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

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

JSONPath Online Evaluator：http://jsonpath.com

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JsonPath 是一種簡單的方法來提取給定JSON文檔的部分內容。 JsonPath有許多編程語言，如Javascript，Python和PHP，Java。JsonPath 提供的 json 解析非常強大，它提供了類似正則表達式的語法，基本上可以滿足所有你想要獲得的 json 內容.

JsonPath 表達式總是引用 JSON 結構，其方式與XPath表達式解析XML文檔的方式類似。JsonPath中的 “根成員對象” 總是被引用為$，不管它是對象還是數(shù)組。

JsonPath 可以使用 點 表示法：$.store.book[0].title
或者 括號 表示法：$['store']['book'][0]['title']

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操作符

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操作符 和 描述

操作符描述

$	查詢根元素。這將開始所有路徑表達式
@	使用過濾謂詞來處理當前節(jié)點。即過濾當前節(jié)點。
*	通配符。 任何可以使用名稱和數(shù)字的地方都可以使用。
..	深層掃描。 任何可以使用名稱的地方都可以使用
.<name>	點，表示子節(jié)點。
['<name>' (, '<name>')]	括號 表示子項。
[<number> (, <number>)]	數(shù)組索引 或 索引
[start:end]	數(shù)組切片操作。
[?(<expression>)]	過濾表達式。 表達式的結果必須是一個 bool 值。

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函數(shù)

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函數(shù)可以在路徑的末尾調用——函數(shù)的輸入是路徑表達式的輸出。函數(shù)輸出由函數(shù)本身決定。

函數(shù)描述輸出

min()	提供數(shù)字數(shù)組的最小值	Double
max()	提供數(shù)字數(shù)組的最大值	Double
avg()	提供數(shù)字數(shù)組的平均值	Double
stddev()	提供數(shù)字數(shù)組的標準偏差值	Double
length()	提供數(shù)組的長度	Integer
sum()	提供數(shù)字數(shù)組的所有元素的和	Double

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過濾器運算符

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過濾器 是 用于篩選數(shù)組的邏輯表達式。一個典型的過濾器應該是 [?(@.age > 18)]，其中 @ 表示當前正在處理的項。可以使用邏輯運算符 && 和 || 創(chuàng)建更復雜的過濾器。字符串文字 必須用 單引號 或 雙引號 括起來 ([?(@.color == 'blue')] or [?(@.color == "blue")])。

操作符描述

==	左邊得值 等于 右邊的值 ( 注意：數(shù)字 1 不等于 字符串 '1' )
!=	不等于
<	小于
<=	小于等于
>	大于
>=	大于等于
=~	匹配正則表達式? [?(@.name =~ /foo.*?/i)]
in	左邊 in 右邊 [?(@.size in ['S', 'M'])]
nin	左邊 not in 右邊
subsetof	左邊是右邊的一個子字符串 [?(@.sizes subsetof ['S', 'M', 'L'])]
anyof	左邊和右邊相交 [?(@.sizes anyof ['M', 'L'])]
noneof	左邊和右邊不相交 [?(@.sizes noneof ['M', 'L'])]
size	（數(shù)組或字符串）長度
empty	（數(shù)組或字符串）為空

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示例

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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 表達式示例：

JsonPath ( 點擊鏈接測試 )結果

$.store.book[*].author	獲取 Json 中 store下book下的所有author值
$..author	獲取 Json 中 所有 author 的值。
$.store.*	獲取 store 下所有東西（ book 和 bicycle ）
$.store..price	獲取 store下以及所有子節(jié)點下的所有 price
$..book[2]	獲取 book數(shù)組的第3個值
$..book[-2]	獲取 book數(shù)組的倒數(shù)第二個值
$..book[0,1]	獲取 book數(shù)組的第一、第二的值
$..book[:2]	獲取 book數(shù)組從索引 0 (包括) 到 索引 2 (不包括) 的所有值?
$..book[1:2]	獲取 book數(shù)組從索引 1 (包括) 到 索引 2 (不包括) 的所有值?
$..book[-2:]	獲取 book數(shù)組從索引 -2 (包括) 到 結尾 的所有值
$..book[2:]	獲取 book數(shù)組從索引 2 (包括) 到 結尾 的所有值
$..book[?(@.isbn)]	獲取 所有節(jié)點以及子節(jié)點中 book 數(shù)組包含 isbn 的所有值
$.store.book[?(@.price < 10)]	獲取 store下 book 數(shù)組中 price < 10 的所有值
$..book[?(@.price <= $['expensive'])]	獲取 所有節(jié)點以及子節(jié)點下 book 數(shù)組中 price <= expensive 的所有值
$..book[?(@.author =~ /.*REES/i)]	獲取所有匹配正則的 book （ 不區(qū)分大小寫 ）
$..*	逐層列出 json 中 的所有值，層級由外到內
$..book.length()	book 數(shù)組的長度

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閱讀文檔

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使用 JsonPath 的最簡單的最直接的方法是通過靜態(tài)讀取 API。

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

如果你只想讀取一次，那么上面的代碼就可以了。如果你還想讀取其他路徑，現(xiàn)在上面不是很好的方法，因為他每次獲取都需要再解析整個文檔。所以，我們可以先解析整個文檔，再選擇調用路徑。

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還提供流暢的API。 這也是最靈活的一個。

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);

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何時返回

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當在 java 中使用 JsonPath 時，重要的是要知道你在結果中期望什么類型。 JsonPath 將自動嘗試將結果轉換為調用者預期的類型。

//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")

當評估路徑時，你需要理解路徑確定的概念。路徑是不確定的，它包含

• ..?：深層掃描操作

• ?(<expression>)?：表達式

• [<number>, <number> (, <number>)]?：多個數(shù)組索引

不確定的路徑總是返回一個列表（由當前的JsonProvider表示）。

默認情況下，MappingProvider SPI提供了一個簡單的對象映射器。 這允許您指定所需的返回類型，MappingProvider將嘗試執(zhí)行映射。 在下面的示例中，演示了Long和Date之間的映射。

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

如果您將JsonPath配置為使用JacksonMappingProvider或GsonMappingProvider，您甚至可以將JsonPath輸出直接映射到POJO中。

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

要獲取完整的泛型類型信息，請使用TypeRef。

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

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謂詞

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在JsonPath中創(chuàng)建過濾器謂詞有三種不同的方法。

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內聯(lián)謂詞

內聯(lián)謂詞是路徑中定義的謂詞。

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

你可以使用?&& 和 ||?結合多個謂詞 [?(@.price < 10 && @.category == 'fiction')] , [?(@.category == 'reference' || @.price > 10)].

你也可以使用！否定一個謂詞 [?(!(@.price < 10 && @.category == 'fiction'))].

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過濾謂詞

謂詞可以使用Filter API構建，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？ 為路徑中的過濾器。 當提供多個過濾器時，它們按照占位符數(shù)量與提供的過濾器數(shù)量相匹配的順序應用。 您可以在一個過濾器操作[？，？]中指定多個謂詞占位符，這兩個謂詞都必須匹配。

過濾器也可以與“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) );

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自定義

第三個選擇是實現(xiàn)你自己的謂詞

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);

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Path vs Value

在 Goessner 實現(xiàn)中，JsonPath 可以返回 Path 或 Value。 值是默認值，上面所有示例返回。 如果你想讓我們查詢的元素的路徑可以通過選項來實現(xiàn)。

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']");

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調整配置

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選項創(chuàng)建配置時，有幾個可以改變默認行為的選項標志。

DEFAULT_PATH_LEAF_TO_NULL

此選項使JsonPath對于缺少的葉子返回null。 考慮下面的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']");

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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.

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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);} });

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Java 操作示例源碼

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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：獲取json中store下book下的所有author值List<String> authors1 = JsonPath.read(json, "$.store.book[*].author");//All authors：獲取所有json中所有author的值List<String> authors2 = JsonPath.read(json, "$..author");//All things, both books and bicycles //authors3返回的是net.minidev.json.JSONArray：獲取json中store下的所有value值，不包含key，如key有兩個，book和bicycleList<Object> authors3 = JsonPath.read(json, "$.store.*");//The price of everything：獲取json中store下所有price的值List<Object> authors4 = JsonPath.read(json, "$.store..price");//The third book：獲取json中book數(shù)組的第3個值List<Object> authors5 = JsonPath.read(json, "$..book[2]");//The first two books：獲取json中book數(shù)組的第1和第2兩個個值List<Object> authors6 = JsonPath.read(json, "$..book[0,1]");//All books from index 0 (inclusive) until index 2 (exclusive)：獲取json中book數(shù)組的前兩個區(qū)間值List<Object> authors7 = JsonPath.read(json, "$..book[:2]");//All books from index 1 (inclusive) until index 2 (exclusive)：獲取json中book數(shù)組的第2個值List<Object> authors8 = JsonPath.read(json, "$..book[1:2]");//Last two books：獲取json中book數(shù)組的最后兩個值List<Object> authors9 = JsonPath.read(json, "$..book[-2:]");//Book number two from tail：獲取json中book數(shù)組的第3個到最后一個的區(qū)間值List<Object> authors10 = JsonPath.read(json, "$..book[2:]");//All books with an ISBN number：獲取json中book數(shù)組中包含isbn的所有值List<Object> authors11 = JsonPath.read(json, "$..book[?(@.isbn)]");//All books in store cheaper than 10：獲取json中book數(shù)組中price<10的所有值List<Object> authors12 = JsonPath.read(json, "$.store.book[?(@.price < 10)]");//All books in store that are not "expensive"：獲取json中book數(shù)組中price<=expensive的所有值List<Object> authors13 = JsonPath.read(json, "$..book[?(@.price <= $['expensive'])]");//All books matching regex (ignore case)：獲取json中book數(shù)組中的作者以REES結尾的所有值（REES不區(qū)分大小寫）List<Object> authors14 = JsonPath.read(json, "$..book[?(@.author =~ /.*REES/i)]");//Give me every thing：逐層列出json中的所有值，層級由外到內List<Object> authors15 = JsonPath.read(json, "$..*");//The number of books：獲取json中book數(shù)組的長度List<Object> authors16 = JsonPath.read(json, "$..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);}}

輸出：

{"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();}/*** 讀取json的一種寫法，得到匹配表達式的所有值* */private static void getJsonValue0(String json) {List<String> authors = JsonPath.read(json, "$.store.book[*].author");print(authors);}/*** 讀取JSON得到某個具體值（推薦使用這種方法，一次解析多次調用）* */private static void getJsonValue1(String json) {Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);String author0 = JsonPath.read(document, "$.store.book[0].author");String author1 = JsonPath.read(document, "$.store.book[1].author");print(author0);print(author1);}/*** 讀取json的一種寫法* */private static void getJsonValue2(String json) {ReadContext ctx = JsonPath.parse(json);// 獲取json中book數(shù)組中包含isbn的作者List<String> authorsOfBooksWithISBN = ctx.read("$.store.book[?(@.isbn)].author");// 獲取json中book數(shù)組中價格大于10的對象List<Map<String, Object>> expensiveBooks = JsonPath.using(Configuration.defaultConfiguration()).parse(json).read("$.store.book[?(@.price > 10)]", List.class);print(authorsOfBooksWithISBN);print("********Map********");printListMap(expensiveBooks);}/*** 讀取JSON得到的值是一個String，所以不能用List存儲 * */private static void getJsonValue3(String json) {//Will throw an java.lang.ClassCastException //List<String> list = JsonPath.parse(json).read("$.store.book[0].author");//由于會拋異常，暫時注釋上面一行，要用的話，應使用下面的格式String author = JsonPath.parse(json).read("$.store.book[0].author");print(author);}/*** 讀取json的一種寫法，支持邏輯表達式，&&和||*/private static void getJsonValue4(String json) {List<Map<String, Object>> books1 = JsonPath.parse(json).read("$.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);}}

輸出：

{"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

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過濾器示例

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java 示例：

public static void main(String[] args) {String json = readtxt();Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);// 過濾器鏈（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, "$.store.book[?]", filter);printOb(books);System.out.println("\n----------------------------------------------\n");// 自定義過濾器Filter mapFilter = new Filter() {@Overridepublic boolean apply(PredicateContext context) {Map<String, Object> map = context.item(Map.class); if (map.containsKey("isbn")) {return true;}return false;}};List<Object> books2 = JsonPath.read(document, "$.store.book[?]", mapFilter);printOb(books2);}

輸出：

{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}

由此可見，使用過濾器，或者使用上述的表達式，都是可以達到理想的效果

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

這句中的Map.class是根據預定的結果類型定義的，如果返回的是String類型值，那就改為String.class

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總結

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