最近在完善某网站，遇到个问题，就是JAVA里怎么使用JSON，后来经过努力，最后发现了json-simple这个好东东，下面把使用方法给大家说说。

JSON ENCODE编码

例子1：

 //import org.json.simple.JSONObject;
  
  JSONObject obj=new JSONObject();
  obj.put("name","foo");
  obj.put("num",new Integer(100));
  obj.put("balance",new Double(1000.21));
  obj.put("is_vip",new Boolean(true));
  obj.put("nickname",null);
  StringWriter out = new StringWriter();
  obj.writeJSONString(out);
  String jsonText = out.toString();
  System.out.print(jsonText);

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

例子2：

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

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

例子3：

  //import java.util.LinkedHashMap;
  //import java.util.Map;
  //import org.json.simple.JSONValue;
  
   Map obj=new LinkedHashMap();
   obj.put("name","foo");
   obj.put("num",new Integer(100));
   obj.put("balance",new Double(1000.21));
   obj.put("is_vip",new Boolean(true));
   obj.put("nickname",null);
   StringWriter out = new StringWriter();
   JSONValue.writeJSONString(obj, out);
   String jsonText = out.toString();
   System.out.print(jsonText); 结果: {"name":"foo","num":100,"balance":1000.21,"is_vip":true,"nickname":null}  

例子4：

 //import org.json.simple.JSONArray;
  
  JSONArray list = new JSONArray();
  list.add("foo");
  list.add(new Integer(100));
  list.add(new Double(1000.21));
  list.add(new Boolean(true));
  list.add(null);
  System.out.print(list); 结果["foo",100,1000.21,true,null]  

JSON DECODE

例子1：

  System.out.println("=======decode=======");
                
  String s="[0,{\"1\":{\"2\":{\"3\":{\"4\":[5,{\"6\":7}]}}}}]";
  Object obj=JSONValue.parse(s);
  JSONArray array=(JSONArray)obj;
  System.out.println("======the 2nd element of array======");
  System.out.println(array.get(1));
  System.out.println();
                
  JSONObject obj2=(JSONObject)array.get(1);
  System.out.println("======field \"1\"==========");
  System.out.println(obj2.get("1"));    

                
  s="{}";
  obj=JSONValue.parse(s);
  System.out.println(obj);
                
  s="[5,]";
  obj=JSONValue.parse(s);
  System.out.println(obj);
                
  s="[5,,2]";
  obj=JSONValue.parse(s);
  System.out.println(obj);

例子2：

  JSONParser parser=new JSONParser();

  System.out.println("=======decode=======");
                
  String s="[0,{\"1\":{\"2\":{\"3\":{\"4\":[5,{\"6\":7}]}}}}]";
  Object obj=parser.parse(s);
  JSONArray array=(JSONArray)obj;
  System.out.println("======the 2nd element of array======");
  System.out.println(array.get(1));
  System.out.println();
                
  JSONObject obj2=(JSONObject)array.get(1);
  System.out.println("======field \"1\"==========");
  System.out.println(obj2.get("1"));    

                
  s="{}";
  obj=parser.parse(s);
  System.out.println(obj);
                
  s="[5,]";
  obj=parser.parse(s);
  System.out.println(obj);
                
  s="[5,,2]";
  obj=parser.parse(s);
  System.out.println(obj);

例子3：

  String jsonText = "[[null, 123.45, \"a\\tb c\"]}, true";
  JSONParser parser = new JSONParser();
                
  try{
    parser.parse(jsonText);
  }
  catch(ParseException pe){
    System.out.println("position: " + pe.getPosition());
    System.out.println(pe);
  }

类库下载地址:http://www.ipkbus.com/down/jsonsimple.tar.gz