我有以下JSON文本。我如何解析它以获得pageName, pagePic, post_id等的值?
{
"pageInfo": {
"pageName": "abc",
"pagePic": "http://example.com/content.jpg"
},
"posts": [
{
"post_id": "123456789012_123456789012",
"actor_id": "1234567890",
"picOfPersonWhoPosted": "http://example.com/photo.jpg",
"nameOfPersonWhoPosted": "Jane Doe",
"message": "Sounds cool. Can't wait to see it!",
"likesCount": "2",
"comments": [],
"timeOfPost": "1234567890"
}
]
}
当前回答
除了其他答案，我推荐这个在线开源服务jsonschema2pojo.org，它可以从json或json模式快速生成Java类，用于GSON, Jackson 1。或者Jackson 2.x。例如，如果你有:
{
"pageInfo": {
"pageName": "abc",
"pagePic": "http://example.com/content.jpg"
}
"posts": [
{
"post_id": "123456789012_123456789012",
"actor_id": 1234567890,
"picOfPersonWhoPosted": "http://example.com/photo.jpg",
"nameOfPersonWhoPosted": "Jane Doe",
"message": "Sounds cool. Can't wait to see it!",
"likesCount": 2,
"comments": [],
"timeOfPost": 1234567890
}
]
}
GSON的jsonschema2pojo.org生成:
@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;
}
其他回答
阅读下面的博文，Java中的JSON。
这篇文章有点老了，但我仍然想回答你的问题。
步骤1:创建数据的POJO类。
步骤2:现在使用JSON创建一个对象。
Employee employee = null;
ObjectMapper mapper = new ObjectMapper();
try {
employee = mapper.readValue(newFile("/home/sumit/employee.json"), Employee.class);
}
catch(JsonGenerationException e) {
e.printStackTrace();
}
如需进一步参考，请参阅以下链接。
我们可以使用JSONObject类将JSON字符串转换为JSON对象， 和遍历JSON对象。使用下面的代码。
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));
}
}
{
"pageInfo": {
"pageName": "abc",
"pagePic": "http://example.com/content.jpg"
},
"posts": [
{
"post_id": "123456789012_123456789012",
"actor_id": "1234567890",
"picOfPersonWhoPosted": "http://example.com/photo.jpg",
"nameOfPersonWhoPosted": "Jane Doe",
"message": "Sounds cool. Can't wait to see it!",
"likesCount": "2",
"comments": [],
"timeOfPost": "1234567890"
}
]
}
Java code :
JSONObject obj = new JSONObject(responsejsonobj);
String pageName = obj.getJSONObject("pageInfo").getString("pageName");
JSONArray arr = obj.getJSONArray("posts");
for (int i = 0; i < arr.length(); i++)
{
String post_id = arr.getJSONObject(i).getString("post_id");
......etc
}
本页的热门答案使用了太简单的例子，比如只有一个属性的对象(例如{name: value})。我认为这个简单但真实的例子可以帮助到一些人。
这是谷歌Translate API返回的JSON:
{
"data":
{
"translations":
[
{
"translatedText": "Arbeit"
}
]
}
}
我想检索“translatedText”属性的值。“Arbeit”使用谷歌的Gson。
两种可能的方法:
Retrieve just one needed attribute 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(); Create Java object from JSON 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;
A -解释
您可以使用Jackson库，将JSON字符串绑定到POJO(普通旧Java对象)实例中。POJO只是一个只有私有字段和公共getter/setter方法的类。Jackson将遍历这些方法(使用反射)，并将JSON对象映射到POJO实例，因为类的字段名与JSON对象的字段名相匹配。
在JSON对象中，它实际上是一个复合对象，主对象由两个子对象组成。因此，我们的POJO类应该具有相同的层次结构。我将把整个JSON对象称为Page对象。Page对象由PageInfo对象和Post对象数组组成。
所以我们必须创建三个不同的POJO类;
页面类，PageInfo类和Post实例数组的组合 PageInfo类 文章类
我唯一用过的包是Jackson ObjectMapper，我们做的是绑定数据;
com.fasterxml.jackson.databind.ObjectMapper
所需的依赖项，jar文件如下所示;
jackson-core-2.5.1.jar jackson-databind-2.5.1.jar jackson-annotations-2.5.0.jar
这里是所需的代码;
主POJO类:页
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;
}
}
C -儿童POJO类:PageInfo
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;
}
}
D -儿童POJO类:Post
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;
}
}
E -样本JSON文件:sampleJSONFile.json
我刚刚将JSON示例复制到这个文件中，并将其放在项目文件夹下。
{
"pageInfo": {
"pageName": "abc",
"pagePic": "http://example.com/content.jpg"
},
"posts": [
{
"post_id": "123456789012_123456789012",
"actor_id": "1234567890",
"picOfPersonWhoPosted": "http://example.com/photo.jpg",
"nameOfPersonWhoPosted": "Jane Doe",
"message": "Sounds cool. Can't wait to see it!",
"likesCount": "2",
"comments": [],
"timeOfPost": "1234567890"
}
]
}
F -演示代码
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());
}
}
G -演示输出
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
