alibaba Fastjson的使用

太过爱你忘了你带给我的痛 2022-02-21 07:06 245阅读 0赞

Fastjson 源码地址：[https://github.com/alibaba/fastjson][https_github.com_alibaba_fastjson]

Fastjson 中文 Wiki：[https://github.com/alibaba/fastjson/wiki/Quick-Start-CN][https_github.com_alibaba_fastjson_wiki_Quick-Start-CN]

Fastjson API文档：[https://www.w3cschool.cn/fastjson/fastjson-beantoarray.html][https_www.w3cschool.cn_fastjson_fastjson-beantoarray.html]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDAyODU0_size_16_color_FFFFFF_t_70][]

### 一、引入依赖 ###

**1）FastJson 是用于java后台处理json格式数据的一个工具包**

2）FastJson 对于json格式字符串的解析主要用到了一下三个类：

（1）JSON：fastJson的解析器，用于JSON格式字符串与JSON对象及javaBean之间的转换。
        （2）JSONObject：fastJson提供的json对象。
        （3）JSONArray：fastJson提供json数组对象。

**3）maven 引入依赖**

<dependency>  
        <groupId>com.alibaba</groupId>  
        <artifactId>fastjson</artifactId>  
        <version>1.2.47</version>  
    </dependency>

### 二、测试demo ###

**注意：JSON字符串是有格式要求的，必须为键值对形式，不是任意的字符串。**

public class User implements Serializable{
    	private static final long serialVersionUID = 1L;
    	
    	private int id;
    	private String username;
    	private String pazzword;
    	private String sex;
    	private Date birthday;
    	private Integer status; //0：未激活， 1：激活
    	private Long ordinal;   //序号
    
        //get / set
    }

**1、javaBean,list,array 转 json string**

**      String jsonString = JSON.toJSONString(object);**

/**
    	 *  javaBean,list,array convert to json string
    	 * 
    	 * @param obj
    	 * @return
    	 */
    	public static String obj2json(Object obj) {
    		return JSON.toJSONString(obj);
    	}
    
    	public static void main(String[] args) {
    		User user = new User();
    		user.setId(100);
    		user.setUsername("李四");
    		user.setPazzword("lisi123");
    		user.setBirthday(new Date());
    		user.setSex("男");
    		user.setStatus(1);
    		user.setOrdinal(10L);
    		
    		User user2 = new User();
    		user2.setId(101);
    		user2.setUsername("王五");
    		user2.setPazzword("wangwu123");
    		user2.setBirthday(new Date());
    		user2.setSex("女");
    		user2.setStatus(1);
    		user2.setOrdinal(11L);
    		
    		System.out.println("=javaBean=\n" + obj2json(user));
    		
    		ArrayList<User> list = new ArrayList<>();
    		list.add(user);
    		list.add(user2);
    		System.out.println("=list=\n" + obj2json(list));
    		
    		Object[] array = new Object[2];
    		array[0] = user;
    		array[1] = user2;
    		
    		System.out.println("=array=\n" + obj2json(array));		
    	}

![20190410163441512.png][]

**2、json string 转 javaBean对象**

**    T t  =  JSON.parseObject(jsonString, T.class);**

public static void main(String[] args) {		
    		String jsonStr = "{\"birthday\":1554885019427,\"id\":100,\"ordinal\":10,\"pazzword\":\"lisi123\",\"sex\":\"男\",\"status\":1,\"username\":\"李四\"}";
    		String jsonStr2 = "{\"birthday\":1554885019427,\"id\":100,\"ordinal\":10,\"pazzword\":\"lisi123\",\"sex\":\"男\",\"status11\":1}";
    		User user3 = JSON.parseObject(jsonStr, User.class);
    		
    		System.out.println("=user=\n" + user3);
    		System.out.println("=user=\n" + JSON.parseObject(jsonStr2, User.class));
    	}

![20190412164048378.png][]

**  注意：javaBean对象 在 json string 中无对应字段时，值为 null**

**3、json string 转 JSONObject**

** JSONObject jsonObject  = JSON.parseObject(jsonString);**

String jsonStr = "{\"birthday\":1554885019427,\"id\":100,\"ordinal\":10,\"pazzword\":\"lisi123\",\"sex\":\"男\",\"status\":1,\"username\":\"李四\"}";
        JSONObject jsonObject  = JSON.parseObject(jsonStr);
        System.out.println(jsonObject);
        System.out.println(jsonObject.get("sex"));

![20190418145014654.png][]

** 注意：JSONObject 可以通过键值对来获取值**

### 三、复杂 jsonStr 的处理 ###

之前有个业务小功能使用到了

public static void main(String[] args) {
    		List<Map<String, Object>> nodesList  = new ArrayList<>();
    		
    		String jsonStr = "{\r\n" + 
    				"    \"title\":\"事项流程图\",\r\n" + 
    				"    \"nodes\":{\r\n" + 
    				"	\"1553438226938\":{\"name\":\"开始\",\"left\":267,\"top\":88,\"type\":\"start round mix\",\"width\":28,\"height\":28,\"alt\":true},\r\n" + 
    				"	\"1553438229007\":{\"name\":\"结束\",\"left\":277,\"top\":412,\"type\":\"end round mix\",\"width\":28,\"height\":28,\"alt\":true},\r\n" + 
    				"	\"1553438231623\":{\"name\":\"节点1\",\"left\":\"237\",\"top\":\"169\",\"type\":\"task\",\"width\":\"104\",\"height\":\"28\",\"alt\":true,\"model\":\"node\",\"xm\":\"张三\",\"xb\":\"男\"},\r\n" + 
    				"	\"1553438232544\":{\"name\":\"节点2左\",\"left\":\"107\",\"top\":\"251\",\"type\":\"task\",\"width\":\"104\",\"height\":\"28\",\"alt\":true,\"model\":\"node\",\"xm\":\"李四\",\"xb\":\"女\"},\r\n" + 
    				"	\"1553438233100\":{\"name\":\"节点2右\",\"left\":\"382\",\"top\":\"251\",\"type\":\"task\",\"width\":\"104\",\"height\":\"28\",\"alt\":true,\"model\":\"node\",\"xm\":\"王五\",\"xb\":\"男\"},\r\n" + 
    				"	\"1553438235571\":{\"name\":\"节点3\",\"left\":\"242\",\"top\":\"333\",\"type\":\"task\",\"width\":\"104\",\"height\":\"28\",\"alt\":true,\"model\":\"node\",\"xm\":\"赵柳\",\"xb\":\"不详\"}\r\n" + 
    				"    },\r\n" + 
    				"    \"lines\":{\r\n" + 
    				"	\"1553438237966\":{\"type\":\"sl\",\"from\":\"1553438226938\",\"to\":\"1553438231623\",\"name\":\"\",\"dash\":false},\r\n" + 
    				"	\"1553438238928\":{\"type\":\"sl\",\"from\":\"1553438231623\",\"to\":\"1553438233100\",\"name\":\"\",\"dash\":false},\r\n" + 
    				"	\"1553438240303\":{\"type\":\"sl\",\"from\":\"1553438231623\",\"to\":\"1553438232544\",\"name\":\"\",\"dash\":false},\r\n" + 
    				"	\"1553438241365\":{\"type\":\"sl\",\"from\":\"1553438232544\",\"to\":\"1553438235571\",\"name\":\"\",\"dash\":false},\r\n" + 
    				"	\"1553438243677\":{\"type\":\"sl\",\"from\":\"1553438233100\",\"to\":\"1553438235571\",\"name\":\"\",\"dash\":false},\r\n" + 
    				"	\"1553438245066\":{\"type\":\"sl\",\"from\":\"1553438235571\",\"to\":\"1553438229007\",\"name\":\"\",\"dash\":false}\r\n" + 
    				"    },\r\n" + 
    				"    \"areas\":{},\r\n" + 
    				"    \"initNum\":13\r\n" + 
    				"}";
    		
    		JSONObject jsonObject  = JSON.parseObject(jsonStr);
    		String jsonNodesStr = jsonObject.getString("nodes");
    		String jsonLinesStr = jsonObject.getString("lines");
    		//jsonStr -- Object -- Map
    		Map<String, Object> nodesMap = (Map<String, Object>) JSON.parse(jsonNodesStr); 
    		Map<String, Object> linesMap = (Map<String, Object>) JSON.parse(jsonLinesStr);
    		
    		for (Entry<String, Object> entry : linesMap.entrySet()) {  
    			// 根据 lines 的 lineId 关系获取单个节点的有用信息添加到 auditList
    			acquireNodeByLineId(nodesList,nodesMap,linesMap,entry.getKey());
    		}  
    		
    		// 将 auditList 按节点大小顺序重新排序
    		Collections.sort(nodesList, new Comparator<Map<String,Object>>() {
    			@Override
    			public int compare(Map<String, Object> o1, Map<String, Object> o2) {
    				String lineToId = String.valueOf(o1.get("lineToId"));
    				String lineToId2 = String.valueOf(o2.get("lineToId"));
    				return lineToId.compareTo(lineToId2);
    			}
    		});
    		
    		System.out.println(jsonObject.get("title"));
    		for (Map<String, Object> map : nodesList) {
    			System.out.println("nodesList == "+ map.toString());
    		}
    	}
    	
    	/**
    	 * 根据 lines 的 lineId 关系获取单个节点的有用信息添加到 list 对象中
    	 * @param auditorList 
    	 * @param nodesMap
    	 * @param linesMap
    	 * @param lineId
    	 * @return
    	 */
    	private static void acquireNodeByLineId(List<Map<String, Object>> nodesList, Map<String, Object> nodesMap, Map<String, Object> linesMap, String lineId) {
    		String jsonLineStr = String.valueOf(linesMap.get(lineId)); 
    		String lineFromId = JSON.parseObject(jsonLineStr).getString("from");
    		String lineToId = JSON.parseObject(jsonLineStr).getString("to");
    		//获取单个节点的信息
    		String jsonNodeStr = String.valueOf(nodesMap.get(lineToId)); 
    		String nodeName = JSON.parseObject(jsonNodeStr).getString("name");
    		String nodeXm = JSON.parseObject(jsonNodeStr).getString("xm");
    		String nodeXb = JSON.parseObject(jsonNodeStr).getString("xb");
    		Map<String, Object> map = new HashMap<>();
    		if(!nodeName.equals("结束")) {
    			map.put("nodename", nodeName);
    			map.put("nodexm", nodeXm);
    			map.put("nodexb", nodeXb);
    			map.put("lineFromId", lineFromId);
    			map.put("lineToId", lineToId);
    			nodesList.add(map);
    		}
    	}

![20190418155902953.png][]

![20190418160212412.png][]

**单流程线**不会出现着各种情况，由于是 **多流程线**，会多出现一个 节点3， 后面可根据需求进一步处理 nodesList 数据

参考文章：[全解析史上最快JSON解析库][JSON]

ends

[https_github.com_alibaba_fastjson]: https://github.com/alibaba/fastjson
[https_github.com_alibaba_fastjson_wiki_Quick-Start-CN]: https://github.com/alibaba/fastjson/wiki/Quick-Start-CN
[https_www.w3cschool.cn_fastjson_fastjson-beantoarray.html]: https://www.w3cschool.cn/fastjson/fastjson-beantoarray.html
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQyNDAyODU0_size_16_color_FFFFFF_t_70]: /images/20220221/f9ca571f3b8144c58de1fcc6ca2727c6.png
[20190410163441512.png]: /images/20220221/5cc4e8a42fa6422388441027ba21c045.png
[20190412164048378.png]: /images/20220221/56b21c4b25c144f59ec0643519415b39.png
[20190418145014654.png]: /images/20220221/054ace78fc774c60be7fa2734d2e4ded.png
[20190418155902953.png]: /images/20220221/4dec285954c740b0b5bf79b579ecf1b9.png
[20190418160212412.png]: /images/20220221/85c9bb1ff8fe42d09af2b397e5550073.png
[JSON]: https://www.cnblogs.com/jajian/p/10051901.html