您可以使用DSM流解析库来解析复杂的json和XML文档。DSM只解析一次数据，不会将所有数据加载到内存中。

假设我们有一个Page类来反序列化给定的json数据。

页面类

public class Page {
    private String pageName;
    private String pageImage;
    private List<Sting> postIds;

    // getter/setter

}

创建一个yaml Mapping文件。

result:
  type: object     # result is array
  path: /posts
  fields:
    pageName:
        path: /pageInfo/pageName
    pageImage:
        path: /pageInfo/pagePic
    postIds:
      path: post_id
      type: array

使用DSM提取字段。

DSM dsm=new DSMBuilder(new File("path-to-yaml-config.yaml")).create(Page.class);
Page page= (Page)dsm.toObject(new path-to-json-data.json");

页面变量序列化为json:

{
  "pageName" : "abc",
  "pageImage" : "http://example.com/content.jpg",
  "postIds" : [ "123456789012_123456789012" ]
}

DSM非常适合处理复杂的json和xml。

Quick-json解析器非常简单，灵活，快速，可定制。试一试

特点:

Compliant with JSON specification (RFC4627) High-Performance JSON parser Supports Flexible/Configurable parsing approach Configurable validation of key/value pairs of any JSON Hierarchy Easy to use # Very small footprint Raises developer friendly and easy to trace exceptions Pluggable Custom Validation support - Keys/Values can be validated by configuring custom validators as and when encountered Validating and Non-Validating parser support Support for two types of configuration (JSON/XML) for using quick-JSON validating parser Requires JDK 1.5 No dependency on external libraries Support for JSON Generation through object serialisation Support for collection type selection during parsing process

它可以这样使用:

JsonParserFactory factory=JsonParserFactory.getInstance();
JSONParser parser=factory.newJsonParser();
Map jsonMap=parser.parseJson(jsonString);

如果你的数据很简单，你不想要外部依赖，可以使用以下几行代码:

/**
 * A very simple JSON parser for one level, everything quoted.
 * @param json the json content.
 * @return a key => value map.
 */
public static Map<String, String> simpleParseJson(String json) {
    Map<String, String> map = new TreeMap<>();
    String qs[] = json.replace("\\\"", "\u0001").replace("\\\\", "\\").split("\"");
    for (int i = 1; i + 3 < qs.length; i += 4) {
        map.put(qs[i].replace('\u0001', '"'), qs[i + 2].replace('\u0001', '"'));
    }
    return map;
}

这些数据

{"name":"John", "age":"30", "car":"a \"quoted\" back\\slash car"}

生成一个包含

{age=30, car=a "quoted" back\slash car, name=John}

这也可以升级为使用未加引号的值…

/**
 * A very simple JSON parser for one level, names are quoted.
 * @param json the json content.
 * @return a key => value map.
 */
public static Map<String, String> simpleParseJson(String json) {
    Map<String, String> map = new TreeMap<>();
    String qs[] = json.replace("\\\"", "\u0001").replace("\\\\",  "\\").split("\"");
    for (int i = 1; i + 1 < qs.length; i += 4) {
        if (qs[i + 1].trim().length() > 1) {
            String x = qs[i + 1].trim();
            map.put(qs[i].replace('\u0001', '"'), x.substring(1, x.length() - 1).trim().replace('\u0001', '"'));
            i -= 2;
        } else {
            map.put(qs[i].replace('\u0001', '"'), qs[i + 2].replace('\u0001', '"'));
        }
    }
    return map;
}

为了解决复杂的结构，它变得很难看… ．.． 对不起! !．.． 但我忍不住把它编码了^^ 这将解析给定的JSON以及更多内容。它产生嵌套的映射和列表。

/**
 * A very simple JSON parser, names are quoted.
 * 
 * @param json the json content.
 * @return a key => value map.
 */
public static Map<String, Object> simpleParseJson(String json) {
    Map<String, Object> map = new TreeMap<>();
    String qs[] = json.replace("\\\"", "\u0001").replace("\\\\", "\\").split("\"");
    int index[] = { 1 };
    recurse(index, map, qs);
    return map;
}

/**
 * Eierlegende Wollmilchsau.
 * 
 * @param index index into array.
 * @param map   the current map to fill.
 * @param qs    the data.
 */
private static void recurse(int[] index, Map<String, Object> map, String[] qs) {
    int i = index[0];
    for (;; i += 4) {
        String end = qs[i - 1].trim(); // check for termination of an object
        if (end.startsWith("}")) {
            qs[i - 1] = end.substring(1).trim();
            i -= 4;
            break;
        }

        String key = qs[i].replace('\u0001', '"');
        String x = qs[i + 1].trim();
        if (x.endsWith("{")) {
            x = x.substring(0, x.length() - 1).trim();
            if (x.endsWith("[")) {
                List<Object> list = new ArrayList<>();
                index[0] = i + 2;
                for (;;) {
                    Map<String, Object> inner = new TreeMap<>();
                    list.add(inner);
                    recurse(index, inner, qs);
                    map.put(key, list);
                    i = index[0];

                    String y = qs[i + 3]; // check for termination of array
                    if (y.startsWith("]")) {
                        qs[i + 3] = y.substring(1).trim();
                        break;
                    }
                }
                continue;
            }

            Map<String, Object> inner = new TreeMap<>();
            index[0] = i + 2;
            recurse(index, inner, qs);
            map.put(key, inner);
            i = index[0];
            continue;
        }
        if (x.length() > 1) { // unquoted
            String value = x.substring(1, x.length() - 1).trim().replace('\u0001', '"');
            if ("[]".equals(value)) // handle empty array
                map.put(key, new ArrayList<>());
            else
                map.put(key, value);
            i -= 2;
        } else {
            map.put(key, qs[i + 2].replace('\u0001', '"'));
        }
    }
    index[0] = i;
}

yield -如果你打印地图:

{pageInfo={pageName=abc, pagePic=http://example.com/content.jpg}, posts=[{actor_id=1234567890, comments=[], likesCount=2, message=Sounds cool. Can't wait to see it!, nameOfPersonWhoPosted=Jane Doe, picOfPersonWhoPosted=http://example.com/photo.jpg, post_id=123456789012_123456789012, timeOfPost=1234567890}]}

Jsoniter (jsoniterator)是一个相对较新的和简单的json库，旨在简单和快速。反序列化json数据所需要做的就是

JsonIterator.deserialize(jsonData, int[].class);

其中jsonData是json数据的字符串。

去官方网站看看吧 获取更多信息。

为了便于示例，让我们假设您有一个只有名称的Person类。

private class Person {
    public String name;

    public Person(String name) {
        this.name = name;
    }
}

谷歌GSON (Maven)

我个人最喜欢的JSON对象序列化/反序列化。

Gson g = new Gson();

Person person = g.fromJson("{\"name\": \"John\"}", Person.class);
System.out.println(person.name); //John

System.out.println(g.toJson(person)); // {"name":"John"}

更新

如果你想获取单个属性，你可以很容易地使用谷歌库:

JsonObject jsonObject = new JsonParser().parse("{\"name\": \"John\"}").getAsJsonObject();

System.out.println(jsonObject.get("name").getAsString()); //John

Org。JSON (Maven)

如果您不需要对象反序列化，而只是获得一个属性，您可以尝试org。json(或查看上面的GSON示例!)

JSONObject obj = new JSONObject("{\"name\": \"John\"}");

System.out.println(obj.getString("name")); //John

杰克逊(Maven)

ObjectMapper mapper = new ObjectMapper();
Person user = mapper.readValue("{\"name\": \"John\"}", Person.class);

System.out.println(user.name); //John

If one wants to create Java object from JSON and vice versa, use GSON or JACKSON third party jars etc. //from object to JSON Gson gson = new Gson(); gson.toJson(yourObject); // from JSON to object yourObject o = gson.fromJson(JSONString,yourObject.class); But if one just want to parse a JSON string and get some values, (OR create a JSON string from scratch to send over wire) just use JaveEE jar which contains JsonReader, JsonArray, JsonObject etc. You may want to download the implementation of that spec like javax.json. With these two jars I am able to parse the json and use the values. These APIs actually follow the DOM/SAX parsing model of XML. Response response = request.get(); // REST call JsonReader jsonReader = Json.createReader(new StringReader(response.readEntity(String.class))); JsonArray jsonArray = jsonReader.readArray(); ListIterator l = jsonArray.listIterator(); while ( l.hasNext() ) { JsonObject j = (JsonObject)l.next(); JsonObject ciAttr = j.getJsonObject("ciAttributes");