fix sonar rule check violations

src/main/java/com/alibaba/druid/mock/MockStatement.java

@@ -36,7 +36,7 @@ public class MockStatement extends StatementBase implements MockStatementBase, S
         }
     }
 
-    protected void checkOpen() throws SQLException, MockConnectionClosedException {
+    protected void checkOpen() throws SQLException {
         if (closed) {
             throw new SQLException();
         }

src/main/java/com/alibaba/druid/sql/parser/Lexer.java

@@ -808,7 +808,7 @@ public class Lexer {
         token = Token.LITERAL_HEX;
     }
 
-    public String hexString() throws NumberFormatException {
+    public String hexString() {
         return new String(buf, np, sp);
     }
 
@@ -876,7 +876,7 @@ public class Lexer {
     }
 
     // QS_TODO negative number is invisible for lexer
-    public Number integerValue() throws NumberFormatException {
+    public Number integerValue() {
         long result = 0;
         boolean negative = false;
         int i = np, max = np + sp;

src/main/java/com/alibaba/druid/support/spring/stat/BeanTypeAutoProxyCreator.java

@@ -52,7 +52,7 @@ public class BeanTypeAutoProxyCreator extends AbstractAutoProxyCreator implement
         this.targetBeanType = targetClass;
     }
 
-    public void setApplicationContext(ApplicationContext context) throws BeansException {
+    public void setApplicationContext(ApplicationContext context) {
         this.context = context;
     }
 

src/main/java/com/alibaba/druid/util/jdbc/StatementBase.java

@@ -58,7 +58,7 @@ public abstract class StatementBase implements Statement {
         this.connection = connection;
     }
 
-    protected void checkOpen() throws SQLException, MockConnectionClosedException {
+    protected void checkOpen() throws SQLException {
         if (closed) {
             throw new SQLException();
         }