And it normally is a complex and "difficult" topic.

In many frameworks and systems just handling security and authentication takes a big amount of effort and code (in many cases it can be 50% or more of all the code written).

**FastAPI** provides several tools to help you deal with **Security** easily, rapidly, in a standard way, without having to study and learn all the security specifications.

 */
package org.codelibs.core.beans.util;

import static org.codelibs.core.collection.CollectionsUtil.newLinkedHashMap;
import static org.codelibs.core.misc.AssertionUtil.assertArgumentNotNull;

import java.util.Map;
import java.util.Map.Entry;
import java.util.function.Consumer;

import org.codelibs.core.beans.BeanDesc;
import org.codelibs.core.beans.PropertyDesc;

    }
    return -1;
  }

  /**
   * Returns the start position of the first occurrence of the specified {@code target} within
   * {@code array}, or {@code -1} if there is no such occurrence.
   *
   * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
   * i, i + target.length)} contains exactly the same elements as {@code target}.
   *

    }
    return -1;
  }

  /**
   * Returns the start position of the first occurrence of the specified {@code target} within
   * {@code array}, or {@code -1} if there is no such occurrence.
   *
   * <p>More formally, returns the lowest index {@code i} such that {@code Arrays.copyOfRange(array,
   * i, i + target.length)} contains exactly the same elements as {@code target}.
   *

Let's continue from the previous example. We wanted to **annotate the function with one type**, but we wanted to be able to return from the function something that actually includes **more data**.

We want FastAPI to keep **filtering** the data using the response model. So that even though the function returns more data, the response will only include the fields declared in the response model.

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.core.misc;

import org.codelibs.core.collection.ArrayUtil;
import org.codelibs.core.lang.StringUtil;

/**
 * Utility class for handling Base64 encoding and decoding.
 *
 * @author higa
 */
public abstract class Base64Util {

    /**

<img src="/img/tutorial/security/image12.png">

## Check the username { #check-the-username }

Here's a more complete example.

Use a dependency to check if the username and password are correct.

Stellen wir uns vor, Sie verfügen über einige **Modelle für maschinelles Lernen**, die Sie zur Bearbeitung von Requests verwenden möchten. 🤖

Die gleichen Modelle werden von den Requests gemeinsam genutzt, es handelt sich also nicht um ein Modell pro Request, pro Benutzer, oder ähnliches.

 * governing permissions and limitations under the License.
 */
package org.codelibs.fess.validation;

import org.codelibs.fess.unit.UnitFessTestCase;
import org.lastaflute.core.message.UserMessages;
import org.lastaflute.core.message.supplier.UserMessagesCreator;
import org.lastaflute.web.servlet.request.RequestManager;
import org.lastaflute.web.validation.ActionValidator;

 * either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */
package org.codelibs.core.convert;

import java.math.BigDecimal;
import java.text.SimpleDateFormat;

import org.codelibs.core.lang.StringUtil;

/**
 * Utility class for conversions related to {@link BigDecimal}.
 *
 * @author higa
 */
public abstract class BigDecimalConversionUtil {