diff --git a/src/main/java/io/github/yezhihao/protostar/converter/MapConverter.java b/src/main/java/io/github/yezhihao/protostar/converter/MapConverter.java
index 5cb14b9..73816a9 100644
--- a/src/main/java/io/github/yezhihao/protostar/converter/MapConverter.java
+++ b/src/main/java/io/github/yezhihao/protostar/converter/MapConverter.java
@@ -27,9 +27,16 @@ public abstract class MapConverter<K, V> extends PrepareLoadStrategy implements
         Map<K, V> map = new TreeMap<>();
         do {
             K key = readKey(input);
-            int len = ByteBufUtils.readInt(input, valueSize());
-            Object value = readValue(key, input.readSlice(len));
-            map.put(key, (V) value);
+            int length = ByteBufUtils.readInt(input, valueSize());
+
+            if (input.isReadable(length)) {
+                int writerIndex = input.writerIndex();
+                input.writerIndex(input.readerIndex() + length);
+                map.put(key, (V) readValue(key, input));
+                input.writerIndex(writerIndex);
+            } else {
+                map.put(key, (V) readValue(key, input));
+            }
         } while (input.isReadable());
         return map;
     }
diff --git a/src/main/java/io/github/yezhihao/protostar/schema/StringSchema.java b/src/main/java/io/github/yezhihao/protostar/schema/StringSchema.java
index 01478e8..f5e4525 100644
--- a/src/main/java/io/github/yezhihao/protostar/schema/StringSchema.java
+++ b/src/main/java/io/github/yezhihao/protostar/schema/StringSchema.java
@@ -8,6 +8,7 @@ import io.netty.util.internal.StringUtil;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.nio.ByteBuffer;
 import java.nio.charset.Charset;
 import java.util.Arrays;
 
@@ -58,24 +59,25 @@ public class StringSchema {
 
         @Override
         public void writeTo(ByteBuf output, int length, String value) {
-            byte[] bytes = value.getBytes(charset);
+            ByteBuffer buffer = charset.encode(value);
             if (length > 0) {
-                int srcPos = length - bytes.length;
+                int srcPos = length - buffer.limit();
 
                 if (srcPos > 0) {
                     byte[] pads = new byte[srcPos];
                     if (pad != 0x00)
                         Arrays.fill(pads, pad);
                     output.writeBytes(pads);
-                    output.writeBytes(bytes);
+                    output.writeBytes(buffer);
                 } else if (srcPos < 0) {
-                    output.writeBytes(bytes, -srcPos, length);
-                    log.info("字符长度超出限制: 长度[{}],数据长度[{}],{}", length, bytes.length, value);
+                    buffer.position(-srcPos);
+                    output.writeBytes(buffer);
+                    log.info("字符长度超出限制: 长度[{}],数据长度[{}],{}", length, buffer.limit(), value);
                 } else {
-                    output.writeBytes(bytes);
+                    output.writeBytes(buffer);
                 }
             } else {
-                output.writeBytes(bytes);
+                output.writeBytes(buffer);
             }
         }
     }