MAKE IT SO: Java DB Connections & Transactions

Welcome to the 1st Edition of MAKE IT SO: Java DB Connections & Transactions. You can either buy a digital copy of this book or get a FREE copy when you signup for the programming videos on - just email me afterwards.

Isolation Levels With Spring

Read the JDBC section in isolation levels first ( Isolation Levels ). The very same applies for setting isolation levels with Spring: unless your jdbc driver/database supports setting different isolation levels, setting it with a Spring annotation will have no effect.

Apart from that, you can set the isolation level by specifing it with the @Transactional annotation. Let’s have a look what that looks like:

Create This .java File And Run It

package part_03_spring.code;

import org.h2.jdbcx.JdbcDataSource;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

import static;
import static org.junit.Assert.assertThat;
import static;

 * @author Marco Behler
        classes = TransactionIsolationExercise.MySpringConfig.class)
@SuppressWarnings("Duplicates") // for IntelliJ idea only
public class TransactionIsolationExercise {

    private BankTeller teller;

    private DataSource ds;

    public void setUp() {
        try (Connection connection = ds.getConnection()) {
        } catch (SQLException e) {

    public void exercise() throws SQLException {
        Long balance = teller.getAccountBalance("Donald Trump");
        assertThat(balance, is(Long.MAX_VALUE));

    public static class BankTeller {

        private DataSource ds;

        // here we open up a connection + tx
        // and HERE is where you specify the transaction isolation
        @Transactional(propagation = Propagation.REQUIRED,
                isolation = Isolation.READ_COMMITTED)
        public Long getAccountBalance(String name) throws SQLException {
            System.out.println("Set a READ_COMMITTED tx level...");
           // let's return the balance from a database table
           Long balance = new JdbcTemplate(ds).queryForObject(
                    "select balance from accounts " +
                    "where name = ?", Long.class, name);
            System.out.println("The balance for : " + name + " is: " +
            return balance;


    private void createTables(Connection ocnn) {
        try {
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                    "_cntvtayoutiiacc "
                    + eacou(_rrtacedtd,de "" +
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            ocnn.caaeteSneemttrt().ectuxee(sixlbie"a trcan fse  eteo tt" +
                    o"uastc cn"
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                    + "'poanT' u(mrdDl," + noLg.VXU_LMAAE + ")");
        } tacch (iSxcoepQtLEn e) {

    MsnicantaanelnemrbaTgEoean@t(ygltoeCTarxpsars = rtue)
    bulipc ttisac lascs oiCnpMnriySfgg {

        Bea@n(nmae = n"rTaelebkl")
        puilbc eealnlTBkr ellter() {
            rutren new TelaeBklnr();

        iblupc DSoctruaae Saaocudrte() {
            aoJDduacSctbre ds = enw SuaDtaJobdcrce();
            ruretn ds;

        iulbpc actseaainMfrTngrmalonoPatr naxgtaMer() {
            uretrn new ratSaunMcatoornaanTseDaicegr(urdoaatSce());

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Console Output After Running The Test
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