diff --git a/pom.xml b/pom.xml
index bb65b9a..6b386bb 100644
--- a/pom.xml
+++ b/pom.xml
@@ -3,7 +3,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>io.github.yezhihao</groupId>
     <artifactId>protostar</artifactId>
-    <version>2.0.1.RELEASE</version>
+    <version>2.0.2.RELEASE</version>
     <packaging>jar</packaging>
 
     <name>Protostar</name>
diff --git a/src/main/java/io/github/yezhihao/protostar/DataType.java b/src/main/java/io/github/yezhihao/protostar/DataType.java
index 7b0d667..98a1b33 100644
--- a/src/main/java/io/github/yezhihao/protostar/DataType.java
+++ b/src/main/java/io/github/yezhihao/protostar/DataType.java
@@ -7,25 +7,25 @@ package io.github.yezhihao.protostar;
  */
 public enum DataType {
 
-    //无符号单字节整型（字节， 8位）
+    /** 无符号单字节整型(8位) */
     BYTE(1),
-    //无符号双字节整型（字节，16位）
+    /** 无符号双字节整型(16位) */
     WORD(2),
-    //无符号四字节整型（字节，32位）
+    /** 无符号四字节整型(32位) */
     DWORD(4),
-    //无符号八字节整型（字节，64位）
+    /** 无符号八字节整型(64位) */
     QWORD(8),
-    //N字节，字节数组
+    /** 字节数组 */
     BYTES(-1),
-    //N字节，BCD8421码
+    /** BCD8421码 */
     BCD8421(-1),
-    //字符串，若无数据置空
+    /** 字符串 */
     STRING(-1),
-    //对象
+    /** 对象 */
     OBJ(-1),
-    //列表
+    /** 列表 */
     LIST(-1),
-    //字典
+    /** 字典 */
     MAP(-1);
 
     public int length;
diff --git a/src/main/java/io/github/yezhihao/protostar/FieldFactory.java b/src/main/java/io/github/yezhihao/protostar/FieldFactory.java
index 5f7a260..63d34f9 100644
--- a/src/main/java/io/github/yezhihao/protostar/FieldFactory.java
+++ b/src/main/java/io/github/yezhihao/protostar/FieldFactory.java
@@ -1,14 +1,11 @@
 package io.github.yezhihao.protostar;
 
-import io.github.yezhihao.protostar.annotation.Convert;
 import io.github.yezhihao.protostar.annotation.Field;
 import io.github.yezhihao.protostar.field.BasicField;
 import io.github.yezhihao.protostar.field.DynamicLengthField;
 import io.github.yezhihao.protostar.field.FixedField;
 import io.github.yezhihao.protostar.field.FixedLengthField;
 import io.github.yezhihao.protostar.schema.*;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 import java.nio.ByteBuffer;
 import java.time.LocalDateTime;
@@ -19,7 +16,7 @@ import java.time.LocalDateTime;
  * home https://gitee.com/yezhihao/jt808-server
  */
 public abstract class FieldFactory {
-    protected static Logger log = LoggerFactory.getLogger(FieldFactory.class.getSimpleName());
+
     public static boolean EXPLAIN = false;
 
     public static BasicField create(Field field, java.lang.reflect.Field f) {
@@ -59,19 +56,16 @@ public abstract class FieldFactory {
                 fieldSchema = StringSchema.Chars.getInstance(field.pad(), field.charset());
                 break;
             case OBJ:
-                if (schema != null) {
+                if (schema != null)
                     fieldSchema = ObjectSchema.getInstance(schema);
-                } else {
-                    Convert convert = f.getAnnotation(Convert.class);
-                    fieldSchema = ConvertSchema.getInstance(convert.converter());
-                }
+                else
+                    fieldSchema = ConvertSchema.getInstance(field.converter());
                 break;
             case LIST:
                 fieldSchema = CollectionSchema.getInstance(schema);
                 break;
             case MAP:
-                Convert convert = f.getAnnotation(Convert.class);
-                fieldSchema = ConvertSchema.getInstance(convert.converter());
+                fieldSchema = ConvertSchema.getInstance(field.converter());
                 break;
             default:
                 throw new RuntimeException("不支持的类型转换");
diff --git a/src/main/java/io/github/yezhihao/protostar/annotation/Convert.java b/src/main/java/io/github/yezhihao/protostar/annotation/Convert.java
deleted file mode 100644
index 3f93d04..0000000
--- a/src/main/java/io/github/yezhihao/protostar/annotation/Convert.java
+++ /dev/null
@@ -1,21 +0,0 @@
-package io.github.yezhihao.protostar.annotation;
-
-import io.github.yezhihao.protostar.converter.Converter;
-
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
-
-/**
- * 启用自定义消息转换
- * @author yezhihao
- * home https://gitee.com/yezhihao/jt808-server
- */
-@Target(ElementType.FIELD)
-@Retention(RetentionPolicy.RUNTIME)
-public @interface Convert {
-
-    Class<? extends Converter> converter();
-
-}
\ No newline at end of file
diff --git a/src/main/java/io/github/yezhihao/protostar/annotation/Field.java b/src/main/java/io/github/yezhihao/protostar/annotation/Field.java
index 22281d5..2d13217 100644
--- a/src/main/java/io/github/yezhihao/protostar/annotation/Field.java
+++ b/src/main/java/io/github/yezhihao/protostar/annotation/Field.java
@@ -1,6 +1,7 @@
 package io.github.yezhihao.protostar.annotation;
 
 import io.github.yezhihao.protostar.DataType;
+import io.github.yezhihao.protostar.converter.Converter;
 
 import java.lang.annotation.*;
 
@@ -23,9 +24,11 @@ public @interface Field {
 
     String charset() default "GBK";
 
-    byte pad() default 0x00;
+    byte pad() default 0;
 
     String desc() default "";
 
     int[] version() default {-1, 0, 1};
+
+    Class<? extends Converter> converter() default Converter.class;
 }
\ No newline at end of file
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 9a83bba..5cb14b9 100644
--- a/src/main/java/io/github/yezhihao/protostar/converter/MapConverter.java
+++ b/src/main/java/io/github/yezhihao/protostar/converter/MapConverter.java
@@ -1,12 +1,18 @@
 package io.github.yezhihao.protostar.converter;
 
+import io.github.yezhihao.protostar.PrepareLoadStrategy;
+import io.github.yezhihao.protostar.Schema;
 import io.github.yezhihao.protostar.util.ByteBufUtils;
 import io.netty.buffer.ByteBuf;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.Map;
 import java.util.TreeMap;
 
-public abstract class MapConverter<K, V> implements Converter<Map<K, V>> {
+public abstract class MapConverter<K, V> extends PrepareLoadStrategy implements Converter<Map<K, V>> {
+
+    private final Logger log = LoggerFactory.getLogger(this.getClass().getSimpleName());
 
     protected abstract K readKey(ByteBuf input);
 
@@ -14,24 +20,31 @@ public abstract class MapConverter<K, V> implements Converter<Map<K, V>> {
 
     protected abstract int valueSize();
 
-    protected abstract V convert(K key, ByteBuf input);
-
-    protected abstract void convert(K key, ByteBuf output, V value);
-
     @Override
     public Map<K, V> convert(ByteBuf input) {
         if (!input.isReadable())
             return null;
         Map<K, V> map = new TreeMap<>();
         do {
-            K id = readKey(input);
+            K key = readKey(input);
             int len = ByteBufUtils.readInt(input, valueSize());
-            Object value = convert(id, input.readSlice(len));
-            map.put(id, (V) value);
+            Object value = readValue(key, input.readSlice(len));
+            map.put(key, (V) value);
         } while (input.isReadable());
         return map;
     }
 
+    public Object readValue(K key, ByteBuf input) {
+        if (!input.isReadable())
+            return null;
+        Schema schema = getSchema(key);
+        if (schema != null)
+            return schema.readFrom(input);
+        byte[] bytes = new byte[input.readableBytes()];
+        input.readBytes(bytes);
+        return bytes;
+    }
+
     @Override
     public void convert(ByteBuf output, Map<K, V> map) {
 
@@ -40,14 +53,22 @@ public abstract class MapConverter<K, V> implements Converter<Map<K, V>> {
         for (Map.Entry<K, V> entry : map.entrySet()) {
             K key = entry.getKey();
             V value = entry.getValue();
-
             writeKey(output, key);
-            int valueSize = valueSize();
+            writeValue(key, output, value);
+        }
+    }
+
+    public void writeValue(K key, ByteBuf output, Object value) {
+        Schema schema = getSchema(key);
+        if (schema != null) {
+            int lengthSize = valueSize();
             int begin = output.writerIndex();
-            output.writeBytes(ByteBufUtils.BLOCKS[valueSize]);
-            convert(key, output, value);
-            int len = output.writerIndex() - begin - valueSize;
-            ByteBufUtils.setInt(output, valueSize, begin, len);
+            output.writeBytes(ByteBufUtils.BLOCKS[lengthSize]);
+            schema.writeTo(output, value);
+            int length = output.writerIndex() - begin - lengthSize;
+            ByteBufUtils.setInt(output, lengthSize, begin, length);
+        } else {
+            log.warn("未注册的信息:ID[{}], VALUE[{}]", key, value);
         }
     }
 }
\ No newline at end of file
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java b/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java
index 5b0ee47..afeb285 100644
--- a/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java
+++ b/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java
@@ -1,40 +1,21 @@
 package io.github.yezhihao.protostar.convert;
 
-import io.github.yezhihao.protostar.IdStrategy;
-import io.github.yezhihao.protostar.Schema;
+import io.github.yezhihao.protostar.PrepareLoadStrategy;
 import io.github.yezhihao.protostar.converter.MapConverter;
+import io.github.yezhihao.protostar.schema.NumberSchema;
+import io.github.yezhihao.protostar.schema.StringSchema;
 import io.netty.buffer.ByteBuf;
-import io.netty.buffer.ByteBufUtil;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 public class AttributeConverter extends MapConverter<Integer, Object> {
 
-    private static final Logger log = LoggerFactory.getLogger(AttributeConverter.class);
-
-    private static final IdStrategy INSTANCE = AttributeType.INSTANCE;
-
     @Override
-    public Object convert(Integer key, ByteBuf input) {
-        if (!input.isReadable())
-            return null;
-        Schema schema = INSTANCE.getSchema(key);
-        if (schema != null)
-            return INSTANCE.readFrom(key, input);
-        byte[] bytes = new byte[input.readableBytes()];
-        input.readBytes(bytes);
-        log.warn("未识别的附加信息：ID[{}], HEX[{}]", key, ByteBufUtil.hexDump(bytes));
-        return bytes;
-    }
+    protected void addSchemas(PrepareLoadStrategy schemaRegistry) {
+        schemaRegistry
+                .addSchema(1, NumberSchema.Int32.INSTANCE)
+                .addSchema(2, StringSchema.Chars.getInstance((byte) 0, "GBK"))
 
-    @Override
-    public void convert(Integer key, ByteBuf output, Object value) {
-        Schema schema = INSTANCE.getSchema(key);
-        if (schema != null) {
-            schema.writeTo(output, value);
-        } else {
-            log.warn("未注册的附加信息：ID[{}], Value[{}]", key, value);
-        }
+                .addSchema(3, Attr1.class)
+                .addSchema(4, Attr2.Schema.INSTANCE);
     }
 
     @Override
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/AttributeType.java b/src/test/java/io/github/yezhihao/protostar/convert/AttributeType.java
deleted file mode 100644
index 610d2c6..0000000
--- a/src/test/java/io/github/yezhihao/protostar/convert/AttributeType.java
+++ /dev/null
@@ -1,21 +0,0 @@
-package io.github.yezhihao.protostar.convert;
-
-import io.github.yezhihao.protostar.IdStrategy;
-import io.github.yezhihao.protostar.PrepareLoadStrategy;
-import io.github.yezhihao.protostar.schema.NumberSchema;
-import io.github.yezhihao.protostar.schema.StringSchema;
-
-public class AttributeType extends PrepareLoadStrategy {
-
-    public static final IdStrategy INSTANCE = new AttributeType();
-
-    @Override
-    protected void addSchemas(PrepareLoadStrategy schemaRegistry) {
-        schemaRegistry
-                .addSchema(1, NumberSchema.Int32.INSTANCE)
-                .addSchema(2, StringSchema.Chars.getInstance((byte) 0, "GBK"))
-
-                .addSchema(3, Attr1.class)
-                .addSchema(4, Attr2.Schema.INSTANCE);
-    }
-}
\ No newline at end of file
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/Test.java b/src/test/java/io/github/yezhihao/protostar/convert/Test.java
index 15ba5f8..1774bfd 100644
--- a/src/test/java/io/github/yezhihao/protostar/convert/Test.java
+++ b/src/test/java/io/github/yezhihao/protostar/convert/Test.java
@@ -2,7 +2,6 @@ package io.github.yezhihao.protostar.convert;
 
 import io.github.yezhihao.protostar.DataType;
 import io.github.yezhihao.protostar.ProtostarUtil;
-import io.github.yezhihao.protostar.annotation.Convert;
 import io.github.yezhihao.protostar.annotation.Field;
 import io.github.yezhihao.protostar.schema.RuntimeSchema;
 import io.netty.buffer.ByteBuf;
@@ -63,8 +62,8 @@ public class Test {
         private int id;
         @Field(index = 3, type = DataType.BCD8421, desc = "日期", version = {0, 1})
         private LocalDateTime dateTime;
-        @Convert(converter = AttributeConverter.class)
-        @Field(index = 4, type = DataType.MAP, desc = "属性", version = {0, 1})
+        @Field(index = 4, type = DataType.MAP, desc = "属性", version = 0, converter = AttributeConverter.class)
+        @Field(index = 4, type = DataType.MAP, desc = "属性", version = 1, converter = AttributeConverterV2.class)
         private Map<Integer, Object> attributes;
 
         public String getName() {