日志增加string字符串格式化标签包括转义，截取，null字符处理

src/main/java/com/nis/util/StringUtils.java

@@ -472,4 +472,32 @@ public class StringUtils extends org.apache.commons.lang3.StringUtils {
 		return true;
 	}
 
+	public static String stringFormat(String str,int len){
+		if(str.trim().equals("null")||str==null){
+			return "";
+		}else{
+			
+		
+		str = Encodes.escapeHtml(str);
+		if(len!=-1){
+			try {
+				StringBuilder sb = new StringBuilder();
+				int currentLength = 0;
+				for (char c : str.toCharArray()) {
+					currentLength += String.valueOf(c).getBytes("GBK").length;
+					if (currentLength <= len - 3) {
+						sb.append(c);
+					} else {
+						sb.append("...");
+						break;
+					}
+				}
+				return sb.toString();
+			} catch (UnsupportedEncodingException e) {
+				e.printStackTrace();
+			}
+		}
+		return str;
+	}
+	}
 }

src/main/webapp/WEB-INF/tlds/fns.tld

@@ -354,6 +354,12 @@
     <example>${fns:getPermissionByNo(str1,list)}</example>  
   </function>
   
-  
+    <function>
+    <description>字符串转义及截取,null转""</description>
+    <name>stringFormat</name>
+    <function-class>com.nis.util.StringUtils</function-class>
+    <function-signature>java.lang.String stringFormat(java.lang.String, int)</function-signature>
+    <example>${fns:stringFormat(str,len)}</example>
+  </function>
   
 </taglib>