improve coding styles

Author: JacksonTian

aliyun-java-sdk-core/src/main/java/com/aliyuncs/AcsRequest.java

@@ -24,7 +24,7 @@ public abstract class AcsRequest<T extends AcsResponse> extends HttpRequest {
     private UserAgentConfig userAgentConfig;
     protected ISignatureComposer composer = null;
     private String version = null;
-    private String product = null;
+    private String product;
     private String actionName = null;
     private String regionId = null;
     private String securityToken = null;
@@ -76,7 +76,7 @@ public static String concatQueryString(Map<String, String> parameters) throws Un
             return null;
         }
 
-        StringBuilder urlBuilder = new StringBuilder("");
+        StringBuilder urlBuilder = new StringBuilder();
         for (Entry<String, String> entry : parameters.entrySet()) {
             String key = entry.getKey();
             String val = entry.getValue();

aliyun-java-sdk-core/src/main/java/com/aliyuncs/RoaAcsRequest.java

@@ -114,7 +114,7 @@ protected void putPathParameter(String name, String value) {
     @Override
     public String composeUrl(String endpoint, Map<String, String> queries) throws UnsupportedEncodingException {
         Map<String, String> mapQueries = (queries == null) ? this.getSysQueryParameters() : queries;
-        StringBuilder urlBuilder = new StringBuilder("");
+        StringBuilder urlBuilder = new StringBuilder();
         urlBuilder.append(this.getSysProtocol().toString());
         urlBuilder.append("://").append(endpoint);
         if (null != this.uriPattern) {

aliyun-java-sdk-core/src/main/java/com/aliyuncs/RpcAcsRequest.java

@@ -131,7 +131,7 @@ public void setSysSecurityToken(String securityToken) {
     @Override
     public String composeUrl(String endpoint, Map<String, String> queries) throws UnsupportedEncodingException {
         Map<String, String> mapQueries = (queries == null) ? this.getSysQueryParameters() : queries;
-        StringBuilder urlBuilder = new StringBuilder("");
+        StringBuilder urlBuilder = new StringBuilder();
         urlBuilder.append(this.getSysProtocol().toString());
         urlBuilder.append("://").append(endpoint);
         if (-1 == urlBuilder.indexOf("?")) {
@@ -166,7 +166,7 @@ public HttpRequest signRequest(Signer signer, AlibabaCloudCredentials credential
                 format);
         headerMap.putAll(this.getSysHeaders());
         headerMap = this.composer.refreshSignParameters(headerMap, signer, null, null);
-        if (imutableMap.get("RegionId") == null && this.getSysRegionId() != null && !this.getSysRegionId().equals("")) {
+        if (imutableMap.get("RegionId") == null && this.getSysRegionId() != null && !this.getSysRegionId().isEmpty()) {
             if ((bodyParams == null || bodyParams.get("RegionId") == null)) {
                 imutableMap.put("RegionId", getSysRegionId());
             }

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/DefaultCredentialsProvider.java

@@ -27,7 +27,7 @@ public DefaultCredentialsProvider() throws ClientException {
         defaultProviders.add(new ProfileCredentialsProvider());
         String roleName = AuthUtils.getEnvironmentECSMetaData();
         if (roleName != null) {
-            if (roleName.length() == 0) {
+            if (roleName.isEmpty()) {
                 throw new ClientException("Environment variable roleName('ALIBABA_CLOUD_ECS_METADATA') cannot be empty");
             }
             defaultProviders.add(new InstanceProfileCredentialsProvider(roleName));

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/LegacyCredentials.java

@@ -5,8 +5,8 @@ public class LegacyCredentials implements AlibabaCloudCredentials {
 
     private final Credential legacyCredential;
 
-    public LegacyCredentials(Credential legacyCrendential) {
-        this.legacyCredential = legacyCrendential;
+    public LegacyCredentials(Credential legacyCredential) {
+        this.legacyCredential = legacyCredential;
     }
 
     @Override

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/ProfileCredentialsProvider.java

@@ -31,7 +31,7 @@ public AlibabaCloudCredentials getCredentials() throws ClientException {
         if (filePath == null) {
             filePath = AuthConstant.DEFAULT_CREDENTIALS_FILE_PATH;
         }
-        if (filePath.length() == 0) {
+        if (filePath.isEmpty()) {
             throw new ClientException("The specified credentials file is empty");
         }
         Wini ini;

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/SHA256withRSASigner.java

@@ -41,8 +41,7 @@ public String signString(String stringToSign, String accessKeySecret) {
             rsaSign.initSign(privateKey);
             rsaSign.update(stringToSign.getBytes(ENCODING));
             byte[] sign = rsaSign.sign();
-            String signature = DatatypeConverter.printBase64Binary(sign);
-            return signature;
+            return DatatypeConverter.printBase64Binary(sign);
         } catch (NoSuchAlgorithmException e) {
             throw new IllegalArgumentException(e.toString());
         } catch (InvalidKeySpecException e) {

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/STSGetSessionAccessKeyCredentialsProvider.java

@@ -65,7 +65,7 @@ private BasicSessionCredentials getNewSessionCredentials() throws ClientExceptio
 
         return new BasicSessionCredentials(
                 response.getSessionAccessKey().getSessionAccessKeyId(),
-                response.getSessionAccessKey().getSessionAccessKeySecert(),
+                response.getSessionAccessKey().getSessionAccessKeySecret(),
                 null,
                 sessionDurationSeconds
         );

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/V3SignatureComposer.java

@@ -84,7 +84,7 @@ private Map<String, String> getCanonicalizedHeadersMap(Map<String, String> heade
     }
 
     private String getCanonicalizedResource(Map<String, String> query) {
-        if (query == null || query.size() == 0) {
+        if (query == null || query.isEmpty()) {
             return "";
         }
         String[] keys = query.keySet().toArray(new String[query.size()]);

aliyun-java-sdk-core/src/main/java/com/aliyuncs/auth/sts/AssumeRoleRequest.java

@@ -19,16 +19,9 @@
 
 package com.aliyuncs.auth.sts;
 
-/**
- * Created by haowei.yao on 2017/9/14.
- */
-
 import com.aliyuncs.RpcAcsRequest;
 import com.aliyuncs.http.ProtocolType;
 
-/**
- * @author auto create
- */
 public class AssumeRoleRequest extends RpcAcsRequest<AssumeRoleResponse> {
 
     private Long durationSeconds;