Spring+MyBatis實(shí)現(xiàn)數(shù)據(jù)讀寫分離的實(shí)例代碼

更新時(shí)間：2017年07月12日 15:14:06 作者：三無(wú)程序員

本篇文章主要介紹了Spring+MyBatis實(shí)現(xiàn)數(shù)據(jù)讀寫分離的實(shí)例代碼，具有一定的參考價(jià)值，感興趣的小伙伴們可以參考一下

本文介紹了Spring Boot + MyBatis讀寫分離，有需要了解Spring+MyBatis讀寫分離的朋友可參考。希望此文章對(duì)各位有所幫助。

其最終實(shí)現(xiàn)功能：

默認(rèn)更新操作都使用寫數(shù)據(jù)源
讀操作都使用slave數(shù)據(jù)源
特殊設(shè)置：可以指定要使用的數(shù)據(jù)源類型及名稱（如果有名稱，則會(huì)根據(jù)名稱使用相應(yīng)的數(shù)據(jù)源）

其實(shí)現(xiàn)原理如下：

通過(guò)Spring AOP對(duì)dao層接口進(jìn)行攔截，并對(duì)需要指定數(shù)據(jù)源的接口在ThradLocal中設(shè)置其數(shù)據(jù)源類型及名稱
通過(guò)MyBatsi的插件，對(duì)根據(jù)更新或者查詢操作在ThreadLocal中設(shè)置數(shù)據(jù)源（dao層沒有指定的情況下）
繼承AbstractRoutingDataSource類。

在此直接寫死使用HikariCP作為數(shù)據(jù)源

其實(shí)現(xiàn)步驟如下：

定義其數(shù)據(jù)源配置文件并進(jìn)行解析為數(shù)據(jù)源
定義AbstractRoutingDataSource類及其它注解
定義Aop攔截
定義MyBatis插件
整合在一起

1.配置及解析類

其配置參數(shù)直接使用HikariCP的配置，其具體參數(shù)可以參考HikariCP。

在此使用yaml格式，名稱為datasource.yaml,內(nèi)容如下：

dds:
 write:
  jdbcUrl: jdbc:mysql://localhost:3306/order
  password: liu123
  username: root
  maxPoolSize: 10
  minIdle: 3
  poolName: master
 read:
  - jdbcUrl: jdbc:mysql://localhost:3306/test
   password: liu123
   username: root
   maxPoolSize: 10
   minIdle: 3
   poolName: slave1
  - jdbcUrl: jdbc:mysql://localhost:3306/test2
   password: liu123
   username: root
   maxPoolSize: 10
   minIdle: 3
   poolName: slave2

定義該配置所對(duì)應(yīng)的Bean，名稱為DBConfig,內(nèi)容如下：

@Component
@ConfigurationProperties(locations = "classpath:datasource.yaml", prefix = "dds")
public class DBConfig {
  private List<HikariConfig> read;
  private HikariConfig write;

  public List<HikariConfig> getRead() {
    return read;
  }

  public void setRead(List<HikariConfig> read) {
    this.read = read;
  }

  public HikariConfig getWrite() {
    return write;
  }

  public void setWrite(HikariConfig write) {
    this.write = write;
  }
}

把配置轉(zhuǎn)換為DataSource的工具類，名稱：DataSourceUtil，內(nèi)容如下：

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;

import javax.sql.DataSource;
import java.util.ArrayList;
import java.util.List;

public class DataSourceUtil {
  public static DataSource getDataSource(HikariConfig config) {
    return new HikariDataSource(config);
  }

  public static List<DataSource> getDataSource(List<HikariConfig> configs) {
    List<DataSource> result = null;
    if (configs != null && configs.size() > 0) {
      result = new ArrayList<>(configs.size());
      for (HikariConfig config : configs) {
        result.add(getDataSource(config));
      }
    } else {
      result = new ArrayList<>(0);
    }

    return result;
  }
}

2.注解及動(dòng)態(tài)數(shù)據(jù)源

定義注解@DataSource，其用于需要對(duì)個(gè)別方法指定其要使用的數(shù)據(jù)源（如某個(gè)讀操作需要在master上執(zhí)行，但另一讀方法b需要在讀數(shù)據(jù)源的具體一臺(tái)上面執(zhí)行）

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface DataSource {
  /**
   * 類型，代表是使用讀還是寫
   * @return
   */
  DataSourceType type() default DataSourceType.WRITE;

  /**
   * 指定要使用的DataSource的名稱
   * @return
   */
  String name() default "";
}

定義數(shù)據(jù)源類型，分為兩種：READ,WRITE，內(nèi)容如下：

public enum DataSourceType {
  READ, WRITE;
}

定義保存這此共享信息的類DynamicDataSourceHolder，在其中定義了兩個(gè)ThreadLocal和一個(gè)map，holder用于保存當(dāng)前線程的數(shù)據(jù)源類型（讀或者寫），pool用于保存數(shù)據(jù)源名稱（如果指定），其內(nèi)容如下：

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class DynamicDataSourceHolder {
  private static final Map<String, DataSourceType> cache = new ConcurrentHashMap<>();
  private static final ThreadLocal<DataSourceType> holder = new ThreadLocal<>();
  private static final ThreadLocal<String> pool = new ThreadLocal<>();

  public static void putToCache(String key, DataSourceType dataSourceType) {
    cache.put(key,dataSourceType);
  }

  public static DataSourceType getFromCach(String key) {
    return cache.get(key);
  }

  public static void putDataSource(DataSourceType dataSourceType) {
    holder.set(dataSourceType);
  }

  public static DataSourceType getDataSource() {
    return holder.get();
  }

  public static void putPoolName(String name) {
    if (name != null && name.length() > 0) {
      pool.set(name);
    }
  }

  public static String getPoolName() {
    return pool.get();
  }

  public static void clearDataSource() {
    holder.remove();
    pool.remove();
  }
}

動(dòng)態(tài)數(shù)據(jù)源類為DynamicDataSoruce,其繼承自AbstractRoutingDataSource，可以根據(jù)返回的key切換到相應(yīng)的數(shù)據(jù)源，其內(nèi)容如下：

import com.zaxxer.hikari.HikariDataSource;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ThreadLocalRandom;

public class DynamicDataSource extends AbstractRoutingDataSource {
  private DataSource writeDataSource;
  private List<DataSource> readDataSource;
  private int readDataSourceSize;
  private Map<String, String> dataSourceMapping = new ConcurrentHashMap<>();

  @Override
  public void afterPropertiesSet() {
    if (this.writeDataSource == null) {
      throw new IllegalArgumentException("Property 'writeDataSource' is required");
    }
    setDefaultTargetDataSource(writeDataSource);
    Map<Object, Object> targetDataSource = new HashMap<>();
    targetDataSource.put(DataSourceType.WRITE.name(), writeDataSource);
    String poolName = ((HikariDataSource)writeDataSource).getPoolName();
    if (poolName != null && poolName.length() > 0) {
      dataSourceMapping.put(poolName,DataSourceType.WRITE.name());
    }
    if (this.readDataSource == null) {
      readDataSourceSize = 0;
    } else {
      for (int i = 0; i < readDataSource.size(); i++) {
        targetDataSource.put(DataSourceType.READ.name() + i, readDataSource.get(i));
        poolName = ((HikariDataSource)readDataSource.get(i)).getPoolName();
        if (poolName != null && poolName.length() > 0) {
          dataSourceMapping.put(poolName,DataSourceType.READ.name() + i);
        }
      }
      readDataSourceSize = readDataSource.size();
    }
    setTargetDataSources(targetDataSource);
    super.afterPropertiesSet();
  }


  @Override
  protected Object determineCurrentLookupKey() {
    DataSourceType dataSourceType = DynamicDataSourceHolder.getDataSource();
    String dataSourceName = null;
    if (dataSourceType == null ||dataSourceType == DataSourceType.WRITE || readDataSourceSize == 0) {
      dataSourceName = DataSourceType.WRITE.name();
    } else {
      String poolName = DynamicDataSourceHolder.getPoolName();
      if (poolName == null) {
        int idx = ThreadLocalRandom.current().nextInt(0, readDataSourceSize);
        dataSourceName = DataSourceType.READ.name() + idx;
      } else {
        dataSourceName = dataSourceMapping.get(poolName);
      }
    }
    DynamicDataSourceHolder.clearDataSource();
    return dataSourceName;
  }

  public void setWriteDataSource(DataSource writeDataSource) {
    this.writeDataSource = writeDataSource;
  }

  public void setReadDataSource(List<DataSource> readDataSource) {
    this.readDataSource = readDataSource;
  }
}

3.AOP攔截

如果在相應(yīng)的dao層做了自定義配置（指定數(shù)據(jù)源），則在些處理。解析相應(yīng)方法上的@DataSource注解，如果存在，并把相應(yīng)的信息保存至上面的DynamicDataSourceHolder中。在此對(duì)com.hfjy.service.order.dao包進(jìn)行做攔截。內(nèi)容如下：

import com.hfjy.service.order.anno.DataSource;
import com.hfjy.service.order.wr.DynamicDataSourceHolder;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;

/**
 * 使用AOP攔截，對(duì)需要特殊方法可以指定要使用的數(shù)據(jù)源名稱(對(duì)應(yīng)為連接池名稱）
 */
@Aspect
@Component
public class DynamicDataSourceAspect {

  @Pointcut("execution(public * com.hfjy.service.order.dao.*.*(*))")
  public void dynamic(){}

  @Before(value = "dynamic()")
  public void beforeOpt(JoinPoint point) {
    Object target = point.getTarget();
    String methodName = point.getSignature().getName();
    Class<?>[] clazz = target.getClass().getInterfaces();
    Class<?>[] parameterType = ((MethodSignature)point.getSignature()).getMethod().getParameterTypes();
    try {
      Method method = clazz[0].getMethod(methodName,parameterType);
      if (method != null && method.isAnnotationPresent(DataSource.class)) {
        DataSource datasource = method.getAnnotation(DataSource.class);
        DynamicDataSourceHolder.putDataSource(datasource.type());
        String poolName = datasource.name();
        DynamicDataSourceHolder.putPoolName(poolName);
        DynamicDataSourceHolder.putToCache(clazz[0].getName() + "." + methodName, datasource.type());
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  @After(value = "dynamic()")
  public void afterOpt(JoinPoint point) {
    DynamicDataSourceHolder.clearDataSource();
  }
}

4.MyBatis插件

如果在dao層沒有指定相應(yīng)的要使用的數(shù)據(jù)源，則在此進(jìn)行攔截，根據(jù)是更新還是查詢?cè)O(shè)置數(shù)據(jù)源的類型，內(nèi)容如下：

import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

import java.util.Properties;

@Intercepts({
    @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),
    @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class,
        RowBounds.class, ResultHandler.class})
})
public class DynamicDataSourcePlugin implements Interceptor {

  @Override
  public Object intercept(Invocation invocation) throws Throwable {
    MappedStatement ms = (MappedStatement)invocation.getArgs()[0];
    DataSourceType dataSourceType = null;
    if ((dataSourceType = DynamicDataSourceHolder.getFromCach(ms.getId())) == null) {
      if (ms.getSqlCommandType().equals(SqlCommandType.SELECT)) {
        dataSourceType = DataSourceType.READ;
      } else {
        dataSourceType = DataSourceType.WRITE;
      }
      DynamicDataSourceHolder.putToCache(ms.getId(), dataSourceType);
    }
    DynamicDataSourceHolder.putDataSource(dataSourceType);
    return invocation.proceed();
  }

  @Override
  public Object plugin(Object target) {
    if (target instanceof Executor) {
      return Plugin.wrap(target, this);
    } else {
      return target;
    }
  }

  @Override
  public void setProperties(Properties properties) {

  }
}

5.整合

在里面定義MyBatis要使用的內(nèi)容及DataSource，內(nèi)容如下：

import com.hfjy.service.order.wr.DBConfig;
import com.hfjy.service.order.wr.DataSourceUtil;
import com.hfjy.service.order.wr.DynamicDataSource;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;

import javax.annotation.Resource;
import javax.sql.DataSource;

@Configuration
@MapperScan(value = "com.hfjy.service.order.dao", sqlSessionFactoryRef = "sqlSessionFactory")
public class DataSourceConfig {
  @Resource
  private DBConfig dbConfig;

  @Bean(name = "dataSource")
  public DynamicDataSource dataSource() {
    DynamicDataSource dataSource = new DynamicDataSource();
    dataSource.setWriteDataSource(DataSourceUtil.getDataSource(dbConfig.getWrite()));
    dataSource.setReadDataSource(DataSourceUtil.getDataSource(dbConfig.getRead()));
    return dataSource;
  }

  @Bean(name = "transactionManager")
  public DataSourceTransactionManager dataSourceTransactionManager(@Qualifier("dataSource") DataSource dataSource) {
    return new DataSourceTransactionManager(dataSource);
  }

  @Bean(name = "sqlSessionFactory")
  public SqlSessionFactory sqlSessionFactory(@Qualifier("dataSource") DataSource dataSource) throws Exception {
    SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
    sessionFactoryBean.setConfigLocation(new ClassPathResource("mybatis-config.xml"));
    sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
        .getResources("classpath*:mapper/*.xml"));
    sessionFactoryBean.setDataSource(dataSource);
    return sessionFactoryBean.getObject();
  }
}

如果不清楚，可以查看github上源碼orderdemo

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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