Иллюстрация проблем

jdbc-transaction/src/main/java/dev/struchkov/example/transaction/problems/DirtyReadExample.java

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+package dev.struchkov.example.transaction.problems;
+
+import dev.struchkov.example.transaction.Repository;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class DirtyReadExample {
+
+    public static void main(String[] args) throws SQLException, InterruptedException {
+        try (
+                final Connection connection = Repository.getConnection();
+                final Statement statement = connection.createStatement()
+        ) {
+            connection.setAutoCommit(false);
+            connection.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
+
+            statement.execute("UPDATE person SET balance = 100000 WHERE id = 1");
+
+            new OtherTransaction().start();
+            Thread.sleep(2000);
+            connection.rollback();
+        }
+
+    }
+
+    static class OtherTransaction extends Thread {
+        @Override
+        public void run() {
+            try (
+                    final Connection connection = Repository.getConnection();
+                    final Statement statement = connection.createStatement()
+            ) {
+                connection.setAutoCommit(false);
+                connection.setTransactionIsolation(Connection.TRANSACTION_READ_UNCOMMITTED);
+
+                final ResultSet resultSet = statement.executeQuery("SELECT * FROM person WHERE id = 1");
+                while (resultSet.next()) {
+                    System.out.println(resultSet.getString("balance"));
+                }
+            } catch (SQLException e) {
+                System.out.println(e.getMessage());
+            }
+        }
+    }
+
+}

jdbc-transaction/src/main/java/dev/struchkov/example/transaction/problems/NonRepeatableRead.java

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+package dev.struchkov.example.transaction.problems;
+
+import dev.struchkov.example.transaction.Repository;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class NonRepeatableRead {
+
+    public static void main(String[] args) {
+        try(
+                final Connection connection = Repository.getConnection();
+                final Statement statement = connection.createStatement()
+        ) {
+            connection.setAutoCommit(false);
+            connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
+
+            final ResultSet resultSet = statement.executeQuery("SELECT * FROM person WHERE id = 1");
+            while (resultSet.next()) {
+                System.out.println(resultSet.getString("balance"));
+            }
+
+            new OtherTransaction().start();
+            Thread.sleep(2000);
+
+            final ResultSet resultSetTwo = statement.executeQuery("SELECT * FROM person WHERE id = 1");
+            while (resultSetTwo.next()) {
+                System.out.println(resultSetTwo.getString("balance"));
+            }
+
+        } catch (SQLException | InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    static class OtherTransaction extends Thread {
+        @Override
+        public void run() {
+            try (
+                    final Connection connection = Repository.getConnection();
+                    final Statement statement = connection.createStatement()
+            ) {
+                connection.setAutoCommit(false);
+                connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
+
+                statement.executeUpdate("UPDATE person SET balance = 100000 WHERE id = 1");
+                connection.commit();
+            } catch (SQLException e) {
+                System.out.println(e.getMessage());
+            }
+        }
+    }
+
+}

jdbc-transaction/src/main/java/dev/struchkov/example/transaction/problems/PhantomRead.java

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+package dev.struchkov.example.transaction.problems;
+
+import dev.struchkov.example.transaction.Repository;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+public class PhantomRead {
+
+    public static void main(String[] args) {
+        try(
+                final Connection connection = Repository.getConnection();
+                final Statement statement = connection.createStatement()
+        ) {
+            connection.setAutoCommit(false);
+            connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
+
+            final ResultSet resultSet = statement.executeQuery("SELECT count(*) FROM person");
+            while (resultSet.next()) {
+                System.out.println(resultSet.getInt(1));
+            }
+
+            new OtherTransaction().start();
+            Thread.sleep(2000);
+
+            final ResultSet resultSetTwo = statement.executeQuery("SELECT count(*) FROM person");
+            while (resultSetTwo.next()) {
+                System.out.println(resultSetTwo.getInt(1));
+            }
+
+        } catch (SQLException | InterruptedException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    static class OtherTransaction extends Thread {
+        @Override
+        public void run() {
+            try (
+                    final Connection connection = Repository.getConnection();
+                    final Statement statement = connection.createStatement()
+            ) {
+                connection.setAutoCommit(false);
+                connection.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED);
+
+                statement.executeUpdate("INSERT INTO person(name, balance) values ('test', 100)");
+                connection.commit();
+            } catch (SQLException e) {
+                System.out.println(e.getMessage());
+            }
+        }
+    }
+
+}