feat: add the README (#5)

Author: sukidayou

.github/workflows/maven-ci.yml

@@ -1,4 +1,4 @@
-name: Build casdoor-java-sdk
+name: Build casvisor-java-sdk
 
 on: [push, pull_request]
 

README.md

@@ -1 +1,54 @@
-# casvisor-java-sdk
+# casvisor-java-sdk
+
+[![GitHub Actions](https://github.com/casvisor/casvisor-java-sdk/actions/workflows/maven-ci.yml/badge.svg)](https://github.com/casvisor/casvisor-java-sdk/actions/workflows/maven-ci.yml)
+[![codebeat badge](https://codebeat.co/badges/e3e92eff-8b71-4903-9764-5126e855b3b6)](https://codebeat.co/projects/github-com-casvisor-casvisor-java-sdk-master)
+[![codecov](https://codecov.io/gh/casvisor/casvisor-java-sdk/branch/master/graph/badge.svg?token=1C2FSTN4J8)](https://codecov.io/gh/casvisor/casvisor-java-sdk)
+[![Maven Central](https://img.shields.io/maven-central/v/org.casbin/casvisor-java-sdk.svg)](https://mvnrepository.com/artifact/org.casbin/casvisor-java-sdk/latest)
+[![Release](https://img.shields.io/github/release/casvisor/casvisor-java-sdk.svg)](https://github.com/casvisor/casvisor-java-sdk/releases/latest)
+[![Discord](https://img.shields.io/discord/1022748306096537660?logo=discord&label=discord&color=5865F2)](https://discord.gg/5rPsrAzK7S)
+
+Casvisor Java SDK is the official Java client for Casvisor, used to interact with Casvisor services.
+
+## Step1. Init Config
+
+Initialization requires 5 parameters, which are all string type:
+
+| Name (in order)  | Must | Description                                           |
+|------------------|------|-------------------------------------------------------|
+| endpoint         | Yes  | Casvisor server URL, such as `http://localhost:16001` |
+| clientId         | Yes  | Application.clientId                                  |
+| clientSecret     | Yes  | Application.clientSecret                              |
+| organizationName | Yes  | Organization name                                     |
+| applicationName  | Yes  | Application name                                      |
+
+### You can either initialize the SDK with global config
+
+```java
+CasvisorConfig config = new CasvisorConfig(endpoint, clientId, clientSecret, certificate, organizationName, applicationName);
+```
+
+## Step2. Get Service and use
+
+Now provide service: ``RecordService``
+You can create them like
+```java
+RecordService recordService = new RecordService(config);
+```
+## RecordService
+
+``RecordService``support basic user operations, like:
+- ``getRecord(String name)``, get one record by record name.
+- ``getRecords()``, get all records.
+- ``updateRecord(Record record)/addRecord(Record record)/deleteRecord(Record record)``, write record to database.
+
+## Contribution
+
+We welcome any form of contribution, including but not limited to:
+
+1. Submit issues and suggestions
+2. Submit Pull Request
+3. Improve documentation
+
+## License
+
+This project is licensed under the [Apache 2.0 License](LICENSE).