FastJson

FastJson

JSONPath 介绍

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Fastjson 1.2.0之后的版本支持JSONPath。这是一个很强大的功能，可以在java框架中当作对象查询语言（OQL）来使用。

API

package com.alibaba.fastjson;public class JSONPath {          // 求值，静态方法public static Object eval(Object rootObject, String path);// 计算Size，Map非空元素个数，对象非空元素个数，Collection的Size，数组的长度。其他无法求值返回-1public static int size(Object rootObject, String path);// 是否包含，path中是否存在对象public static boolean contains(Object rootObject, String path) { }// 是否包含，path中是否存在指定值，如果是集合或者数组，在集合中查找value是否存在public static boolean containsValue(Object rootObject, String path, Object value) { }// 修改制定路径的值，如果修改成功，返回true，否则返回falsepublic static boolean set(Object rootObject, String path, Object value) {}// 在数组或者集合中添加元素public static boolean array_add(Object rootObject, String path,  values);
}

建议缓存JSONPath对象，这样能够提高求值的性能。

支持语法

以下两种写法的语义是相同的：

$.store.book[0].title

和

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

语法示例

API 示例

例1

public void test_entity() throws Exception {Entity entity = new Entity(123, new Object());Assert.Value(), JSONPath.eval(entity, "$.value")); Assert.ains(entity, "$.value"));Assert.ainsValue(entity, "$.id", 123));Assert.ainsValue(entity, "$.value", Value())); Assert.assertEquals(2, JSONPath.size(entity, "$"));Assert.assertEquals(0, JSONPath.size(new Object[], "$")); 
}public static class Entity {private Integer id;private String name;private Object value;public Entity() {}public Entity(Integer id, Object value) { this.id = id; this.value = value; }public Entity(Integer id, String name) { this.id = id; this.name = name; }public Entity(String name) { this.name = name; }public Integer getId() { return id; }public Object getValue() { return value; }        public String getName() { return name; }public void setId(Integer id) { this.id = id; }public void setName(String name) { this.name = name; }public void setValue(Object value) { this.value = value; }
}

例2

读取集合多个元素的某个属性

List<Entity> entities = new ArrayList<Entity>();
entities.add(new Entity("wenshao"));
entities.add(new Entity("ljw2083"));List<String> names = (List<String>)JSONPath.eval(entities, "$.name"); // 返回enties的所有名称
Assert.(0).getName(), (0));
Assert.(1).getName(), (1));

例3

返回集合中多个元素

List<Entity> entities = new ArrayList<Entity>();
entities.add(new Entity("wenshao"));
entities.add(new Entity("ljw2083"));
entities.add(new Entity("Yako"));List<Entity> result = (List<Entity>)JSONPath.eval(entities, "[1,2]"); // 返回下标为1和2的元素
Assert.assertEquals(2, result.size());
Assert.(1), (0));
Assert.(2), (1));

例4

按范围返回集合的子集

List<Entity> entities = new ArrayList<Entity>();
entities.add(new Entity("wenshao"));
entities.add(new Entity("ljw2083"));
entities.add(new Entity("Yako"));List<Entity> result = (List<Entity>)JSONPath.eval(entities, "[0:2]"); // 返回下标从0到2的元素
Assert.assertEquals(3, result.size());
Assert.(0), (0));
Assert.(1), (1));
Assert.(2), (1));

例5

通过条件过滤，返回集合的子集

List<Entity> entities = new ArrayList<Entity>();
entities.add(new Entity(1001, "ljw2083"));
entities.add(new Entity(1002, "wenshao"));
entities.add(new Entity(1003, "yakolee"));
entities.add(new Entity(1004, null));List<Object> result = (List<Object>) JSONPath.eval(entities, "[id in (1001)]");
Assert.assertEquals(1, result.size());
Assert.(0), (0));

例6

根据属性值过滤条件判断是否返回对象，修改对象，数组属性添加元素

Entity entity = new Entity(1001, "ljw2083");
Assert.assertSame(entity , JSONPath.eval(entity, "[id = 1001]"));
Assert.assertNull(JSONPath.eval(entity, "[id = 1002]"));JSONPath.set(entity, "id", 123456); //将id字段修改为123456
Assert.assertEquals(123456, Id().intValue());JSONPath.set(entity, "value", new int[0]); //将value字段赋值为长度为0的数组
JSONPath.arrayAdd(entity, "value", 1, 2, 3); //将value字段的数组添加元素1,2,3

例7

Map root = Collections.singletonMap("company", //Collections.singletonMap("departs", //Arrays.asList( //Collections.singletonMap("id",1001), //Collections.singletonMap("id",1002), //Collections.singletonMap("id", 1003) //) //));List<Object> ids = (List<Object>) JSONPath.eval(root, "$..id");
assertEquals(3, ids.size());
assertEquals(1001, (0));
assertEquals(1002, (1));
assertEquals(1003, (2));

具体用例测试请看下面

/*** @author itguang* @create 2017-12-10 10:03**/@RunWith(SpringRunner.class)
@SpringBootTest
@Slf4j
public class JSONpathControllerTest {@Testpublic void test() {User user = new User("itguang", "123456", "123@qq");String username = (String) JSONPath.eval(user, "$.username");log.info("$.username = {}", username);Entity entity = new Entity(123, user);User user1 = (User) JSONPath.eval(entity, "$.value");log.info("user={}", String());}@Testpublic void test2() {User user = new User("itguang", "123456", "123@qq");Entity entity = new Entity(123, user);//判断entity中是否有 databoolean contains = ains(entity, "$.data");Assert.assertTrue(contains);//判断 entity.data.username 属性值是否为 itguangboolean containsValue = ainsValue(entity, "$.data.username", "itguang");Assert.assertTrue(containsValue);Assert.assertEquals(2, JSONPath.size(entity, "$"));}@Testpublic void test3() {List<Entity> entities = new ArrayList<Entity>();entities.add(new Entity("逻辑"));entities.add(new Entity("叶文杰"));entities.add(new Entity("程心"));//返回集合中多个元素List<String> names = (List<String>) JSONPath.eval(entities, "$.name");log.info("返回集合中多个元素names={}", names);//返回下标 0 和 2 的元素List<Entity> result = (List<Entity>) JSONPath.eval(entities, "[0,2]");log.info("返回下标 0 和 2 的元素={}", result);// 返回下标从0到2的元素List<Entity> result2 = (List<Entity>) JSONPath.eval(entities, "[0:2]");log.info("返回下标从0到2的元素={}", result2);}@Testpublic void test4() {List<Entity> entities = new ArrayList<Entity>();entities.add(new Entity(1001, "逻辑"));entities.add(new Entity(1002, "程心"));entities.add(new Entity(1003, "叶文杰"));entities.add(new Entity(1004, null));//通过条件过滤，返回集合的子集List<Entity> result = (List<Entity>) JSONPath.eval(entities, "[id in (1001)]");log.info("通过条件过滤，返回集合的子集={}", result);}/*** 使用JSONPrase 解析JSON字符串或者Object对象* <p>* read(String json, String path)//直接使用json字符串匹配* <p>* eval(Object rootObject, String path) //直接使用 对象匹配* <p>* <p>* {"store":{"bicycle":{"color":"red","price":19.95},"book":[{"author":"Nigel Rees","price":8.95,"category":"reference","title":"Sayings of the Century"},{"author":"Evelyn Waugh","price":12.99,"isbn":"0-553-21311-3","category":"fiction","title":"Sword of Honour"}]}}*/@Testpublic void test5() {String jsonStr = "{n" +"    "store": {n" +"        "bicycle": {n" +"            "color": "red",n" +"            "price": 19.95n" +"        },n" +"        "book": [n" +"            {n" +"                "author": "刘慈欣",n" +"                "price": 8.95,n" +"                "category": "科幻",n" +"                "title": "三体"n" +"            },n" +"            {n" +"                "author": "itguang",n" +"                "price": 12.99,n" +"                "category": "编程语言",n" +"                "title": "go语言实战"n" +"            }n" +"        ]n" +"    }n" +"}";JSONObject jsonObject = JSON.parseObject(jsonStr);log.String());//得到所有的书List<Book> books = (List<Book>) JSONPath.eval(jsonObject, "$.store.book");log.info("books={}", books);//得到所有的书名List<String> titles = (List<String>) JSONPath.eval(jsonObject, "$.store.book.title");log.info("titles={}", titles);//第一本书titleString title = (String) ad(jsonStr, "$.store.book[0].title");log.info("title={}", title);//price大于10元的bookList<Book> list = (List<Book>) ad(jsonStr, "$.store.book[price > 10]");log.info("price大于10元的book={}",list);//price大于10元的titleList<String> list2 =(List<String>) ad(jsonStr, "$.store.book[price > 10].title");log.info("price大于10元的title={}",list2);//category(类别)为科幻的bookList<Book> list3 = (List<Book>) ad(jsonStr,"$.store.book[category = '科幻']");log.info("category(类别)为科幻的book={}",list3);//bicycle的所有属性值Collection<String> values = (Collection<String>) JSONPath.eval(jsonObject, "$.store.bicycle.*");log.info("bicycle的所有属性值={}",values);//bicycle的color和price属性值List<String> read =(List<String>) ad(jsonStr, "$.store.bicycle['color','price']");log.info("bicycle的color和price属性值={}",read);}}

源码地址

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