学习Java工具库FastJson的使用 -我爱编程

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学习Java工具库FastJson的使用

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FastJson是Java中的一个工具库，可以把Java对象转换为Json格式，同样也可以吧Json格式转换为Java对象。下面，我们来一起学习FastJson工具库的具体使用内容。

一、fastJson将json格式字符串转化成List集合

注：json格式字符串必须符合数组型格式如[{"a":a},{"b":b}]

场景一：前端向后台传递数组格式的json字符串，如何转化成List集合

List<AccountBean> readJson2List =JSON.parseArray(json, AccountBean.class)注意这里是Bean.class而不是List.class

	@Test
	public void readJson2ListBean() {
		String json = "[{"address": "address2","name":"haha2","id":2,"email":"email2"},{"address":"address","name":"haha","id":1,"email":"email"}]";
		List<AccountBean> readJson2List =JSON.parseArray(json, AccountBean.class);
		//输出测试
		JsonUtils.beanToJson(readJson2List);
	}

场景二：前端向后台传递数组格式的json字符串，如何转化成List<HashMap<String,Object>>集合

	@Test
	public void readJson2ListMap() {
		String json = "[{"address": "address2","name":"haha2","id":2,"email":"email2"},{"address":"address","name":"haha","id":1,"email":"email"}]";
		List<HashMap> readJson2List =JSON.parseArray(json,HashMap.class);
		//输出测试
		JsonUtils.beanToJson(readJson2List);
	}

二、fastJson将json格式字符串转化成对象

场景一：前端向后台传递数组格式的json字符转化成Bean对象

@Test
	public void readJson2Bean() {
		String json = "{"address": "address2","name":"haha2","id":2,"email":"email2"}";
		AccountBean accountBean  =JSON.parseObject(json,AccountBean.class);
		//输出测试
		JsonUtils.beanToJson(accountBean);
	}

场景二：前端向后台传递数组格式的json字符串Map<String,Object>集合

@Test
	public void readJson2Map() {
		String json = "{"address": "address2","name":"haha2","id":2,"email":"email2"}";
		HashMap<String,Object> accountBean  =JSON.parseObject(json,Map.class);
		//输出测试
		JsonUtils.beanToJson(accountBean);
	}

测试：

三、FastJson将对象或集合转化成json格式字符串

@Test
	public void beanAndCollectionTOJson() {
		AccountBean	bean = new AccountBean();
		bean.setAddress("china-Guangzhou");
		bean.setEmail("hoojo_@126.com");
		bean.setId(1);
		bean.setName("hoojo");
		String json  = JSON.toJSONString(bean);
		System.out.println(json);
	}

四、FastJson将json格式字符串转化成json对象

@Test
	public void jsonStringTOJsonBean() {
		String json = "{"address": "address2","name":"haha2","id":2,"email":"email2"}";
		JSONObject parse = (JSONObject) JSON.parse(json);
		String address = (String) parse.get("address");
		System.out.println("输出address=="+address);
	}

五、FastJson将json格式字符串转化成json数组

	@Test
	public void jsonString2JsonArray() {
		String json = "[{"address": "address2","name":"haha2","id":2,"email":"email2"},{"address":"address","name":"haha","id":1,"email":"email"}]";
		JSONArray parseArray = JSON.parseArray(json);
		//输出测试
		JsonUtils.beanToJson(parseArray.get(0));
	}

六、FastJson将java对象转化成json对象

@Test
	public void beanAndCollectionTOJsonBean() {
		AccountBean	bean = new AccountBean();
		bean.setAddress("china-Guangzhou");
		bean.setEmail("hoojo_@126.com");
		bean.setId(1);
		bean.setName("hoojo");
		JSONObject json  = (JSONObject) JSON.toJSON(bean);
		json.get("address");
		System.out.println(json);
	}