规则引擎--QLExpress：ql的一些使用场景

QLExpress的各种使用场景, 可参考：https://toscode.gitee.com/cuibo119/QLExpress

表达式中使用对象

 @Test
 public void testABC() throws Exception {
    
    
      String express = "object.amount * 2 + object.volume";
      ExpressRunner runner = new ExpressRunner(false, true);
      DefaultContext<String, Object> context = new DefaultContext<>();
      ObjectBean tempObject = new ObjectBean(100, 60);
      context.put("object", tempObject);
      Object result = runner.execute(express, context, null, false, true);
      System.out.println(result);
      Assert.assertNotSame("数据执行错误", 200, result);
  }

最后的语法树:
1:   STAT_BLOCK:STAT_BLOCK                                                         	STAT_BLOCK
2:      STAT_SEMICOLON:STAT_SEMICOLON	STAT_SEMICOLON
3:         +:+	+
4:            *:*	*
5:               .:FIELD_CALL	FIELD_CALL
6:                  object:ID	ID
6:                  amount:CONST_STRING	CONST
5:               2:CONST_INTEGER	CONST
4:            .:FIELD_CALL	FIELD_CALL
5:               object:ID	ID
5:               volume:CONST_STRING	CONST


1:LoadAttr:object
2:OP : FieldCall:amount OPNUMBER[1]
3:LoadData 2
4:OP : * OPNUMBER[2]
5:LoadAttr:object
6:OP : FieldCall:volume OPNUMBER[1]
7:OP : + OPNUMBER[2]

260

自定义运算符

/**
 * 定义连加的操作符
 */
public class AddNOperator extends Operator {
    
    
    @Override
    public Object executeInner(Object[] list) {
    
    
        int r = 0;
        for (Object item : list) {
    
    
            r = r + (Integer)item;
        }
        return r;
    }
}

使用

@Test
public void testAddNByFunction() throws Exception {
    
    
     //定义表达式，相当于1+2+3+4
     String exp = "addN(1,2,3,4)";
     ExpressRunner runner = new ExpressRunner();
     //定义方法addN，其实现为AddNOperator
     runner.addFunction("addN", new AddNOperator());
     int r = (Integer)runner.execute(exp, null, null, false, false);
     System.out.println(r);
     Assert.assertEquals("操作符执行错误", 10, r);
 }

脚本中自定义函数

@Test
public void testFunc() throws Exception {
    
    
    ExpressRunner runner = new ExpressRunner();
    DefaultContext<String, Object> context = new DefaultContext<String, Object>();
    context.put("a", 3);
    context.put("b", 1);
    String express = "function add(int a,int b){" +
            "return a+b;" +
            "};" +
            "return add(a,b);";
    Object funcResult = runner.execute(express, context, null, false, false);
    System.out.println("add(a,b)=" + funcResult);
}

扩展操作符：替换if,then,else等关键字

@Test
public void testReplaceIfThenElse() throws Exception {
    
    
    ExpressRunner runner = new ExpressRunner();
    DefaultContext<String, Object> context = new DefaultContext<String, Object>();
    runner.addOperatorWithAlias("如果", "if", null);
    runner.addOperatorWithAlias("则", "then", null);
    runner.addOperatorWithAlias("否则", "else", null);
    context.put("语文", 100);
    context.put("数学", 100);
    context.put("英语", 100);
    String express = "如果 ((语文+数学+英语)>270) 则 return 1;否则 return 0;";
    Object result = runner.execute(express, context, null, true, false);
    System.out.println(result);
}

使用类方法

public class AvgClass {
    
    
    public AvgClass() {
    
    
    }

    public double avg(double a, double b){
    
    
        return 0.5 * (a + b);
    }
}

@Test
public void testMethod() throws Exception {
    
    
    ExpressRunner runner = new ExpressRunner();
    DefaultContext<String, Object> context = new DefaultContext<String, Object>();
    context.put("a", 2.5);
    context.put("b", 3.5);

    runner.addFunctionOfClassMethod("取平均值", AvgClass.class.getName(), "avg",
            new String[]{
    
    "double", "double"}, null);

    String exp = "return 取平均值(a, b);";
    Object result = runner.execute(exp, context, null, false, false);
    System.out.println(result); // 3.0
}