How to parse and process JSON forms in Java?

How to parse and process JSON forms in Java?

With the development of the Internet, JSON (JavaScript Object Notation) has become a format widely used for data transmission and interaction. In Java development, we often need to parse and process JSON forms. This article will introduce how to use common JSON libraries in Java to parse and process JSON forms, with corresponding code examples.

1. Import JSON library
First, we need to import a suitable JSON library. Common JSON libraries include JSON-java, Jackson, Gson, etc. In this article, we will use the JSON-java library, which is a JSON library officially maintained by Java. It is easy to use and powerful.

1. Add the following dependencies in the pom.xml file:

   <dependency>
    <groupId>org.json</groupId>
    <artifactId>json</artifactId>
    <version>20210307</version>
   </dependency>

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2. Import related libraries in the Java class:

   import org.json.JSONArray;
   import org.json.JSONObject;

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2. Parse JSON form
The JSON form is usually a string, and we need to parse it into a Java object for operation and processing.

1. Parse a simple JSON form:

   String jsonStr = "{"name": "John", "age": 25, "city": "New York"}";
   
   JSONObject jsonObj = new JSONObject(jsonStr);
   
   String name = jsonObj.getString("name");
   int age = jsonObj.getInt("age");
   String city = jsonObj.getString("city");
   
   System.out.println("Name: " + name);
   System.out.println("Age: " + age);
   System.out.println("City: " + city);

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2. Parse a JSON form containing an array:

   String jsonStr = "{"students": [{"name": "John", "age": 25}, {"name": "Bob", "age": 28}]}";
   
   JSONObject jsonObj = new JSONObject(jsonStr);
   JSONArray students = jsonObj.getJSONArray("students");
   
   for (int i = 0; i < students.length(); i++) {
    JSONObject student = students.getJSONObject(i);
    String name = student.getString("name");
    int age = student.getInt("age");
    System.out.println("Name: " + name + ", Age: " + age);
   }

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3. Generate JSON form
In addition to parsing JSON forms, sometimes we also need to generate new JSON forms in Java.

1. Generate a simple JSON form:

   JSONObject jsonObj = new JSONObject();
   jsonObj.put("name", "John");
   jsonObj.put("age", 25);
   jsonObj.put("city", "New York");
   
   String jsonStr = jsonObj.toString();
   System.out.println(jsonStr);

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2. Generate a JSON form containing an array:

   JSONArray students = new JSONArray();
   
   JSONObject student1 = new JSONObject();
   student1.put("name", "John");
   student1.put("age", 25);
   
   JSONObject student2 = new JSONObject();
   student2.put("name", "Bob");
   student2.put("age", 28);
   
   students.put(student1);
   students.put(student2);
   
   JSONObject jsonObj = new JSONObject();
   jsonObj.put("students", students);
   
   String jsonStr = jsonObj.toString();
   System.out.println(jsonStr);

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The above are some basic operations for parsing and processing JSON forms in Java. By using a suitable JSON library, we can easily parse JSON forms into Java objects and manipulate them, as well as generate new JSON forms. I hope this article will help you process JSON forms in Java development.

Summary
This article introduces the basic steps for parsing and processing JSON forms in Java and provides corresponding code examples. In actual development, we can choose the appropriate JSON library to operate JSON data according to business needs. By using the JSON library properly, we can parse and process JSON data more efficiently. I hope this article can help you better handle JSON forms in Java development.

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