json-simple

摘自：http://blog.163.com/wangchaofeng888@126/blog/static/2992738520111114611238/

Example 1-1 - Encode a JSON object

  //import org.json.simple.JSONObject;
  
  JSONObject obj=newJSONObject();
  obj.put("name","foo");
  obj.put("num",newInteger(100));
  obj.put("balance",newDouble(1000.21));
  obj.put("is_vip",newBoolean(true));
  obj.put("nickname",null);
  System.out.print(obj);

Result: {"balance":1000.21,"num":100,"nickname":null,"is_vip":true,"name":"foo"}

Please note that the order of output entries is determined by the iterator implementation of the underlying java.util.Map implementation of JSONObject (which is java.util.HashMap?). If you want to preserve the order of output entries, please use an implementation such as java.util.LinkedHashMap? (see example 1-3). Please referMapping Between JSON and Java Entities for more information.

Example 1-2 - Encode a JSON object - Streaming

  //import org.json.simple.JSONObject;
  
  JSONObject obj=newJSONObject();
  obj.put("name","foo");
  obj.put("num",newInteger(100));
  obj.put("balance",newDouble(1000.21));
  obj.put("is_vip",newBoolean(true));
  obj.put("nickname",null);
  StringWriterout=newStringWriter();
  obj.writeJSONString(out);
  String jsonText =out.toString();
  System.out.print(jsonText);

Result: {"balance":1000.21,"num":100,"nickname":null,"is_vip":true,"name":"foo"}

Please note that the order of output entries is determined by the iterator implementation of the underlying java.util.Map implementation of JSONObject (which is java.util.HashMap). If you want to preserve the order of output entries, please use an implementation such as java.util.LinkedHashMap (see example 1-3). Please refer Mapping Between JSON and Java Entities for more information.

Example 1-3 - Encode a JSON object - Using Map

  //import java.util.LinkedHashMap;
  //import java.util.Map;
  //import org.json.simple.JSONValue;
  
  Map obj=newLinkedHashMap();
  obj.put("name","foo");
  obj.put("num",newInteger(100));
  obj.put("balance",newDouble(1000.21));
  obj.put("is_vip",newBoolean(true));
  obj.put("nickname",null);
  String jsonText =JSONValue.toJSONString(obj);
  System.out.print(jsonText);

Result: {"name":"foo","num":100,"balance":1000.21,"is_vip":true,"nickname":null}

Now the order of the object entries is preserved, which is different from example 1-1. Please refer Mapping Between JSON and Java Entities for more information.

Example 1-4 - Encode a JSON object - Using Map and streaming

  //import java.util.LinkedHashMap;
  //import java.util.Map;
  //import org.json.simple.JSONValue;
  
   Map obj=newLinkedHashMap();
   obj.put("name","foo");
   obj.put("num",newInteger(100));
   obj.put("balance",newDouble(1000.21));
   obj.put("is_vip",newBoolean(true));
   obj.put("nickname",null);
   StringWriterout=newStringWriter();
   JSONValue.writeJSONString(obj,out);
   String jsonText =out.toString();
   System.out.print(jsonText);

Result: {"name":"foo","num":100,"balance":1000.21,"is_vip":true,"nickname":null}

Please refer Mapping Between JSON and Java Entities for more information.

Example 2-1 - Encode a JSON array

  //import org.json.simple.JSONArray;
  
  JSONArray list =newJSONArray();
  list.add("foo");
  list.add(newInteger(100));
  list.add(newDouble(1000.21));
  list.add(newBoolean(true));
  list.add(null);
  System.out.print(list);

Result: ["foo",100,1000.21,true,null]

Example 2-2 - Encode a JSON array - Streaming

  //import org.json.simple.JSONArray;
  
  JSONArray list =newJSONArray();
  list.add("foo");
  list.add(newInteger(100));
  list.add(newDouble(1000.21));
  list.add(newBoolean(true));
  list.add(null);
  StringWriterout=newStringWriter();
  list.writeJSONString(out);
  String jsonText =out.toString();
  System.out.print(jsonText);

Result: ["foo",100,1000.21,true,null]

Please refer Mapping Between JSON and Java Entities for more information.

Example 2-3 - Encode a JSON array - Using List

  //import org.json.simple.JSONValue;
  
  LinkedList list =newLinkedList();
  list.add("foo");
  list.add(newInteger(100));
  list.add(newDouble(1000.21));
  list.add(newBoolean(true));
  list.add(null);
  String jsonText =JSONValue.toJSONString(list);
  System.out.print(jsonText);

Result: ["foo",100,1000.21,true,null]

Please refer Mapping Between JSON and Java Entities for more information.

Example 2-4 - Encode a JSON array - Using List and streaming

  //import org.json.simple.JSONValue;

  LinkedList list =newLinkedList();
  list.add("foo");
  list.add(newInteger(100));
  list.add(newDouble(1000.21));
  list.add(newBoolean(true));
  list.add(null);
  StringWriterout=newStringWriter();
  JSONValue.writeJSONString(list,out);
  String jsonText =out.toString();
  System.out.print(jsonText);

Result: ["foo",100,1000.21,true,null]

Please refer Mapping Between JSON and Java Entities for more information.

Example 3 - Merge two JSON objects

  //import org.json.simple.JSONObject;
  
  JSONObject obj1 =newJSONObject();
  obj1.put("name","foo");
  obj1.put("num",newInteger(100));
  obj1.put("balance",newDouble(1000.21));
                
  JSONObject obj2 =newJSONObject();
  obj2.put("is_vip",newBoolean(true));
  obj2.put("nickname",null);
  obj2.putAll(obj1);
  System.out.print(obj2);

Result: {"balance":1000.21,"num":100,"nickname":null,"is_vip":true,"name":"foo"}, the same as the one of Example 1.

Example 4 - Merge two JSON arrays

  JSONArray list1 =newJSONArray();
  list1.add("foo");
  list1.add(newInteger(100));
  list1.add(newDouble(1000.21));
  
  JSONArray list2 =newJSONArray();
  list2.add(newBoolean(true));
  list2.add(null);
  list2.addAll(list1);
  System.out.print(list2);

Result: [true,null,"foo",100,1000.21], the order of which is different from the one of Example 2.

Example 5-1 - Combination of JSON primitives, JSON object and JSON arrays

  JSONArray list1 =newJSONArray();
  list1.add("foo");
  list1.add(newInteger(100));
  list1.add(newDouble(1000.21));
  
  JSONArray list2 =newJSONArray();
  list2.add(newBoolean(true));
  list2.add(null);
                
  JSONObject obj =newJSONObject();
  obj.put("name","foo");
  obj.put("num",newInteger(100));
  obj.put("balance",newDouble(1000.21));
  obj.put("is_vip",newBoolean(true));
  obj.put("nickname",null);
    
  obj.put("list1", list1);
  obj.put("list2", list2);
                
  System.out.println(obj);

Result: {"balance":1000.21,"list2":true,null,"num":100,"list1":["foo",100,1000.21],"nickname":null,"is_vip":true,"name":"foo"}

Example 5-2 - Combination of JSON primitives, Map and List

  Map m1 =newLinkedHashMap();
  Map m2 =newHashMap();
  List  l1 =newLinkedList();

  m1.put("k11","v11");
  m1.put("k12","v12");
  m1.put("k13","v13");
  m2.put("k21","v21");
  m2.put("k22","v22");
  m2.put("k23","v23");
  l1.add(m1);
  l1.add(m2);

  String jsonString =JSONValue.toJSONString(l1);
                
  System.out.println(jsonString);

Result: [{"k11":"v11","k12":"v12","k13":"v13"},{"k22":"v22","k21":"v21","k23":"v23"}]

Example 5-3 - Combination of JSON primitives, JSONObject, Map and List, and streaming

  StringWriterout=newStringWriter();
        
  JSONObject obj =newJSONObject();
  LinkedHashMap m1 =newLinkedHashMap();
  LinkedList l1 =newLinkedList();
  obj.put("k1","v1");
  obj.put("k2", m1);
  obj.put("k3", l1);
  m1.put("mk1","mv1");
  l1.add("lv1");
  l1.add("lv2");
  m1.put("mk2", l1);
        
  obj.writeJSONString(out);
  System.out.println("jsonString:");
  System.out.println(out.toString());
  String jsonString = obj.toJSONString();
  System.out.println(jsonString);

Result:

  jsonString:
  {"k3":["lv1","lv2"],"k1":"v1","k2":{"mk1":"mv1","mk2":["lv1","lv2"]}}
  {"k3":["lv1","lv2"],"k1":"v1","k2":{"mk1":"mv1","mk2":["lv1","lv2"]}}

Example 6-1 - Customize JSON outputs

/*class User implements JSONAware{
        private int id;
        private String name;
        private String password;
        
        public User(int id, String name, String password){
                this.id = id;
                this.name = name;
                this.password = password;
        }
        
        public String toJSONString(){
                StringBuffer sb = new StringBuffer();
                
                sb.append("{");
                
                sb.append(JSONObject.escape("userName"));
                sb.append(":");
                sb.append("\"" + JSONObject.escape(name) + "\"");
                
                sb.append(",");
                
                sb.append(JSONObject.escape("ID"));
                sb.append(":");
                sb.append(id);
                
                sb.append("}");
                
                return sb.toString();
        }
}*/

  JSONArray users =newJSONArray();
  users.add(newUser(123,"foo1","secret1"));
  users.add(newUser(124,"foo2","secret2"));
  users.add(newUser(125,"\"foo2\"","secret2"));
  System.out.println(users);

Result: [{userName:"foo1",ID:123},{userName:"foo2",ID:124},{userName:"\"foo2\"",ID:125}]

User.toJSONString() seems to be a bit complicated. The purpose is to demonstrate the usage of JSONObject.escape(). It can be simpler:

  publicString toJSONString(){
    JSONObject obj =newJSONObject();
    obj.put("userName", name);
    obj.put("ID",newInteger(id));
    return obj.toString();
  }

Please refer Mapping Between JSON and Java Entities for more information. (Note: If you are using version 1.0.2 or earlier, you need to override Object.toString() of your bean to get customized output.)

Example 6-2 - Customize JSON outputs - Streaming

/*class User implements JSONStreamAware{
        private int id;
        private String name;
        private String password;
        
        public User(int id, String name, String password){
                this.id = id;
                this.name = name;
                this.password = password;
        }
        
       public void writeJSONString (Writer out) throws IOException{
                LinkedHashMap obj = new LinkedHashMap();
                obj.put("userName", name);
                obj.put("ID", new Integer(id));
                JSONValue.writeJSONString(obj, out);
       }
}*/

  JSONArray users =newJSONArray();
  users.add(newUser(123,"foo1","secret1"));
  users.add(newUser(124,"foo2","secret2"));
  users.add(newUser(125,"\"foo2\"","secret2"));
  StringWriterout=newStringWriter();
  users.writeJSONString(out);
  System.out.println(out.toString());

Result: [{"userName":"foo1","ID":123},{"userName":"foo2","ID":124},{"userName":"\"foo2\"","ID":125}]

Please note that you don't have to implement JSONStreamAware to support streaming output of your bean, you can only implement JSONAware instead of JSONStreamAware. In the latter case, JSONAware.toString() is called and the result is written to the output stream. You can implement JSONStreamAware for better performance. If a class implements both JSONStreamAware and JSONAware, JSONStreamAware is given precedence while streaming. Please refer Mapping Between JSON and Java Entities for more information.