jsonpath - 使用 JSONPath 解析 JSON 完整内容详解

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。下面我把官网介绍的每个表达式用代码实现，可以更直观的知道该怎么用它。

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

以下是从GitHub中用我蹩脚的英格利希，翻译过来的，将就着看吧，推荐去管网上面阅读。

JsonPath可在Central Maven存储库中找到。 Maven用户将其添加到您的POM。

<dependency>
    <groupId>com.jayway.jsonpath</groupId>
    <artifactId>json-path</artifactId>
    <version>2.2.0</version>
</dependency>

如果您需要帮助，请在Stack Overflow中提问。 标记问题'jsonpath'和'java'。

JsonPath表达式总是以与XPath表达式结合使用XML文档相同的方式引用JSON结构。

JsonPath中的“根成员对象”始终称为$，无论是对象还是数组。

JsonPath表达式可以使用点表示法

$.store.book [0].title

或括号表示法

$['store']['book'][0]['title']

操作符

操作说明
$ 查询根元素。这将启动所有路径表达式。
@ 当前节点由过滤谓词处理。
* 通配符，必要时可用任何地方的名称或数字。
.. 深层扫描。 必要时在任何地方可以使用名称。
.<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。 表达式必须求值为一个布尔值。

函数

函数可以在路径的尾部调用，函数的输出是路径表达式的输出，该函数的输出是由函数本身所决定的。

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

过滤器运算符

过滤器是用于筛选数组的逻辑表达式。一个典型的过滤器将是[?(@.age > 18)]，其中@表示正在处理的当前项目。 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')] 或者 [?(@.color == "blue")]).

操作符描述
== left等于right（注意1不等于'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 左边存在于右边 [?(@.size in ['S', 'M'])]
nin 左边不存在于右边
size （数组或字符串）长度
empty （数组或字符串）为空

Java操作示例

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 (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 获取所有json中所有author的值
$.store.* 所有的东西，书籍和自行车
$.store..price 获取json中store下所有price的值
$..book[2] 获取json中book数组的第3个值
$..book[-2] 倒数的第二本书
$..book[0,1] 前两本书
$..book[:2] 从索引0（包括）到索引2（排除）的所有图书
$..book[1:2] 从索引1（包括）到索引2（排除）的所有图书
$..book[-2:] 获取json中book数组的最后两个值
$..book[2:] 获取json中book数组的第3个到最后一个的区间值
$..book[?(@.isbn)] 获取json中book数组中包含isbn的所有值
$.store.book[?(@.price < 10)] 获取json中book数组中price<10的所有值
$..book[?(@.price <= $['expensive'])] 获取json中book数组中price<=expensive的所有值
$..book[?(@.author =~ /.*REES/i)] 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）
$..* 逐层列出json中的所有值，层级由外到内
$..book.length() 获取json中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。

// 抛出 java.lang.ClassCastException 异常
List<String> list = JsonPath.parse(json).read("$.store.book[0].author")

// 正常
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() {
    @Override
    public 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();

// 正常
String gender0 = JsonPath.using(conf).parse(json).read("$[0]['gender']");
// 异常 PathNotFoundException thrown
String gender1 = JsonPath.using(conf).parse(json).read("$[1]['gender']");

Configuration conf2 = conf.addOptions(Option.DEFAULT_PATH_LEAF_TO_NULL);

// 正常
String gender0 = JsonPath.using(conf2).parse(json).read("$[0]['gender']");
// 正常 (返回 null)
String gender1 = JsonPath.using(conf2).parse(json).read("$[1]['gender']");

 

ALWAYS_RETURN_LIST

此选项配置JsonPath返回列表

Configuration conf = Configuration.defaultConfiguration();

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

SUPPRESS_EXCEPTIONS

该选项确保不会从路径评估传播异常。 遵循这些简单的规则：

  • 如果选项ALWAYS_RETURN_LIST存在，将返回一个空列表

  • 如果选项ALWAYS_RETURN_LIST不存在返回null

JsonProvider SPI

JsonPath is shipped with three different JsonProviders:

更改配置默认值只能在应用程序初始化时完成。 强烈不建议在运行时进行更改，尤其是在多线程应用程序中。

Configuration.setDefaults(new Configuration.Defaults() {

    private final JsonProvider jsonProvider = new JacksonJsonProvider();
    private final MappingProvider mappingProvider = new JacksonMappingProvider();
      
    @Override
    public JsonProvider jsonProvider() {
        return jsonProvider;
    }

    @Override
    public MappingProvider mappingProvider() {
        return mappingProvider;
    }
    
    @Override
    public Set<Option> options() {
        return EnumSet.noneOf(Option.class);
    }
});

 

请注意，JacksonJsonProvider需要com.fasterxml.jackson.core：jackson-databind：2.4.5，GsonJsonProvider需要在您的类路径上使用com.google.code.gson：gson：2.3.1。

Cache SPI

在JsonPath 2.1.0中，引入了一种新的Cache SPI。 这允许API消费者以适合其需求的方式配置路径缓存。 缓存必须在首次访问之前配置，或者抛出JsonPathException。 JsonPath附带两个缓存实现

  • com.jayway.jsonpath.spi.cache.LRUCache（默认，线程安全）

  • com.jayway.jsonpath.spi.cache.NOOPCache（无缓存）

如果要实现自己的缓存，API很简单。

CacheProvider.setCache(new Cache() {
    //Not thread safe simple cache
    private Map<String, JsonPath> map = new HashMap<String, JsonPath>();

    @Override
    public JsonPath get(String key) {
        return map.get(key);
    }

    @Override
    public void put(String key, JsonPath jsonPath) {
        map.put(key, jsonPath);
    }
});

 

Java操作示例源码

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
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bicycle
        List<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

Java
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 Rees

Evelyn 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
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() {
        @Override
        public 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

我的示例只简单判断了一下isbn属性，可以根据实际情况进行变更条件

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

posted @ 2018-08-29 19:23  舞羊  阅读(80784)  评论(1)  编辑  收藏  举报