json和map和对象之间的互相转换
一,对象和json互转
1.对象转json(String)**
public static void convertObject() {
Student stu=new Student();
stu.setName("JSON");
stu.setAge("23");
stu.setAddress("北京市西城区");
//1、使用JSONObject
JSONObject json = JSONObject.fromObject(stu);
//2、使用JSONArray
JSONArray array=JSONArray.fromObject(stu);
String strJson=json.toString();
String strArray=array.toString();
System.out.println("strJson:"+strJson);
System.out.println("strArray:"+strArray);
}
2.json(String)转对象
public static void jsonStrToJava(){
//定义两种不同格式的字符串
String objectStr="{\"name\":\"JSON\",\"age\":\"24\",\"address\":\"北京市西城区\"}";
String arrayStr="[{\"name\":\"JSON\",\"age\":\"24\",\"address\":\"北京市西城区\"}]";
//1、使用JSONObject
JSONObject jsonObject=JSONObject.fromObject(objectStr);
Student stu=(Student)JSONObject.toBean(jsonObject, Student.class);
//2、使用JSONArray
JSONArray jsonArray=JSONArray.fromObject(arrayStr);
//获得jsonArray的第一个元素
Object o=jsonArray.get(0);
JSONObject jsonObject2=JSONObject.fromObject(o);
Student stu2=(Student)JSONObject.toBean(jsonObject2, Student.class);
System.out.println("stu:"+stu);
System.out.println("stu2:"+stu2);
}
对象和json互转工具类
package com.Dingyu.util;
import java.util.List;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.ObjectMapper;
/**
*
*/
public class JsonUtils {
// 定义jackson对象
private static final ObjectMapper MAPPER = new ObjectMapper();
/**
* 将对象转换成json字符串。
* <p>Title: pojoToJson</p>
* <p>Description: </p>
* @param data
* @return
*/
public static String objectToJson(Object data) {
try {
String string = MAPPER.writeValueAsString(data);
return string;
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return null;
}
/**
* 将json结果集转化为对象
*
* @param jsonData json数据
* @param clazz 对象中的object类型
* @return
*/
public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {
try {
T t = MAPPER.readValue(jsonData, beanType);
return t;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
/**
* 将json数据转换成pojo对象list
* <p>Title: jsonToList</p>
* <p>Description: </p>
* @param jsonData
* @param beanType
* @return
*/
public static <T>List<T> jsonToList(String jsonData, Class<T> beanType) {
JavaType javaType = MAPPER.getTypeFactory().constructParametricType(List.class, beanType);
try {
List<T> list = MAPPER.readValue(jsonData, javaType);
return list;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
二,Map与Json之间的转化
1.将json字符串转化成map格式
package com.dbzhang.demo;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.core.JsonParseException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class Json2Map {
/**
* 该方法主要是用来将json字符串转化成map集合
* @param args
* @throws IOException
* @throws JsonMappingException
* @throws JsonParseException
*/
public static void main(String[] args){
String json = "{\"name\":\"zdb\",\"age\":\"26\"}";
Map<String,String> map = new HashMap<String,String>();
ObjectMapper mapper = new ObjectMapper();
try {
map = mapper.readValue(json, new TypeReference<HashMap<String, String>>() {
});
System.out.println(map);
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
输出结果如下:
2.将Map转化成JSON格式:
package com.dbzhang.demo;
import java.util.HashMap;
import java.util.Map;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class Map2Json {
/**
* 这个类主要将map转化成json
* @param args
*/
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
Map<String,String> map = new HashMap<String,String>();
String json = "";
map.put("name", "zdb");
map.put("age", "25");
try {
json = mapper.writeValueAsString(map);
System.out.println(json);
} catch (JsonProcessingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
输出结果为:
3.map转成Json文件:
package com.dbzhang.demo;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import com.fasterxml.jackson.core.JsonGenerationException;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class Map2JsonFile {
/**
* 这个方法主要是用来将map转化成Json文件
* @param args
*/
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
Map<String,Object> map = new HashMap<String,Object>();
map.put("name", "lisi");
map.put("age", 28);
List<Object> list = new ArrayList<Object>();
list.add("登上");
list.add("旅游");
map.put("hobby", list);
try {
mapper.writeValue(new File("F:/json.text"), map);
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
输出结果:
三,对象与map的互相转换
/**
* 将对象装换为map
*
* @param bean
* @return
*/
public static <T> Map<String, Object> beanToMap(T bean) {
Map<String, Object> map = Maps.newHashMap();
if (bean != null) {
BeanMap beanMap = BeanMap.create(bean);
for (Object key : beanMap.keySet()) {
map.put(key + "", beanMap.get(key));
}
}
return map;
}
/**
* 将map装换为javabean对象
*
* @param map
* @param bean
* @return
*/
public static <T> T mapToBean(Map<String, Object> map, T bean) {
BeanMap beanMap = BeanMap.create(bean);
beanMap.putAll(map);
return bean;
}
List与List<Map<String, Object>>相互转换:
/**
* 将List<T>转换为List<Map<String, Object>>
*
* @param objList
* @return
* @throws JsonGenerationException
* @throws JsonMappingException
* @throws IOException
*/
public static <T> List<Map<String, Object>> objectsToMaps(List<T> objList) {
List<Map<String, Object>> list = Lists.newArrayList();
if (objList != null && objList.size() > 0) {
Map<String, Object> map = null;
T bean = null;
for (int i = 0, size = objList.size(); i < size; i++) {
bean = objList.get(i);
map = beanToMap(bean);
list.add(map);
}
}
return list;
}
/**
* 将List<Map<String,Object>>转换为List<T>
*
* @param maps
* @param clazz
* @return
* @throws InstantiationException
* @throws IllegalAccessException
*/
public static <T> List<T> mapsToObjects(List<Map<String, Object>> maps, Class<T> clazz)
throws InstantiationException, IllegalAccessException {
List<T> list = Lists.newArrayList();
if (maps != null && maps.size() > 0) {
Map<String, Object> map = null;
T bean = null;
for (int i = 0, size = maps.size(); i < size; i++) {
map = maps.get(i);
bean = clazz.newInstance();
mapToBean(map, bean);
list.add(bean);
}
}
return list;
}
总结:无论是json转对象,还是对象转map,差不多都用到了json为中间桥梁,都不是一种方法,我这里写的只是自己的一些总结,请根据自己情况而定。