Github ：https://github.com/json-path/JsonPath

http://www.ibloger.net/article/2329.html

JSONPath Online Evaluator：http://jsonpath.com

JsonPath 是一种简单的方法来提取给定JSON文档的部分内容。 JsonPath有许多编程语言，如Javascript，Python和PHP，Java。JsonPath 提供的 json 解析非常强大，它提供了类似正则表达式的语法，基本上可以满足所有你想要获得的 json 内容.

JsonPath 表达式总是引用 JSON 结构，其方式与XPath表达式解析XML文档的方式类似。JsonPath中的 “根成员对象” 总是被引用为$，不管它是对象还是数组。

JsonPath 可以使用点表示法：$.store.book[0].title
或者括号表示法：$['store']['book'][0]['title']

操作符

操作符和描述

操作符	描述
`$`	查询根元素。这将开始所有路径表达式
`@`	使用过滤谓词来处理当前节点。即过滤当前节点。
`*`	通配符。任何可以使用名称和数字的地方都可以使用。
`..`	深层扫描。任何可以使用名称的地方都可以使用
`.<name>`	点，表示子节点。
`['<name>' (, '<name>')]`	括号表示子项。
`[<number> (, <number>)]`	数组索引或索引
`[start:end]`	数组切片操作。
`[?(<expression>)]`	过滤表达式。表达式的结果必须是一个 bool 值。

函数

函数可以在路径的末尾调用——函数的输入是路径表达式的输出。函数输出由函数本身决定。

函数	描述	输出
min()	提供数字数组的最小值	Double
max()	提供数字数组的最大值	Double
avg()	提供数字数组的平均值	Double
stddev()	提供数字数组的标准偏差值	Double
length()	提供数组的长度	Integer
sum()	提供数字数组的所有元素的和	Double

过滤器运算符

过滤器是用于筛选数组的逻辑表达式。一个典型的过滤器应该是 [?(@.age > 18)]，其中 @ 表示当前正在处理的项。可以使用逻辑运算符 && 和 || 创建更复杂的过滤器。字符串文字必须用单引号或双引号括起来 ([?(@.color == 'blue')] or [?(@.color == "blue")])。

操作符	描述
==	左边得值等于右边的值 ( 注意：数字 1 不等于字符串 '1' )
!=	不等于
<	小于
<=	小于等于
>	大于
>=	大于等于
=~	匹配正则表达式 [?(@.name =~ /foo.*?/i)]
in	左边 in 右边 [?(@.size in ['S', 'M'])]
nin	左边 not in 右边
subsetof	左边是右边的一个子字符串 [?(@.sizes subsetof ['S', 'M', 'L'])]
anyof	左边和右边相交 [?(@.sizes anyof ['M', 'L'])]
noneof	左边和右边不相交 [?(@.sizes noneof ['M', 'L'])]
size	（数组或字符串）长度
empty	（数组或字符串）为空

示例

示例 Json：

{"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
}

JsonPath 表达式示例：

JsonPath ( 点击链接测试 )	结果
$.store.book[*].author	获取 Json 中 store下book下的所有author值
$..author	获取 Json 中所有 author 的值。
$.store.*	获取 store 下所有东西（ book 和 bicycle ）
$.store..price	获取 store下以及所有子节点下的所有 price
$..book[2]	获取 book数组的第3个值
$..book[-2]	获取 book数组的倒数第二个值
$..book[0,1]	获取 book数组的第一、第二的值
$..book[:2]	获取 book数组从索引 0 (包括) 到索引 2 (不包括) 的所有值
$..book[1:2]	获取 book数组从索引 1 (包括) 到索引 2 (不包括) 的所有值
$..book[-2:]	获取 book数组从索引 -2 (包括) 到结尾的所有值
$..book[2:]	获取 book数组从索引 2 (包括) 到结尾的所有值
$..book[?(@.isbn)]	获取所有节点以及子节点中 book 数组包含 isbn 的所有值
$.store.book[?(@.price < 10)]	获取 store下 book 数组中 price < 10 的所有值
$..book[?(@.price <= $['expensive'])]	获取所有节点以及子节点下 book 数组中 price <= expensive 的所有值
$..book[?(@.author =~ /.*REES/i)]	获取所有匹配正则的 book （不区分大小写）
$..*	逐层列出 json 中的所有值，层级由外到内
$..book.length()	book 数组的长度

阅读文档

使用 JsonPath 的最简单的最直接的方法是通过静态读取 API。

String json = "...";List<String> authors = JsonPath.read(json, "$.store.book[*].author");

如果你只想读取一次，那么上面的代码就可以了。如果你还想读取其他路径，现在上面不是很好的方法，因为他每次获取都需要再解析整个文档。所以，我们可以先解析整个文档，再选择调用路径。

String json = "...";
Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);String author0 = JsonPath.read(document, "$.store.book[0].author");
String author1 = JsonPath.read(document, "$.store.book[1].author");

JsonPath还提供流畅的API。这也是最灵活的一个。

String json = "...";ReadContext ctx = JsonPath.parse(json);List<String> authorsOfBooksWithISBN = ctx.read("$.store.book[?(@.isbn)].author");List<Map<String, Object>> expensiveBooks = JsonPath.using(configuration).parse(json).read("$.store.book[?(@.price > 10)]", List.class);

何时返回

当在 java 中使用 JsonPath 时，重要的是要知道你在结果中期望什么类型。 JsonPath 将自动尝试将结果转换为调用者预期的类型。

//Will throw an java.lang.ClassCastException
List<String> list = JsonPath.parse(json).read("$.store.book[0].author")//Works fine
String author = JsonPath.parse(json).read("$.store.book[0].author")

当评估路径时，你需要理解路径确定的概念。路径是不确定的，它包含

.. ：深层扫描操作
?(<expression>) ：表达式
[<number>, <number> (, <number>)] ：多个数组索引

不确定的路径总是返回一个列表（由当前的JsonProvider表示）。

默认情况下，MappingProvider SPI提供了一个简单的对象映射器。这允许您指定所需的返回类型，MappingProvider将尝试执行映射。在下面的示例中，演示了Long和Date之间的映射。

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

如果您将JsonPath配置为使用JacksonMappingProvider或GsonMappingProvider，您甚至可以将JsonPath输出直接映射到POJO中。

Book book = JsonPath.parse(json).read("$.store.book[0]", Book.class);

要获取完整的泛型类型信息，请使用TypeRef。

TypeRef<List<String>> typeRef = new TypeRef<List<String>>() {};List<String> titles = JsonPath.parse(JSON_DOCUMENT).read("$.store.book[*].title", typeRef);

谓词

在JsonPath中创建过滤器谓词有三种不同的方法。

内联谓词

内联谓词是路径中定义的谓词。

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

你可以使用 && 和 || 结合多个谓词 [?(@.price < 10 && @.category == 'fiction')] , [?(@.category == 'reference' || @.price > 10)].

你也可以使用！否定一个谓词 [?(!(@.price < 10 && @.category == 'fiction'))].

过滤谓词

谓词可以使用Filter API构建，如下所示：

import static com.jayway.jsonpath.JsonPath.parse;
import static com.jayway.jsonpath.Criteria.where;
import static com.jayway.jsonpath.Filter.filter;
...
...Filter cheapFictionFilter = filter(where("category").is("fiction").and("price").lte(10D)
);List<Map<String, Object>> books =  parse(json).read("$.store.book[?]", cheapFictionFilter);

注意占位符？为路径中的过滤器。当提供多个过滤器时，它们按照占位符数量与提供的过滤器数量相匹配的顺序应用。您可以在一个过滤器操作[？，？]中指定多个谓词占位符，这两个谓词都必须匹配。

过滤器也可以与“OR”和“AND”

Filter fooOrBar = filter(where("foo").exists(true)).or(where("bar").exists(true)
);Filter fooAndBar = filter(where("foo").exists(true)).and(where("bar").exists(true)
);

自定义

第三个选择是实现你自己的谓词

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

Path vs Value

在 Goessner 实现中，JsonPath 可以返回 Path 或 Value。值是默认值，上面所有示例返回。如果你想让我们查询的元素的路径可以通过选项来实现。

Configuration conf = Configuration.builder().options(Option.AS_PATH_LIST).build();List<String> pathList = using(conf).parse(json).read("$..author");assertThat(pathList).containsExactly("$['store']['book'][0]['author']","$['store']['book'][1]['author']","$['store']['book'][2]['author']","$['store']['book'][3]['author']");

调整配置

选项创建配置时，有几个可以改变默认行为的选项标志。

DEFAULT_PATH_LEAF_TO_NULL

此选项使JsonPath对于缺少的叶子返回null。考虑下面的json

[{"name" : "john","gender" : "male"},{"name" : "ben"}
]

Configuration conf = Configuration.defaultConfiguration();//Works fine
String gender0 = JsonPath.using(conf).parse(json).read("$[0]['gender']");
//PathNotFoundException thrown
String gender1 = JsonPath.using(conf).parse(json).read("$[1]['gender']");Configuration conf2 = conf.addOptions(Option.DEFAULT_PATH_LEAF_TO_NULL);//Works fine
String gender0 = JsonPath.using(conf2).parse(json).read("$[0]['gender']");
//Works fine (null is returned)
String gender1 = JsonPath.using(conf2).parse(json).read("$[1]['gender']");

ALWAYS_RETURN_LIST
This option configures JsonPath to return a list even when the path is definite.

Configuration conf = Configuration.defaultConfiguration();//Works fine
List<String> genders0 = JsonPath.using(conf).parse(json).read("$[0]['gender']");
//PathNotFoundException thrown
List<String> genders1 = JsonPath.using(conf).parse(json).read("$[1]['gender']");

SUPPRESS_EXCEPTIONS
This option makes sure no exceptions are propagated from path evaluation. It follows these simple rules:

If option ALWAYS_RETURN_LIST is present an empty list will be returned
If option ALWAYS_RETURN_LIST is NOT present null returned

JsonProvider SPI

JsonPath is shipped with five different JsonProviders:

JsonSmartJsonProvider (default)
JacksonJsonProvider
JacksonJsonNodeJsonProvider
GsonJsonProvider
JsonOrgJsonProvider

Changing the configuration defaults as demonstrated should only be done when your application is being initialized. Changes during runtime is strongly discouraged, especially in multi threaded applications.

Configuration.setDefaults(new Configuration.Defaults() {private final JsonProvider jsonProvider = new JacksonJsonProvider();private final MappingProvider mappingProvider = new JacksonMappingProvider();@Overridepublic JsonProvider jsonProvider() {return jsonProvider;}@Overridepublic MappingProvider mappingProvider() {return mappingProvider;}@Overridepublic Set<Option> options() {return EnumSet.noneOf(Option.class);}
});

Note that the JacksonJsonProvider requires com.fasterxml.jackson.core:jackson-databind:2.4.5 and the GsonJsonProvider requires com.google.code.gson:gson:2.3.1 on your classpath.

Cache SPI

In JsonPath 2.1.0 a new Cache SPI was introduced. This allows API consumers to configure path caching in a way that suits their needs. The cache must be configured before it is accesses for the first time or a JsonPathException is thrown. JsonPath ships with two cache implementations

com.jayway.jsonpath.spi.cache.LRUCache (default, thread safe)
com.jayway.jsonpath.spi.cache.NOOPCache (no cache)

If you want to implement your own cache the API is simple.

CacheProvider.setCache(new Cache() {//Not thread safe simple cacheprivate Map<String, JsonPath> map = new HashMap<String, JsonPath>();@Overridepublic JsonPath get(String key) {return map.get(key);}@Overridepublic void put(String key, JsonPath jsonPath) {map.put(key, jsonPath);}
});

Java 操作示例源码

示例 Json：

{"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": "JavaWeb","author": "X-rapido","title": "Top-link","isbn": "0-553-211231-3","price": 32.68},{"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
}

java 示例：

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.Iterator;
import java.util.List;
import com.jayway.jsonpath.JsonPath;public class TestJsonPath {public static void main(String[] args) {String sjson = readtxt();print("--------------------------------------getJsonValue--------------------------------------");getJsonValue(sjson);}private static String readtxt() {StringBuilder sb = new StringBuilder();try {FileReader fr = new FileReader("D:/books.txt");BufferedReader bfd = new BufferedReader(fr);String s = "";while((s=bfd.readLine())!=null) {sb.append(s);}} catch (Exception e) {e.printStackTrace();}System.out.println(sb.toString());return sb.toString();}private static void getJsonValue(String json) {//The authors of all books：获取json中store下book下的所有author值List<String> authors1 = JsonPath.read(json, "$.store.book[*].author");//All authors：获取所有json中所有author的值List<String> authors2 = JsonPath.read(json, "$..author");//All things, both books and bicycles //authors3返回的是net.minidev.json.JSONArray：获取json中store下的所有value值，不包含key，如key有两个，book和bicycleList<Object> authors3 = JsonPath.read(json, "$.store.*");//The price of everything：获取json中store下所有price的值List<Object> authors4 = JsonPath.read(json, "$.store..price");//The third book：获取json中book数组的第3个值List<Object> authors5 = JsonPath.read(json, "$..book[2]");//The first two books：获取json中book数组的第1和第2两个个值List<Object> authors6 = JsonPath.read(json, "$..book[0,1]");//All books from index 0 (inclusive) until index 2 (exclusive)：获取json中book数组的前两个区间值List<Object> authors7 = JsonPath.read(json, "$..book[:2]");//All books from index 1 (inclusive) until index 2 (exclusive)：获取json中book数组的第2个值List<Object> authors8 = JsonPath.read(json, "$..book[1:2]");//Last two books：获取json中book数组的最后两个值List<Object> authors9 = JsonPath.read(json, "$..book[-2:]");//Book number two from tail：获取json中book数组的第3个到最后一个的区间值List<Object> authors10 = JsonPath.read(json, "$..book[2:]");//All books with an ISBN number：获取json中book数组中包含isbn的所有值List<Object> authors11 = JsonPath.read(json, "$..book[?(@.isbn)]");//All books in store cheaper than 10：获取json中book数组中price<10的所有值List<Object> authors12 = JsonPath.read(json, "$.store.book[?(@.price < 10)]");//All books in store that are not "expensive"：获取json中book数组中price<=expensive的所有值List<Object> authors13 = JsonPath.read(json, "$..book[?(@.price <= $['expensive'])]");//All books matching regex (ignore case)：获取json中book数组中的作者以REES结尾的所有值（REES不区分大小写）List<Object> authors14 = JsonPath.read(json, "$..book[?(@.author =~ /.*REES/i)]");//Give me every thing：逐层列出json中的所有值，层级由外到内List<Object> authors15 = JsonPath.read(json, "$..*");//The number of books：获取json中book数组的长度List<Object> authors16 = JsonPath.read(json, "$..book.length()");print("**********authors1**********");print(authors1);print("**********authors2**********");print(authors2);print("**********authors3**********");printOb(authors3);print("**********authors4**********");printOb(authors4);print("**********authors5**********");printOb(authors5);print("**********authors6**********");printOb(authors6);print("**********authors7**********");printOb(authors7);print("**********authors8**********");printOb(authors8);print("**********authors9**********");printOb(authors9);print("**********authors10**********");printOb(authors10);print("**********authors11**********");printOb(authors11);print("**********authors12**********");printOb(authors12);print("**********authors13**********");printOb(authors13);print("**********authors14**********");printOb(authors14);print("**********authors15**********");printOb(authors15);print("**********authors16**********");printOb(authors16);}private static void print(List<String> list) {for(Iterator<String> it = list.iterator();it.hasNext();) {System.out.println(it.next());}}private static void printOb(List<Object> list) {for(Iterator<Object> it = list.iterator();it.hasNext();) {System.out.println(it.next());}}private static void print(String s) {System.out.println("\n"+s);}}

输出：

{"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":"JavaWeb","author":"X-rapido","title":"Top-link","isbn":"0-553-211231-3","price":32.68},{"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}--------------------------------------getJsonValue--------------------------------------
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/D:/workSpaces/SupportPackge/MavenRepository/org/apache/logging/log4j/log4j-slf4j-impl/2.0.2/log4j-slf4j-impl-2.0.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/D:/workSpaces/SupportPackge/MavenRepository/org/slf4j/slf4j-log4j12/1.7.10/slf4j-log4j12-1.7.10.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.**********authors1**********
Nigel Rees
Evelyn Waugh
Herman Melville
X-rapido
J. R. R. Tolkien**********authors2**********
Nigel Rees
Evelyn Waugh
Herman Melville
X-rapido
J. R. R. Tolkien**********authors3**********
[{"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":"JavaWeb","author":"X-rapido","title":"Top-link","isbn":"0-553-211231-3","price":32.68},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}]
{color=red, price=19.95}**********authors4**********
8.95
12.99
8.99
32.68
22.99
19.95**********authors5**********
{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}**********authors6**********
{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}**********authors7**********
{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}**********authors8**********
{category=fiction, author=Evelyn Waugh, title=Sword of Honour, price=12.99}**********authors9**********
{category=JavaWeb, author=X-rapido, title=Top-link, isbn=0-553-211231-3, price=32.68}
{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}**********authors10**********
{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}
{category=JavaWeb, author=X-rapido, title=Top-link, isbn=0-553-211231-3, price=32.68}
{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}**********authors11**********
{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}
{category=JavaWeb, author=X-rapido, title=Top-link, isbn=0-553-211231-3, price=32.68}
{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}**********authors12**********
{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}
{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}**********authors13**********
{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}
{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}**********authors14**********
{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}**********authors15**********
{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":"JavaWeb","author":"X-rapido","title":"Top-link","isbn":"0-553-211231-3","price":32.68},{"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}}
10
[{"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":"JavaWeb","author":"X-rapido","title":"Top-link","isbn":"0-553-211231-3","price":32.68},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}]
{color=red, price=19.95}
{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=JavaWeb, author=X-rapido, title=Top-link, isbn=0-553-211231-3, price=32.68}
{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}
reference
Nigel Rees
Sayings of the Century
8.95
fiction
Evelyn Waugh
Sword of Honour
12.99
fiction
Herman Melville
Moby Dick
0-553-21311-3
8.99
JavaWeb
X-rapido
Top-link
0-553-211231-3
32.68
fiction
J. R. R. Tolkien
The Lord of the Rings
0-395-19395-8
22.99
red
19.95**********authors16**********
5

示例 2：

import java.io.BufferedReader;
import java.io.FileReader;
import java.util.Iterator;
import java.util.List;
import java.util.Map;import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.ReadContext;public class TestJsonPath3 {public static void main(String[] args) {String sjson = readtxt();print("-----------------------getJsonValue0-----------------------");getJsonValue0(sjson);print("-----------------------getJsonValue1-----------------------");getJsonValue1(sjson);print("-----------------------getJsonValue2-----------------------");getJsonValue2(sjson);print("-----------------------getJsonValue3-----------------------");getJsonValue3(sjson);print("-----------------------getJsonValue4-----------------------");getJsonValue4(sjson);}private static String readtxt() {StringBuilder sb = new StringBuilder();try {FileReader fr = new FileReader("D:/books.txt");BufferedReader bfd = new BufferedReader(fr);String s = "";while((s=bfd.readLine())!=null) {sb.append(s);}} catch (Exception e) {e.printStackTrace();}System.out.println(sb.toString());return sb.toString();}/*** 读取json的一种写法，得到匹配表达式的所有值* */private static void getJsonValue0(String json) {List<String> authors = JsonPath.read(json, "$.store.book[*].author");print(authors);}/*** 读取JSON得到某个具体值（推荐使用这种方法，一次解析多次调用）* */private static void getJsonValue1(String json) {Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);String author0 = JsonPath.read(document, "$.store.book[0].author");String author1 = JsonPath.read(document, "$.store.book[1].author");print(author0);print(author1);}/*** 读取json的一种写法* */private static void getJsonValue2(String json) {ReadContext ctx = JsonPath.parse(json);// 获取json中book数组中包含isbn的作者List<String> authorsOfBooksWithISBN = ctx.read("$.store.book[?(@.isbn)].author");// 获取json中book数组中价格大于10的对象List<Map<String, Object>> expensiveBooks = JsonPath.using(Configuration.defaultConfiguration()).parse(json).read("$.store.book[?(@.price > 10)]", List.class);print(authorsOfBooksWithISBN);print("********Map********");printListMap(expensiveBooks);}/*** 读取JSON得到的值是一个String，所以不能用List存储 * */private static void getJsonValue3(String json) {//Will throw an java.lang.ClassCastException    //List<String> list = JsonPath.parse(json).read("$.store.book[0].author");//由于会抛异常，暂时注释上面一行，要用的话，应使用下面的格式String author = JsonPath.parse(json).read("$.store.book[0].author");print(author);}/*** 读取json的一种写法，支持逻辑表达式，&&和||*/private static void getJsonValue4(String json) {List<Map<String, Object>> books1 =  JsonPath.parse(json).read("$.store.book[?(@.price < 10 && @.category == 'fiction')]");List<Map<String, Object>> books2 =  JsonPath.parse(json).read("$.store.book[?(@.category == 'reference' || @.price > 10)]");print("********books1********");printListMap(books1);print("********books2********");printListMap(books2);}private static void print(List<String> list) {for(Iterator<String> it = list.iterator();it.hasNext();) {System.out.println(it.next());}}private static void printListMap(List<Map<String, Object>> list) {for(Iterator<Map<String, Object>> it = list.iterator();it.hasNext();) {Map<String, Object> map = it.next();for(Iterator iterator =map.entrySet().iterator();iterator.hasNext();) {System.out.println(iterator.next());}}}private static void print(String s) {System.out.println("\n"+s);}}

输出：

{"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":"JavaWeb","author":"X-rapido","title":"Top-link","isbn":"0-553-211231-3","price":32.68},{"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}-----------------------getJsonValue0-----------------------
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/D:/workSpaces/SupportPackge/MavenRepository/org/apache/logging/log4j/log4j-slf4j-impl/2.0.2/log4j-slf4j-impl-2.0.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/D:/workSpaces/SupportPackge/MavenRepository/org/slf4j/slf4j-log4j12/1.7.10/slf4j-log4j12-1.7.10.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console.
Nigel Rees
Evelyn Waugh
Herman Melville
X-rapido
J. R. R. Tolkien-----------------------getJsonValue1-----------------------Nigel ReesEvelyn Waugh-----------------------getJsonValue2-----------------------
Herman Melville
X-rapido
J. R. R. Tolkien********Map********
category=fiction
author=Evelyn Waugh
title=Sword of Honour
price=12.99
category=JavaWeb
author=X-rapido
title=Top-link
isbn=0-553-211231-3
price=32.68
category=fiction
author=J. R. R. Tolkien
title=The Lord of the Rings
isbn=0-395-19395-8
price=22.99-----------------------getJsonValue3-----------------------Nigel Rees-----------------------getJsonValue4-----------------------********books1********
category=fiction
author=Herman Melville
title=Moby Dick
isbn=0-553-21311-3
price=8.99********books2********
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=JavaWeb
author=X-rapido
title=Top-link
isbn=0-553-211231-3
price=32.68
category=fiction
author=J. R. R. Tolkien
title=The Lord of the Rings
isbn=0-395-19395-8
price=22.99

过滤器示例

java 示例：

public static void main(String[] args) {String json = readtxt();Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);// 过滤器链（查找包含isbn并category中有fiction或JavaWeb的值）Filter filter = Filter.filter(Criteria.where("isbn").exists(true).and("category").in("fiction", "JavaWeb"));List<Object> books = JsonPath.read(document, "$.store.book[?]", filter);printOb(books);System.out.println("\n----------------------------------------------\n");// 自定义过滤器Filter mapFilter = new Filter() {@Overridepublic boolean apply(PredicateContext context) {Map<String, Object> map = context.item(Map.class);    if (map.containsKey("isbn")) {return true;}return false;}};List<Object> books2 = JsonPath.read(document, "$.store.book[?]", mapFilter);printOb(books2);}

输出：

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}
{category=JavaWeb, author=X-rapido, title=Top-link, isbn=0-553-211231-3, price=32.68}
{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}----------------------------------------------{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}
{category=JavaWeb, author=X-rapido, title=Top-link, isbn=0-553-211231-3, price=32.68}
{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}

由此可见，使用过滤器，或者使用上述的表达式，都是可以达到理想的效果

示例中的books2中，注意到context.item(Map.class)；这句话

这句中的Map.class是根据预定的结果类型定义的，如果返回的是String类型值，那就改为String.class

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操作符

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