Expose properties in DefaultParameterHandler.java

[johnny2002]

In order to extend mybatis to support batch sql by Preparedstatement, we need to add an plugin, thus, in the pulgin, we need to get "mappedStatement", "parameterObject","boundSql" from DefaultParameterHandler.java. While, these 3 properties are all private, so we have to use reflect.

Suggest to add getters for these 3 properties.
Full path:
/src/main/java/org/apache/ibatis/scripting/defaults/DefaultParameterHandler.java

[johnny2002]

sample code to use these properties as below:

public class BatchParameterHandler implements Interceptor {

    public Object intercept(Invocation invocation) throws Throwable {
        if (invocation.getTarget() instanceof DefaultParameterHandler) {
            DefaultParameterHandler parameterHandler = (DefaultParameterHandler) invocation.getTarget();

            MappedStatement mappedStatement = (MappedStatement) ReflectUtils.getValueByFieldName(parameterHandler, "mappedStatement");

            Object paramObj = ReflectUtils.getValueByFieldName(parameterHandler, "parameterObject");
            if (paramObj instanceof BatchParameter) {

                PreparedStatement ps = (PreparedStatement) invocation.getArgs()[0];
                BoundSql boundSql = (BoundSql) ReflectUtils.getValueByFieldName(parameterHandler, "boundSql");

                @SuppressWarnings({ "unchecked", "rawtypes" })
                List<Object> parameterObject = (List) ((BatchParameter) paramObj).getData();

                ps.clearBatch();
                ps.clearParameters();

                @SuppressWarnings("rawtypes")
                int batchSize = ((BatchParameter) paramObj).getBatchSize();
                int i = 0;
                for (Object pobject : parameterObject) {
                    DefaultParameterHandler handler = new DefaultParameterHandler(mappedStatement, pobject, boundSql);
                    handler.setParameters(ps);
                    ps.addBatch();
                    i += 1;
                    if (i % batchSize == 0) {
                        ps.executeBatch();
                    }
                }
                if (parameterObject.size() % batchSize != 0) {
                    ps.executeBatch();
                }

                return i;
            }
        }

        return invocation.proceed();
    }

    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }

    public void setProperties(Properties properties) {

    }

}

[bitgaoshu]

defaultExecutorType can satisfy ?

[johnny2002]

defaultExecutorType

defaultExecutorType looks attractive, while, how can I use BATCH only for specified SQL IDs and others use SIMPLE?

[bitgaoshu]

in different sqlSession?

[johnny2002]

in different sqlSession?

Hi bitgaoshu, happy Chinese New Year to you!
Seems this can resolve ExecutorType probleam. While, another problem is that BATCH ExecutorType actually also execute each line a time, but I want to use PreparedStatement.addBatch() to execute many lines a time, this way is far more efficient. If only you can add another ExecutorType to use PreparedStatement.addBatch().

[johnny2002]

So, even my problem is resolved by adding aonther ExecutorType, I think, Expose properties in DefaultParameterHandler.java can bring more flexiblity to developers, why not do it?
As a generic framework, extensibility is very important to users.
For simular situation, I have suggestted Spring framework to did many same things. see:
spring-projects/spring-framework#25323
spring-cloud/spring-cloud-openfeign#278
OpenFeign/feign#1162
apache/shardingsphere#7471

[harawata]

Hello @johnny2002 !

I'm sorry about the belated response.
As @bitgaoshu pointed out, MyBatis already has batch executor type to execute batch operation.
I would suggest you to take a look at this demo.

Regarding your request, there have been similar requests before, but we have no plan to expose those internal variables (they are intentionally hidden from the public API).
You are welcome to use reflection (at your own risk) if necessary.

BATCH ExecutorType actually also execute each line a time, but I want to use PreparedStatement.addBatch() to execute many lines a time

I'm pretty sure MyBatis uses addBatch().