在日常工作中，会接到用户提出一张订单，修改后需要记录每次修改的信息，然后需要查看修改前后的差异信息这样的需求。要实现这样的功能方式有很多。下面介绍下JSONassert的简单使用，也方便自己后续使用查看。

JSONassert GitHub地址：https://github.com/skyscreamer/JSONassert

1、准备

Maven依赖：

<dependency>
    <groupId>org.skyscreamer</groupId>
    <artifactId>jsonassert</artifactId>
    <version>1.5.0</version>
    <scope>test</scope>
</dependency>

初始化数据：

private Grade getBeforeGrade(){
	Grade grade = new Grade();
	grade.setCode("A01");
	grade.setName("三年级1班");

	List<Student> students = Lists.newArrayList();
	students.add(new Student().setCode("001").setName("小A"));
	students.add(new Student().setCode("002").setName("小B"));
	grade.setStudents(students);
	return grade;
}

private Grade getAfterGrade(){
	Grade grade = new Grade();
	grade.setCode("A02");
	grade.setName("三年级2班");

	List<Student> students = Lists.newArrayList();
	students.add(new Student().setCode("001").setName("小A"));
	students.add(new Student().setCode("003").setName("小C"));
	grade.setStudents(students);
	return grade;
}

2、简单使用

CustomComparator customComparator = new CustomComparator(JSONCompareMode.NON_EXTENSIBLE);
try {
	JSONCompareResult result = JSONCompare.compareJSON(JSON.toJSONString(before), JSON.toJSONString(after), customComparator);
	result.getFieldFailures().forEach(fieldComparisonFailure -> {
		System.out.println(String.format("变更字段：%s，变更前值：%s，变更后值：%s",fieldComparisonFailure.getField(),fieldComparisonFailure.getExpected(),fieldComparisonFailure.getActual()));
	});
}catch (Exception e){
	e.printStackTrace();
}
输出结果：
变更字段：name，变更前值：小A，变更后值：小B

3、扩展功能

3.1、排除不需要对比的字段

CustomComparator customComparator = new CustomComparator(JSONCompareMode.NON_EXTENSIBLE,
                new Customization("name",(o1,o2)->true));
--------------------------------------------------------------
输出结果：
变更字段：code，变更前值：A01，变更后值：A02

如果JSON对象里面有集合，对比时也需要排除：

ArrayValueMatcher<Object> arrayValueMatcher = new ArrayValueMatcher(new CustomComparator(JSONCompareMode.NON_EXTENSIBLE,
                new Customization("students[*].code",(o1,o2)->true)));

CustomComparator customComparator = new CustomComparator(JSONCompareMode.NON_EXTENSIBLE,
	new Customization("name",(o1,o2)->true),
	new Customization("students",arrayValueMatcher));
------------------------------------------------------------
输出结果：
变更字段：code，变更前值：A01，变更后值：A02
变更字段：students[1].name，变更前值：小B，变更后值：小C