[乐意黎原创] glassfish里抛出Note: string:///XXX_jsp.java from uses unchecked or unsafe operations.

glassfish里抛出如下错误：

org.apache.jasper.JasperException: PWC6033: Unable to compile class for JSP

PWC6199: Generated servlet error:
string:///XXXX_jsp.java:169: constant string too long

PWC6199: Generated servlet error:
Note: string:///XXXX_jsp.java from  uses unchecked or unsafe operations.

折腾了好久，始终找不到原因。
最后，经老大指点，并实际测试。终于发现原因 
是由于glassfish里 把genStrAsCharArray 项设为 true 导致的。
解决办法：

具体为：
把 $GLASSFISH_HOME/domains/domain1/config/default-web.xml 里的 
<param-name>genStrAsCharArray</param-name>
<param-value>true</param-value>

修改为：

<param-name>genStrAsCharArray</param-name>
<param-value>false</param-value>

  
  
  
  

   
   
   
   
 
    
 
     
genStrAsCharArray
 
     
false
 
     
If set to true, generates text strings as char arrays, which improves performance in some cases.
 
    
 
   
  
  
  
  
The default-web.xml file defines features such as filters and security constraints that apply to all web applications.  The parameter, development=true, (the default value for developer profile) enables changes made to JSPTM – code to be  instantly visible to the clients. However, there is a cost associated with this. To avoid the cost of checking whether the JSP code  has been modified and hence its recompilation, the first parameter, development=false, can be used to set development to false since this scenario is unlikely in a production system.  This check affects application scalability when multiple users request the same JSP class. The second parameter, genStrAsCharArray=true, changes the way the JSPs are generated by generating char arrays for every static strings in the JSP class like for example, the HTML tags.  By default, the JSPcode  writer must call the toCharArray() on every String on every invocation of the JSPclass.
Settings in  default-web.xml.  ($GLASSFISH_HOME/domains/domain1/config/default-web.xml)
<init-param>
<param-name>development</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>genStrAsCharArray</param-name>
<param-value>true</param-value> #->  此处上面应该修改为false </init-param>
The more  configuration optimization can be done using the document from SUN you can download it 


With this setting all String values are declared as static char[] as follows:
static char[] _char_array_1 = "someString".toCharArray();
and used as follows:
out.write(_char_array_1);
instead of being used as follows:
out.write("someString");
This has two clear benefits:
  
  
  
  

   
   
   
   
A char[] has less memory overhead than String.
   
   
   
   
The toCharArray() doesn't need to be (implicitly) called on every out.write(string) anymore.
  
  
  
  
Sounds like microoptimization, but those little bits counts a lot in a heavily visited website.
This setting is by the way not JBoss AS specific. It's Jasper specific, the JSP compiler of Apache Tomcat which is also used in under each JBoss AS and Sun Glassfish.
参考网址:  http://docs.oracle.com/cd/E19879-01/820-4343/abedw/index.htmlhttp://www.binbert.com/blog/2010/04/glassfish-performance-tunning/

作者： 乐意黎，原创。禁止转载
原文地址： http://blog.csdn.net/aerchi/article/details/45394231