springEL编程式使用 (原创)

java示例代码

SpringELTest.java

package com.tingcream.pagehelper.extend;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.junit.Test;
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.ParserContext;
import org.springframework.expression.spel.standard.SpelExpressionParser;

import com.tingcream.pagehelper.model.User;

public class SpringELTest {
	
	@Test
	public void test1() {
		 try {
		     ExpressionParser parser = new SpelExpressionParser();
			 Expression exp = parser.parseExpression("'Hello World'.length()"); 
			 int length=exp.getValue(Integer.class);
			 System.out.println(length);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	@Test
	public void    test2() {
		try {
			 User user =new User();
			  user.setAddr("北京");
			  user.setUsername("张三");
			  user.setPhone("1356666666");
			 ExpressionParser parser = new SpelExpressionParser();
			
			 Expression exp = parser.parseExpression("username");
			 System.out.println(exp.getValue(user,String.class));;
			 
			 exp.setValue(user, "张三2");
			 System.out.println(exp.getValue(user,String.class));;
			
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	@Test
	public void test3() {
		List list =new ArrayList();
		list.add("aaa");
		list.add("bbbb");
		list.add("ccccc");
		 ExpressionParser parser = new SpelExpressionParser();
		Integer s= parser.parseExpression("[0].length()").getValue(list,Integer.class);
		System.out.println(s);
	}
	@Test
	public void test4() {
		try {
			Map map =new HashMap();
			map.put("name", "张小明");
			map.put("age", 22);
			map.put("city", "广州");
			 ExpressionParser parser = new SpelExpressionParser();
			  Expression exp= parser.parseExpression("#{['name']}", ParserContext.TEMPLATE_EXPRESSION);
			  String name = exp.getValue(map,String.class);
			  System.out.println(name);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	 
}

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spring EL 官方文档：

https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#expressions