jsonpath - 使用 JSONPath 解析 JSON
纪秋月
JsonPath是一种简单的方法来提取给定JSON文档的部分内容。
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 |
| 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 |
$..book.length() | 获取json中book数组的长度 |
更多操作
使用JsonPath的最简单的最直接的方法是通过静态读取API。
String json = "...";
List<String> authors = JsonPath.read(json, "$.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);
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:
JsonSmartJsonProvider(default)JacksonJsonProviderJacksonJsonNodeJsonProviderGsonJsonProviderJsonOrgJsonProvider
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
}
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
{"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
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
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