JsonPath全英文文档学习

1、文档地址

github地址

2、引入依赖

<dependency><groupId>com.jayway.jsonpath</groupId><artifactId>json-path</artifactId><version>2.9.0</version>
</dependency>

全英文文档可借助谷歌浏览器翻译

但谷歌浏览器无法翻译

3、浏览翻译问题修复

因为谷歌翻译下架了。所以下载一个别的强大的浏览器edge浏览器

下载安装沉浸式翻译插件

翻译成功

can you speck chinese ，yes

4、文档学习

4.1、Operator

4.2、Functions

4.3、Filter 运算符

4.4、json示例

{"store": {"book": [{"category": "reference","author": "Nigel Rees","title": "Sayings of the Century","price": 8.95},{"category": "fiction","author": "Evelyn Waugh","title": "Sword of Honour","price": 12.99},{"category": "fiction","author": "Herman Melville","title": "Moby Dick","isbn": "0-553-21311-3","price": 8.99},{"category": "fiction","author": "J. R. R. Tolkien","title": "The Lord of the Rings","isbn": "0-395-19395-8","price": 22.99}],"bicycle": {"color": "red","price": 19.95}},"expensive": 10
}

5、实战

5.1、获取json数组下的多个元素

$.父级.key[*].元素

 List<String> authorList = JsonPath.read(jsonStr, "$.store.book[*].author");List<String> categoryList = JsonPath.read(jsonStr, "$.store.book[*].category");log.info("authorList:{}",authorList);log.info("categoryList:{}",categoryList);

必须填写父级一层一层找下去，否则爆异常

5.2、获取json数组下的多个元素（循环遍历时无元素自动占位）

比如取book下的isbn。第0，第1位下无此元素。则第2,3位自动占位到list的0,1位

List<String> isbnList = JsonPath.read(jsonStr, "$.store.book[*].isbn");
log.info("isbnList:{}",isbnList);

###如果多次使用JsonPath.read()需要先解析json。拿到object后。在调用.read()方法

        // 初始化一次Object document = Configuration.defaultConfiguration().jsonProvider().parse(jsonStr);List<String> authorList = JsonPath.read(document, "$.store.book[*].author");List<String> categoryList = JsonPath.read(document, "$.store.book[*].category");List<String> isbnList = JsonPath.read(document, "$.store.book[*].isbn");log.info("authorList:{}",authorList);log.info("categoryList:{}",categoryList);log.info("isbnList:{}",isbnList);

5.3、获取json数组下的单个元素

直接取jsonArray下元素：

        String author0 = JsonPath.read(document, "$.store.book[0].author");log.info("author0：{}",author0);

动态遍历获取jsonArray下元素

 if (!CollectionUtils.isEmpty(authorList)) {for (int i = 0; i < authorList.size(); i++) {// 拼接动态jsonPathString jsonPathStrPrefix = "$.store.book[";String jsonPathStrSuffix = "].author";String author = JsonPath.read(document, jsonPathStrPrefix.concat(String.valueOf(i)).concat(jsonPathStrSuffix));System.out.println(author);}}

5.4、获取json数组下存在某个元素的其他元素集合

ReadContext ctx = JsonPath.parse(jsonStr);List<String> authorsOfBooksWithISBN = ctx.read("$.store.book[?(@.isbn)].author");System.out.println("authorsOfBooksWithISBN:"+authorsOfBooksWithISBN);

5.5、根据json数组重组List<Map<String,Object>>

获取价格>10的 books数组

 List<Map<String, Object>> expensiveBooks = JsonPath.using(Configuration.defaultConfiguration()).parse(jsonStr).read("$.store.book[?(@.price > 10)]", List.class);

或者

List<Map<String, Object>> books =  JsonPath.parse(jsonStr).read("$.store.book[?(@.price > 10)]");

5.6、时间戳转date

  String json = "{\"date_as_long\" : 1411455611975}";Date date = JsonPath.parse(json).read("$['date_as_long']", Date.class);System.out.println("date:"+date);

5.7、json数组转对象

Book

package com.ljs.gulimall.product.entity;import lombok.Data;@Data
public class Book {private String category;private String author;private String title;private Double price;private String isbn;
}

Book book = JsonPath.parse(jsonStr).read("$.store.book[0]", Book.class);
System.out.println("book:"+book);

5.8、筛选器获取List<Map<String,Object>>

获取json数组book下category元素是fiction且价格小于10的集合

  Filter cheapFictionFilter = filter(where("category").is("fiction").and("price").lte(10D));List<Map<String, Object>> books =parse(jsonStr).read("$.store.book[?]", cheapFictionFilter);System.out.println("books:"+books);

5.9、筛选器根据字段是否存在获取List<Map<String,Object>>

 Filter fooOrBar = filter(where("isbn").exists(true)).or(where("category").exists(true));Filter fooAndBar = filter(where("isbn").exists(true)).and(where("foo").exists(true));List<Map<String, Object>> bookAnd =parse(jsonStr).read("$.store.book[?]", fooAndBar);System.out.println("bookAnd:"+bookAnd);List<Map<String, Object>> bookOr =parse(jsonStr).read("$.store.book[?]", fooOrBar);System.out.println("bookOr:"+bookOr);

5.10、根据json数组三参数获取List< Object>

   Predicate booksWithISBN = new Predicate() {@Overridepublic boolean apply(PredicateContext ctx) {return ctx.item(Map.class).containsKey("isbn");}};List<Object> books =parse(jsonStr).read("$.store.book[?].isbn", List.class, booksWithISBN);System.out.println("books:"+books);

5.11、set元素值

String newJson = JsonPath.parse(jsonStr).set("$['store']['book'][0]['author']", "ljs").jsonString();
System.out.println("jsonStr:"+newJson);

5.12、避免空路径异常（DEFAULT_PATH_LEAF_TO_NULL）

 Configuration configuration = Configuration.defaultConfiguration();//Works fine
String gender0 = JsonPath.using(configuration).parse(str).read("$[0]['gender']");
//PathNotFoundException thrown
String gender1 = JsonPath.using(configuration).parse(str).read("$[1]['gender']");System.out.println("gender0:"+gender0);
System.out.println("gender1:"+gender1);

    Configuration conf2 = configuration.addOptions(Option.DEFAULT_PATH_LEAF_TO_NULL);//Works fine
String gender0 = JsonPath.using(conf2).parse(str).read("$[0]['gender']");
//Works fine (null is returned)
String gender1 = JsonPath.using(conf2).parse(str).read("$[1]['gender']");
System.out.println("gender0:"+gender0);
System.out.println("gender1:"+gender1);

5.13、返回列表（ALWAYS_RETURN_LIST）

 Configuration configuration = Configuration.defaultConfiguration();
List<String> genders0 = JsonPath.using(configuration).parse(str).read("$[0]['gender']");
System.out.println("genders0:"+genders0);

Configuration configuration = Configuration.defaultConfiguration();
Configuration conf2 = configuration.addOptions(Option.ALWAYS_RETURN_LIST);//Works fine
List<String> genders0 = JsonPath.using(conf2).parse(str).read("$[0]['gender']");
System.out.println("genders0:"+genders0);

5.14、不从路径评估传播异常（SUPPRESS_EXCEPTIONS）

如果存在选项 ALWAYS_RETURN_LIST，将返回一个空列表

如果选项 ALWAYS_RETURN_LIST 不存在，则返回 null

5.15、从路径评估抛出异常设置（REQUIRE_PROPERTIES）

Configuration configuration = Configuration.defaultConfiguration();
//Works fine
List<String> genders = JsonPath.using(configuration).parse(str).read("$[*]['gender']");
System.out.println("genders:"+genders);

Configuration configuration = Configuration.defaultConfiguration();
Configuration conf2 = configuration.addOptions(Option.REQUIRE_PROPERTIES);//PathNotFoundException thrown
List<String> genders = JsonPath.using(conf2).parse(str).read("$[*]['gender']");
System.out.println("genders:"+genders);