给我一段实现了sentinel持久化适配器的代码

以下是一个实现了Sentinel持久化适配器的示例代码：

public class SentinelFileDataSourceAdapter implements ReadableDataSource<String, List<FlowRule>> {
    private String filePath;

    public SentinelFileDataSourceAdapter(String filePath) {
        this.filePath = filePath;
    }

    @Override
    public List<FlowRule> loadConfig() throws Exception {
        List<FlowRule> rules = new ArrayList<>();
        File file = new File(filePath);
        if (!file.exists()) {
            return rules;
        }
        BufferedReader reader = new BufferedReader(new FileReader(file));
        String line;
        while ((line = reader.readLine()) != null) {
            FlowRule rule = JSON.parseObject(line, FlowRule.class);
            rules.add(rule);
        }
        reader.close();
        return rules;
    }

    @Override
    public void addEntry(String key, List<FlowRule> value) throws Exception {
        throw new UnsupportedOperationException("Not supported");
    }

    @Override
    public void removeEntry(String key) throws Exception {
        throw new UnsupportedOperationException("Not supported");
    }
}

该适配器实现了Sentinel的`ReadableDataSource`接口，并实现了`loadConfig`方法，从文件中读取规则并返回。注意，在`addEntry`和`removeEntry`方法中抛出了`UnsupportedOperationException`，因为这个适配器只是一个只读的数据源，无法修改规则。

这个适配器可以使用以下代码注册到Sentinel的流控规则中：

String ruleFilePath = "/path/to/rule/file";
ReadableDataSource<String, List<FlowRule>> ruleDataSource = new SentinelFileDataSourceAdapter(ruleFilePath);
FlowRuleManager.register2Property(ruleDataSource.getProperty());