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MySQL - Java 간단예제

MySQL - JAVA 간단예제


https://dev.mysql.com/downloads/
에서 Connector/J를 설치해야 한다. (Connector .jar 파일이 프로젝트에 있어야 한다)


[소스 코드]
2015년, 필자가 고등학교때 작성한 코드~
지금 보면 고쳐야 할 부분이 많다.

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import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
 
public class DBConnection {
        private String url;
        private int port;
        private String dbName;
        private String userName;
 
        private Connection db_conn = null;
        private PreparedStatement db_pstmt = null;
        private ResultSet db_rs = null;
 
        public static int QUERY_SUCCESS = 1;
        public static int QUERY_OKAY = 0;
        public static int QUERY_FAIL = -1;
 
 
        public int query(String sql) {
                reConnect();
 
                try {
                        db_pstmt = db_conn.prepareStatement(sql);
 
                        switch (db_pstmt.executeUpdate()) {
                        case 1:
                                return QUERY_SUCCESS;
                        case 0:
                                return QUERY_OKAY;
                        }
                } catch (Exception e) {
                        return QUERY_FAIL;
                }
 
                return QUERY_FAIL;
        }
 
        public int selectQuery(String sql) {
                reConnect();
                int nSize = 0;
 
                try {
                        db_pstmt = db_conn.prepareStatement(sql);
                        db_rs = db_pstmt.executeQuery();
 
                        db_rs.last();
                        nSize = db_rs.getRow();
                        db_rs.beforeFirst();
                } catch (Exception e) {
                        return QUERY_FAIL;
                }
 
                return nSize;
        }
 
        public boolean hasNext() {
                boolean b = false;
                try {
                        b = db_rs.next();
                } catch (Exception e) {
                        return false;
                }
                return b;
        }
 
        public String getSelectData(String columnLabel) {
                String str = "";
                try {
                        str = db_rs.getString(columnLabel);
                } catch (Exception e) {}
 
                return str;
        }
 
        public String getSelectData(int columnIndex) {
                String str = "";
                try {
                        str = db_rs.getString(columnIndex);
                } catch (Exception e) {}
 
                return str;
        }
 
        public boolean isConnect() {
                if (selectQuery("select 1") == QUERY_SUCCESS) {
                        return true;
                }
                return false;
        }
 
        private void reConnect() {
                try {
                        db_pstmt = db_conn.prepareStatement("select 1");
                        db_rs = db_pstmt.executeQuery();
                } catch (Exception e) {}
        }
 
        public int connect(String url, int port, String dbName, String userName, String passwd) {
                this.url = url;
                this.port = port;
                this.dbName = dbName;
                this.userName = userName;
 
                try {
                        Class.forName("com.mysql.jdbc.Driver");
                        db_conn = DriverManager.getConnection(
                                        "jdbc:mysql://" + url + ":" + port + "/" + dbName + "?autoReconnect=true", userName, passwd);
                        System.out.println("Successful to Connect Mysql Server at " + url + " port " + port);
                } catch (Exception e) {
                        release();
                        return QUERY_FAIL;
                }
 
                return QUERY_SUCCESS;
        }
 
        public void release() {
                try {
                        if (db_rs != null){db_rs.close();}
                        if (db_pstmt != null){db_pstmt.close();}
                        if (db_conn != null){db_conn.close();}
                } catch (Exception e) {}
        }
 
        /*
        public static void main(String args[]){
                // Init
                DBConnection conn = new DBConnection();
                System.out.println(conn.connect("@호스트명",3306,"@DB명","@사용자명","@비밀번호"));
                // INSERT / UPDATE / DELETE 쿼리 등
                System.out.println(conn.query("INSERT INTO test VALUES('ttt')"));
                // SELECT 쿼리
                System.out.println(conn.selectQuery("SELECT * FROM test"));
                while (conn.hasNext()) {
                        System.out.println(conn.getSelectData("key"));
                        System.out.println(conn.getSelectData("value"));
                }
                // Release
                conn.release();
        }
        */
}
cs
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