diff --git a/README.md b/README.md
index fa7a85e..995aa96 100644
--- a/README.md
+++ b/README.md
@@ -222,6 +222,55 @@ public class Main{
 
 ```
 
+- Add global context to avoid duplicated @RLPEncoding and @RLPDecoding
+
+```java
+public class Main{
+    public static class LocalDateDecoder implements RLPDecoder<LocalDate> {
+        @Override
+        public LocalDate decode(RLPElement rlpElement) {
+            if(rlpElement.isNull()) return null;
+            int[] data = rlpElement.as(int[].class);
+            return LocalDate.of(data[0], data[1], data[2]);
+        }
+    }
+
+    public class LocalDateEncoder implements RLPEncoder<LocalDate> {
+        @Override
+        public RLPElement encode(LocalDate localDate) {
+            return RLPElement.readRLPTree(
+                    new int[]{localDate.getYear(), localDate.getMonthValue(), localDate.getDayOfMonth()}
+            );
+        }
+    }
+
+    @Data
+    @AllArgsConstructor
+    @NoArgsConstructor
+    public static class User{
+        private LocalDate birthDay;
+    }
+
+    public static void main(String[] args){
+        RLPContext context = RLPContext
+                .newInstance()
+                .withDecoder(LocalDate.class, new LocalDateDecoder())
+                .withEncoder(LocalDate.class, new LocalDateEncoder());
+        RLPMapper mapper = new RLPMapper().withContext(context);
+        User u = new User();
+        element = mapper.readRLPTree(u);
+        User decoded = mapper.decode(element, User.class);
+        assert decoded.birthDay == null;
+
+        u.birthDay = LocalDate.now();
+        byte[] encoded = mapper.encode(u);
+        decoded = mapper.decode(encoded, User.class);
+        System.out.println(decoded.birthDay.format(DateTimeFormatter.ISO_DATE));    
+    }
+
+}
+```
+
 ## Benchmark 
 
 - see RLPTest.performanceDecode for benchmark
diff --git a/build.gradle b/build.gradle
index 3b32d19..bc4b3b8 100644
--- a/build.gradle
+++ b/build.gradle
@@ -4,7 +4,7 @@ plugins {
 }
 
 group 'org.tdf'
-version '1.1.17'
+version '1.1.18'
 
 sourceCompatibility = 1.8
 
@@ -22,7 +22,10 @@ ext{
 dependencies {
     testCompile group: 'junit', name: 'junit', version: '4.12'
     compileOnly "org.projectlombok:lombok:${lombokVersion}"
+    testCompileOnly "org.projectlombok:lombok:${lombokVersion}"
     annotationProcessor "org.projectlombok:lombok:${lombokVersion}"
+    testAnnotationProcessor "org.projectlombok:lombok:${lombokVersion}"
+
     testCompile "commons-codec:commons-codec:${commonsCodecVersion}"
     testCompile "com.madgag.spongycastle:core:${scastleVersion}" // for rlp encoding
     testCompile "com.madgag.spongycastle:prov:${scastleVersion}" // for rlp encoding
diff --git a/src/main/java/org/tdf/rlp/RLPDecoder.java b/src/main/java/org/tdf/rlp/RLPDecoder.java
index 3365bd5..707ea7b 100644
--- a/src/main/java/org/tdf/rlp/RLPDecoder.java
+++ b/src/main/java/org/tdf/rlp/RLPDecoder.java
@@ -1,7 +1,14 @@
 package org.tdf.rlp;
 
+import lombok.NonNull;
+
 public interface RLPDecoder<T> {
-    T decode(RLPElement element);
+    /**
+     *
+     * @param element the element may equals to RLPItem.NULL
+     * @return
+     */
+    T decode(@NonNull RLPElement element);
 
     class None implements RLPDecoder<Object> {
         @Override
diff --git a/src/main/java/org/tdf/rlp/RLPEncoder.java b/src/main/java/org/tdf/rlp/RLPEncoder.java
index 0ce59c9..db9dfc8 100644
--- a/src/main/java/org/tdf/rlp/RLPEncoder.java
+++ b/src/main/java/org/tdf/rlp/RLPEncoder.java
@@ -1,7 +1,14 @@
 package org.tdf.rlp;
 
+import lombok.NonNull;
+
 public interface RLPEncoder<T> {
-    RLPElement encode(T o);
+    /**
+     *
+     * @param o non-null object
+     * @return encoded result
+     */
+    RLPElement encode(@NonNull T o);
 
     class None implements RLPEncoder<Object> {
         @Override
diff --git a/src/test/java/org/tdf/rlp/LocalDateDecoder.java b/src/test/java/org/tdf/rlp/LocalDateDecoder.java
new file mode 100644
index 0000000..1e113f6
--- /dev/null
+++ b/src/test/java/org/tdf/rlp/LocalDateDecoder.java
@@ -0,0 +1,14 @@
+package org.tdf.rlp;
+
+import lombok.NonNull;
+
+import java.time.LocalDate;
+
+public class LocalDateDecoder implements RLPDecoder<LocalDate> {
+    @Override
+    public LocalDate decode(@NonNull RLPElement rlpElement) {
+        if(rlpElement.isNull()) return null;
+        int[] data = rlpElement.as(int[].class);
+        return LocalDate.of(data[0], data[1], data[2]);
+    }
+}
diff --git a/src/test/java/org/tdf/rlp/LocalDateEncoder.java b/src/test/java/org/tdf/rlp/LocalDateEncoder.java
new file mode 100644
index 0000000..83c7fa5
--- /dev/null
+++ b/src/test/java/org/tdf/rlp/LocalDateEncoder.java
@@ -0,0 +1,15 @@
+package org.tdf.rlp;
+
+import lombok.NonNull;
+
+import java.time.LocalDate;
+import java.util.Arrays;
+
+public class LocalDateEncoder implements RLPEncoder<LocalDate> {
+    @Override
+    public RLPElement encode(@NonNull LocalDate localDate) {
+        return RLPElement.readRLPTree(
+                Arrays.asList(localDate.getYear(), localDate.getMonthValue(), localDate.getDayOfMonth())
+        );
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/org/tdf/rlp/RLPTest.java b/src/test/java/org/tdf/rlp/RLPTest.java
index 78601c5..fe11d75 100644
--- a/src/test/java/org/tdf/rlp/RLPTest.java
+++ b/src/test/java/org/tdf/rlp/RLPTest.java
@@ -1,5 +1,8 @@
 package org.tdf.rlp;
 
+import lombok.AllArgsConstructor;
+import lombok.Data;
+import lombok.NoArgsConstructor;
 import org.apache.commons.codec.binary.Hex;
 import org.junit.Ignore;
 import org.junit.Test;
@@ -13,6 +16,8 @@
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Paths;
 import java.security.SecureRandom;
+import java.time.LocalDate;
+import java.time.format.DateTimeFormatter;
 import java.util.*;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
@@ -1685,4 +1690,36 @@ public void testDecodeContainer() throws Exception{
         assert dummmy4.dum != null;
         assert dummmy4.dum.size() == 0;
     }
+
+    @Test
+    public void testContext(){
+        RLPContext context = RLPContext
+                .newInstance()
+                .withDecoder(LocalDate.class, new LocalDateDecoder())
+                .withEncoder(LocalDate.class, new LocalDateEncoder());
+        RLPMapper mapper = new RLPMapper().withContext(context);
+        LocalDate now = LocalDate.now();
+        RLPElement element = mapper.readRLPTree(now);
+        for(long l : element.as(long[].class)){
+            System.out.println(l);
+        }
+        assert now.equals(mapper.decode(element, LocalDate.class));
+
+        User u = new User();
+        element = mapper.readRLPTree(u);
+        User decoded = mapper.decode(element, User.class);
+        assert decoded.birthDay == null;
+
+        u.birthDay = LocalDate.now();
+        byte[] encoded = mapper.encode(u);
+        decoded = mapper.decode(encoded, User.class);
+        System.out.println(decoded.birthDay.format(DateTimeFormatter.ISO_DATE));
+    }
+
+    @Data
+    @AllArgsConstructor
+    @NoArgsConstructor
+    public static class User{
+        private LocalDate birthDay;
+    }
 }