如果不使用Maven从Maven仓库下载构件，可以使用Java代码手动下载构件并添加到项目中。以下是一个示例代码：

import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.URL;

public class MavenArtifactDownloader {
    public static void main(String[] args) {
        String groupId = "com.example";
        String artifactId = "my-library";
        String version = "1.0.0";
        String repositoryUrl = "https://repo.maven.apache.org/maven2/";

        String artifactUrl = repositoryUrl + groupId.replace(".", "/") + "/" + artifactId + "/" + version + "/" + artifactId + "-" + version + ".jar";

        try {
            downloadArtifact(artifactUrl, artifactId + "-" + version + ".jar");
            System.out.println("Artifact downloaded successfully.");
        } catch (IOException e) {
            System.out.println("Failed to download artifact: " + e.getMessage());
        }
    }

    private static void downloadArtifact(String artifactUrl, String fileName) throws IOException {
        URL url = new URL(artifactUrl);
        BufferedInputStream in = new BufferedInputStream(url.openStream());
        FileOutputStream fileOutputStream = new FileOutputStream(fileName);

        byte[] buffer = new byte[1024];
        int bytesRead;
        while ((bytesRead = in.read(buffer, 0, 1024)) != -1) {
            fileOutputStream.write(buffer, 0, bytesRead);
        }

        fileOutputStream.close();
        in.close();
    }
}

在上面的代码中，我们指定了要下载的构件的groupId、artifactId和version。然后，我们构建了构件在Maven仓库中的URL，并使用downloadArtifact()方法下载构件。下载的构件将保存为当前目录下的文件artifactId-version.jar。

请注意，上述示例直接从Maven中央仓库下载构件。如果您要下载的构件位于其他Maven仓库中，您需要提供该仓库的URL，并相应地构建构件的URL。