如何在Java中解析JSON_Java_Json_Parsing

如何在Java中解析JSON

java json parsing

如何在Java中解析JSON,java,json,parsing,Java,Json,Parsing,我有以下JSON文本。如何解析它以获得pageName、pagePic、post\u id等值 { “页面信息”：{ “页面名称”：“abc”， “pagePic”：http://example.com/content.jpg" }, “员额”：[ { “post_id”：“123456789012_123456789012”， “演员id”：“1234567890”， “发布者的照片”：http://example.com/photo.jpg", “发布者姓名”：“简·多伊”， “消息”：“听

我有以下JSON文本。如何解析它以获得

pageName

、

pagePic

、

post\u id

等值

{
“页面信息”：{
“页面名称”：“abc”，
“pagePic”：http://example.com/content.jpg"
},
“员额”：[
{
“post_id”：“123456789012_123456789012”，
“演员id”：“1234567890”，
“发布者的照片”：http://example.com/photo.jpg",
“发布者姓名”：“简·多伊”，
“消息”：“听起来很酷。迫不及待地想看它！”，
“LikeCount”：“2”，
“评论”：[…]，
“邮局时间”：“1234567890”
}
]
}

非常简单、灵活、快速且可定制。试试看

特点：

符合JSON规范（RFC4627）
高性能JSON解析器
支持灵活/可配置的解析方法
任何JSON层次结构的键/值对的可配置验证
易于使用#占地面积非常小
引发开发人员友好且易于跟踪的异常
可插拔自定义验证支持-可以在遇到时通过配置自定义验证程序来验证密钥/值
验证和非验证解析器支持
支持两种类型的配置（JSON/XML）以使用快速JSON验证解析器
需要JDK1.5
不依赖外部库
支持通过对象序列化生成JSON
在解析过程中支持集合类型选择

它可以这样使用：

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

JSONParser jsonParser = new JSONParser();
JSONObject obj = (JSONObject) jsonParser.parse(contentString);
String product = (String) jsonObject.get("productId");

我认为最好的做法应该是通过仍在进行中的官方文件。

图书馆很容易使用

只要记住（在强制转换或使用诸如

getJSONObject

和

getJSONArray

之类的方法时）在JSON表示法中

```
[…]
```
表示一个数组，所以库将把它解析为
```
JSONArray
```
```
{…}
```
表示一个对象，所以库将把它解析为
```
JSONObject
```

示例代码如下：

import org.json.*;

String jsonString = ... ; //assign your JSON String here
JSONObject obj = new JSONObject(jsonString);
String pageName = obj.getJSONObject("pageInfo").getString("pageName");

JSONArray arr = obj.getJSONArray("posts"); // notice that `"posts": [...]`
for (int i = 0; i < arr.length(); i++)
{
    String post_id = arr.getJSONObject(i).getString("post_id");
    ......
}

import org.json.*；
字符串jsonString=//在此处指定JSON字符串
JSONObject obj=新的JSONObject（jsonString）；
String pageName=obj.getJSONObject（“pageInfo”）.getString（“pageName”）；
JSONArray arr=obj.getJSONArray（“posts”）；//请注意“posts”：[…]`
对于（int i=0；i


您可以从以下内容中找到更多示例：
可下载的罐子：
这让我惊讶于它是多么的简单。您只需将保存JSON的字符串
传递给默认org.JSON包中JSONObject的构造函数即可
JSONArray rootOfPage =  new JSONArray(JSONString);

完成了。放下话筒。
这也适用于JSONObjects
。之后，您可以使用对象上的get（）
方法查看对象的层次结构
如果希望从JSON创建Java对象，反之亦然，请使用GSON或JACKSON第三方JAR等
//from object to JSON 
Gson gson = new Gson();
gson.toJson(yourObject);

// from JSON to object 
yourObject o = gson.fromJson(JSONString,yourObject.class);


但是，如果你只想解析一个JSON字符串并获取一些值（或者从头创建一个JSON字符串通过网络发送），只需使用JaveeeJAR，它包含JsonReader、JsonArray、JsonObject等。你可能需要下载该规范的实现，比如javax.JSON。通过这两个JAR，我能够解析json并使用这些值
这些API实际上遵循XML的DOM/SAX解析模型
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");


请这样做：
JsonParserFactory factory=JsonParserFactory.getInstance();
JSONParser parser=factory.newJsonParser();
Map jsonMap=parser.parseJson(jsonString);

JSONParser jsonParser = new JSONParser();
JSONObject obj = (JSONObject) jsonParser.parse(contentString);
String product = (String) jsonObject.get("productId");

{
“页面信息”：{
“页面名称”：“abc”，
“pagePic”：http://example.com/content.jpg"
},
“员额”：[
{
“post_id”：“123456789012_123456789012”，
“演员id”：“1234567890”，
“发布者的照片”：http://example.com/photo.jpg",
“发布者姓名”：“简·多伊”，
“消息”：“听起来很酷。迫不及待地想看它！”，
“LikeCount”：“2”，
“评论”：[…]，
“邮局时间”：“1234567890”
}
]
}
Java代码：
JSONObject obj=新的JSONObject（responsejsonobj）；
String pageName=obj.getJSONObject（“pageInfo”）.getString（“pageName”）；
JSONArray arr=obj.getJSONArray（“posts”）；
对于（int i=0；i
为了示例，让我们假设您有一个类Person只有一个名称
private class Person {
    public String name;

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

()
我个人最喜欢的是对象的JSON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
如果您想获取单个属性，也可以使用Google库轻松完成：
JsonObject jsonObject = new JsonParser().parse("{\"name\": \"John\"}").getAsJsonObject();

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

()
如果您不需要对象反序列化，只需要获取一个属性，您可以尝试org.json（或查看上面的示例！）
()
如果您有一些表示JSON字符串（jsonString）的Java类（比如Message），那么您可以将JSON库用于：
Message message= new ObjectMapper().readValue(jsonString, Message.class);

您可以从message对象获取其任何属性。
几乎所有给出的答案都需要在访问感兴趣的属性中的值之前将JSON完全反序列化为Java对象。另一种选择是使用类似于JSON的XPath并允许遍历JSON对象，而不是走这条路线
这是一个规范，JayWay的好人为该规范创建了一个Java实现，您可以在这里找到：
因此，基本上要使用它，请将其添加到您的项目中，例如：

com.jayway.jsonpath
json路径
${version}

以及使用：
String pageName=JsonPath.read（yourJsonString，“$.pageInfo.pageName”）；
字符串pagePic=JsonPath.read（yourJsonString，“$.pageInfo.pa
Message message= new ObjectMapper().readValue(jsonString, Message.class);

@Generated("org.jsonschema2pojo")
public class Container {
    @SerializedName("pageInfo")
    @Expose
    public PageInfo pageInfo;
    @SerializedName("posts")
    @Expose
    public List<Post> posts = new ArrayList<Post>();
}

@Generated("org.jsonschema2pojo")
public class PageInfo {
    @SerializedName("pageName")
    @Expose
    public String pageName;
    @SerializedName("pagePic")
    @Expose
    public String pagePic;
}

@Generated("org.jsonschema2pojo")
public class Post {
    @SerializedName("post_id")
    @Expose
    public String postId;
    @SerializedName("actor_id")
    @Expose
    public long actorId;
    @SerializedName("picOfPersonWhoPosted")
    @Expose
    public String picOfPersonWhoPosted;
    @SerializedName("nameOfPersonWhoPosted")
    @Expose
    public String nameOfPersonWhoPosted;
    @SerializedName("message")
    @Expose
    public String message;
    @SerializedName("likesCount")
    @Expose
    public long likesCount;
    @SerializedName("comments")
    @Expose
    public List<Object> comments = new ArrayList<Object>();
    @SerializedName("timeOfPost")
    @Expose
    public long timeOfPost;
}

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import com.google.gson.Gson;

public class GsonExample {
    public static void main(String[] args) {

    Gson gson = new Gson();

    try {

        BufferedReader br = new BufferedReader(
            new FileReader("c:\\file.json"));

        //convert the json string back to object
        DataObject obj = gson.fromJson(br, DataObject.class);

        System.out.println(obj);

    } catch (IOException e) {
        e.printStackTrace();
    }

    }
}

javax.json.JsonReader jr = 
    javax.json.Json.createReader(new StringReader(jsonText));
javax.json.JsonObject jo = jr.readObject();

//Read the page info.
javax.json.JsonObject pageInfo = jo.getJsonObject("pageInfo");
System.out.println(pageInfo.getString("pageName"));

//Read the posts.
javax.json.JsonArray posts = jo.getJsonArray("posts");
//Read the first post.
javax.json.JsonObject post = posts.getJsonObject(0);
//Read the post_id field.
String postId = post.getString("post_id");

class MyModel {

    private PageInfo pageInfo;
    private ArrayList<Post> posts = new ArrayList<>();
}

class PageInfo {

    private String pageName;
    private String pagePic;
}

class Post {

    private String post_id;

    @SerializedName("actor_id") // <- example SerializedName
    private String actorId;

    private String picOfPersonWhoPosted;
    private String nameOfPersonWhoPosted;
    private String message;
    private String likesCount;
    private ArrayList<String> comments;
    private String timeOfPost;
}

MyModel model = gson.fromJson(jsonString, MyModel.class);

implementation 'com.google.code.gson:gson:2.8.6' // or earlier versions

public class MyObj {

    private PageInfo pageInfo;
    private List<Post> posts;

    static final class PageInfo {
        private String pageName;
        private String pagePic;
    }

    static final class Post {
        private String post_id;
        @JsonProperty("actor_id");
        private String actorId;
        @JsonProperty("picOfPersonWhoPosted")
        private String pictureOfPoster;
        @JsonProperty("nameOfPersonWhoPosted")
        private String nameOfPoster;
        private String likesCount;
        private List<String> comments;
        private String timeOfPost;
    }

    private static final ObjectMapper JACKSON = new ObjectMapper();
    public static void main(String[] args) throws IOException {
        MyObj o = JACKSON.readValue(args[0], MyObj.class); // assumes args[0] contains your json payload provided in your question.
    }
}

com.fasterxml.jackson.databind.ObjectMapper

package com.levo.jsonex.model;

public class Page {
    
    private PageInfo pageInfo;
    private Post[] posts;

    public PageInfo getPageInfo() {
        return pageInfo;
    }

    public void setPageInfo(PageInfo pageInfo) {
        this.pageInfo = pageInfo;
    }

    public Post[] getPosts() {
        return posts;
    }

    public void setPosts(Post[] posts) {
        this.posts = posts;
    }
    
}

package com.levo.jsonex.model;

public class PageInfo {
    
    private String pageName;
    private String pagePic;
    
    public String getPageName() {
        return pageName;
    }
    
    public void setPageName(String pageName) {
        this.pageName = pageName;
    }
    
    public String getPagePic() {
        return pagePic;
    }
    
    public void setPagePic(String pagePic) {
        this.pagePic = pagePic;
    }
    
}

package com.levo.jsonex.model;

public class Post {
    
    private String post_id;
    private String actor_id;
    private String picOfPersonWhoPosted;
    private String nameOfPersonWhoPosted;
    private String message;
    private int likesCount;
    private String[] comments;
    private int timeOfPost;

    public String getPost_id() {
        return post_id;
    }

    public void setPost_id(String post_id) {
        this.post_id = post_id;
    }

    public String getActor_id() {
        return actor_id;
    }

    public void setActor_id(String actor_id) {
        this.actor_id = actor_id;
    }

    public String getPicOfPersonWhoPosted() {
        return picOfPersonWhoPosted;
    }
    
    public void setPicOfPersonWhoPosted(String picOfPersonWhoPosted) {
        this.picOfPersonWhoPosted = picOfPersonWhoPosted;
    }

    public String getNameOfPersonWhoPosted() {
        return nameOfPersonWhoPosted;
    }

    public void setNameOfPersonWhoPosted(String nameOfPersonWhoPosted) {
        this.nameOfPersonWhoPosted = nameOfPersonWhoPosted;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public int getLikesCount() {
        return likesCount;
    }

    public void setLikesCount(int likesCount) {
        this.likesCount = likesCount;
    }

    public String[] getComments() {
        return comments;
    }

    public void setComments(String[] comments) {
        this.comments = comments;
    }

    public int getTimeOfPost() {
        return timeOfPost;
    }

    public void setTimeOfPost(int timeOfPost) {
        this.timeOfPost = timeOfPost;
    }
    
}

package com.levo.jsonex;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.levo.jsonex.model.Page;
import com.levo.jsonex.model.PageInfo;
import com.levo.jsonex.model.Post;

public class JSONDemo {
    
    public static void main(String[] args) {
        ObjectMapper objectMapper = new ObjectMapper();
        
        try {
            Page page = objectMapper.readValue(new File("sampleJSONFile.json"), Page.class);
            
            printParsedObject(page);
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }
    
    private static void printParsedObject(Page page) {
        printPageInfo(page.getPageInfo());
        System.out.println();
        printPosts(page.getPosts());
    }

    private static void printPageInfo(PageInfo pageInfo) {
        System.out.println("Page Info;");
        System.out.println("**********");
        System.out.println("\tPage Name : " + pageInfo.getPageName());
        System.out.println("\tPage Pic  : " + pageInfo.getPagePic());
    }
    
    private static void printPosts(Post[] posts) {
        System.out.println("Page Posts;");
        System.out.println("**********");
        for(Post post : posts) {
            printPost(post);
        }
    }
    
    private static void printPost(Post post) {
        System.out.println("\tPost Id                   : " + post.getPost_id());
        System.out.println("\tActor Id                  : " + post.getActor_id());
        System.out.println("\tPic Of Person Who Posted  : " + post.getPicOfPersonWhoPosted());
        System.out.println("\tName Of Person Who Posted : " + post.getNameOfPersonWhoPosted());
        System.out.println("\tMessage                   : " + post.getMessage());
        System.out.println("\tLikes Count               : " + post.getLikesCount());
        System.out.println("\tComments                  : " + Arrays.toString(post.getComments()));
        System.out.println("\tTime Of Post              : " + post.getTimeOfPost());
    }
    
}

Page Info;
****(*****
    Page Name : abc
    Page Pic  : http://example.com/content.jpg
Page Posts;
**********
    Post Id                   : 123456789012_123456789012
    Actor Id                  : 1234567890
    Pic Of Person Who Posted  : http://example.com/photo.jpg
    Name Of Person Who Posted : Jane Doe
    Message                   : Sounds cool. Can't wait to see it!
    Likes Count               : 2
    Comments                  : []
    Time Of Post              : 1234567890

 String json  = callToTranslateApi("work", "de");
 JsonObject jsonObject = new JsonParser().parse(json).getAsJsonObject();
 return jsonObject.get("data").getAsJsonObject()
         .get("translations").getAsJsonArray()
         .get(0).getAsJsonObject()
         .get("translatedText").getAsString();

 class ApiResponse {
     Data data;      
     class Data {
         Translation[] translations;         
         class Translation {
             String translatedText;
         }
      }
  }

  Gson g = new Gson();
  String json =callToTranslateApi("work", "de");
  ApiResponse response = g.fromJson(json, ApiResponse.class);
  return response.data.translations[0].translatedText;

$.pageInfo.pageName = abc
$.pageInfo.pagePic = http://example.com/content.jpg
$.posts[0].post_id  = 123456789012_123456789012

{
   "pageInfo": {
         "pageName": "abc",
         "pagePic": "http://example.com/content.jpg"
    }
}

class PageInfo {

    private String pageName;
    private String pagePic;

    // Getters and setters
}

    PageInfo pageInfo = JsonPath.parse(jsonString).read("$.pageInfo", PageInfo.class);

<dependency>
    <groupId>com.jayway.jsonpath</groupId>
    <artifactId>json-path</artifactId>
    <version>2.2.0</version>
</dependency>

private static final String EXTRACTOR_SCRIPT =
    "var fun = function(raw) { " +
    "var json = JSON.parse(raw); " +
    "return [json.pageInfo.pageName, json.pageInfo.pagePic, json.posts[0].post_id];};";

public void run() throws ScriptException, NoSuchMethodException {
    ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
    engine.eval(EXTRACTOR_SCRIPT);
    Invocable invocable = (Invocable) engine;
    JSObject result = (JSObject) invocable.invokeFunction("fun", JSON);
    result.values().forEach(e -> System.out.println(e));
}

var fun = function(raw) {JSON.parse(raw).entries};

(JSObject) invocable.invokeFunction("fun", json);

new JSONObject(JSON).getJSONArray("entries");

mapper.readValue(JSON, Entries.class).getEntries();

ObjectMapper mapper = new ObjectMapper();
JsonNode yourObj = mapper.readTree("{\"k\":\"v\"}");

JSONObject jsonObj = new JSONObject(<jsonStr>);

String id = jsonObj.getString("pageInfo");

JSONObject jObj = new JSONObject(contents.trim());
Iterator<?> keys = jObj.keys();

while( keys.hasNext() ) {
  String key = (String)keys.next();
  if ( jObj.get(key) instanceof JSONObject ) {           
    System.out.println(jObj.getString(String key));
  }
}

Gson gson = new Gson();
JsonObject jsonObject = gson.fromJson(jsonAsString, JsonObject.class);

String pageName = jsonObject.getAsJsonObject("pageInfo").get("pageName").getAsString();
String pagePic = jsonObject.getAsJsonObject("pageInfo").get("pagePic").getAsString();
String postId = jsonObject.getAsJsonArray("posts").get(0).getAsJsonObject().get("post_id").getAsString();

JsonArray posts = jsonObject.getAsJsonArray("posts");
for (JsonElement post : posts) {
  String postId = post.getAsJsonObject().get("post_id").getAsString();
  //do something
}

@Model(className="RepositoryInfo", properties = {
    @Property(name = "id", type = int.class),
    @Property(name = "name", type = String.class),
    @Property(name = "owner", type = Owner.class),
    @Property(name = "private", type = boolean.class),
})
final class RepositoryCntrl {
    @Model(className = "Owner", properties = {
        @Property(name = "login", type = String.class)
    })
    static final class OwnerCntrl {
    }
}

List<RepositoryInfo> repositories = new ArrayList<>();
try (InputStream is = initializeStream(args)) {
    Models.parse(CONTEXT, RepositoryInfo.class, is, repositories);
}

System.err.println("there is " + repositories.size() + " repositories");
repositories.stream().filter((repo) -> repo != null).forEach((repo) -> {
    System.err.println("repository " + repo.getName() + 
        " is owned by " + repo.getOwner().getLogin()
    );
})

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

JSONArray ja = new JSONArray(String jsonString);