JSONPath 解析 JSON 内容详解（翻译自 github）

不念不忘少年蓝@ 2023-06-12 16:21 10阅读 0赞

Github ：[https://github.com/json-path/JsonPath][https_github.com_json-path_JsonPath]

[http://www.ibloger.net/article/2329.html][http_www.ibloger.net_article_2329.html]

JSONPath Online Evaluator：[http://jsonpath.com][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

<table> 
 <thead> 
  <tr> 
   <th>操作符</th> 
   <th>描述</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td><code>$</code></td> 
   <td>查询根元素。这将开始所有路径表达式</td> 
  </tr> 
  <tr> 
   <td><code>@</code></td> 
   <td>使用过滤谓词来处理当前节点。即过滤当前节点。</td> 
  </tr> 
  <tr> 
   <td><code>*</code></td> 
   <td>通配符。 任何可以使用名称和数字的地方都可以使用。</td> 
  </tr> 
  <tr> 
   <td><code>..</code></td> 
   <td>深层扫描。 任何可以使用名称的地方都可以使用</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。 表达式的结果必须是一个 bool 值。</td> 
  </tr> 
 </tbody> 
</table>

# 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。

<table> 
 <thead> 
  <tr> 
   <th style="width:137px;">函数</th> 
   <th style="width:378px;">描述</th> 
   <th style="width:333px;">输出</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td style="width:137px;">min()</td> 
   <td style="width:378px;">提供数字数组的最小值</td> 
   <td style="width:333px;">Double</td> 
  </tr> 
  <tr> 
   <td style="width:137px;">max()</td> 
   <td style="width:378px;">提供数字数组的最大值</td> 
   <td style="width:333px;">Double</td> 
  </tr> 
  <tr> 
   <td style="width:137px;">avg()</td> 
   <td style="width:378px;">提供数字数组的平均值</td> 
   <td style="width:333px;">Double</td> 
  </tr> 
  <tr> 
   <td style="width:137px;">stddev()</td> 
   <td style="width:378px;">提供数字数组的标准偏差值</td> 
   <td style="width:333px;">Double</td> 
  </tr> 
  <tr> 
   <td style="width:137px;">length()</td> 
   <td style="width:378px;">提供数组的长度</td> 
   <td style="width:333px;">Integer</td> 
  </tr> 
  <tr> 
   <td style="width:137px;">sum()</td> 
   <td style="width:378px;">提供数字数组的所有元素的和</td> 
   <td style="width:333px;">Double</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 \[?(@.color == "blue")\]**)。

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

# 示例 #

示例 Json：

JsonPath 表达式示例：

<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=$.store.book%5B*%5D.author" rel="nofollow">$.store.book[*].author</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=$..author" rel="nofollow">$..author</a></td> 
   <td>获取 Json 中 所有 author 的值。</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store.*" rel="nofollow">$.store.*</a></td> 
   <td>获取 store 下所有东西（ book 和 bicycle ）</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store..price" rel="nofollow">$.store..price</a></td> 
   <td>获取 store下以及所有子节点下的所有 price</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B2%5D" rel="nofollow">$..book[2]</a></td> 
   <td>获取 book数组的第3个值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B2%5D" rel="nofollow">$..book[-2]</a></td> 
   <td>获取 book数组的倒数第二个值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B0,1%5D" rel="nofollow">$..book[0,1]</a></td> 
   <td>获取 book数组的第一、第二的值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B:2%5D" rel="nofollow">$..book[:2]</a></td> 
   <td>获取 book数组从索引 0 (包括) 到 索引 2 (不包括) 的所有值&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B1:2%5D" rel="nofollow">$..book[1:2]</a></td> 
   <td>获取 book数组从索引 1 (包括) 到 索引 2 (不包括) 的所有值&nbsp;</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B-2:%5D" rel="nofollow">$..book[-2:]</a></td> 
   <td>获取 book数组从索引 -2 (包括) 到 结尾 的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B2:%5D" rel="nofollow">$..book[2:]</a></td> 
   <td>获取 book数组从索引 2 (包括) 到 结尾 的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B?%28@.isbn%29%5D" rel="nofollow">$..book[?(@.isbn)]</a></td> 
   <td>获取 所有节点以及子节点中 book 数组包含 isbn 的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$.store.book%5B?%28@.price%20%3C%2010%29%5D" rel="nofollow">$.store.book[?(@.price &lt; 10)]</a></td> 
   <td>获取 store下 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">$..book[?(@.price &lt;= $['expensive'])]</a></td> 
   <td>获取 所有节点以及子节点下 book 数组中 price &lt;= expensive 的所有值</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book%5B?%28@.author%20=~%20/.*REES/i%29%5D" rel="nofollow">$..book[?(@.author =~ /.*REES/i)]</a></td> 
   <td>获取所有匹配正则的 book （ 不区分大小写 ）</td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..*" rel="nofollow">$..*</a></td> 
   <td> <p>逐层列出 json 中 的所有值，层级由外到内</p> </td> 
  </tr> 
  <tr> 
   <td><a href="http://jsonpath.herokuapp.com/?path=$..book.length%28%29" rel="nofollow">$..book.length()</a></td> 
   <td>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。

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

**ALWAYS\_RETURN\_LIST**  
This option configures JsonPath to return a list even when the path is `definite`.

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

**SUPPRESS\_EXCEPTIONS**  
This option makes sure no exceptions are propagated from path evaluation. It follows these simple rules:

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

### JsonProvider SPI ###

JsonPath is shipped with five different JsonProviders:

*  [JsonSmartJsonProvider][] (default)
 *  [JacksonJsonProvider][]
 *  [JacksonJsonNodeJsonProvider][JacksonJsonProvider]
 *  [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();
          
        @Override
        public JsonProvider jsonProvider() {
            return jsonProvider;
        }
    
        @Override
        public MappingProvider mappingProvider() {
            return mappingProvider;
        }
        
        @Override
        public 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 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 #

示例 Json：

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：

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：

### 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() {
    		@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

[https_github.com_json-path_JsonPath]: https://github.com/json-path/JsonPath
[http_www.ibloger.net_article_2329.html]: http://www.ibloger.net/article/2329.html
[http_jsonpath.com]: http://jsonpath.com
[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