Java基础之FastJson详解

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);
 }

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