算法表达式

(1)

ExpressionParser parser = new SpelExpressionParser();

(2)

StandardEvaluationContext context = new StandardEvaluationContext();
// evals to "Hello World"

(3)

String helloWorld = (String) parser.parseExpression("'Hello World'").getValue();

(4)

double avogadrosNumber  = (Double) parser.parseExpression("6.0221415E+23").getValue();

(5)

int maxValue = (Integer) parser.parseExpression("0x7FFFFFFF").getValue();

(6)

boolean trueValue = (Boolean) parser.parseExpression("true").getValue();

(7)

Object nullValue = parser.parseExpression("null").getValue();

(8)

int year = (Integer) parser.parseExpression("Birthdate.Year + 1900").getValue(context);

(9)

boolean trueValue = parser.parseExpression("2 == 2").getValue(Boolean.class);

(10)

boolean trueValue = parser.parseExpression("'black' < 'block'").getValue(Boolean.class);

(11)

boolean falseValue = parser.parseExpression("'xyz' instanceof T(int)").getValue(Boolean.class);

(12)

boolean trueValue = parser.parseExpression("'5.00' matches '^-?\\d+(\\.\\d{2})?$'").getValue(Boolean.class);