创建JSONArray的常用四种方法



创建JSONArray的常用四种方法

1.从头或者从零开始，创建一个JSONArray(Creating a JSONArray from scratch)
实例1：


Java代码 
JSONArray jsonArray = new JSONArray().element("JSON").element("1").element("2.0").element("true");  
assertEquals("JSON", jsonArray.getString(0));  
assertEquals(1, jsonArray.getInt(1));  
assertEquals(2.0d, jsonArray.getDouble(2), 0d);  
assertTrue(jsonArray.getBoolean(3));  


3.使用一个Collection来创建一个JSONArray(Creating a JSONArray from a Collection)
实例1：

Java代码 
List list = new ArrayList(); 
list.add( "JSON" );  
list.add( "1" );  
list.add( "2.0" );  
list.add( "true" );  
JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON( list ); assertEquals( "JSON", jsonArray.getString(0) );  
assertEquals( 1, jsonArray.getInt(1) );  
assertEquals( 2.0d, jsonArray.getDouble(2), 0d );  
assertTrue( jsonArray.getBoolean(3) );  


4.使用一个Array来创建一个JSONArray(Creating a JSONArray from an array)
实例1：

Java代码 
Object[] array = new Object[] { "JSON", 1, 2.0, true };  
JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(array); assertEquals("JSON", jsonArray.getString(0)); 
assertEquals(1, jsonArray.getInt(1));  
assertEquals(2.0d, jsonArray.getDouble(2), 0d);  
assertTrue(jsonArray.getBoolean(3));  
 
//实例2：  
Object[] array = new Object[] { "JSON", 1, 2.0, true };  
JSONArray jsonArray = JSONArray.fromObject(array);  
assertEquals("JSON", jsonArray.getString(0));  
assertEquals(1, jsonArray.getInt(1));  
assertEquals(2.0d, jsonArray.getDouble(2), 0d);  
assertTrue(jsonArray.getBoolean(3));  


由此可见，无论要转换的源是哪种类型，都可以使用(JSONArray) JSONSerializer.toJSON()或JSONArray.fromObject()来转换;

常用的三种扩展功能

1.使用一个JSON格式化字符串来创建一个JSONFunction(JavaScript functions) 
实例：

Java代码 
String str = "{func: function( param ){ doSomethingWithParam(param); }}";  
JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(str); JSONFunction func = (JSONFunction) jsonObject.get("func"); ArrayAssertions.assertEquals(new String[] { "param" }, func.getParams());  
assertEquals("doSomethingWithParam(param);", func.getText());  

 
注：函数的写法要注意function(){},参数param是可选的！

2.排除一个JSON格式化字符串的某些属性(Exclude properties)
实例：

Java代码 
String str = "{'string':'JSON', 'integer': 1, 'double': 2.0, 'boolean': true}";  
JsonConfig jsonConfig = new JsonConfig();  
jsonConfig.setExcludes(new String[] { "double", "boolean" }); JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(str, jsonConfig);  
assertEquals("JSON", jsonObject.getString("string"));  
assertEquals(1, jsonObject.getInt("integer")); 
assertFalse(jsonObject.has("double"));  
assertFalse(jsonObject.has("boolean"));  


3.排除一个JSON格式化字符串的某些属性,使用过滤器(Exclude properties (with filters)
实例：
Java代码 
String str = "{'string':'JSON', 'integer': 1, 'double': 2.0, 'boolean': true}"; 
JsonConfig jsonConfig = new JsonConfig(); jsonConfig.setJsonPropertyFilter(new PropertyFilter() {  
   public boolean apply(Object source, String name, Object value) { 
         if ("double".equals(name) || "boolean".equals(name))  
          { return true; } 
              return false; } });  
JSONObject jsonObject = (JSONObject) JSONSerializer.toJSON(str, jsonConfig);  
assertEquals("JSON", jsonObject.getString("string"));  
assertEquals(1, jsonObject.getInt("integer"));  
assertFalse(jsonObject.has("double"));  
assertFalse(jsonObject.has("boolean"));  


JSONObject-Java常用的四种用法
1.JSONObject to DynaBean

Java代码 
String json = "{name=\"json\",bool:true,int:1,double:2.2}"; JSONObject jsonObject = JSONObject.fromObject(json); //抽象的写法：DynaBean bean = (DynaBean) JSONSerializer.toJava( jsonObject ); Object bean = JSONObject.toBean(jsonObject);  
//Object bean1 = JSONSerializer.toJava(jsonObject);  
assertEquals(jsonObject.get("name"), PropertyUtils.getProperty(bean, "name")); 
assertEquals(jsonObject.get("bool"), PropertyUtils.getProperty(bean, "bool"));  
assertEquals(jsonObject.get("int"), PropertyUtils.getProperty(bean, "int"));  
assertEquals(jsonObject.get("double"), PropertyUtils.getProperty(bean, "double"));  


2.JSONObject to JavaBean

Java代码 
String json = "{name:\"zhangsan\",age:25,hight:1.72,sex:true}"; JSONObject jsonObject = JSONObject.fromObject(json);  
UserBean bean = (UserBean) JSONObject.toBean(jsonObject, UserBean.class);  
System.out.println(jsonObject);  


3.JSONArray to List

Java代码 
String json = "[\"first\",\"second\"]";  
JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(json); 
List output = (List) JSONSerializer.toJava(jsonArray);  


4.JSONArray to array

Java代码 
String json = "[\"first\",\"second\"]"; 
JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(json); JsonConfig jsonConfig = new JsonConfig();  
jsonConfig.setArrayMode(JsonConfig.MODE_OBJECT_ARRAY);  
Object[] output = (Object[]) JSONSerializer.toJava(jsonArray, jsonConfig);  
Object[] expected = new Object[] { "first", "second" }; ArrayAssertions.assertEquals(expected, output);   


理论上，这样就可以了，但时，有异常Caused by: java.lang.NoSuchMethodException: com.json.Json$UserBean.()
  
2.使用一个JSON格式化字符串来创建一个JSONArray(Creating a JSONArray from a JSON formatted string) 
实例1：

Java代码 
String str = "['JSON', 1, 2.0, true]"; //注意该字符串的格式"[ , ]" JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON( str ); assertEquals( "JSON", jsonArray.getString(0) );  
assertEquals( 1, jsonArray.getInt(1) );  
assertEquals( 2.0d, jsonArray.getDouble(2), 0d );  
assertTrue( jsonArray.getBoolean(3) );  


Java代码 
List list = new ArryList(); list.add("a"); list.add("b"); Map> map = new HashMap>(); map.put("list",list); MessageUtils.outputJSONResult(JSONObject.fromObject(map).toString(), response); public class MessageUtils { public static void outputJSONResult(String result, HttpServletResponse response) { try { response.setHeader("ContentType", "text/json"); response.setCharacterEncoding("utf-8"); PrintWriter pw = response.getWriter(); pw.write(result); pw.flush(); pw.close(); } catch (IOException e) { e.printStackTrace(); } }