关于javaWeb开发中json数据的处理总计

时间：2022-12-23 13:10:39

关于javaWeb开发中json数据的处理总结

前言：java中常见的json解析类库有Gson、json-lib、jackson 一、jackson进行JSON解析和序列化：（依赖包下载地址http://wiki.fasterxml.com/JacksonDownload） (1)所需包： jackson-core-2.2.3.jar（核心jar包，下载地址） jackson-annotations-2.2.3.jar（该包提供Json注解支持，下载地址）
 jackson-databind-2.2.3.jar（下载地址） (2)序列化User类：使用writeValueAsString() 
        User user = new User();  
        user.setName("小民");   
        user.setEmail("xiaomin@sina.com");  
        user.setAge(20);  

        SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd");  
        user.setBirthday(dateformat.parse("1996-10-01"));         

        /** 
         * ObjectMapper是JSON操作的核心，Jackson的所有JSON操作都是在ObjectMapper中实现。 
         * ObjectMapper有多个JSON序列化的方法，可以把JSON字符串保存File、OutputStream等不同的介质中。 
         * writeValue(File arg0, Object arg1)把arg1转成json序列，并保存到arg0文件中。 
         * writeValue(OutputStream arg0, Object arg1)把arg1转成json序列，并保存到arg0输出流中。 
         * writeValueAsBytes(Object arg0)把arg0转成json序列，并把结果输出成字节数组。 
         * writeValueAsString(Object arg0)把arg0转成json序列，并把结果输出成字符串。 
         */  
        ObjectMapper mapper = new ObjectMapper();  

        //User类转JSON  
        //输出结果：{"name":"小民","age":20,"birthday":844099200000,"email":"xiaomin@sina.com"}  
        String json = mapper.writeValueAsString(user);  
        System.out.println(json); 


//Java集合转JSON          //输出结果：[{"name":"小民","age":20,"birthday":844099200000,"email":"xiaomin@sina.com"}]          List<User> users = new ArrayList<User>();          users.add(user);          String jsonlist = mapper.writeValueAsString(users);          System.out.println(jsonlist); 


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/**   * 将map转换成json字符串 */ public static String writeMapJSON(Map<String, Object> map) { String jsonString ="";ObjectMapper objectMapper = new ObjectMapper();try {  jsonString = objectMapper.writeValueAsString(map); } catch (IOException e) {  e.printStackTrace();  }  return jsonString;} 


/**   * 将list<Map>转换成json字符串   */ public static String writeListMapJSON(List<Map<String,String>> listMap) {String jsonString ="";ObjectMapper objectMapper = new ObjectMapper();try {  jsonString = objectMapper.writeValueAsString(listMap);  } catch (IOException e) {  e.printStackTrace();  } return jsonString;} 

(2)JSON转Java类[JSON反序列化]使用readValue();
   public static void main(String[] args) throws ParseException, IOException {  
        String json = "{\"name\":\"小民\",\"age\":20,\"birthday\":844099200000,\"email\":\"xiaomin@sina.com\"}";  

        /** 
         * ObjectMapper支持从byte[]、File、InputStream、字符串等数据的JSON反序列化。 
         */  
        ObjectMapper mapper = new ObjectMapper();  
        User user = mapper.readValue(json, User.class);  
        System.out.println(user);  
    } 


/** * 将数组对象转换成json字符串 */public static String writeArrayJSON(String[] array) {String jsonString ="";ObjectMapper objectMapper = new ObjectMapper();    try {    jsonString = objectMapper.writeValueAsString(array);        } catch (IOException e) {        e.printStackTrace();    }    return jsonString;}


/**   * json字符串转换成Map   */ @SuppressWarnings("unchecked")public static Map<String,Object> readJsonMapObject(String jsonString){ObjectMapper objectMapper = new ObjectMapper();Map<String,Object> map = new LinkedHashMap<String,Object>();try{map = objectMapper.readValue(jsonString, Map.class);  }catch (JsonParseException e) {  e.printStackTrace();  } catch (JsonMappingException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  return map;}


/**   * json字符串转换成list   */ @SuppressWarnings("unchecked")public static List<String> readJsonList(String jsonString){ObjectMapper objectMapper = new ObjectMapper();List<String> list = new ArrayList<String>();try{list = objectMapper.readValue(jsonString, List.class);  }catch (JsonParseException e) {  e.printStackTrace();  } catch (JsonMappingException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  return list;}


/**   * json字符串转换成list<map>   */ @SuppressWarnings("unchecked")public static List<Map<String, String>> readJsonListMap(String jsonString){ObjectMapper objectMapper = new ObjectMapper();List<Map<String, String>> list = new ArrayList<Map<String, String>>();try{list = objectMapper.readValue(jsonString, List.class);  }catch (JsonParseException e) {  e.printStackTrace();  } catch (JsonMappingException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  return list;}public static List<Map<String, Object>> readJsonListMapObj(String jsonString){ObjectMapper objectMapper = new ObjectMapper();List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();try{list = objectMapper.readValue(jsonString, List.class);  }catch (JsonParseException e) {  e.printStackTrace();  } catch (JsonMappingException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  return list;}


/** * json字符串转换成map<map>   * @param jsonString * @return */public static Map<String, Map<String, Object>> readJsonToMapObj(String jsonString){ObjectMapper objectMapper = new ObjectMapper();Map<String, Map<String, Object>> list = null;try{list = objectMapper.readValue(jsonString,Map.class); }catch (JsonParseException e) {  e.printStackTrace();  } catch (JsonMappingException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  return list;}


二、json-lib进行JSON解析：

(1)使用JSONArray.fromObject()函数：http://www.cnblogs.com/sunzn/archive/2013/02/12/2910241.html
二、Gson进行JSON解析：(1)使用toJson()方法：
public static String getJson(Object list) {
Gson gson = new Gson();
return gson.toJson(list);
}


示例：http://blog.csdn.net/axuanqq/article/details/51441590








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