【實用場景】基於mybatis-plus實現資料來源動態操作、自定義載入
阿新 • • 發佈：2021-11-24
簡介
基於springboot，mybatis plus集成了一套多資料來源的解決方案，在使用時引入相應的外掛dynamic-datasource-spring-boot-starter，可以實現資料來源的動態新增、刪除等功能，對於多租戶或者分庫等操作可以根據AOP切面代理到不同的資料來源、實現單一系統資料隔離的目的。
程式碼示例
mavne依賴
<!--mybatis-plus--> <dependency> <groupId>com.baomidou</groupId> <artifactId>mybatis-plus-boot-starter</artifactId> <version>3.4.3.4</version> </dependency> <!--dynamic-datasource--> <dependency> <groupId>com.baomidou</groupId> <artifactId>dynamic-datasource-spring-boot-starter</artifactId> <version>3.4.1</version> </dependency>
資料來源增加、移除
@RestController @RequestMapping("/datasources") public class DataSourceController { @Resource private DataSource dataSource; @Resource private DefaultDataSourceCreator dataSourceCreator; @GetMapping("list") public Set<String> list() { DynamicRoutingDataSource ds = (DynamicRoutingDataSource) dataSource; return ds.getDataSources().keySet(); } @PostMapping("add") public Set<String> add(@Validated @RequestBody DataSourceDTO dto) { DataSourceProperty dataSourceProperty = new DataSourceProperty(); BeanUtils.copyProperties(dto, dataSourceProperty); DynamicRoutingDataSource ds = (DynamicRoutingDataSource) dataSource; DataSource dataSource = dataSourceCreator.createDataSource(dataSourceProperty); ds.addDataSource(dto.getPollName(), dataSource); return ds.getDataSources().keySet(); } @DeleteMapping("remove") public void remove(String name) { DynamicRoutingDataSource ds = (DynamicRoutingDataSource) dataSource; ds.removeDataSource(name); } }
預設的資料來源連線池載入順序為: druid>hikaricp>beecp>dbcp>spring basic
資料來源切換
基於AOP切換
添加註解,排除不做切換的介面
package com.starsray.dynamic.datasource.annotation; import java.lang.annotation.*; /** * <p> * 使用者標識僅可以使用預設資料來源 * </p> * * @author starsray * @since 2021-11-10 */ @Target({ElementType.METHOD}) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface DefaultDs { }
切面具體實現
package com.starsray.dynamic.datasource.interceptor;
import com.baomidou.dynamic.datasource.toolkit.DynamicDataSourceContextHolder;
import com.starsray.dynamic.datasource.annotation.DefaultDs;
import com.starsray.dynamic.datasource.exception.ExceptionEnum;
import com.starsray.dynamic.datasource.exception.GlobalException;
import lombok.RequiredArgsConstructor;
import org.apache.commons.lang3.StringUtils;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.AfterReturning;
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.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import java.lang.reflect.Method;
/**
* <p>
* 資料來源選擇器切面
* </p>
*
* @author starsray
* @since 2021-11-10
*/
@Aspect
@Component
@RequiredArgsConstructor(onConstructor_ = @Autowired)
public class DsInterceptor implements HandlerInterceptor {
@Pointcut("execution(public * com.starsray.dynamic.datasource.controller.*.*(..))")
public void datasourcePointcut() {
}
/**
* 前置操作，攔截具體請求，獲取header裡的資料來源id，設定執行緒變數裡，用於後續切換資料來源
*/
@Before("datasourcePointcut()")
public void doBefore(JoinPoint joinPoint) {
Signature signature = joinPoint.getSignature();
MethodSignature methodSignature = (MethodSignature) signature;
Method method = methodSignature.getMethod();
// 排除不可切換資料來源的方法
DefaultDs annotation = method.getAnnotation(DefaultDs.class);
if (null != annotation) {
DynamicDataSourceContextHolder.push("master");
} else {
RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
ServletRequestAttributes attributes = (ServletRequestAttributes) requestAttributes;
assert attributes != null;
HttpServletRequest request = attributes.getRequest();
String header = request.getHeader("tenantName");
if (StringUtils.isNotBlank(header)) {
DynamicDataSourceContextHolder.push(header);
} else {
throw new GlobalException(ExceptionEnum.NOT_TENANT);
}
}
}
/**
* 後置操作，設定回預設的資料來源id
*/
@AfterReturning("datasourcePointcut()")
public void doAfter() {
DynamicDataSourceContextHolder.push("master");
}
}
基於重寫處理器
mybatis plus提供了預設處理器來決定使用的資料來源，可以重寫處理器實現自定義引數，比如從請求header裡面獲取引數切換資料來源。
@DS("#header.tenantId")
自定義處理器
public class HeaderProcessor extends DsProcessor {
private static final String HEADER = "#header";
@Override
public boolean matches(String key) {
return key.startsWith(HEADER);
}
@Override
public String doDetermineDatasource(MethodInvocation invocation, String key) {
HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
return request.getHeader(key.substring(8));
}
}
註冊自定義處理器
@Configuration
public class CustomerDynamicDataSourceConfig{
@Bean
public DsProcessor dsProcessor() {
DsHeaderProcessor headerProcessor = new DsHeaderProcessor();
DsSessionProcessor sessionProcessor = new DsSessionProcessor();
DsSpelExpressionProcessor spelExpressionProcessor = new DsSpelExpressionProcessor();
headerProcessor.setNextProcessor(sessionProcessor);
sessionProcessor.setNextProcessor(spelExpressionProcessor);
return headerProcessor;
}
}
如果有場景需要手動切換資料來源，可以使用元件提供的工具來實現。
DynamicDataSourceContextHolder.push("master");
自定義資料來源
mybatis plus提供了一個介面來載入資料來源資訊。
public interface DynamicDataSourceProvider {
Map<String, DataSource> loadDataSources();
}
這個介面有一個抽象實現類AbstractDataSourceProvider,通過模板方法定義了載入資料來源來源的方式，mybatis plus通過YmlDynamicDataSourceProvider實現了讀取yml檔案配置來初始化資料來源的方式。
public abstract class AbstractDataSourceProvider implements DynamicDataSourceProvider {
private static final Logger log = LoggerFactory.getLogger(AbstractDataSourceProvider.class);
@Autowired
private DefaultDataSourceCreator defaultDataSourceCreator;
public AbstractDataSourceProvider() {
}
protected Map<String, DataSource> createDataSourceMap(Map<String, DataSourceProperty> dataSourcePropertiesMap) {
Map<String, DataSource> dataSourceMap = new HashMap(dataSourcePropertiesMap.size() * 2);
Iterator var3 = dataSourcePropertiesMap.entrySet().iterator();
while(var3.hasNext()) {
Entry<String, DataSourceProperty> item = (Entry)var3.next();
String dsName = (String)item.getKey();
DataSourceProperty dataSourceProperty = (DataSourceProperty)item.getValue();
String poolName = dataSourceProperty.getPoolName();
if (poolName == null || "".equals(poolName)) {
poolName = dsName;
}
dataSourceProperty.setPoolName(poolName);
dataSourceMap.put(dsName, this.defaultDataSourceCreator.createDataSource(dataSourceProperty));
}
return dataSourceMap;
}
}
如果有需要從資料庫載入資料來源資訊，可以重寫AbstractJdbcDataSourceProvider中的executeStmt方法來載入資料庫配置資訊。示例：
package com.digital.cnzz.dynamic.ds.provider;
import com.baomidou.dynamic.datasource.provider.AbstractJdbcDataSourceProvider;
import com.baomidou.dynamic.datasource.provider.DynamicDataSourceProvider;
import com.baomidou.dynamic.datasource.spring.boot.autoconfigure.DataSourceProperty;
import com.digital.cnzz.dynamic.ds.config.DefaultDsConfig;
import com.digital.cnzz.dynamic.ds.constant.DsDriverEnum;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import javax.annotation.Resource;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.HashMap;
import java.util.Map;
@Primary
@Configuration
public class DsProvider {
@Resource
private DefaultDsConfig defaultDsConfig;
@Bean
public DynamicDataSourceProvider jdbcDynamicDataSourceProvider() {
return new AbstractJdbcDataSourceProvider(defaultDsConfig.getDriverClassName(), defaultDsConfig.getUrl(), defaultDsConfig.getUsername(), defaultDsConfig.getPassword()) {
@Override
protected Map<String, DataSourceProperty> executeStmt(Statement statement) {
Map<String, DataSourceProperty> dataSourcePropertiesMap = null;
ResultSet rs = null;
try {
dataSourcePropertiesMap = new HashMap<>();
rs = statement.executeQuery("SELECT * FROM DYNAMIC_DATASOURCE_INSTANCE");
while (rs.next()) {
String name = rs.getString("name");
DataSourceProperty property = new DataSourceProperty();
property.setDriverClassName(rs.getString("driver"));
property.setUrl(rs.getString("url"));
property.setUsername(rs.getString("username"));
property.setPassword(rs.getString("password"));
dataSourcePropertiesMap.put(name, property);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (rs != null) {
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
}
try {
statement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
return dataSourcePropertiesMap;
}
};
}
}
通過讀取原始碼可以發現，如果還有其他需要自定義載入資料來源的方式，只需要繼承AbstractDataSourceProvider抽象類，實現DynamicDataSourceProvider介面，重寫loadDataSources方法就可以實現自定義資料來源。
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