Java基礎 json知識點

原創 Little-小样 2020-06-27 18:53
jackjson

  1. jackson在springboot的使用
    1.1 各種註解的使用

    • 返回結果測試
      @JsonIgnore：json序列化時忽略，可用於密碼
      @JsonProperty()：json序列化時，取一個別名
      @JsonFormat(pattern=“yyyy-MM-dd hh:mm:ss”,local=“zh”,timezone=“GMT+8”):用於規範時間格式
      @JsonInclude(Include.NOT_NULL) :json字段不爲空
    • 訪問不是默認路徑下的靜態頁面

    1.2 導入依賴

    	<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-thymeleaf</artifactId>
	</dependency>

    1.3 通過訪問controller，然後進行靜態頁面的跳轉

  2. jackson基礎轉載自
    2.1 jackson基本實現類：ObjectMapper

    import java.io.IOException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;

public class JacksonTester {
   public static void main(String args[]){
      ObjectMapper mapper = new ObjectMapper();
      String jsonString = "{\"name\":\"Mahesh\", \"age\":21}";

      //map json to student
      try {
         Student student = mapper.readValue(jsonString, Student.class);
         System.out.println(student);
         mapper.enable(SerializationConfig.Feature.INDENT_OUTPUT);
         jsonString = mapper.writeValueAsString(student);
         System.out.println(jsonString);

      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}
class Student {
   private String name;
   private int age;
   public Student(){}
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String toString(){
      return "Student [ name: "+name+", age: "+ age+ " ]";
   }	
}

    2.2 將json序列化到文件以及反序列化

    	import java.io.File;
import java.io.IOException;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      try {
         Student student = new Student();
         student.setAge(10);
         student.setName("Mahesh");
         tester.writeJSON(student);

         Student student1 = tester.readJSON();
         System.out.println(student1);

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

   private void writeJSON(Student student) throws JsonGenerationException, JsonMappingException, IOException{
      ObjectMapper mapper = new ObjectMapper();	
      mapper.writeValue(new File("student.json"), student);
   }

   private Student readJSON() throws JsonParseException, JsonMappingException, IOException{
      ObjectMapper mapper = new ObjectMapper();
      Student student = mapper.readValue(new File("student.json"), Student.class);
      return student;
   }
}

class Student {
   private String name;
   private int age;
   public Student(){}
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String toString(){
      return "Student [ name: "+name+", age: "+ age+ " ]";
   }	
}

    2.3 json數據與java類型之間的轉換

    import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
         try {
            ObjectMapper mapper = new ObjectMapper();
			//創建map
            Map<String,Object> studentDataMap = new HashMap<String,Object>(); 
            //創建數組
            int[] marks = {1,2,3};
			//創建學生對象
            Student student = new Student();
            student.setAge(10);
            student.setName("Mahesh");
            // JAVA Object
            studentDataMap.put("student", student);
            // JAVA String
            studentDataMap.put("name", "Mahesh Kumar");   		
            // JAVA Boolean
            studentDataMap.put("verified", Boolean.FALSE);
            // Array
            studentDataMap.put("marks", marks);

            mapper.writeValue(new File("student.json"), studentDataMap);
            //result student.json
			//{ 
            //   "student":{"name":"Mahesh","age":10},
            //   "marks":[1,2,3],
            //   "verified":false,
            //   "name":"Mahesh Kumar"
            //}
            studentDataMap = mapper.readValue(new File("student.json"), Map.class);

            System.out.println(studentDataMap.get("student"));
            System.out.println(studentDataMap.get("name"));
            System.out.println(studentDataMap.get("verified"));
            System.out.println(studentDataMap.get("marks"));
      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
            e.printStackTrace();
      }
   }
}

class Student {
   private String name;
   private int age;
   public Student(){}
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String toString(){
      return "Student [ name: "+name+", age: "+ age+ " ]";
   }	
}

    2.4 json全數據綁定

    	import java.io.File;
import java.io.IOException;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      try {
         Student student = new Student();
         student.setAge(10);
         student.setName("Mahesh");
         tester.writeJSON(student);

         Student student1 = tester.readJSON();
         System.out.println(student1);

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

   private void writeJSON(Student student) throws JsonGenerationException, JsonMappingException, IOException{
      ObjectMapper mapper = new ObjectMapper();	
      mapper.writeValue(new File("student.json"), student);
   }

   private Student readJSON() throws JsonParseException, JsonMappingException, IOException{
      ObjectMapper mapper = new ObjectMapper();
      Student student = mapper.readValue(new File("student.json"), Student.class);
      return student;
   }
}

class Student {
   private String name;
   private int age;
   public Student(){}
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String toString(){
      return "Student [ name: "+name+", age: "+ age+ " ]";
   }	
}

    2.5 Jackson數據綁定泛型

    import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
         try {
            ObjectMapper mapper = new ObjectMapper();

            Map userDataMap = new HashMap();
            UserData studentData = new UserData(); 
            int[] marks = {1,2,3};

            Student student = new Student();
            student.setAge(10);
            student.setName("Mahesh");
            // JAVA Object
            studentData.setStudent(student);
            // JAVA String
            studentData.setName("Mahesh Kumar");
            // JAVA Boolean
            studentData.setVerified(Boolean.FALSE);
            // Array
            studentData.setMarks(marks);
            TypeReference ref = new TypeReference>() { };
            userDataMap.put("studentData1", studentData);
            mapper.writeValue(new File("student.json"), userDataMap);
            //{
            //   "studentData1":
            //	 {
            //		"student":
            //		{
            //			"name":"Mahesh",
            //			"age":10
            //      },
            //      "name":"Mahesh Kumar",
            //      "verified":false,
            //      "marks":[1,2,3]
            //   }
            //}
            userDataMap = mapper.readValue(new File("student.json"), ref);

            System.out.println(userDataMap.get("studentData1").getStudent());
            System.out.println(userDataMap.get("studentData1").getName());
            System.out.println(userDataMap.get("studentData1").getVerified());
            System.out.println(Arrays.toString(userDataMap.get("studentData1").getMarks()));
      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
            e.printStackTrace();
      }
   }
}

class Student {
   private String name;
   private int age;
   public Student(){}
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public String toString(){
      return "Student [ name: "+name+", age: "+ age+ " ]";
   }	
}

class UserData {
   private Student student;
   private String name;
   private Boolean verified;
   private int[] marks;

   public UserData(){}

   public Student getStudent() {
      return student;
   }
   public void setStudent(Student student) {
      this.student = student;
   }
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public Boolean getVerified() {
      return verified;
   }
   public void setVerified(Boolean verified) {
      this.verified = verified;
   }
   public int[] getMarks() {
      return marks;
   }
   public void setMarks(int[] marks) {
      this.marks = marks;
   }		
}

    2.6 json可創建一顆樹並返回根節點

    //Create an ObjectMapper instance
ObjectMapper mapper = new ObjectMapper();	
String jsonString = "{\"name\":\"Mahesh Kumar\", \"age\":21,\"verified\":false,\"marks\": [100,90,85]}";
//create tree from JSON
JsonNode rootNode = mapper.readTree(jsonString);
// 遍歷模型
JsonNode nameNode = rootNode.path("name");
System.out.println("Name: "+ nameNode.getTextValue());
JsonNode marksNode = rootNode.path("marks");
Iterator iterator = marksNode.getElements();

    2.6.1 樹到JSON轉換

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

import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.node.ArrayNode;
import org.codehaus.jackson.node.ObjectNode;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      try {
         ObjectMapper mapper = new ObjectMapper();

         JsonNode rootNode = mapper.createObjectNode();
         JsonNode marksNode = mapper.createArrayNode();
         ((ArrayNode)marksNode).add(100);
         ((ArrayNode)marksNode).add(90);
         ((ArrayNode)marksNode).add(85);
         ((ObjectNode) rootNode).put("name", "Mahesh Kumar");
         ((ObjectNode) rootNode).put("age", 21);
         ((ObjectNode) rootNode).put("verified", false);
         ((ObjectNode) rootNode).put("marks",marksNode);

         mapper.writeValue(new File("student.json"), rootNode);

         rootNode = mapper.readTree(new File("student.json"));

         JsonNode nameNode = rootNode.path("name");
         System.out.println("Name: "+ nameNode.getTextValue());

         JsonNode ageNode = rootNode.path("age");
         System.out.println("Age: " + ageNode.getIntValue());

         JsonNode verifiedNode = rootNode.path("verified");
         System.out.println("Verified: " + (verifiedNode.getBooleanValue() ? "Yes":"No"));

         JsonNode marksNode1 = rootNode.path("marks");
         Iterator<JsonNode> iterator = marksNode1.getElements();
         System.out.print("Marks: [ ");
         while (iterator.hasNext()) {
            JsonNode marks = iterator.next();
            System.out.print(marks.getIntValue() + " "); 
         }
         System.out.println("]");
      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

    2.6.2 從樹到Java對象轉換

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

import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.node.ArrayNode;
import org.codehaus.jackson.node.ObjectNode;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      try {
         ObjectMapper mapper = new ObjectMapper();

         JsonNode rootNode = mapper.createObjectNode();
         JsonNode marksNode = mapper.createArrayNode();
         ((ArrayNode)marksNode).add(100);
         ((ArrayNode)marksNode).add(90);
         ((ArrayNode)marksNode).add(85);
         ((ObjectNode) rootNode).put("name", "Mahesh Kumar");
         ((ObjectNode) rootNode).put("age", 21);
         ((ObjectNode) rootNode).put("verified", false);
         ((ObjectNode) rootNode).put("marks",marksNode);

         mapper.writeValue(new File("student.json"), rootNode);

         rootNode = mapper.readTree(new File("student.json"));

         Student student = mapper.treeToValue(rootNode, Student.class);

         System.out.println("Name: "+ student.getName());
         System.out.println("Age: " + student.getAge());
         System.out.println("Verified: " + (student.isVerified() ? "Yes":"No"));
         System.out.println("Marks: "+Arrays.toString(student.getMarks()));
      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

class Student {
   String name;
   int age;
   boolean verified;
   int[] marks;
   public String getName() {
      return name;
   }
   public void setName(String name) {
      this.name = name;
   }
   public int getAge() {
      return age;
   }
   public void setAge(int age) {
      this.age = age;
   }
   public boolean isVerified() {
      return verified;
   }
   public void setVerified(boolean verified) {
      this.verified = verified;
   }
   public int[] getMarks() {
      return marks;
   }
   public void setMarks(int[] marks) {
      this.marks = marks;
   }
}

    2.7 流式API
    2.7.1 寫入

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

import org.codehaus.jackson.JsonEncoding;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      try {        	
         JsonFactory jasonFactory = new JsonFactory();

         JsonGenerator jsonGenerator = jasonFactory.createJsonGenerator(new File(
            "student.json"), JsonEncoding.UTF8);
         // {
         jsonGenerator.writeStartObject();
         // "name" : "Mahesh Kumar"
         jsonGenerator.writeStringField("name", "Mahesh Kumar"); 
         // "age" : 21
         jsonGenerator.writeNumberField("age", 21);
         // "verified" : false
         jsonGenerator.writeBooleanField("verified", false); 
         // "marks" : [100, 90, 85]
         jsonGenerator.writeFieldName("marks"); 
         // [
         jsonGenerator.writeStartArray(); 
         // 100, 90, 85
         jsonGenerator.writeNumber(100); 
         jsonGenerator.writeNumber(90); 
         jsonGenerator.writeNumber(85); 
         // ]
         jsonGenerator.writeEndArray(); 
         // }
         jsonGenerator.writeEndObject(); 
         jsonGenerator.close();       	 

         //result student.json
         //{ 
         //   "name":"Mahesh Kumar",
         //   "age":21,
         //   "verified":false,
         //   "marks":[100,90,85]
         //}
         ObjectMapper mapper = new ObjectMapper();
         Map<String,Object> dataMap = mapper.readValue(new File("student.json"), Map.class);

         System.out.println(dataMap.get("name"));
         System.out.println(dataMap.get("age"));
         System.out.println(dataMap.get("verified"));
         System.out.println(dataMap.get("marks"));
      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}

    2.7.2 使用JsonParser 讀取JSON

    import java.io.File;
import java.io.IOException;

import org.codehaus.jackson.JsonEncoding;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerator;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.JsonToken;
import org.codehaus.jackson.map.JsonMappingException;

public class JacksonTester {
   public static void main(String args[]){
      JacksonTester tester = new JacksonTester();
      try {        	
         JsonFactory jasonFactory = new JsonFactory();

         JsonGenerator jsonGenerator = jasonFactory.createJsonGenerator(new File(
            "student.json"), JsonEncoding.UTF8);
         jsonGenerator.writeStartObject();
         jsonGenerator.writeStringField("name", "Mahesh Kumar"); 
         jsonGenerator.writeNumberField("age", 21);
         jsonGenerator.writeBooleanField("verified", false); 
         jsonGenerator.writeFieldName("marks"); 
         jsonGenerator.writeStartArray(); // [
         jsonGenerator.writeNumber(100); 
         jsonGenerator.writeNumber(90); 
         jsonGenerator.writeNumber(85); 
         jsonGenerator.writeEndArray(); 
         jsonGenerator.writeEndObject(); 
         jsonGenerator.close();       	 

         //result student.json
         //{ 
         //   "name":"Mahesh Kumar",
         //   "age":21,
         //   "verified":false,
         //   "marks":[100,90,85]
         //}

         JsonParser jsonParser = jasonFactory.createJsonParser(new File("student.json"));
         while (jsonParser.nextToken() != JsonToken.END_OBJECT) {
            //get the current token
            String fieldname = jsonParser.getCurrentName();
            if ("name".equals(fieldname)) {
               //move to next token
               jsonParser.nextToken();
               System.out.println(jsonParser.getText());        	 
            }
            if("age".equals(fieldname)){
               //move to next token
               jsonParser.nextToken();
               System.out.println(jsonParser.getNumberValue());        	 
            }
            if("verified".equals(fieldname)){
               //move to next token
               jsonParser.nextToken();
               System.out.println(jsonParser.getBooleanValue());        	 
            }
            if("marks".equals(fieldname)){
               //move to [ 
               jsonParser.nextToken();
               // loop till token equal to "]"
               while (jsonParser.nextToken() != JsonToken.END_ARRAY) {
                  System.out.println(jsonParser.getNumberValue()); 
               }
            }
         }
      } catch (JsonParseException e) {
         e.printStackTrace();
      } catch (JsonMappingException e) {
         e.printStackTrace();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}
Fastjson

轉載來源：https://blog.csdn.net/srj1095530512/article/details/82529759
這個文章 fastjson講的很清楚，而且有對應的源碼分析，我就不多加總結了，有興趣的小哥可以去看看。
下面只是單純取出測試類以及測試代碼

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
 
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
 
 
public class MyJson {
	
	public static void main(String[] args) {
		
		List<Student> list=new ArrayList<>();
		Student student=new Student("bob",24);
		Student student12=new Student("lily", 23);
		list.add(student);
		list.add(student12);
		System.out.println("*******javaBean  to jsonString*******");
		String str1=JSON.toJSONString(student);
		System.out.println(str1);
		System.out.println(JSON.toJSONString(list));
		System.out.println();
		
		System.out.println("******jsonString to javaBean*******");
		//Student stu1=JSON.parseObject(str1,new TypeReference<Student>(){});
		Student stu1=JSON.parseObject(str1,Student.class);
		System.out.println(stu1);
		System.out.println();
		
		System.out.println("******javaBean to jsonObject******");
		JSONObject jsonObject1=(JSONObject)JSON.toJSON(student);
		System.out.println(jsonObject1.getString("name"));
		System.out.println();
		
		System.out.println("******jsonObject to javaBean******");
		Student student2=JSON.toJavaObject(jsonObject1, Student.class);
		System.out.println(student2);
		System.out.println();
		
		System.out.println("*******javaBean to jsonArray******");
		List<Student> stulist=new ArrayList<>();
		for(int i=0;i<5;i++){
			stulist.add(new Student("student"+i, i));
			
		}
		JSONArray jsonArrays=(JSONArray)JSON.toJSON(stulist);
		for(int i=0;i<jsonArrays.size();i++){
		System.out.println(jsonArrays.getJSONObject(i));
		}
		System.out.println();
		
		System.out.println("*****jsonArry to javalist******");
		List<Student> myList=new ArrayList<>();
		for(int i=0;i<jsonArrays.size();i++){
			
		Student student3=JSON.toJavaObject(jsonArrays.getJSONObject(i), Student.class);
			myList.add(student3);
		}
		for(Student stu:myList){
			System.out.println(stu);
		}
		
	        System.out.println();
		
		System.out.println("*****jsonObject to jsonString*****");
		String str4=JSON.toJSONString(jsonObject1);
		System.out.println(str4);
		System.out.println();
		
		System.out.println("*******jsonString to jsonObject*****");
		JSONObject jso1=JSON.parseObject(str1);
		System.out.println(jso1.getString("name"));
		System.out.println();
		
		System.out.println("*****jsonString to jsonArray*****");
		JSONArray jArray=JSON.parseArray(JSON.toJSONString(stulist));
		for(int i=0;i<jArray.size();i++){
		System.out.println(jArray.getJSONObject(i));
		}
		System.out.println();
	}
 
}


public class Student {
	
	private String name;
	private int age;
	
	public Student() {
		// TODO Auto-generated constructor stub
	}
	
	public Student(String name,int age){
		this.name=name;
		this.age=age;
	}
	
	public void setName(String name){
		this.name=name;
		
	}
	
	public String getName(){
		return name;
	}
	
	public void setAge(int age){
		this.age=age;
	}
	
	public int getAge(){
		return age;
	}
	
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return "student [name="+name+" , "+"age="+age+"]";
	}
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