Java根据表达式获取对象中的值及设置值的例子

//------------------------------------------------- 考试信息列表
ExamInfoDict examInfoDict = new ExamInfoDict();
examInfoDict.setId(1);
examInfoDict.setExamType(0);
examInfoDict.setAnswerIs(1);
ExamInfoDict examInfoDict1 = new ExamInfoDict();
examInfoDict1.setId(2);
examInfoDict1.setExamType(0);
examInfoDict1.setAnswerIs(0);
ExamInfoDict examInfoDict2 = new ExamInfoDict();
examInfoDict2.setId(3);
examInfoDict2.setExamType(1);
examInfoDict2.setAnswerIs(0);
List<ExamInfoDict> examInfoDicts = new ArrayList<ExamInfoDict>();
examInfoDicts.add(examInfoDict);
examInfoDicts.add(examInfoDict1);
examInfoDicts.add(examInfoDict2);
//------------------------------------------------- 用户信息
UserInfoDict userInfoDict = new UserInfoDict();
userInfoDict.setId(1);
userInfoDict.setPhotoPath("yx.mm.com");
userInfoDict.setRealName("张三");
userInfoDict.setExamInfoDict(examInfoDicts);
Map<String, Object> tempMap = new HashMap<String, Object>();
tempMap.put("userInfo", userInfoDict);
tempMap.put("flag", 1);
下面，我们使用BeanPath获取这个Map下此用户第一门考试的ID：
BeanPath resolver = new BeanPath("userInfo.examInfoDict[0].id");
Object result = resolver.get(tempMap);//ID为1
只需两句（甚至一句）即可完成复杂Bean中各层次对象的获取。

  		Map<String, Object> map = new HashMap<>();
        map.put("name", "张三");
        map.put("age", 18);
        Map<String, Object> score = new HashMap<>();
        score.put("math", 100);
        score.put("english", 99);
        List<String> likeFood = new ArrayList<>();
        likeFood.add("apple");
        likeFood.add("banana");
        map.put("score", score);
        map.put("likeFood", likeFood);
        BeanPath matchScorePath = BeanPath.create("score.math");
        BeanPath likeFoodPath = BeanPath.create("likeFood[1]");
        // 输出结果
        System.out.println("matchScore"+matchScorePath.get(map));
        System.out.println("likeFood"+likeFoodPath.get(map));
        // 设置值
        matchScorePath.set(map, 90);
        likeFoodPath.set(map, "orange");
        System.out.println(((Map<String,Object>)map.get("score")).get("math"));
        System.out.println(((List)map.get("likeFood")).get(1));
        // 设置不存在的值
        BeanPath likeFoodPath1 = BeanPath.create("likeFood[2]");
        likeFoodPath1.set(map, "pear");
        System.out.println(((List)map.get("likeFood")).get(2));