JSONObjec的作用详解——Web网络系列学习笔记

Posted 2021-12-06 来老铁干了这碗代码

JSONObject只是一种数据结构，可以理解为JSON格式的数据结构（key-value 结构），可以使用put方法给json对象添加元素。JSONObject可以很方便的转换成字符串，也可以很方便的把其他对象转换成JSONObject对象。

总而言之，JSONObject是一种中间结构，并且在网络中有很快的传输速度。

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1. 依赖包：fastjson

 <dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.28</version>
 </dependency>

2. 通过原生生成json数据格式。

JSONObject zhangsan = new JSONObject();
        try {
            //添加
            zhangsan.put("name", "张三");
            zhangsan.put("age", 18.4);
            zhangsan.put("birthday", "1900-20-03");
            zhangsan.put("majar", new String[] {"哈哈","嘿嘿"});
            zhangsan.put("null", null);
            zhangsan.put("house", false);
            System.out.println(zhangsan.toString());
        } catch (JSONException e) {
            e.printStackTrace();
        }

3. 通过hashMap数据结构生成

HashMap<String, Object> zhangsan = new HashMap<>();
   
   zhangsan.put("name", "张三");
   zhangsan.put("age", 18.4);
   zhangsan.put("birthday", "1900-20-03");
   zhangsan.put("majar", new String[] {"哈哈","嘿嘿"});
   zhangsan.put("null", null);
   zhangsan.put("house", false);
   System.out.println(new JSONObject(zhangsan).toString());

---

4. 通过实体生成

 Student student = new Student();
 student.setId(1);
 student.setAge("20");
 student.setName("张三");
 //生成json格式
 System.out.println(JSON.toJSON(student));
 //对象转成string
 String stuString = JSONObject.toJSONString(student);

---

5. JSON字符串转换成JSON对象

String studentString = "{\\"id\\":1,\\"age\\":2,\\"name\\":\\"zhang\\"}";
 
//JSON字符串转换成JSON对象
JSONObject jsonObject1 = JSONObject.parseObject(stuString);
 
System.out.println(jsonObject1);

---

6. list对象转listJson

ArrayList<Student> studentLsit = new ArrayList<>();
Student student1 = new Student();
student1.setId(1);
student1.setAge("20");
student1.setName("asdasdasd");

studentLsit.add(student1);

Student student2 = new Student();
student2.setId(2);
student2.setAge("20");
student2.setName("aaaa:;aaa");

studentLsit.add(student2);

//list转json字符串
String string = JSON.toJSON(studentLsit).toString();
System.out.println(string);

//json字符串转listJson格式
JSONArray jsonArray = JSONObject.parseArray(string);

System.out.println(jsonArray);

---

7. fastjson包中的Json源码

  // IntelliJ API Decompiler stub source generated from a class file
  // Implementation of methods is not available

package com.alibaba.fastjson;

public class JSONObject extends com.alibaba.fastjson.JSON implements java.util.Map<java.lang.String,java.lang.Object>, java.lang.Cloneable, java.io.Serializable, java.lang.reflect.InvocationHandler {
    private static final long serialVersionUID = 1L;
    private static final int DEFAULT_INITIAL_CAPACITY = 16;
    private final java.util.Map<java.lang.String,java.lang.Object> map;

    public JSONObject() { /* compiled code */ }

    public JSONObject(java.util.Map<java.lang.String,java.lang.Object> map) { /* compiled code */ }

    public JSONObject(boolean ordered) { /* compiled code */ }

    public JSONObject(int initialCapacity) { /* compiled code */ }

    public JSONObject(int initialCapacity, boolean ordered) { /* compiled code */ }

    public int size() { /* compiled code */ }

    public boolean isEmpty() { /* compiled code */ }

    public boolean containsKey(java.lang.Object key) { /* compiled code */ }

    public boolean containsValue(java.lang.Object value) { /* compiled code */ }

    public java.lang.Object get(java.lang.Object key) { /* compiled code */ }

    public com.alibaba.fastjson.JSONObject getJSONObject(java.lang.String key) { /* compiled code */ }

    public com.alibaba.fastjson.JSONArray getJSONArray(java.lang.String key) { /* compiled code */ }

    public <T> T getObject(java.lang.String key, java.lang.Class<T> clazz) { /* compiled code */ }

    public <T> T getObject(java.lang.String key, java.lang.reflect.Type type) { /* compiled code */ }

    public <T> T getObject(java.lang.String key, com.alibaba.fastjson.TypeReference typeReference) { /* compiled code */ }

    public java.lang.Boolean getBoolean(java.lang.String key) { /* compiled code */ }

    public byte[] getBytes(java.lang.String key) { /* compiled code */ }

    public boolean getBooleanValue(java.lang.String key) { /* compiled code */ }

    public java.lang.Byte getByte(java.lang.String key) { /* compiled code */ }

    public byte getByteValue(java.lang.String key) { /* compiled code */ }

    public java.lang.Short getShort(java.lang.String key) { /* compiled code */ }

    public short getShortValue(java.lang.String key) { /* compiled code */ }

    public java.lang.Integer getInteger(java.lang.String key) { /* compiled code */ }

    public int getIntValue(java.lang.String key) { /* compiled code */ }

    public java.lang.Long getLong(java.lang.String key) { /* compiled code */ }

    public long getLongValue(java.lang.String key) { /* compiled code */ }

    public java.lang.Float getFloat(java.lang.String key) { /* compiled code */ }

    public float getFloatValue(java.lang.String key) { /* compiled code */ }

    public java.lang.Double getDouble(java.lang.String key) { /* compiled code */ }

    public double getDoubleValue(java.lang.String key) { /* compiled code */ }

    public java.math.BigDecimal getBigDecimal(java.lang.String key) { /* compiled code */ }

    public java.math.BigInteger getBigInteger(java.lang.String key) { /* compiled code */ }

    public java.lang.String getString(java.lang.String key) { /* compiled code */ }

    public java.util.Date getDate(java.lang.String key) { /* compiled code */ }

    public java.sql.Date getSqlDate(java.lang.String key) { /* compiled code */ }

    public java.sql.Timestamp getTimestamp(java.lang.String key) { /* compiled code */ }

    public java.lang.Object put(java.lang.String key, java.lang.Object value) { /* compiled code */ }

    public com.alibaba.fastjson.JSONObject fluentPut(java.lang.String key, java.lang.Object value) { /* compiled code */ }

    public void putAll(java.util.Map<? extends java.lang.String,? extends java.lang.Object> m) { /* compiled code */ }

    public com.alibaba.fastjson.JSONObject fluentPutAll(java.util.Map<? extends java.lang.String,? extends java.lang.Object> m) { /* compiled code */ }

    public void clear() { /* compiled code */ }

    public com.alibaba.fastjson.JSONObject fluentClear() { /* compiled code */ }

    public java.lang.Object remove(java.lang.Object key) { /* compiled code */ }

    public com.alibaba.fastjson.JSONObject fluentRemove(java.lang.Object key) { /* compiled code */ }

    public java.util.Set<java.lang.String> keySet() { /* compiled code */ }

    public java.util.Collection<java.lang.Object> values() { /* compiled code */ }

    public java.util.Set<java.util.Map.Entry<java.lang.String,java.lang.Object>> entrySet() { /* compiled code */ }

    public java.lang.Object clone() { /* compiled code */ }

    public boolean equals(java.lang.Object obj) { /* compiled code */ }

    public int hashCode() { /* compiled code */ }

    public java.lang.Object invoke(java.lang.Object proxy, java.lang.reflect.Method method, java.lang.Object[] args) throws java.lang.Throwable { /* compiled code */ }

    public java.util.Map<java.lang.String,java.lang.Object> getInnerMap() { /* compiled code */ }

    private void readObject(java.io.ObjectInputStream in) throws java.io.IOException, java.lang.ClassNotFoundException { /* compiled code */ }

    public <T> T toJavaObject(java.lang.Class<T> clazz) { /* compiled code */ }

    public <T> T toJavaObject(java.lang.Class<T> clazz, com.alibaba.fastjson.parser.ParserConfig config, int features) { /* compiled code */ }

    static class SecureObjectInputStream extends java.io.ObjectInputStream {
        static java.lang.reflect.Field[] fields;
        static volatile boolean fields_error;

        static void ensureFields() { /* compiled code */ }

        public SecureObjectInputStream(java.io.ObjectInputStream in) throws java.io.IOException { /* compiled code */ }

        protected java.lang.Class<?> resolveClass(java.io.ObjectStreamClass desc) throws java.io.IOException, java.lang.ClassNotFoundException { /* compiled code */ }

        protected java.lang.Class<?> resolveProxyClass(java.lang.String[] interfaces) throws java.io.IOException, java.lang.ClassNotFoundException { /* compiled code */ }

        protected void readStreamHeader() throws java.io.IOException, java.io.StreamCorruptedException { /* compiled code */ }
    }
}