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_LISTis present an empty list will be returned - If option
ALWAYS_RETURN_LISTis 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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