Mybatis Plugin（攔截器）的開發
阿新 • • 發佈：2018-09-05
nsa commit 步驟 ring rac oot div eth 我們 1.Plugin
MyBatis 允許使用插件來攔截的方法調用包括：
• Executor (update, query, flushStatements, commit, rollback,
getTransaction, close, isClosed)
• ParameterHandler (getParameterObject, setParameters)
• ResultSetHandler (handleResultSets, handleOutputParameters)
註意;可以通過插件攔截到這四個對象，修改參數等操作： 你必須要知道的類:• StatementHandler (prepare, parameterize, batch, update, query)
- org.apache.ibatis.plugin.Plugin
- org.apache.ibatis.reflection.SystemMetaObject
- 實現 Interceptor 接口
- 三個方法執行順序
- setProperties()
- plugin()
- intercept()
1FirstIntercepter=====>setProperties 2 FirstIntercepter====>pluginorg.apache.ibatis.executor.CachingExecutor@64485a47 3 FirstIntercepter====>pluginorg.apache.ibatis.scripting.defaults.DefaultParameterHandler@2f0a87b3 4 FirstIntercepter====>pluginorg.apache.ibatis.executor.resultset.DefaultResultSetHandler@4fcd19b35 FirstIntercepter====>pluginorg.apache.ibatis.executor.statement.RoutingStatementHandler@2fd66ad3 6 DEBUG 09-05 11:56:24,696 ==> Preparing: select * from employee where id=? (BaseJdbcLogger.java:159) 7 FirstIntercepter:===>intercept 8 DEBUG 09-05 11:56:24,722 ==> Parameters: 1(Integer) (BaseJdbcLogger.java:159) 9 DEBUG 09-05 11:56:24,739 <== Total: 1 (BaseJdbcLogger.java:159) 10 Employee [id=1, lastName=tom, gender=1, email[email protected], depid=null]
- 給你的攔截器簽名：
1 /** 2 * 完成插件簽名： 3 * 告訴MyBatis當前插件用來攔截哪個對象的哪個方法 4 * type:要攔截的四大類型 5 * method：攔截那個方法 6 * args：這個方法的入參 7 * */ 8 @Intercepts({ 9 @Signature(type=StatementHandler.class, 10 method="parameterize", 11 args=java.sql.Statement.class 12 ) 13 }) 14 public class FirstIntercepter implements Interceptor
- mybatis-cfg.xml中配置插件
- 這裏註意配置plugins的標簽順序，以免出錯，在environments上面
<!-- plugins 插件的配置 實際上是使用：intercepter原理代理的 --> <plugins> <plugin interceptor="mybatis.intercepter.FirstIntercepter"> <property name="param1" value="root"/> <property name="param2" value="root"/> </plugin> </plugins>
3.多個插件的執行
- 、多個插件依次生成目標對象的代理對象，層層包裹，先聲明的先包裹；形成代理鏈
- 、可以理解為:初始化執行
- 執行log
- FirstIntercepter=====>setProperties
1 MySecondIntercepter====>setProperties:{param1=root} 2 FirstIntercepter====>pluginorg.apache.ibatis.executor.CachingExecutor@64485a47 3 MySecondIntercepter====>plugin:org.apache.ibatis.executor.CachingExecutor@64485a47 4 FirstIntercepter====>pluginorg.apache.ibatis.scripting.defaults.DefaultParameterHandler@2f0a87b3 5 MySecondIntercepter====>plugin:org.apache.ibatis.scripting.defaults.DefaultParameterHandler@2f0a87b3 6 FirstIntercepter====>pluginorg.apache.ibatis.executor.resultset.DefaultResultSetHandler@4fcd19b3 7 MySecondIntercepter====>plugin:org.apache.ibatis.executor.resultset.DefaultResultSetHandler@4fcd19b3 8 FirstIntercepter====>pluginorg.apache.ibatis.executor.statement.RoutingStatementHandler@2fd66ad3 9 MySecondIntercepter====>plugin:org.apache.ibatis.executor.statement.RoutingStatementHandler@2fd66ad3 10 DEBUG 09-05 12:07:01,928 ==> Preparing: select * from employee where id=? (BaseJdbcLogger.java:159) 11 MySecondIntercepter====>intercept:public abstract void org.apache.ibatis.executor.statement.StatementHandler.parameterize(java.sql.Statement) throws java.sql.SQLException 12 FirstIntercepter:===>intercept 13 DEBUG 09-05 12:07:01,954 ==> Parameters: 1(Integer) (BaseJdbcLogger.java:159) 14 DEBUG 09-05 12:07:01,968 <== Total: 1 (BaseJdbcLogger.java:159) 15 Employee [id=1, lastName=tom, gender=1, email[email protected], depid=null]
4.實現攔截修改參數
- sql
<!-- Employee getSelectEmp(Integer id); --> <select id="getSelectEmp" parameterType="java.lang.Integer" resultType="mybatis.bean.Employee"> select * from employee where id=#{id} </select>
- 這裏我們攔截id：
-
1 @Intercepts({ 2 @Signature(type=StatementHandler.class, 3 method="parameterize", 4 args=java.sql.Statement.class 5 ) 6 })
業務邏輯intercept方法中
1 /** 2 * 1：業務邏輯處理的方法： 3 */ 4 @Override 5 public Object intercept(Invocation invocation) throws Throwable { 6 //在這裏可以進行業務邏輯修改 7 System.out.println("FirstIntercepter:===>intercept"+invocation.getMethod()); 8 9 MetaObject metaObject = SystemMetaObject.forObject(invocation.getTarget()); 10 //拿到target的元數據 StatementHandler==>ParameterHandler===> 11 //DefaultParameterHandler==>>parameterObject 12 Object value = metaObject.getValue("parameterHandler.parameterObject"); 13 System.out.println("sql "+value.toString()); 14 //修改完sql語句要用的參數 15 metaObject.setValue("parameterHandler.parameterObject", 2); 16 Object object = invocation.proceed(); 17 return object; 18 }
- 打印log，
- 可以看到原來入參為1，現在經過攔截器修改入參為2
1 DEBUG 09-05 12:36:23,387 ==> Preparing: select * from employee where id=? (BaseJdbcLogger.java:159) 2 MySecondIntercepter====>intercept:public abstract void org.apache.ibatis.executor.statement.StatementHandler.parameterize(java.sql.Statement) throws java.sql.SQLException 3 FirstIntercepter:===>interceptpublic abstract void org.apache.ibatis.executor.statement.StatementHandler.parameterize(java.sql.Statement) throws java.sql.SQLException 4 sql 1 5 DEBUG 09-05 12:36:23,418 ==> Parameters: 2(Integer) (BaseJdbcLogger.java:159) 6 DEBUG 09-05 12:36:23,432 <== Total: 1 (BaseJdbcLogger.java:159) 7 Employee [id=2, lastName=cat, gender=0, email[email protected], depid=null]
Mybatis Plugin（攔截器）的開發