使用 JSONPath 解析 JSON 完整内容详解

待我称王封你为后i 2022-10-17 14:00 315阅读 0赞

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][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 ###

<table> 
 <thead> 
  <tr> 
   <th>操作</th> 
   <th>说明</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><code>$</code></td> 
   <td>查询根元素。这将启动所有路径表达式。</td> 
  </tr> 
  <tr> 
   <td><code>@</code></td> 
   <td>当前节点由过滤谓词处理。</td> 
  </tr> 
  <tr> 
   <td><code>*</code></td> 
   <td>通配符，必要时可用任何地方的名称或数字。</td> 
  </tr> 
  <tr> 
   <td><code>..</code></td> 
   <td>深层扫描。 必要时在任何地方可以使用名称。</td> 
  </tr> 
  <tr> 
   <td><code>.&lt;name&gt;</code></td> 
   <td>点，表示子节点</td> 
  </tr> 
  <tr> 
   <td><code>['&lt;name&gt;' (, '&lt;name&gt;')]</code></td> 
   <td>括号表示子项</td> 
  </tr> 
  <tr> 
   <td><code>[&lt;number&gt; (, &lt;number&gt;)]</code></td> 
   <td>数组索引或索引</td> 
  </tr> 
  <tr> 
   <td><code>[start:end]</code></td> 
   <td>数组切片操作</td> 
  </tr> 
  <tr> 
   <td><code>[?(&lt;expression&gt;)]</code></td> 
   <td>过滤表达式。 表达式必须求值为一个布尔值。</td> 
  </tr> 
 </tbody> 
</table>

### 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。

<table> 
 <thead> 
  <tr> 
   <th>函数</th> 
   <th>描述</th> 
   <th>输出</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><code>min()</code></td> 
   <td>提供数字数组的最小值</td> 
   <td><code>Double</code></td> 
  </tr> 
  <tr> 
   <td><code>max()</code></td> 
   <td>提供数字数组的最大值</td> 
   <td><code>Double</code></td> 
  </tr> 
  <tr> 
   <td><code>avg()</code></td> 
   <td>提供数字数组的平均值</td> 
   <td><code>Double</code></td> 
  </tr> 
  <tr> 
   <td><code>stddev()</code></td> 
   <td>提供数字数组的标准偏差值</td> 
   <td><code>Double</code></td> 
  </tr> 
  <tr> 
   <td><code>length()</code></td> 
   <td>提供数组的长度</td> 
   <td>Integer</td> 
  </tr> 
 </tbody> 
</table>

### 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 \[?(@.color == "blue")\]).

<table> 
 <thead> 
  <tr> 
   <th>操作符</th> 
   <th>描述</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><code>==</code></td> 
   <td>left等于right（注意1不等于'1'）</td> 
  </tr> 
  <tr> 
   <td><code>!=</code></td> 
   <td>不等于</td> 
  </tr> 
  <tr> 
   <td><code>&lt;</code></td> 
   <td>小于</td> 
  </tr> 
  <tr> 
   <td><code>&lt;=</code></td> 
   <td>小于等于</td> 
  </tr> 
  <tr> 
   <td><code>&gt;</code></td> 
   <td>大于</td> 
  </tr> 
  <tr> 
   <td><code>&gt;=</code></td> 
   <td>大于等于</td> 
  </tr> 
  <tr> 
   <td><code>=~</code></td> 
   <td>匹配正则表达式[?(@.name =~ /foo.*?/i)]</td> 
  </tr> 
  <tr> 
   <td><code>in</code></td> 
   <td>左边存在于右边 [?(@.size in ['S', 'M'])]</td> 
  </tr> 
  <tr> 
   <td><code>nin</code></td> 
   <td>左边不存在于右边</td> 
  </tr> 
  <tr> 
   <td><code>size</code></td> 
   <td>（数组或字符串）长度</td> 
  </tr> 
  <tr> 
   <td><code>empty</code></td> 
   <td>（数组或字符串）为空</td> 
  </tr> 
 </tbody> 
</table>

### 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
    }

<table> 
 <thead> 
  <tr> 
   <th>JsonPath (点击链接测试)</th> 
   <th>结果</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store.book%5B*%5D.author" rel="nofollow"><code>$.store.book[*].author</code></a></td> 
   <td>获取json中store下book下的所有author值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..author" rel="nofollow"><code>$..author</code></a></td> 
   <td>获取所有json中所有author的值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store.*" rel="nofollow"><code>$.store.*</code></a></td> 
   <td>所有的东西，书籍和自行车</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store..price" rel="nofollow"><code>$.store..price</code></a></td> 
   <td>获取json中store下所有price的值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B2%5D" rel="nofollow"><code>$..book[2]</code></a></td> 
   <td>获取json中book数组的第3个值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B2%5D" rel="nofollow"><code>$..book[-2]</code></a></td> 
   <td>倒数的第二本书</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B0,1%5D" rel="nofollow"><code>$..book[0,1]</code></a></td> 
   <td>前两本书</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B:2%5D" rel="nofollow"><code>$..book[:2]</code></a></td> 
   <td>从索引0（包括）到索引2（排除）的所有图书</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B1:2%5D" rel="nofollow"><code>$..book[1:2]</code></a></td> 
   <td>从索引1（包括）到索引2（排除）的所有图书</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B-2:%5D" rel="nofollow"><code>$..book[-2:]</code></a></td> 
   <td>获取json中book数组的最后两个值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B2:%5D" rel="nofollow"><code>$..book[2:]</code></a></td> 
   <td>获取json中book数组的第3个到最后一个的区间值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B?%28@.isbn%29%5D" rel="nofollow"><code>$..book[?(@.isbn)]</code></a></td> 
   <td>获取json中book数组中包含isbn的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store.book%5B?%28@.price%20%3C%2010%29%5D" rel="nofollow"><code>$.store.book[?(@.price &lt; 10)]</code></a></td> 
   <td>获取json中book数组中price&lt;10的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B?%28@.price%20%3C=%20$%5B%27expensive%27%5D%29%5D" rel="nofollow"><code>$..book[?(@.price &lt;= $['expensive'])]</code></a></td> 
   <td>获取json中book数组中price&lt;=expensive的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B?%28@.author%20=~%20/.*REES/i%29%5D" rel="nofollow"><code>$..book[?(@.author =~ /.*REES/i)]</code></a></td> 
   <td>获取json中book数组中的作者以REES结尾的所有值（REES不区分大小写）</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..*" rel="nofollow"><code>$..*</code></a></td> 
   <td>逐层列出json中的所有值，层级由外到内</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book.length%28%29" rel="nofollow"><code>$..book.length()</code></a></td> 
   <td>获取json中book数组的长度</td> 
  </tr> 
 </tbody> 
</table>

### 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。

Java

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。

Java

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。

Java

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。

Java

// 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。

Java

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。

Java

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。

Java

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。

Java

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：

Java

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”

Java

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

Java

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。

Java

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"
       }
    ]

Java

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

Java

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:

*  [`JsonSmartJsonProvider`][JsonSmartJsonProvider] (default)
 *  [`JacksonJsonProvider`][JacksonJsonProvider]
 *  [`JacksonJsonNodeJsonProvider`][JacksonJsonProvider]
 *  [`GsonJsonProvider`][GsonJsonProvider]
 *  [`JsonOrgJsonProvider`][JsonOrgJsonProvider]

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。

Java

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。

Java

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

java

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

[https_github.com_json-path_JsonPath]: https://github.com/json-path/JsonPath
[Stack Overflow]: http://stackoverflow.com/questions/tagged/jsonpath
[JsonSmartJsonProvider]: https://code.google.com/p/json-smart/
[JacksonJsonProvider]: https://github.com/FasterXML/jackson
[GsonJsonProvider]: https://code.google.com/p/google-gson/
[JsonOrgJsonProvider]: http://www.json.org/java/index.html