fix https://github.com/apache/rocketmq-exporter/issues/56
diff --git a/src/main/java/org/apache/rocketmq/exporter/controller/RMQMetricsController.java b/src/main/java/org/apache/rocketmq/exporter/controller/RMQMetricsController.java
index e6fe31c..3b19d8e 100644
--- a/src/main/java/org/apache/rocketmq/exporter/controller/RMQMetricsController.java
+++ b/src/main/java/org/apache/rocketmq/exporter/controller/RMQMetricsController.java
@@ -40,6 +40,6 @@
         StringWriter writer = new StringWriter();
         metricsService.metrics(writer);
         response.setHeader("Content-Type", "text/plain; version=0.0.4; charset=utf-8");
-        response.getOutputStream().print(writer.toString());
+        response.getOutputStream().write(writer.toString().getBytes("utf-8"));
     }
 }