mybatis运行时拦截ParameterHandler注入参数
在实现多租户系统时，每个租户下的用户，角色，权限，菜单都是独立的，每张表里都有租户Id字段 (tenantId)，每次做数据库操作的时候都需要带上这个字段，很烦。
现在的需求就是在mybatis向sql设置参数时拦截，获取当前登录用户的tenantId，若参数的集合中没有 tenantId，将当前登录用户的tenantId 放到 sql参数的集合中，
这样就不必在业务代码中关心租户信息了。
具体的做法就是拦截ParameterHandler的 setParameters 方法, 将 tenantId 添加到要设置到参数中，如果是 insert 操作 需要 sql 生成钱拦截，将tenantId设置到实体中
代码如下
package com.ipampas.panshi.interceptor; import org.apache.commons.lang.StringUtils; import org.apache.ibatis.binding.MapperMethod; import org.apache.ibatis.executor.Executor; import org.apache.ibatis.executor.parameter.ParameterHandler; import org.apache.ibatis.mapping.BoundSql; import org.apache.ibatis.mapping.MappedStatement; import org.apache.ibatis.mapping.ParameterMapping; import org.apache.ibatis.mapping.SqlCommandType; import org.apache.ibatis.plugin.*; import org.apache.ibatis.session.RowBounds; import org.springframework.beans.BeanUtils; import org.springframework.util.ClassUtils; import java.beans.PropertyDescriptor; import java.lang.reflect.Field; import java.lang.reflect.InvocationTargetException; import java.sql.PreparedStatement; import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.Properties; /** * User : liulu * Date : 2017/12/1 11:30 * version $Id: ParamInterceptor.java, v 0.1 Exp $ */ @Intercepts({ @Signature(type = ParameterHandler.class, method = "setParameters", args = PreparedStatement.class), @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}), @Signature(type = Executor.class, method = "createCacheKey", args = {MappedStatement.class, Object.class, RowBounds.class, BoundSql.class}) } ) public class ParamInterceptor implements Interceptor { private static final String PARAM_KEY = "tenantId"; @Override public Object intercept(Invocation invocation) throws Throwable { // 拦截 Executor 的 update 方法 生成sql前将 tenantId 设置到实体中 if (invocation.getTarget() instanceof Executor && invocation.getArgs().length == 2) { return invokeUpdate(invocation); } // 拦截 Executor 的 createCacheKey 方法，pageHelper插件会拦截 query 方法，调用此方法，提前将参数设置到参数集合中 if (invocation.getTarget() instanceof Executor && invocation.getArgs().length == 4) { return invokeCacheKey(invocation); } //拦截 ParameterHandler 的 setParameters 方法 动态设置参数 if (invocation.getTarget() instanceof ParameterHandler) { return invokeSetParameter(invocation); } return null; } private Object invokeCacheKey(Invocation invocation) throws Exception { Executor executor = (Executor) invocation.getTarget(); MappedStatement ms = (MappedStatement) invocation.getArgs()[0]; if (ms.getSqlCommandType() != SqlCommandType.SELECT) { return invocation.proceed(); } Object parameterObject = invocation.getArgs()[1]; RowBounds rowBounds = (RowBounds) invocation.getArgs()[2]; BoundSql boundSql = (BoundSql) invocation.getArgs()[3]; List<String> paramNames = new ArrayList<>(); boolean hasKey = hasParamKey(paramNames, boundSql.getParameterMappings()); if (!hasKey) { return invocation.proceed(); } // 改写参数 parameterObject = processSingle(parameterObject, paramNames); return executor.createCacheKey(ms, parameterObject, rowBounds, boundSql); } private Object invokeUpdate(Invocation invocation) throws Exception { Executor executor = (Executor) invocation.getTarget(); // 获取第一个参数 MappedStatement ms = (MappedStatement) invocation.getArgs()[0]; // 非 insert 语句 不处理 if (ms.getSqlCommandType() != SqlCommandType.INSERT) { return invocation.proceed(); } // mybatis的参数对象 Object paramObj = invocation.getArgs()[1]; if (paramObj == null) { return invocation.proceed(); } // 插入语句只传一个基本类型参数, 不做处理 if (ClassUtils.isPrimitiveOrWrapper(paramObj.getClass()) || String.class.isAssignableFrom(paramObj.getClass()) || Number.class.isAssignableFrom(paramObj.getClass())) { return invocation.proceed(); } processParam(paramObj); return executor.update(ms, paramObj); } private Object invokeSetParameter(Invocation invocation) throws Exception { ParameterHandler parameterHandler = (ParameterHandler) invocation.getTarget(); PreparedStatement ps = (PreparedStatement) invocation.getArgs()[0]; // 反射获取 BoundSql 对象，此对象包含生成的sql和sql的参数map映射 Field boundSqlField = parameterHandler.getClass().getDeclaredField("boundSql"); boundSqlField.setAccessible(true); BoundSql boundSql = (BoundSql) boundSqlField.get(parameterHandler); List<String> paramNames = new ArrayList<>(); // 若参数映射没有包含的key直接返回 boolean hasKey = hasParamKey(paramNames, boundSql.getParameterMappings()); if (!hasKey) { return invocation.proceed(); } // 反射获取 参数对像 Field parameterField = parameterHandler.getClass().getDeclaredField("parameterObject"); parameterField.setAccessible(true); Object parameterObject = parameterField.get(parameterHandler); // 改写参数 parameterObject = processSingle(parameterObject, paramNames); // 改写的参数设置到原parameterHandler对象 parameterField.set(parameterHandler, parameterObject); parameterHandler.setParameters(ps); return null; } // 判断已生成sql参数映射中是否包含tenantId private boolean hasParamKey(List<String> paramNames, List<ParameterMapping> parameterMappings) { boolean hasKey = false; for (ParameterMapping parameterMapping : parameterMappings) { if (StringUtils.equals(parameterMapping.getProperty(), PARAM_KEY)) { hasKey = true; } else { paramNames.add(parameterMapping.getProperty()); } } return hasKey; } private Object processSingle(Object paramObj, List<String> paramNames) throws Exception { Map<String, Object> paramMap = new MapperMethod.ParamMap<>(); if (paramObj == null) { paramMap.put(PARAM_KEY, 1L); paramObj = paramMap; // 单参数 将 参数转为 map } else if (ClassUtils.isPrimitiveOrWrapper(paramObj.getClass()) || String.class.isAssignableFrom(paramObj.getClass()) || Number.class.isAssignableFrom(paramObj.getClass())) { if (paramNames.size() == 1) { paramMap.put(paramNames.iterator().next(), paramObj); paramMap.put(PARAM_KEY, 1L); paramObj = paramMap; } } else { processParam(paramObj); } return paramObj; } private void processParam(Object parameterObject) throws IllegalAccessException, InvocationTargetException { // 处理参数对象 如果是 map 且map的key 中没有 tenantId，添加到参数map中 // 如果参数是bean，反射设置值 if (parameterObject instanceof Map) { ((Map) parameterObject).putIfAbsent(PARAM_KEY, 1L); } else { PropertyDescriptor ps = BeanUtils.getPropertyDescriptor(parameterObject.getClass(), PARAM_KEY); if (ps != null && ps.getReadMethod() != null && ps.getWriteMethod() != null) { Object value = ps.getReadMethod().invoke(parameterObject); if (value == null) { ps.getWriteMethod().invoke(parameterObject, 1L); } } } } @Override public Object plugin(Object target) { return Plugin.wrap(target, this); } @Override public void setProperties(Properties properties) { } }
