Eugene Burtsev's blog

Java 7 Try-with-resources and MyBatis

With Java 7 came analog of using construction from C# - try-with-resources. This feature is very well for automatically close resources such as database connections, etc. For example:

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try (SqlSession session = ConnectionFactory.getSqlSessionFactory().openSession()) {
  // Work with session
  session.commit();
}

But there are an trouble - class org.apache.ibatis.session.SqlSession from MyBatis 3.0.6 does not implement AutoCloseable interface which is required to work try-with-resources construction. I hope that in next version it will be fixed, but now I can offer small workaround.

The first implement a wrapper for SqlSession class implements the interface AutoCloseable:

SqlSession.java
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package net.burtsev.example.dao.mybatis.session;

import java.io.Closeable;
import java.sql.Connection;
import java.util.List;
import java.util.Map;

import org.apache.ibatis.executor.BatchResult;
import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;

@SuppressWarnings("rawtypes")
public class SqlSession implements org.apache.ibatis.session.SqlSession, Closeable {

  private org.apache.ibatis.session.SqlSession wrappedSession;

  SqlSession(org.apache.ibatis.session.SqlSession wrappedSession) {
      this.wrappedSession = wrappedSession;
  }

  @Override
  public Object selectOne(String statement) {
      return wrappedSession.selectOne(statement);
  }

  @Override
  public Object selectOne(String statement, Object parameter) {
      return wrappedSession.selectOne(statement, parameter);
  }

  @Override
  public List selectList(String statement) {
      return wrappedSession.selectList(statement);
  }

  @Override
  public List selectList(String statement, Object parameter) {
      return wrappedSession.selectList(statement, parameter);
  }

  @Override
  public List selectList(String statement, Object parameter, RowBounds rowBounds) {
      return wrappedSession.selectList(statement, parameter, rowBounds);
  }

  @Override
  public Map selectMap(String statement, String mapKey) {
      return wrappedSession.selectMap(statement, mapKey);
  }

  @Override
  public Map selectMap(String statement, Object parameter, String mapKey) {
      return wrappedSession.selectMap(statement, parameter, mapKey);
  }

  @Override
  public Map selectMap(String statement, Object parameter, String mapKey, RowBounds rowBounds) {
      return wrappedSession.selectMap(statement, parameter, mapKey, rowBounds);
  }

  @Override
  public void select(String statement, Object parameter, ResultHandler handler) {
      wrappedSession.select(statement, parameter, handler);
  }

  @Override
  public void select(String statement, ResultHandler handler) {
      wrappedSession.select(statement, handler);
  }

  @Override
  public void select(String statement, Object parameter, RowBounds rowBounds, ResultHandler handler) {
      wrappedSession.select(statement, parameter, rowBounds, handler);
  }

  @Override
  public int insert(String statement) {
      return wrappedSession.insert(statement);
  }

  @Override
  public int insert(String statement, Object parameter) {
      return wrappedSession.insert(statement, parameter);
  }

  @Override
  public int update(String statement) {
      return wrappedSession.update(statement);
  }

  @Override
  public int update(String statement, Object parameter) {
      return wrappedSession.update(statement, parameter);
  }

  @Override
  public int delete(String statement) {
      return wrappedSession.delete(statement);
  }

  @Override
  public int delete(String statement, Object parameter) {
      return wrappedSession.delete(statement, parameter);
  }

  @Override
  public void commit() {
      wrappedSession.commit();
  }

  @Override
  public void commit(boolean force) {
      wrappedSession.commit(force);
  }

  @Override
  public void rollback() {
      wrappedSession.rollback();
  }

  @Override
  public void rollback(boolean force) {
      wrappedSession.rollback(force);
  }

  @Override
  public List<BatchResult> flushStatements() {
      return wrappedSession.flushStatements();
  }

  @Override
  public void close() {
      wrappedSession.close();
  }

  @Override
  public void clearCache() {
      wrappedSession.clearCache();
  }

  @Override
  public Configuration getConfiguration() {
      return wrappedSession.getConfiguration();
  }

  @Override
  public <T> T getMapper(Class<T> type) {
      return wrappedSession.getMapper(type);
  }

  @Override
  public Connection getConnection() {
      return wrappedSession.getConnection();
  }

}

Also we need write wrapper for SqlSessionFactory class which can work with our custom SqlSession:

SqlSessionFactory.java
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package net.burtsev.example.dao.mybatis.session;

import java.sql.Connection;

import org.apache.ibatis.session.Configuration;
import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.TransactionIsolationLevel;

public class SqlSessionFactory implements org.apache.ibatis.session.SqlSessionFactory {

  private org.apache.ibatis.session.SqlSessionFactory wrappedFactory;

  SqlSessionFactory(org.apache.ibatis.session.SqlSessionFactory wrappedFactory) {
      this.wrappedFactory = wrappedFactory;
  }

  @Override
  public SqlSession openSession() {
      return new SqlSession(wrappedFactory.openSession());
  }

  @Override
  public SqlSession openSession(boolean autoCommit) {
      return new SqlSession(wrappedFactory.openSession(autoCommit));
  }

  @Override
  public SqlSession openSession(Connection connection) {
      return new SqlSession(wrappedFactory.openSession(connection));
  }

  @Override
  public SqlSession openSession(TransactionIsolationLevel level) {
      return new SqlSession(wrappedFactory.openSession(level));
  }

  @Override
  public SqlSession openSession(ExecutorType execType) {
      return new SqlSession(wrappedFactory.openSession(execType));
  }

  @Override
  public SqlSession openSession(ExecutorType execType, boolean autoCommit) {
      return new SqlSession(wrappedFactory.openSession(execType, autoCommit));
  }

  @Override
  public SqlSession openSession(ExecutorType execType, TransactionIsolationLevel level) {
      return new SqlSession(wrappedFactory.openSession(execType, level));
  }

  @Override
  public SqlSession openSession(ExecutorType execType, Connection connection) {
      return new SqlSession(wrappedFactory.openSession(execType, connection));
  }

  @Override
  public Configuration getConfiguration() {
      return wrappedFactory.getConfiguration();
  }

}

Below I provide iBatis initialization code. It looks as usual, except the line 18, where we initialize our wrapper.

ConnectionFactory.java
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package net.burtsev.example.dao.mybatis.session;

import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public final class ConnectionFactory {

  private static SqlSessionFactory sqlSessionFactory;
  private static Reader reader;

  static {
      try {
          reader = Resources.getResourceAsReader("mybatis-config.xml");

          if (sqlSessionFactory == null) {
              sqlSessionFactory = new SqlSessionFactory(new SqlSessionFactoryBuilder().build(reader, Settings.getInstance()));
              sqlSessionFactory.getConfiguration().addMappers("net.burtsev.example.dao.mybatis.mappers");
          }
      } catch (Exception e) {
          e.printStackTrace();
      }
  }

  private ConnectionFactory() { }

  public static SqlSessionFactory getSqlSessionFactory() {
      return sqlSessionFactory;
  }
}

That’s all - now we can now enjoy java7 features in our project:)

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