map --> json

接下来介绍Map对象与json的相互转换

Map类型的转换就需要用到

GsonBuilder().enableComplexMapKeySerialization().create()类生成Gson对象
1.      Map<String, String>类型的转换：

这里直接贴关键代码，其他代码可参考前两篇文章，或下载代码。

private String seven() {
Gson gson2 = new GsonBuilder().enableComplexMapKeySerialization().create();
Map<String, String> map = new HashMap<String, String>();
map.put("key1", "value1");
map.put("key2", "value2");
map.put("key3", "value3");

return gson2.toJson(map);
}
 

结果为：

把json数据转换为Map<String, String>：

private String seven() {
Gson gson2 = new GsonBuilder().enableComplexMapKeySerialization().create();
Map<String, String> map = new HashMap<String, String>();
map.put("key1", "value1");
map.put("key2", "value2");
map.put("key3", "value3");

String jsonString = gson.toJson(map);
Type type = new TypeToken<Map<String, String>>() {}.getType();
Map<String, String> map2 = gson2.fromJson(jsonString, type);

String showString = "";
for (String keyString : map2.keySet()) {
showString += keyString + ":" + map2.get(keyString) + " ----- ";
}

showString += "---------------------- ";
return showString;
}
 

结果为：

2.      Map<Object, String>类型的转换：

private String eight() {
Gson gson2 = new GsonBuilder().enableComplexMapKeySerialization().create();
Map<ToJsonBeanOne, String> map = new LinkedHashMap<ToJsonBeanOne, String>();
map.put(new ToJsonBeanOne(1, "小熊1", 21), "value1");
map.put(new ToJsonBeanOne(2, "小熊2", 21), "value2");
map.put(new ToJsonBeanOne(3, "小熊3", 21), "value3");

return gson2.toJson(map);
}

结果为：

把json数据转换为Map<Object, String>：

private String eight() {
Gson gson2 = new GsonBuilder().enableComplexMapKeySerialization().create();
Map<ToJsonBeanOne, String> map = new LinkedHashMap<ToJsonBeanOne, String>();
map.put(new ToJsonBeanOne(1, "小熊1", 21), "value1");
map.put(new ToJsonBeanOne(2, "小熊2", 21), "value2");
map.put(new ToJsonBeanOne(3, "小熊3", 21), "value3");

String jsonString = gson2.toJson(map);

Type type = new TypeToken<Map<ToJsonBeanOne, String>>() {}.getType();
Map<ToJsonBeanOne, String> map2 = gson.fromJson(jsonString, type);

String showString = "";
for (ToJsonBeanOne beanOne : map2.keySet()) {
showString += "key: " + beanOne.toString() + "value:" + map2.get(beanOne) + " ----- ";
}

showString += "---------------------- ";
return showString;
}
结果为：

 

3. Map<String, Object>类型的转换：
private String nine() {
Gson gson2 = new GsonBuilder().enableComplexMapKeySerialization().create();
Map<String, ToJsonBeanOne> map = new LinkedHashMap<String, ToJsonBeanOne>();
map.put("key1", new ToJsonBeanOne(1, "小熊1", 21));
map.put("key2", new ToJsonBeanOne(2, "小熊2", 21));
map.put("key3", new ToJsonBeanOne(3, "小熊3", 21));

return gson2.toJson(map);
}
 

结果为：

 

把json数据转换为Map<String, Object>：

private String nine() {
Gson gson2 = new GsonBuilder().enableComplexMapKeySerialization().create();
Map<String, ToJsonBeanOne> map = new LinkedHashMap<String, ToJsonBeanOne>();
map.put("key1", new ToJsonBeanOne(1, "小熊1", 21));
map.put("key2", new ToJsonBeanOne(2, "小熊2", 21));
map.put("key3", new ToJsonBeanOne(3, "小熊3", 21));
String jsonString = gson2.toJson(map);

Type type = new TypeToken<Map<String, ToJsonBeanOne>>() {}.getType();
Map<String, ToJsonBeanOne> map2 = gson.fromJson(jsonString, type);

String showString = "";
for (String keyString : map2.keySet()) {
showString += "key: " + keyString + " value: " + map2.get(keyString).toString() + "----- ";
}

showString += "---------------------- ";
return showString;
}
 

结果为：

原文链接：https://blog.csdn.net/a249900679/article/details/51386660