Statement statement = connection.createStatement();
Class clazz = Class.forname("oracle.jdbc.OracleStatement");
if(statement.isWrapperFor(clazz)){
  OracleStatement oracleStatement = (OracleStatement)stmt.unwrap(clazz);
  // do otherthing
}

String JDBC_URL = "jdbc:mysql://10.88.88.2:3306/learnjdbc?useSSL=false&characterEncoding=utf8&allowPublicKeyRetrieval=true";
String JDBC_USER = "learn";
String JDBC_PASSWORD = "learnpassword";
Connection connection = null;
try {
    connection = DriverManager.getConnection(JDBC_URL, JDBC_USER, JDBC_PASSWORD);
} catch (SQLException throwables) {
    throwables.printStackTrace();
}finally {
    if(null != connection){
        connection.close();
    }
}

ResultSet resultSet = null;
try (Connection connection = DriverManager.getConnection(JDBCConstant.JDBC_URL,JDBCConstant.JDBC_USER,JDBCConstant.JDBC_PASSWORD);
      PreparedStatement preparedStatement = connection.prepareStatement("SELECT id, grade, name, gender FROM students WHERE gender=?")){
    preparedStatement.setObject(1,1);
    resultSet = preparedStatement.executeQuery();
    while (resultSet.next()){
        long id = resultSet.getLong(1); // 注意：索引从1开始
        long grade = resultSet.getLong(2);
        String name = resultSet.getString(3);
        int gender = resultSet.getInt(4);
        System.out.println(String.format("id:%s grade:%s name:%s gender:%s",id,grade,name,gender));
    }
} catch (SQLException throwables) {
    throwables.printStackTrace();
}finally {
    if(null != resultSet){
        resultSet.close();
    }
}

try (Connection conn = DriverManager.getConnection(JDBCConstant.JDBC_URL, JDBCConstant.JDBC_USER, JDBCConstant.JDBC_PASSWORD);
  PreparedStatement ps = conn.prepareStatement("INSERT INTO students (id, grade, name, gender, score) VALUES (?,?,?,?,?)")){
  int index = 1;
  ps.setObject(index++, 999); // 注意：索引从1开始
  ps.setObject(index++, 1); // grade
  ps.setObject(index++, "Bob"); // name
  ps.setObject(index++, 0); // gender
  ps.setObject(index++, 100); // score
  int n = ps.executeUpdate(); // 1
  System.out.println(String.format("flag:%s",n));
}

try (Connection conn = DriverManager.getConnection(JDBCConstant.JDBC_URL, JDBCConstant.JDBC_USER, JDBCConstant.JDBC_PASSWORD);
    PreparedStatement ps = conn.prepareStatement("INSERT INTO students (grade, name, gender, score) VALUES (?,?,?,?)", Statement.RETURN_GENERATED_KEYS)){
    int index = 1;
    ps.setObject(index++, 2); // grade
    ps.setObject(index++, "Bob2"); // name
    ps.setObject(index++, 0); // gender
    ps.setObject(index++, 90); // score
    int n = ps.executeUpdate(); // 1
    System.out.println(String.format("flag:%s",n));
    // 通过`getGeneratedKeys`获取自动生成的id
    try (ResultSet resultSet = ps.getGeneratedKeys()) {
        if (resultSet.next()){
            long id = resultSet.getLong(1);
            System.out.println(String.format("id:%s",id));
        }
    }
}

try (Connection conn = DriverManager.getConnection(JDBCConstant.JDBC_URL, JDBCConstant.JDBC_USER, JDBCConstant.JDBC_PASSWORD);
PreparedStatement ps = conn.prepareStatement("UPDATE students SET name=? WHERE id=?")){
  int index = 1;
  ps.setObject(index++, "Bob"); // 注意：索引从1开始
  ps.setObject(index++, 999);
  int n = ps.executeUpdate(); // 返回更新的行数
  System.out.println(String.format("更新的行数:%s",n));
} catch (SQLException throwables) {
    throwables.printStackTrace();
}

try (Connection conn = DriverManager.getConnection(JDBCConstant.JDBC_URL, JDBCConstant.JDBC_USER, JDBCConstant.JDBC_PASSWORD);
PreparedStatement ps = conn.prepareStatement("DELETE FROM students WHERE id=?")){
    int index = 1;
    ps.setObject(index++, 999); // 注意：索引从1开始
    int n = ps.executeUpdate(); // 删除的行数
    System.out.println(String.format("删除的行数:%s",n));
} catch (SQLException throwables) {
    throwables.printStackTrace();
}

PreparedStatement ps = null;
Connection connection = null;
try {
    connection = DriverManager.getConnection(JDBCConstant.JDBC_URL,JDBCConstant.JDBC_USER,JDBCConstant.JDBC_PASSWORD);
    boolean autoCommit = connection.getAutoCommit();
    System.out.println(String.format("autoCommit:%s",autoCommit));
    connection.setAutoCommit(false);
    ps = connection.prepareStatement("UPDATE students SET name=? WHERE id=?");
    int index = 1;
    ps.setObject(index++, "Bob"); // 注意：索引从1开始
    ps.setObject(index++, 999);
    int n = ps.executeUpdate(); // 返回更新的行数
    System.out.println(String.format("更新的行数:%s",n));
    ps.close();
    ps = connection.prepareStatement("UPDATE students SET name=? WHERE id=?");
    index = 1;
    ps.setObject(index++, "Bob999"); // 注意：索引从1开始
    ps.setObject(index++, 999);
    n = ps.executeUpdate(); // 返回更新的行数
    System.out.println(String.format("更新的行数:%s",n));
    connection.commit();
    connection.setAutoCommit(true);
} catch (SQLException throwables) {
    connection.rollback();
    throwables.printStackTrace();
}finally {
    if(null != connection){
        connection.close();
    }
    if(null != ps){
        ps.close();
    }
}

try (PreparedStatement ps = conn.prepareStatement("INSERT INTO students (name, gender, grade, score) VALUES (?, ?, ?, ?)")) {
    // 对同一个PreparedStatement反复设置参数并调用addBatch():
    for (Student s : students) {
        ps.setString(1, s.name);
        ps.setBoolean(2, s.gender);
        ps.setInt(3, s.grade);
        ps.setInt(4, s.score);
        ps.addBatch(); // 添加到batch
    }
    // 执行batch:
    int[] ns = ps.executeBatch();
    for (int n : ns) {
        System.out.println(n + " inserted."); // batch中每个SQL执行的结果数量
    }
}

ResultSet resultSet = null;
DataSource dataSource = JDBCConstant.getDataSource();
try (Connection connection = dataSource.getConnection();
      PreparedStatement preparedStatement = connection.prepareStatement("SELECT id, grade, name, gender FROM students WHERE gender=?")){
    preparedStatement.setObject(1,1);
    resultSet = preparedStatement.executeQuery();
    while (resultSet.next()){
        long id = resultSet.getLong(1); // 注意：索引从1开始
        long grade = resultSet.getLong(2);
        String name = resultSet.getString(3);
        int gender = resultSet.getInt(4);
        System.out.println(String.format("id:%s grade:%s name:%s gender:%s",id,grade,name,gender));
    }
} catch (SQLException throwables) {
    throwables.printStackTrace();
}finally {
    if(null != resultSet){
        resultSet.close();
    }
}

# 这里应该是对实现类做了混淆
org.jeecg.modules.online.cgform.c.a#b(org.jeecg.modules.online.cgform.model.a)

# 这里应该是对实现类做了混淆
org.jeecg.modules.online.cgform.c.a#h

# 这里应该是对实现类做了混淆
org.jeecg.modules.online.cgform.c.a#a(java.lang.String, com.alibaba.fastjson.JSONObject, javax.servlet.http.HttpServletRequest)

# 这里应该是对实现类做了混淆
org.jeecg.modules.online.cgform.c.a#f

# 这里应该是对实现类做了混淆
org.jeecg.modules.online.cgform.c.a#a(java.lang.String, com.alibaba.fastjson.JSONObject)

# 这里应该是对实现类做了混淆
org.jeecg.modules.online.cgform.c.a#a(java.lang.String, javax.servlet.http.HttpServletRequest)

//org.jeecg.modules.system.controller.LoginController#randomImage
//生成随机验证码
String code = RandomUtil.randomString(BASE_CHECK_CODES,4);
String lowerCaseCode = code.toLowerCase();
//验证码小写后+时间戳 md5后作为key
String realKey = MD5Util.MD5Encode(lowerCaseCode+key, "utf-8");
//缓存redis
redisUtil.set(realKey, lowerCaseCode, 60);

//org.jeecg.modules.system.controller.LoginController#login
//获取输入的验证码
String captcha = sysLoginModel.getCaptcha();
if(captcha==null){
    result.error500("验证码无效");
    return result;
}
String lowerCaseCaptcha = captcha.toLowerCase();
//输入的验证码+时间戳 md5后作为key
String realKey = MD5Util.MD5Encode(lowerCaseCaptcha+sysLoginModel.getCheckKey(), "utf-8");
//获取redis里面缓存的验证码
Object checkCode = redisUtil.get(realKey);
//当进入登录页时，有一定几率出现验证码错误 #1714
if(checkCode==null || !checkCode.toString().equals(lowerCaseCaptcha)) {
  result.error500("验证码错误");
  return result;
}