Java中json处理工具JsonPath的使用教程

{
    "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
}

    // 读取json字符串的expensive叶子节点的值
    Object expensive = JsonPath.read(jsonStr, "$.expensive");
    log.info("expensive value: {}, class: {}", expensive, expensive.getClass().getCanonicalName());
    // 读取json字符串store节点下bicycle节点的值
    Object bicycle = JsonPath.read(jsonStr, "$.store.bicycle");
    log.info("bicycle value: {}, class: {}", bicycle, bicycle.getClass().getCanonicalName());
    // 读取json字符串store下第一个book节点的值
    Object book = JsonPath.read(jsonStr, "$.store.book[0]");
    log.info("book value: {}, class: {}", book, book.getClass().getCanonicalName());
    // 读取json字符串所有的author后代节点的值
    Object authors = JsonPath.read(jsonStr, "$..author");
    log.info("authors value: {}, class: {}", authors, authors.getClass().getCanonicalName());
    // 读取json字符串中所有price值小于10的值
    Object books = JsonPath.read(jsonStr, "$.store.book[?(@.price < 10)]");
    log.info("books value: {}, class: {}", books, books.getClass().getCanonicalName());

Long expensive = JsonPath.parse(jsonStr).read("$.expensive", Long.class);
Bicycle bicycle = JsonPath.parse(jsonStr).read("$.store.bicycle", Bicycle.class);

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.15.2</version>
    </dependency>

Configuration.setDefaults(new Configuration.Defaults() {
    // 底层使用jackson
    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);
    }
});
TypeRef<List<String>> typeRef = new TypeRef<List<String>>() {};
List<String> authors = JsonPath.parse(jsonStr).read("$..author", typeRef);

Object book = JsonPath.read(jsonStr, "$.store.book[0]");
String target = "{\"x\": 128}";
String modified = JsonPath.parse(target).set("$.x", book).jsonString();

Object book = JsonPath.read(jsonStr, "$.store.book[0]");
String target = "{\"x\": 128}";
String modified = JsonPath.parse(target).put("$", "k", book).jsonString();

String target = "{\"x\": [128]}";
String modified = JsonPath.parse(target).put("$.x", 300).jsonString();

String target = "{\"x\": [128]}";
String modified = JsonPath.parse(target).renameKey("$", "x", "y").jsonString();

String target = "{\"x\": [128]}";
String modified = JsonPath.parse(target).delete("$.x").jsonString();

public enum Option {
    DEFAULT_PATH_LEAF_TO_NULL,
    ALWAYS_RETURN_LIST,
    AS_PATH_LIST,
    SUPPRESS_EXCEPTIONS,
    REQUIRE_PROPERTIES
}

Configuration conf = Configuration.builder()
   .options(Option.AS_PATH_LIST).build();
List<String> pathList = JsonPath.using(conf).parse(jsonStr).read("$..author");
// 返回的是author节点的路径列表
assertThat(pathList).containsExactly(
    "$['store']['book'][0]['author']",
    "$['store']['book'][1]['author']",
    "$['store']['book'][2]['author']",
    "$['store']['book'][3]['author']");

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);
    }
});

Object book = JsonPath.read(jsonStr, "$.store.book[0]");

DocumentContext context = JsonPath.parse(jsonStr)
Long expensive = context.read("$.expensive", Long.class);
Bicycle bicycle = context.read("$.store.bicycle", Bicycle.class);

com.jayway.jsonpath.spi.cache.LRUCache (default, thread safe)
com.jayway.jsonpath.spi.cache.NOOPCache (no cache)

CacheProvider.setCache(new LRUCache(100));

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);
    }
});