Drools 7规则文件中如何检查插入的String类型事实内容？

Hey there! Sounds like you're already up and running with inserting String facts into Drools 7 and executing rules—great start! To modify your rule to check if the String contains the substring et (instead of matching an exact value), you can use either Drools' built-in syntax or directly call Java's String.contains() method in your DRL condition.

Here's a complete example of what your DRL rule would look like:

package com.your.package.name;

rule "Detect Substring 'et' in String Fact"
    when
        // Option 1: Use Drools' built-in 'contains' operator
        $inputStr: String(this contains "et")
        
        // Option 2: Call Java's native String.contains() method (equivalent to Option 1)
        // $inputStr: String(contains("et"))
    then
        System.out.println("Does contain 'et'");
end

Let's break this down: #

• Matching the String Fact: The $inputStr: String(...) part tells Drools to look for any inserted fact of type String.
• Substring Check:
  • this contains "et" is Drools' native way to check if the String (referenced by this) includes the substring "et".
  • Alternatively, contains("et") directly invokes Java's String.contains(CharSequence) method—this works because Drools allows calling valid Java methods on objects in rule conditions.

Testing this rule: #

• If you insert a String fact with value like "test" or "eternal", the rule will trigger and print "Does contain 'et'".
• If you insert your original value "asdf", the rule won't fire since "asdf" doesn't include the substring "et".

Just make sure you're inserting a pure String fact (not wrapped in another object) and that there are no conflicting rules that might interfere with this check. That's all there is to it!

内容的提问来源于stack exchange，提问作者mikeb