Java Persistence. Часть -1. До JDBC: как Java работала с базами данных

URL url =  new URL("http://server/query.cgi?id=1");
InputStream in = url.openStream();

public class BookApplet extends Applet {
    private TextArea output;
    public void init() {
        output = new TextArea();
        add(output);
        loadBooks();
    }
    private void loadBooks() {
        Vector books = new Vector();
        try {
            URL url = new URL("http://library.com/books.cgi");
            DataInputStream in = new DataInputStream(url.openStream());
            String line;
            while ((line = in.readLine()) != null) {
                StringTokenizer tokenizer = new StringTokenizer(line, ";");
                Book book = new Book();
                book.setId((new Long(tokenizer.nextToken())).longValue());
                book.setTitle(tokenizer.nextToken());
                book.setAuthor(tokenizer.nextToken());
                books.addElement(book);
            }
            in.close();
        } catch (Exception e) {
            output.appendText( "Error: " + e.toString()
            );
        }
        }
    }
}

URL url = new URL("http://library.com/book.cgi?id=1");
BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
List<Book> books = new ArrayList<>();
String line;
while ((line = reader.readLine()) != null) {
    String[] parts = line.split(";");
    Book book = new Book();
    book.setId(Long.parseLong(parts[0]));
    book.setTitle(parts[1]);
    book.setAuthor(parts[2]);
    books.add(book);
}

#!/usr/bin/perl
use DBI;
my $dbh = DBI->connect(
    "dbi:Oracle:LIBRARY",
    "scott",
    "tiger"
);
my $sth = $dbh->prepare(
    "SELECT id, title, author FROM BOOK"
);
$sth->execute();
print "Content-Type: text/plain\n\n";
while (my @row = $sth->fetchrow_array()) {
    print $row[0]
        . ";"
        . $row[1]
        . ";"
        . $row[2]
        . "\n";
}
$sth->finish();
$dbh->disconnect();

public class OracleClient {
    static {
        System.loadLibrary("myapp");
    }
    public native void connect(String server, String user, String password);
    public native String getBookByAuthorAndTitle(String author, String title);
    public native void disconnect();
}

#include <jni.h>
#include <oci.h>
#include <string.h>
extern OCIEnv    *g_env;
extern OCISvcCtx *g_svc;
extern OCIError  *g_err;
JNIEXPORT jstring JNICALL
Java_OracleClient_getBookByAuthorAndTitle(JNIEnv* env, jobject obj, jstring author, jstring title)
{
    OCIStmt *stmt = NULL;
    OCIBind *authorBind = NULL;
    OCIBind *titleBind = NULL;
    OCIDefine *titleDefine = NULL;
    const char* authorName = env->GetStringUTFChars(author, NULL);
    const char* bookTitle = env->GetStringUTFChars(title, NULL);
    char resultTitle[256];
    memset(resultTitle, 0, sizeof(resultTitle));
    sb2 resultTitleInd = 0;
    const char* sql =
            "SELECT title "
            "FROM BOOK "
            "WHERE author = :author "
            "AND title = :title";
    OCIHandleAlloc(g_env, (void**) &stmt, OCI_HTYPE_STMT, 0, NULL);
    OCIStmtPrepare(stmt, g_err, (text*) sql, (ub4) strlen(sql), OCI_NTV_SYNTAX, OCI_DEFAULT);
    OCIBindByName(stmt, &authorBind, g_err, (text*) ":author", -1, (void*) authorName, 
           (sb4) strlen(authorName) + 1, SQLT_STR, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT);
    OCIBindByName(stmt, &titleBind, g_err, (text*) ":title", -1, (void*) bookTitle,
            (sb4) strlen(bookTitle) + 1, SQLT_STR, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT);
    OCIDefineByPos(stmt, &titleDefine, g_err, 1, resultTitle, sizeof(resultTitle), 
            SQLT_STR, &resultTitleInd, NULL, NULL, OCI_DEFAULT);
    OCIStmtExecute(g_svc, stmt, g_err, 0, 0, NULL, NULL, OCI_DEFAULT);
    sword fetchStatus = OCIStmtFetch2(stmt, g_err, 1, OCI_FETCH_NEXT, 0, OCI_DEFAULT);
    jstring result;
    if (fetchStatus == OCI_SUCCESS && resultTitleInd != -1) {
        result = env->NewStringUTF(resultTitle);
    } else {
        result = env->NewStringUTF("");
    }
    env->ReleaseStringUTFChars(author, authorName);
    env->ReleaseStringUTFChars(title, bookTitle);
    OCIHandleFree(stmt, OCI_HTYPE_STMT);
    return result;
}

OracleClient client = new OracleClient();
client.connect("oracle.company.com", "scott", "tiger");
String book = client.getBookByAuthorAndTitle("Jane Austen", "Pride and Prejudice");
client.disconnect();
System.out.println(book);

Connection connection =
        DriverManager.getConnection(
                "jdbc:oracle:thin:@localhost:1521:xe",
                "user",
                "password"
        );
        
PreparedStatement ps =
        connection.prepareStatement(
                "SELECT id, title FROM book WHERE id = ?"
        );
        
ps.setLong(1, 1L);
ResultSet rs = ps.executeQuery();
while (rs.next()) {
    long id = rs.getLong("id");
    String title = rs.getString("title");
    Book book = new Book();
    book.setId(id); 
    book.setTitle(title); 
}

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection connection = DriverManager.getConnection("jdbc:odbc:LibraryDB");
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(
                "SELECT id, title, author "
                + "FROM BOOK"
        ); 

public class OracleClient {
    static {
        System.loadLibrary("library");
    }
    public native String[] getBooksByAuthor(String author);
}

#include <jni.h>
#include <oci.h>
#include <string.h>
extern OCIEnv    *g_env;
extern OCISvcCtx *g_svc;
extern OCIError  *g_err;
JNIEXPORT jobjectArray JNICALL
Java_OracleClient_getBooksByAuthor(JNIEnv* env, jobject obj, jstring author)
{
    OCIStmt *stmt = NULL;
    OCIBind *authorBind = NULL;
    OCIDefine *titleDefine = NULL;
    const char* authorName = env->GetStringUTFChars(author, NULL);
    char resultTitle[256];
    sb2 resultTitleInd = 0;
    const char* sql =
            "SELECT title "
            "FROM BOOK "
            "WHERE author = :author";
    OCIHandleAlloc(g_env, (void**) &stmt, OCI_HTYPE_STMT, 0, NULL);
    OCIStmtPrepare(stmt, g_err, (text*) sql, (ub4) strlen(sql),
                   OCI_NTV_SYNTAX, OCI_DEFAULT);
    OCIBindByName(stmt, &authorBind, g_err, (text*) ":author", -1,
                  (void*) authorName, (sb4) strlen(authorName) + 1,
                  SQLT_STR, NULL, NULL, NULL, 0, NULL, OCI_DEFAULT);
    OCIDefineByPos(stmt, &titleDefine, g_err, 1,
                   resultTitle, sizeof(resultTitle),
                   SQLT_STR, &resultTitleInd,
                   NULL, NULL, OCI_DEFAULT);
    OCIStmtExecute(g_svc, stmt, g_err, 0, 0, NULL, NULL, OCI_DEFAULT);
    jobjectArray result =
            env->NewObjectArray(
                    10,
                    env->FindClass("java/lang/String"),
                    NULL
            );
    int index = 0;
    while (index < 10 && OCIStmtFetch2(stmt, g_err, 1, OCI_FETCH_NEXT, 0, OCI_DEFAULT) == OCI_SUCCESS) {
        if (resultTitleInd != -1) {
            env->SetObjectArrayElement(result, index,env->NewStringUTF(resultTitle));
        }
        index++;
        memset(resultTitle, 0, sizeof(resultTitle));
    }
    env->ReleaseStringUTFChars(author, authorName);
    OCIHandleFree(stmt, OCI_HTYPE_STMT);
    return result;
}

OracleClient client = new OracleClient();
String[] books = client.getBooksByAuthor("Jane Austen");
for (int i = 0; i < books.length;i++) {
    System.out.println(books[i]);
}

Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection connection = DriverManager.getConnection("jdbc:odbc:LibraryDB");
PreparedStatement ps =
        connection.prepareStatement(
                "SELECT title "
                + "FROM BOOK "
                + "WHERE author = ?"
        );
ps.setString(1, "Jane Austen");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
  System.out.println(rs.getString("title")
    );
}

public interface BookRepository extends JpaRepository<Book, Long> {
    List<Book> findByAuthor(String author);
}

List<Book> books = bookRepository.findByAuthor("Jane Austen");
for (Book book : books) {
    System.out.println(book.getTitle());
}