App.java

importcom.google.gson.Gson;
importcom.mysql.cj.jdbc.exceptions.CommunicationsException;

importstaticspark.Spark.*;

importjava.nio.file.Files;
importjava.nio.file.Paths;
importjava.sql.*;
importjava.util.ArrayList;
importjava.util.List;

publicclassApp {

publicstaticvoidmain(String[] args) throwsException {
Class.forName("com.mysql.cj.jdbc.Driver");

prepare();

port(8080);

get("/", (req, res) -> newGson().toJson(titles()));
 }

privatestaticList<String> titles() {
try (Connectionconn = connect()) {
List<String> titles = newArrayList<>();
try (Statementstmt = conn.createStatement()) {
try (ResultSetrs = stmt.executeQuery("SELECT title FROM blog")) {
while (rs.next()) {
titles.add(rs.getString("title"));
 }
 }
 }
returntitles;
 } catch (Exceptionex) {
returnnewArrayList<>();
 }
 }

publicstaticvoidprepare() throwsException {
try (Connectionconn = connect()) {
recreateTable(conn);
insertData(conn);
 }
 }

privatestaticvoidinsertData(Connectionconn) throwsSQLException {
for (inti = 0; i < 5; i++) {
try (PreparedStatementstmt = conn.prepareStatement("INSERT INTO blog (title) VALUES (?);")) {
stmt.setString(1, "Blog post #" + i);
stmt.execute();
 }
 }
 }

privatestaticvoidrecreateTable(Connectionconn) throwsSQLException {
try (Statementstmt = conn.createStatement()) {
stmt.execute("DROP TABLE IF EXISTS blog");
stmt.execute("CREATE TABLE IF NOT EXISTS blog (id int NOT NULL AUTO_INCREMENT, title varchar(255), PRIMARY KEY (id))");
 }
 }


privatestaticConnectionconnect() throwsException {
for (inti = 0; i < 60; i++) {
try {
returnDriverManager.getConnection("jdbc:mysql://db/example?allowPublicKeyRetrieval=true&useSSL=false", "root", Files.lines(Paths.get("/run/secrets/db-password")).findFirst().get());
 } catch (CommunicationsExceptionex) {
Thread.sleep(1000L);
continue;
 } catch (Exceptionex) {
throwex;
 }
 }
thrownewRuntimeException("Unable to connect to MySQL");
 }
}