用maven引入fastjson jar包

<dependency>
   <groupId>com.alibaba</groupId>
   <artifactId>fastjson</artifactId>
   <version>1.2.24</version>
</dependency>


Map map=new HashMap();
map.put("page_size","10");
map.put("page_index","1");
String  param= JSON.toJSONString(map);

===========================================================

		Map<String, Object> resultMap = new HashMap<>();
        resultMap.put("type", type);
        resultMap.put("id", 10);
        resultMap.put("name", "name");
        JSONArray jArray = new JSONArray();
        jArray.add(resultMap);
        String str = jArray.toString();

展开全部

Map转成32313133353236313431303231363533e58685e5aeb931333363393633json格式

Map map = new HashMap();

map.put(“users”, users);

map.put(“u”, u);

1.转成JSONArray类型

JSONArray json = JSONArray.fromObject(map);

System.out.println(json.toString());//

[{“users”:[{“password”:“1234”,“username”:“cxl”},

{“password”:“1234”,“username”:“lhl”}],“u”:{“password”:“1234”,“username”:“lhl”}}]

response.getWriter().print(json.toString);

js中取数据：alert(data[0].users[0].username);

2.转成JSONObject类型

JSONObject json = JSONObject.fromObject(map);

System.out.println(json);//

{“user”:[{“password”:“1234”,“username”:“cxl”},

{“password”:“1234”,“username”:“lhl”}],“u”:{“password”:“1234”,“username”:“lhl”}}

response.getWriter().print(json);

js中取数据：alert(data.user[0].username);

记录：265

场景：Java对象转换为Map；Map转换为Java对象；Map转换为Json字符串。

本例环境：JDK 1.8

1.Java对象转换为Map

普通java对象的属性和属性值，转换为Map的Key和Value。

方法：

public static Map<String, Object> object2Map(Object obj) throws Exception {
 Map<String, Object> map = new HashMap<String, Object>();
 Field[] fields = obj.getClass().getDeclaredFields();
 for (Field field : fields) {
   field.setAccessible(true);
   map.put(field.getName(), field.get(obj));
 }
 return map;
}

测试：

GirlInfo girlInfo2 = new  GirlInfo("小州",Double.valueOf("165"),
    Double.valueOf("102"),"C","杭州");
Map<String,Object> map2 = MapToObjectUtils.object2Map(girlInfo2);

2.Map转换为Java对象

Map的Key和Value转换为普通java对象的属性和属性值。

方法：

public static <T> T map2Object(Map<String, Object> map, Class<T> clazz) {
  if (map == null) {
      return null; }
  T obj = null;
  try {
   obj = clazz.newInstance();
   Field[] fields = clazz.getDeclaredFields();
   for (Field field : fields) {
    int modifiers = field.getModifiers();
    //判断Static属性或者Final属性
    if (Modifier.isStatic(modifiers) || Modifier.isFinal(modifiers)) {
        continue;
    } else {
      //设置为true后,反射即可访问私有变量
      field.setAccessible(true);
      field.set(obj, map.get(field.getName()));
    }}
  } catch (Exception e) {
     e.printStackTrace();
  }
     return obj;
}

测试：

Map<String,Object> map = new HashMap<String,Object>();
map.put("name","小杭");
map.put("height",Double.valueOf("162"));
map.put("weight",Double.valueOf("100"));
map.put("cup","B");
map.put("city","杭州");
GirlInfo girlInfo = MapToObjectUtils.map2Object(map,GirlInfo.class);

3.Map转换为Json字符串

Map的Key和Value转换为JSON字符串格式。

方法：

public static String mapToJsonString(Map map){
  JSONObject json = new JSONObject();
  Iterator<Map.Entry<String, String>> entries = map.entrySet().iterator();
  while (entries.hasNext()) {
    Map.Entry<String, String> entry = entries.next();
    json.put(entry.getKey(),entry.getValue());
  }
  return json.toString();
}

测试：

Map<String,Object> map3 = new HashMap<String,Object>();
map3.put("name","小杭");
map3.put("height",Double.valueOf("162"));
map3.put("weight",Double.valueOf("100"));
map3.put("cup","B");
map3.put("city","杭州");
String result = MapToObjectUtils.mapToJsonString(map3);

数据格式：

{
  "city":"杭州",
  "name":"小杭",
  "weight":100.0,
  "height":162.0,
  "cup":"B"
}

4.实体类GirlInfo

测试中使用到的GirlInfo类

public class GirlInfo implements Serializable {

 private String name;
 private Double height;
 private Double weight;
 private String cup;
 private String city;
 public GirlInfo(){}
 public GirlInfo(String name,Double height, 
     Double weight,String cup,String city){
  this.name = name;
  this.height = height;
  this.weight = weight;
  this.cup=cup;
  this.city = city;
 }
 public String getName() {
     return name;
 }
 public void setName(String name) {
     this.name = name;
 }
 public Double getHeight() {
     return height;
 }
 public void setHeight(Double height) {
     this.height = height;
 }
 public Double getWeight() {
     return weight;
 }
 public void setWeight(Double weight) {
     this.weight = weight;
 }
 public String getCup() {
     return cup;
 }
 public void setCup(String cup) {
     this.cup = cup;
 }
 public String getCity() {
     return city;
 }
 public void setCity(String city) {
     this.city = city;
 }
}

以上，感谢。

2021年12月16日