OGNL使用例子

导入相关的jar包

		<dependency>
			<groupId>ognl</groupId>
			<artifactId>ognl</artifactId>
			<version>3.3.4</version>
		</dependency>

使用例子代码

package com.lomi.ognl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONUtil;
import com.lomi.entity.Goods;
import com.lomi.entity.out.GoodsOut;
import ognl.Ognl;
import ognl.OgnlContext;
import ognl.OgnlException;
import org.junit.Test;

import java.util.Arrays;
import java.util.Map;

/**
 *
 *  ognl 对象图导航语言，可以通过表达式从Java对象，json ，map中获取到值
 *  如果表达式取到不存在的属性值会报错
 *
 * @author ZHANGYUKUN
 */
public class OGNLTest {


    public static String  staticValue = "静态属性";
    public static String getStaticValue() {
        return staticValue;
    }

    private String name = "张三丰";
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

    /**
     * 使用 # 是区_value里面的值,没有#取的root里面的值
     *
     * @throws OgnlException
     */
    @Test
    public void t1() throws OgnlException {
        //this就是root节点
        OgnlContext context = (OgnlContext) Ognl.createDefaultContext(this);
        context.put("goods",Goods.randomGoods());

        Object ognlName1 = Ognl.parseExpression("#goods.name");
        Object ognlName2 = Ognl.parseExpression("name");

        Object name1 = Ognl.getValue( ognlName1, context, context.getRoot());
        Object name2 = Ognl.getValue( ognlName2, context, context.getRoot());

        System.out.println("获取到的name1："  + name1);
        System.out.println("获取到的name2："  + name2);

    }

    /**
     *   context 里面的值的时候，可以任意传入 context ，context只是一个map 而已，不一定非要用  OGNLContext的 _value 属性
     * @throws OgnlException
     */
    @Test
    public void t2() throws OgnlException {
        Map<String, Object> objectMap = BeanUtil.beanToMap(Goods.randomGoods());

        OgnlContext context = (OgnlContext) Ognl.createDefaultContext( objectMap );


        //并且这个 context 不一定需要是 OgnlContext里面的 _value
        Object ognl = Ognl.parseExpression("#id");
        Object value2 = Ognl.getValue(ognl, objectMap  ,context.getRoot());
        System.out.println(value2);
    }


    /**
     *  如果是Java对象 取不存在的属性会报错
     * @throws OgnlException
     */
    @Test
    public void t3() throws OgnlException {
        Map<String, Object> objectMap = BeanUtil.beanToMap(Goods.randomGoods());

        OgnlContext context = (OgnlContext) Ognl.createDefaultContext( objectMap );


        //并且这个 context 不一定需要是 OgnlContext里面的 _value
        Object ognl = Ognl.parseExpression("#id.name");
        Object value2 = Ognl.getValue(ognl, objectMap  ,context.getRoot());
        System.out.println(value2);
    }


    /**
     *  map取不到不会报错，但是继续取下级就会报错
     * @throws OgnlException
     */
    @Test
    public void t4() throws OgnlException {
        Map<String, Object> objectMap = BeanUtil.beanToMap(Goods.randomGoods());

        OgnlContext context = (OgnlContext) Ognl.createDefaultContext( objectMap );


        //并且这个 context 不一定需要是 OgnlContext里面的 _value
        Object ognl = Ognl.parseExpression("#name2");
        Object value2 = Ognl.getValue(ognl, objectMap  ,context.getRoot());
        System.out.println(value2);
    }



    /**
     * 获取数组的值
     * @throws OgnlException
     */
    @Test
    public void t5() throws OgnlException {
        Map<String, Object> objectMap = BeanUtil.beanToMap(Goods.randomGoods());
        objectMap.put("list", Arrays.asList(  Goods.randomGoods(),Goods.randomGoods(),Goods.randomGoods() ));

        System.out.println(JSONUtil.formatJsonStr( JSONUtil.toJsonStr(  objectMap ) ));

        OgnlContext context = (OgnlContext) Ognl.createDefaultContext( objectMap );


        //并且这个 context 不一定需要是 OgnlContext里面的 _value
        Object ognl = Ognl.parseExpression("#list[0].name");
        Object value1 = Ognl.getValue(ognl, objectMap  ,context.getRoot());
        System.out.println(value1);


        //投影语法，取到把 集合里面的某个属性取出来构成一个集合
        Object ognl2 = Ognl.parseExpression("#list.{name}");
        Object value2 = Ognl.getValue(ognl2, objectMap  ,context.getRoot());
        System.out.println(value2);


        //筛选
        Object ognl3 = Ognl.parseExpression("#list.{? stock>2000}");
        Object value3 = Ognl.getValue(ognl3, objectMap  ,context.getRoot());
        System.out.println(value3);


        //筛选以后取第一个
        Object ognl4 = Ognl.parseExpression("#list.{^ stock>2000}");
        Object value4 = Ognl.getValue(ognl4, objectMap  ,context.getRoot());
        System.out.println(value4);

        //筛选以后取最后一个
        Object ognl5 = Ognl.parseExpression("#list.{$ stock>2000}");
        Object value5 = Ognl.getValue(ognl5, objectMap  ,context.getRoot());
        System.out.println(value5);

    }


    /**获取静态值
     * @throws OgnlException
     */
    @Test
    public void t6() throws OgnlException {
        //this就是root节点
        OgnlContext context = (OgnlContext) Ognl.createDefaultContext(this);

        Object ognlName1 = Ognl.parseExpression("@com.lomi.ognl.OGNLTest@staticValue");
        Object name1 = Ognl.getValue( ognlName1, context, context.getRoot());

        System.out.println("获取到的name1："  + name1);
    }

    /**调用方法
     * @throws OgnlException
     */
    @Test
    public void t7() throws OgnlException {
        //this就是root节点
        OgnlContext context = (OgnlContext) Ognl.createDefaultContext(this);

        //调用普通方法
        Object ognlName1 = Ognl.parseExpression("getName()");
        Object name1 = Ognl.getValue( ognlName1, context, context.getRoot());

        //调用有参数的方法
        Object ognlName2 = Ognl.parseExpression("setName( '张三' )");
        Object name2 = Ognl.getValue( ognlName2, context, context.getRoot());


        Object name3 = Ognl.getValue( ognlName1, context, context.getRoot());

        //静态方法
        Object name4 = Ognl.getValue( "@com.lomi.ognl.OGNLTest@getStaticValue()", context, context.getRoot());

        System.out.println("获取到的name1："  + name1);
        System.out.println("获取到的name2："  + name2);
        System.out.println("获取到的name3："  + name3);
        System.out.println("获取到的name4："  + name4);
    }


    /**
     * 逗号表达式，每个都执行，获取的值是最后一个
     *
     * @throws OgnlException
     */
    @Test
    public void t8() throws OgnlException {
        //this就是root节点
        OgnlContext context = (OgnlContext) Ognl.createDefaultContext(this);

        //调用普通方法
        Object ognlName1 = Ognl.parseExpression("getName(),@com.lomi.ognl.OGNLTest@getStaticValue()");
        Object ognlName2 = Ognl.parseExpression("@com.lomi.ognl.OGNLTest@getStaticValue(),getName()");
        Object name1 = Ognl.getValue( ognlName1, context, context.getRoot());
        Object name2 = Ognl.getValue( ognlName2, context, context.getRoot());

        System.out.println("获取到的name1："  + name1);
        System.out.println("获取到的name2："  + name2);
    }




}