diff --git a/pom.xml b/pom.xml
index a1c153c..e8803f3 100644
--- a/pom.xml
+++ b/pom.xml
@@ -48,12 +48,11 @@
             <scope>test</scope>
         </dependency>
         <dependency>
-            <groupId>com.google.code.gson</groupId>
-            <artifactId>gson</artifactId>
-            <version>2.8.6</version>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.30</version>
             <scope>test</scope>
         </dependency>
-
         <dependency>
             <groupId>org.slf4j</groupId>
             <artifactId>slf4j-api</artifactId>
diff --git a/src/test/java/io/github/yezhihao/protostar/Test.java b/src/test/java/io/github/yezhihao/protostar/Test.java
deleted file mode 100644
index 21c66e2..0000000
--- a/src/test/java/io/github/yezhihao/protostar/Test.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package io.github.yezhihao.protostar;
-
-public class Test {
-
-    public static void main(String[] args) {
-        System.out.println();
-    }
-}
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/Attr1.java b/src/test/java/io/github/yezhihao/protostar/convert/Attr1.java
new file mode 100644
index 0000000..c719a1a
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/convert/Attr1.java
@@ -0,0 +1,46 @@
+package io.github.yezhihao.protostar.convert;
+
+import io.github.yezhihao.protostar.DataType;
+import io.github.yezhihao.protostar.annotation.Field;
+
+public class Attr1 {
+
+    private String name;
+    private int id;
+
+    public Attr1() {
+    }
+
+    public Attr1(String name, int id) {
+        this.name = name;
+        this.id = id;
+    }
+
+    @Field(index = 0, type = DataType.STRING, lengthSize = 1, desc = "名称")
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    @Field(index = 1, type = DataType.WORD, desc = "ID")
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+
+    @Override
+    public String toString() {
+        final StringBuilder sb = new StringBuilder("Attr1{");
+        sb.append("name='").append(name).append('\'');
+        sb.append(", id=").append(id);
+        sb.append('}');
+        return sb.toString();
+    }
+}
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/Attr2.java b/src/test/java/io/github/yezhihao/protostar/convert/Attr2.java
new file mode 100644
index 0000000..88cb819
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/convert/Attr2.java
@@ -0,0 +1,66 @@
+package io.github.yezhihao.protostar.convert;
+
+import io.netty.buffer.ByteBuf;
+
+import java.nio.charset.StandardCharsets;
+
+public class Attr2 {
+
+    private int type;
+    private String content;
+
+    public Attr2() {
+    }
+
+    public Attr2(int type, String content) {
+        this.type = type;
+        this.content = content;
+    }
+
+    public int getType() {
+        return type;
+    }
+
+    public void setType(int type) {
+        this.type = type;
+    }
+
+    public String getContent() {
+        return content;
+    }
+
+    public void setContent(String content) {
+        this.content = content;
+    }
+
+    @Override
+    public String toString() {
+        final StringBuilder sb = new StringBuilder("Attr2{");
+        sb.append("type=").append(type);
+        sb.append(", content='").append(content).append('\'');
+        sb.append('}');
+        return sb.toString();
+    }
+
+    public static class Schema implements io.github.yezhihao.protostar.Schema<Attr2> {
+
+        public static final Schema INSTANCE = new Schema();
+
+        private Schema() {
+        }
+
+        @Override
+        public Attr2 readFrom(ByteBuf input) {
+            Attr2 message = new Attr2();
+            message.type = input.readInt();
+            message.content = input.readCharSequence(input.readableBytes(), StandardCharsets.UTF_8).toString();
+            return message;
+        }
+
+        @Override
+        public void writeTo(ByteBuf output, Attr2 message) {
+            output.writeInt(message.type);
+            output.writeCharSequence(message.content, StandardCharsets.UTF_8);
+        }
+    }
+}
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java b/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java
new file mode 100644
index 0000000..5b0ee47
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/convert/AttributeConverter.java
@@ -0,0 +1,54 @@
+package io.github.yezhihao.protostar.convert;
+
+import io.github.yezhihao.protostar.IdStrategy;
+import io.github.yezhihao.protostar.Schema;
+import io.github.yezhihao.protostar.converter.MapConverter;
+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;
+    }
+
+    @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);
+        }
+    }
+
+    @Override
+    protected Integer readKey(ByteBuf input) {
+        return (int) input.readUnsignedByte();
+    }
+
+    @Override
+    protected void writeKey(ByteBuf output, Integer key) {
+        output.writeByte(key);
+    }
+
+    @Override
+    protected int valueSize() {
+        return 1;
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/io/github/yezhihao/protostar/convert/AttributeType.java b/src/test/java/io/github/yezhihao/protostar/convert/AttributeType.java
new file mode 100644
index 0000000..fe4a664
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/convert/AttributeType.java
@@ -0,0 +1,21 @@
+package io.github.yezhihao.protostar.convert;
+
+import io.github.yezhihao.protostar.IdStrategy;
+import io.github.yezhihao.protostar.PrepareLoadStrategy;
+import io.github.yezhihao.protostar.schema.IntSchema;
+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, IntSchema.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
new file mode 100644
index 0000000..d68e1ad
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/convert/Test.java
@@ -0,0 +1,114 @@
+package io.github.yezhihao.protostar.convert;
+
+import io.github.yezhihao.protostar.DataType;
+import io.github.yezhihao.protostar.ProtostarUtil;
+import io.github.yezhihao.protostar.Schema;
+import io.github.yezhihao.protostar.annotation.Convert;
+import io.github.yezhihao.protostar.annotation.Field;
+import io.github.yezhihao.protostar.annotation.Fs;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
+
+import java.time.LocalDateTime;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class Test {
+
+    public static void main(String[] args) {
+        Map<Integer, Schema<Foo>> multiVersionSchema = ProtostarUtil.getSchema(Foo.class);
+        Schema<Foo> schema_v0 = multiVersionSchema.get(0);
+        Schema<Foo> schema_v1 = multiVersionSchema.get(1);
+
+        ByteBuf buffer = Unpooled.buffer(32);
+        schema_v0.writeTo(buffer, foo());
+        String hex = ByteBufUtil.hexDump(buffer);
+        System.out.println(hex);
+
+        Foo foo = schema_v0.readFrom(buffer);
+        System.out.println(foo);
+        System.out.println("=========================version: 0");
+
+        buffer = Unpooled.buffer(32);
+        schema_v1.writeTo(buffer, foo());
+        hex = ByteBufUtil.hexDump(buffer);
+        System.out.println(hex);
+
+        foo = schema_v1.readFrom(buffer);
+        System.out.println(foo);
+        System.out.println("=========================version: 1");
+    }
+
+    public static Foo foo() {
+        Foo foo = new Foo();
+        foo.setName("张三");
+        foo.setId(128);
+        foo.setDateTime(LocalDateTime.of(2020, 7, 7, 19, 23, 59));
+        Map<Integer, Object> attrs = new TreeMap<>();
+        attrs.put(1, 123);
+        attrs.put(2, "李四");
+        attrs.put(3, new Attr1("test", 1));
+        attrs.put(4, new Attr2(2, "test2"));
+        foo.setAttributes(attrs);
+        return foo;
+    }
+
+    public static class Foo {
+
+        private String name;
+        private int id;
+        private LocalDateTime dateTime;
+        private Map<Integer, Object> attributes;
+
+        @Fs({@Field(index = 0, type = DataType.STRING, lengthSize = 1, desc = "名称", version = 0),
+                @Field(index = 0, type = DataType.STRING, length = 10, desc = "名称", version = 1)})
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        @Fs({@Field(index = 1, type = DataType.WORD, desc = "ID", version = 0),
+                @Field(index = 1, type = DataType.DWORD, desc = "ID", version = 1)})
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        @Field(index = 3, type = DataType.BCD8421, desc = "日期", version = {0, 1})
+        public LocalDateTime getDateTime() {
+            return dateTime;
+        }
+
+        public void setDateTime(LocalDateTime dateTime) {
+            this.dateTime = dateTime;
+        }
+
+        @Convert(converter = AttributeConverter.class)
+        @Field(index = 4, type = DataType.MAP, desc = "属性", version = {0, 1})
+        public Map<Integer, Object> getAttributes() {
+            return attributes;
+        }
+
+        public void setAttributes(Map<Integer, Object> attributes) {
+            this.attributes = attributes;
+        }
+
+        @Override
+        public String toString() {
+            final StringBuilder sb = new StringBuilder("Foo{");
+            sb.append("name='").append(name).append('\'');
+            sb.append(", id=").append(id);
+            sb.append(", dateTime=").append(dateTime);
+            sb.append(", attributes=").append(attributes);
+            sb.append('}');
+            return sb.toString();
+        }
+    }
+}
diff --git a/src/test/java/io/github/yezhihao/protostar/multiversion/Test.java b/src/test/java/io/github/yezhihao/protostar/multiversion/Test.java
new file mode 100644
index 0000000..a59b9be
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/multiversion/Test.java
@@ -0,0 +1,94 @@
+package io.github.yezhihao.protostar.multiversion;
+
+import io.github.yezhihao.protostar.DataType;
+import io.github.yezhihao.protostar.ProtostarUtil;
+import io.github.yezhihao.protostar.Schema;
+import io.github.yezhihao.protostar.annotation.Field;
+import io.github.yezhihao.protostar.annotation.Fs;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
+
+import java.time.LocalDateTime;
+import java.util.Map;
+
+public class Test {
+
+    public static void main(String[] args) {
+        Map<Integer, Schema<Foo>> multiVersionSchema = ProtostarUtil.getSchema(Foo.class);
+        Schema<Foo> schema_v0 = multiVersionSchema.get(0);
+        Schema<Foo> schema_v1 = multiVersionSchema.get(1);
+
+        ByteBuf buffer = Unpooled.buffer(32);
+        schema_v0.writeTo(buffer, foo());
+        String hex = ByteBufUtil.hexDump(buffer);
+        System.out.println(hex);
+
+        Foo foo = schema_v0.readFrom(buffer);
+        System.out.println(foo);
+        System.out.println("=========================version: 0");
+
+        buffer = Unpooled.buffer(32);
+        schema_v1.writeTo(buffer, foo());
+        hex = ByteBufUtil.hexDump(buffer);
+        System.out.println(hex);
+
+        foo = schema_v1.readFrom(buffer);
+        System.out.println(foo);
+        System.out.println("=========================version: 1");
+    }
+
+    public static Foo foo() {
+        Foo foo = new Foo();
+        foo.setName("张三");
+        foo.setId(128);
+        foo.setDateTime(LocalDateTime.of(2020, 7, 7, 19, 23, 59));
+        return foo;
+    }
+
+    public static class Foo {
+
+        private String name;
+        private int id;
+        private LocalDateTime dateTime;
+
+        @Fs({@Field(index = 0, type = DataType.STRING, lengthSize = 1, desc = "名称", version = 0),
+                @Field(index = 0, type = DataType.STRING, length = 10, desc = "名称", version = 1)})
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        @Fs({@Field(index = 1, type = DataType.WORD, desc = "ID", version = 0),
+                @Field(index = 1, type = DataType.DWORD, desc = "ID", version = 1)})
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        @Field(index = 3, type = DataType.BCD8421, desc = "日期", version = {0, 1})
+        public LocalDateTime getDateTime() {
+            return dateTime;
+        }
+
+        public void setDateTime(LocalDateTime dateTime) {
+            this.dateTime = dateTime;
+        }
+
+        @Override
+        public String toString() {
+            final StringBuilder sb = new StringBuilder("Foo{");
+            sb.append("name='").append(name).append('\'');
+            sb.append(", id=").append(id);
+            sb.append(", dateTime=").append(dateTime);
+            sb.append('}');
+            return sb.toString();
+        }
+    }
+}
diff --git a/src/test/java/io/github/yezhihao/protostar/simple/Test.java b/src/test/java/io/github/yezhihao/protostar/simple/Test.java
new file mode 100644
index 0000000..49671f4
--- /dev/null
+++ b/src/test/java/io/github/yezhihao/protostar/simple/Test.java
@@ -0,0 +1,83 @@
+package io.github.yezhihao.protostar.simple;
+
+import io.github.yezhihao.protostar.DataType;
+import io.github.yezhihao.protostar.FieldFactory;
+import io.github.yezhihao.protostar.ProtostarUtil;
+import io.github.yezhihao.protostar.Schema;
+import io.github.yezhihao.protostar.annotation.Field;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
+import io.netty.buffer.Unpooled;
+
+import java.time.LocalDateTime;
+import java.util.Map;
+
+public class Test {
+
+    public static void main(String[] args) {
+        FieldFactory.EXPLAIN = true;
+
+        Map<Integer, Schema<Foo>> multiVersionSchema = ProtostarUtil.getSchema(Foo.class);
+        Schema<Foo> schema = multiVersionSchema.get(0);
+
+        ByteBuf buffer = Unpooled.buffer(32);
+        schema.writeTo(buffer, foo());
+        String hex = ByteBufUtil.hexDump(buffer);
+        System.out.println(hex);
+
+        Foo foo = schema.readFrom(buffer);
+        System.out.println(foo);
+    }
+
+    public static Foo foo() {
+        Foo foo = new Foo();
+        foo.setName("张三");
+        foo.setId(128);
+        foo.setDateTime(LocalDateTime.of(2020, 7, 7, 19, 23, 59));
+        return foo;
+    }
+
+    public static class Foo {
+
+        private String name;
+        private int id;
+        private LocalDateTime dateTime;
+
+        @Field(index = 0, type = DataType.STRING, lengthSize = 1, desc = "名称")
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        @Field(index = 1, type = DataType.WORD, desc = "ID")
+        public int getId() {
+            return id;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        @Field(index = 3, type = DataType.BCD8421, desc = "日期")
+        public LocalDateTime getDateTime() {
+            return dateTime;
+        }
+
+        public void setDateTime(LocalDateTime dateTime) {
+            this.dateTime = dateTime;
+        }
+
+        @Override
+        public String toString() {
+            final StringBuilder sb = new StringBuilder("Foo{");
+            sb.append("name='").append(name).append('\'');
+            sb.append(", id=").append(id);
+            sb.append(", dateTime=").append(dateTime);
+            sb.append('}');
+            return sb.toString();
+        }
+    }
+}