeed : cluster.name:" + connectionConfig.getClusterName());
    }




    /**【设置自动提交文档】*/
    public BulkProcessor getBulkProcessor(TransportClient client) {
        //自动批量提交方式
        if (staticBulkProcessor == null) {
            try {
                staticBulkProcessor = BulkProcessor.builder(client,
                        new BulkProcessor.Listener() {
                            public void beforeBulk(long executionId, BulkRequest request) {
                                //提交前调用
                                //System.out.println(new Date().toString() + " before");
                            }
                            public void afterBulk(long executionId, BulkRequest request, BulkResponse response) {
                                //提交结束后调用（无论成功或失败）
                                if(response.hasFailures()){
                                    logger.error("有文档提交失败！" + response.buildFailureMessage());
                                    //return;
                                }
                            }
                            public void afterBulk(long executionId, BulkRequest request, Throwable failure) {
                                //提交结束且失败时调用
                                System.out.println( " 有文档提交失败！after failure=" + failure.getMessage());
                                //return;
                            }
                        })
                        .setBulkActions(1000)//文档数量达到1000时提交
                        .setBulkSize(new ByteSizeValue(5, ByteSizeUnit.MB))//总文档体积达到5MB时提交 //
                        .setFlushInterval(TimeValue.timeValueSeconds(5))//每5S提交一次（无论文档数量、体积是否达到阈值）
                        .setConcurrentRequests(10)//加1后为可并行的提交请求数，即设为0代表只可1个请求并行，设为1为2个并行
                        .build();
                //staticBulkProcessor.awaitClose(10, TimeUnit.MINUTES);//关闭，如有未提交完成的文档则等待完成，最多等待10分钟
            } catch (Exception e) {//关闭时抛出异常
                e.printStackTrace();
            }
        }
        return staticBulkProcessor;
    }



    public BulkProcessor getStaticBulkProcessor() {
        return staticBulkProcessor;
    }

    public void setStaticBulkProcessor(BulkProcessor staticBulkProcessor) {
        this.staticBulkProcessor = staticBulkProcessor;
    }


}

 下面几篇博客讲的比较清楚

  https://www.jianshu.com/p/6f0a59623090

  https://blog.csdn.net/joenqc/article/details/66479154

  https://blog.csdn.net/u013185616/article/details/52335864