Optimize parseCharset method for best performance. (#15203)

Author: Stellar1999

dubbo-remoting/dubbo-remoting-http12/src/main/java/org/apache/dubbo/remoting/http12/HttpUtils.java

@@ -16,6 +16,7 @@
  */
 package org.apache.dubbo.remoting.http12;
 
+import org.apache.dubbo.common.constants.CommonConstants;
 import org.apache.dubbo.common.io.StreamUtils;
 import org.apache.dubbo.common.utils.StringUtils;
 import org.apache.dubbo.remoting.http12.exception.DecodeException;
@@ -81,7 +82,7 @@ public static List<HttpCookie> decodeCookies(String value) {
         return cookies;
     }
 
-    public static String getCharsetFromContentType(String contentType) {
+    public static String parseCharset(String contentType) {
         String charset = null;
         if (contentType == null) {
             charset = StringUtils.EMPTY_STRING;
@@ -91,7 +92,12 @@ public static String getCharsetFromContentType(String contentType) {
                 charset = StringUtils.EMPTY_STRING;
             } else {
                 charset = contentType.substring(index + CHARSET_PREFIX.length()).trim();
-                charset = charset.split(";")[0];
+                int splits = charset.indexOf(CommonConstants.SEMICOLON_SEPARATOR);
+                if (splits == -1) {
+                    return charset;
+                } else {
+                    return charset.substring(0, splits).trim();
+                }
             }
         }
         return charset;

dubbo-remoting/dubbo-remoting-http12/src/main/java/org/apache/dubbo/remoting/http12/message/DefaultHttpRequest.java

@@ -243,7 +243,7 @@ public String charset() {
         String charset = this.charset;
         if (charset == null) {
             String contentType = contentType();
-            charset = HttpUtils.getCharsetFromContentType(contentType);
+            charset = HttpUtils.parseCharset(contentType);
             this.charset = charset;
         }
         return charset.isEmpty() ? null : charset;

dubbo-remoting/dubbo-remoting-http12/src/main/java/org/apache/dubbo/remoting/http12/message/DefaultHttpResponse.java

@@ -166,7 +166,7 @@ public String charset() {
         String charset = this.charset;
         if (charset == null) {
             String contentType = contentType();
-            charset = HttpUtils.getCharsetFromContentType(contentType);
+            charset = HttpUtils.parseCharset(contentType);
             this.charset = charset;
         }
         return charset.isEmpty() ? null : charset;

dubbo-remoting/dubbo-remoting-http12/src/test/java/org/apache/dubbo/remoting/http12/message/codec/HttpUtilsTest.java

@@ -24,15 +24,14 @@
 public class HttpUtilsTest {
 
     @Test
-    void testGetCharsetFromContentType() {
-        String charset = HttpUtils.getCharsetFromContentType("text/html;charset=utf-8");
+    void testParseCharset() {
+        String charset = HttpUtils.parseCharset("text/html;charset=utf-8");
         Assertions.assertEquals("utf-8", charset);
-        charset = HttpUtils.getCharsetFromContentType("text/html");
+        charset = HttpUtils.parseCharset("text/html");
         Assertions.assertEquals("", charset);
-        charset = HttpUtils.getCharsetFromContentType("application/json;charset=utf-8; boundary=__X_PAW_BOUNDARY__");
+        charset = HttpUtils.parseCharset("application/json;charset=utf-8; boundary=__X_PAW_BOUNDARY__");
         Assertions.assertEquals("utf-8", charset);
-        charset =
-                HttpUtils.getCharsetFromContentType("multipart/form-data; charset=utf-8; boundary=__X_PAW_BOUNDARY__");
+        charset = HttpUtils.parseCharset("multipart/form-data; charset=utf-8; boundary=__X_PAW_BOUNDARY__");
         Assertions.assertEquals("utf-8", charset);
     }
 }