org.springframework.expression.spel.SpelEvaluationException -在null上找不到属性或字段

import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.StandardEvaluationContext;

public class SpelExample {
    public static void main(String[] args) {
        // 创建表达式解析器
        ExpressionParser parser = new SpelExpressionParser();

        // 创建评估上下文
        StandardEvaluationContext context = new StandardEvaluationContext();

        // 设置对象属性
        MyObject myObject = new MyObject();
        myObject.setName("John");
        context.setVariable("obj", myObject);

        try {
            // 评估表达式
            String expression = "#obj.name";
            String result = parser.parseExpression(expression).getValue(context, String.class);
            System.out.println("Result: " + result);
        } catch (org.springframework.expression.spel.SpelEvaluationException ex) {
            System.out.println("Error: " + ex.getMessage());
        }
    }
}

class MyObject {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}