I am the author of multilspy, which is a LSP client in Python, with a library interface and is intended to be used to build applications around language servers. It handles the configuration and initialization of different language servers, and offers a simple interface. It currently supports running Eclipse JDT.LS for Java, rust-analyzer for Rust, OmniSharp for C# and jedi-language-server for Python. You can install it using pip by running:

pip install multilspy

Example usage of multilspy:

from multilspy import SyncLanguageServer
from multilspy.multilspy_config import MultilspyConfig
from multilspy.multilspy_logger import MultilspyLogger
...
config = MultilspyConfig.from_dict({"code_language": "java"}) # Also supports "python", "rust", "csharp"
logger = MultilspyLogger()
lsp = SyncLanguageServer.create(config, logger, "/abs/path/to/project/root/")
with lsp.start_server():
    result = lsp.request_definition(
        "relative/path/to/code_file.java", # Filename of location where request is being made
        163, # line number of symbol for which request is being made
        4 # column number of symbol for which request is being made
    )
    result2 = lsp.request_completions(
        ...
    )
    result3 = lsp.request_references(
        ...
    )
    ...