创建JSONArray的常用四种方法

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mb648972af0d702 2023-06-23 00:15:48 ©著作权

文章标签 jsonarray json JSON Java 文章分类 JavaScript 前端开发

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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.<init>()

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<String> list = new ArryList<String>(); list.add("a"); list.add("b"); Map<String,List<String>> map = new HashMap<String,List<String>>(); 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(); } }