diff --git a/src/samples/PostObjectSample.java b/src/samples/PostObjectSample.java
index 6e56fa93..fd378f46 100644
--- a/src/samples/PostObjectSample.java
+++ b/src/samples/PostObjectSample.java
@@ -22,9 +22,7 @@
 import javax.activation.MimetypesFileTypeMap;
 import javax.crypto.Mac;
 import javax.crypto.spec.SecretKeySpec;
-
 import org.apache.commons.codec.binary.Base64;
-
 import java.io.*;
 import java.net.HttpURLConnection;
 import java.net.URL;
@@ -53,94 +51,98 @@ public class PostObjectSample {
     // The key name for the file to upload.
     private String key = "<key>";
 
-    
-    private void PostObject() throws Exception {
+    private void postObject() throws Exception {
         // append the 'bucketname.' prior to the domain, such as http://bucket1.oss-cn-hangzhou.aliyuncs.com.
-        String urlStr = endpoint.replace("http://", "http://" + bucketName+ ".");
-        
+        String urlStr = endpoint.replace("http://", "http://" + bucketName + ".");
+
         // form fields
         Map<String, String> formFields = new LinkedHashMap<String, String>();
-        
+
         // key
         formFields.put("key", this.key);
         // Content-Disposition
         formFields.put("Content-Disposition", "attachment;filename="
-                + localFilePath);
+            + localFilePath);
         // OSSAccessKeyId
         formFields.put("OSSAccessKeyId", accessKeyId);
         // policy
-        String policy = "{\"expiration\": \"2120-01-01T12:00:00.000Z\",\"conditions\": [[\"content-length-range\", 0, 104857600]]}";
+        String policy
+            = "{\"expiration\": \"2120-01-01T12:00:00.000Z\",\"conditions\": [[\"content-length-range\", 0, 104857600]]}";
         String encodePolicy = new String(Base64.encodeBase64(policy.getBytes()));
         formFields.put("policy", encodePolicy);
         // Signature
         String signaturecom = computeSignature(accessKeySecret, encodePolicy);
         formFields.put("Signature", signaturecom);
+        // Set security token.
+        formFields.put("x-oss-security-token", "<yourSecurityToken>");
 
         String ret = formUpload(urlStr, formFields, localFilePath);
-        
+
         System.out.println("Post Object [" + this.key + "] to bucket [" + bucketName + "]");
         System.out.println("post reponse:" + ret);
     }
-    
-    private static String computeSignature(String accessKeySecret, String encodePolicy) 
-            throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
+
+    private static String computeSignature(String accessKeySecret, String encodePolicy)
+        throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
         // convert to UTF-8
         byte[] key = accessKeySecret.getBytes("UTF-8");
         byte[] data = encodePolicy.getBytes("UTF-8");
-        
+
         // hmac-sha1
         Mac mac = Mac.getInstance("HmacSHA1");
         mac.init(new SecretKeySpec(key, "HmacSHA1"));
         byte[] sha = mac.doFinal(data);
-        
+
         // base64
         return new String(Base64.encodeBase64(sha));
     }
 
     private static String formUpload(String urlStr, Map<String, String> formFields, String localFile)
-            throws Exception {
+        throws Exception {
         String res = "";
         HttpURLConnection conn = null;
         String boundary = "9431149156168";
-        
+
         try {
             URL url = new URL(urlStr);
-            conn = (HttpURLConnection) url.openConnection();
+            conn = (HttpURLConnection)url.openConnection();
             conn.setConnectTimeout(5000);
             conn.setReadTimeout(30000);
             conn.setDoOutput(true);
             conn.setDoInput(true);
             conn.setRequestMethod("POST");
-            conn.setRequestProperty("User-Agent", 
-                    "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
+            conn.setRequestProperty("User-Agent",
+                "Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.6)");
+            // Set Content-MD5. The MD5 value is calculated based on the whole message body.
+            conn.setRequestProperty("Content-MD5", "<yourContentMD5>");
             conn.setRequestProperty("Content-Type",
-                    "multipart/form-data; boundary=" + boundary);
+                "multipart/form-data; boundary=" + boundary);
             OutputStream out = new DataOutputStream(conn.getOutputStream());
-            
+
             // text
             if (formFields != null) {
                 StringBuffer strBuf = new StringBuffer();
                 Iterator<Entry<String, String>> iter = formFields.entrySet().iterator();
                 int i = 0;
-                
+
                 while (iter.hasNext()) {
                     Entry<String, String> entry = iter.next();
                     String inputName = entry.getKey();
                     String inputValue = entry.getValue();
-                    
+
                     if (inputValue == null) {
                         continue;
                     }
-                    
+
                     if (i == 0) {
                         strBuf.append("--").append(boundary).append("\r\n");
                         strBuf.append("Content-Disposition: form-data; name=\""
-                                + inputName + "\"\r\n\r\n");
+                            + inputName + "\"\r\n\r\n");
                         strBuf.append(inputValue);
                     } else {
                         strBuf.append("\r\n").append("--").append(boundary).append("\r\n");
                         strBuf.append("Content-Disposition: form-data; name=\""
-                                + inputName + "\"\r\n\r\n");
+                            + inputName + "\"\r\n\r\n");
                         strBuf.append(inputValue);
                     }
 
@@ -159,9 +161,9 @@ private static String formUpload(String urlStr, Map<String, String> formFields,
 
             StringBuffer strBuf = new StringBuffer();
             strBuf.append("\r\n").append("--").append(boundary)
-                    .append("\r\n");
+                .append("\r\n");
             strBuf.append("Content-Disposition: form-data; name=\"file\"; "
-                    + "filename=\"" + filename + "\"\r\n");
+                + "filename=\"" + filename + "\"\r\n");
             strBuf.append("Content-Type: " + contentType + "\r\n\r\n");
 
             out.write(strBuf.toString().getBytes());
@@ -198,13 +200,13 @@ private static String formUpload(String urlStr, Map<String, String> formFields,
                 conn = null;
             }
         }
-        
+
         return res;
     }
 
     public static void main(String[] args) throws Exception {
         PostObjectSample ossPostObject = new PostObjectSample();
-        ossPostObject.PostObject();
+        ossPostObject.postObject();
     }
 
 }