Spring AOP從入門到放棄之多數據源讀寫動態切換

時間  2019-11-12
標籤 spring aop 入門 放棄 之多 數據 讀寫 動態 切換 欄目 Spring 简体版
原文   原文鏈接

項目中若是須要由多個數據源，好比3個，一個主兩個從。主庫主要是寫操做，兩個從庫作讀操做。 那麼在spring boot中怎麼使用AOP判斷程序是讀仍是寫，而且分配到不一樣的數據源中呢？css

本文重要是 的代碼是使用 spring boot 、druid、mybatis、mybatis plus等技術作支持的。html

邏輯步驟

大概的邏輯爲， 一、引入durid 二、配置三個數據源，1個寫，2個讀，兩個從庫實現簡單的負載功能。 三、配置mybatis 四、配置mybatis plus 五、配置aop 六、定義卻點 讀（select）的方法操做，使用讀庫的數據源，其餘的 update、delete、insert等使用寫庫的數據源 七、給寫庫配置spring 的事務，出現異常的時候回滾。java

引入jar

這裏不累贅寫 mysql 、druid等jar包的引入。mysql

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>

配置Druid

@Configuration
public class DruidConfig {
    /**
     * 註冊DruidServlet
     * http://localhost:8080/druid/datasource.html查看監控信息
     * @return
     */
    @Bean
    public ServletRegistrationBean druidServletRegistrationBean() {
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean();
        servletRegistrationBean.setServlet(new StatViewServlet());
        servletRegistrationBean.addUrlMappings("/druid/*");
        return servletRegistrationBean;
    }

    /**
     * 註冊DruidFilter攔截
     *
     * @return
     */
    @Bean
    public FilterRegistrationBean duridFilterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new WebStatFilter());
        Map<String, String> initParams = new HashMap<String, String>();
        //設置忽略請求
        initParams.put("exclusions", "*.js,*.gif,*.jpg,*.bmp,*.png,*.css,*.ico,/monitor/druid/*");
        filterRegistrationBean.setInitParameters(initParams);
        filterRegistrationBean.addUrlPatterns("/*");
        return filterRegistrationBean;
    }
}

配置yml

writedatasource:
  url: jdbc:mysql://xx.x.x.x:3306/slife?useUnicode=true&characterEncoding=utf8&useSSL=false
  driverClass: com.mysql.jdbc.Driver
  username: xx
  password: cdd
  initialSize: 1
  minIdle: 1
  maxActive: 20
  testOnBorrow: true
  timeBetweenEvictionRunsMillis: 60000
  minEvictableIdleTimeMillis: 300000
  validationQuery: SELECT 1 FROM DUAL
  testWhileIdle: true
  testOnReturn: false
  poolPreparedStatements: true
  maxPoolPreparedStatementPerConnectionSize: 20
  filters: stat,wall,logback
  #connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
  useGlobalDataSourceStat: true


mybatis:
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.slife.entity


readdatasource01:
  url: jdbc:mysql://xx.x.x.x:3306/slife?useUnicode=true&characterEncoding=utf8&useSSL=false
  driverClass: com.mysql.jdbc.Driver
  username: xx
  password: cdd
  initialSize: 1
  minIdle: 1
  maxActive: 20
  testOnBorrow: true
  timeBetweenEvictionRunsMillis: 60000
  minEvictableIdleTimeMillis: 300000
  validationQuery: SELECT 1 FROM DUAL
  testWhileIdle: true
  testOnReturn: false
  poolPreparedStatements: true
  maxPoolPreparedStatementPerConnectionSize: 20
  filters: stat,wall,logback
  #connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
  useGlobalDataSourceStat: true


readdatasource02:
  url: jdbc:mysql://xx.x.x.x:3306/slife?useUnicode=true&characterEncoding=utf8&useSSL=false
  driverClass: com.mysql.jdbc.Driver
  username: xx
  password: cdd
  initialSize: 1
  minIdle: 1
  maxActive: 20
  testOnBorrow: true
  timeBetweenEvictionRunsMillis: 60000
  minEvictableIdleTimeMillis: 300000
  validationQuery: SELECT 1 FROM DUAL
  testWhileIdle: true
  testOnReturn: false
  poolPreparedStatements: true
  maxPoolPreparedStatementPerConnectionSize: 20
  filters: stat,wall,logback
  #connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
  useGlobalDataSourceStat: true

加載配置文件數據

/**
 * 只提供了經常使用的屬性，若是有須要，本身添加
 *
 */
@Component
@ConfigurationProperties(prefix = "writedatasource")
public class WriteProperties extends DataProperties{

}


/**
 * 只提供了經常使用的屬性，若是有須要，本身添加
 *
 */
@Component
@ConfigurationProperties(prefix = "readdatasource02")
public class ReadProperties2 extends DataProperties{

}

@ConfigurationProperties(prefix = "druid")
public class DruidProperties {
    private String url;
    private String username;
    private String password;
    private String driverClass;

    private int maxActive;
    private int minIdle;
    private int initialSize;
    private boolean testOnBorrow;
    private String filters;
    。
    。
    。
    。
get  set  省略

三、定義數據源

public enum DataSourceType {
    read("read", "從庫"),
    write("write", "主庫");

    private String type;

    private String name;

    DataSourceType(String type, String name) {
        this.type = type;
        this.name = name;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

簡單的負載均衡配置

public class BlifeAbstractRoutingDataSource extends AbstractRoutingDataSource {
    private  int dataSourceNumber;
    private AtomicInteger count = new AtomicInteger(0);

    public BlifeAbstractRoutingDataSource(int dataSourceNumber) {
        this.dataSourceNumber = dataSourceNumber;
    }

    @Override
    protected Object determineCurrentLookupKey() {
        String typeKey = DataSourceContextHolder.getJdbcType();
        if (DataSourceType.write.getType().equals(typeKey)){
            return DataSourceType.write.getType();
        }
        // 讀 簡單負載均衡
        int number = count.getAndAdd(1);
        int lookupKey = number % dataSourceNumber;
        return new Integer(lookupKey);
    }
}

把數據源加ThreadLocal中

public class DataSourceContextHolder {
    private static final ThreadLocal<String> LOCAL = new ThreadLocal<String>();

    private static Logger logger = LoggerFactory.getLogger(DataSourceContextHolder.class);

    public static ThreadLocal<String> getLocal() {
        return LOCAL;
    }

    /**
     * 讀多是多個庫
     */
    public static void read() {

        LOCAL.set(DataSourceType.read.getType());
    }

    /**
     * 寫只有一個庫
     */
    public static void write() {
        logger.debug("writewritewrite");
        LOCAL.set(DataSourceType.write.getType());
    }

    public static String getJdbcType() {
        return LOCAL.get();
    }
}

配置寫庫的事物

讀庫 通常沒配置事物的需求，固然配置了只讀會有更好的效果。git

@Configuration
@EnableTransactionManagement
public class DataSourceTransactionManager extends DataSourceTransactionManagerAutoConfiguration {

    private Logger logger= LoggerFactory.getLogger(getClass());

    /**
     * 自定義事務
     * MyBatis自動參與到spring事務管理中，無需額外配置，
     * 只要org.mybatis.spring.SqlSessionFactoryBean引用的數據源與
     * DataSourceTransactionManager引用的數據源一致便可，不然事務管理會不起做用。
     * @return
     */
    @Resource(name = "writeDataSource1")
    private DataSource dataSource;

    @Bean(name = "transactionManager")
    public org.springframework.jdbc.datasource.DataSourceTransactionManager transactionManagers() {
        logger.info("-------------------- transactionManager init ---------------------");
        return new org.springframework.jdbc.datasource.DataSourceTransactionManager(dataSource);
    }
}

約定方法，讀寫動態切換

@Aspect
@Component
@Order(-100)// 保證該AOP在@Transactional以前執行
public class DataSourceAop {
    private  Logger logger = LoggerFactory.getLogger(getClass());



    @Before("execution(* com.slife.dao..*.select*(..)) || execution(* com.slife.dao..*.get*(..))")
    public void setReadDataSourceType() {
        DataSourceContextHolder.read();
        logger.info("dataSource切換到：Read");
    }

    @Before("execution(* com.slife.dao..*.*insert*(..)) || execution(* com.slife.dao..*.*update*(..))")
    public void setWriteDataSourceType() {
        DataSourceContextHolder.write();
        logger.info("dataSource切換到：write");
    }
}

運行項目，執行結果

這裏寫圖片描述

這裏寫圖片描述

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