先说下我自己的理解，一般而言，JSON字符串要转为java对象需要自己写一个跟JSON一模一样的实体类bean，然后用bean.class作为参数传给对应的方法，实现转化成功。
上述这种方法太麻烦了。其实有一种东西叫jsonObject可以直接不用新建实体类bean，而实现转化，先说org.json.JSONObject这个JSONObject，贴上代码：
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.json.JSONObject;
public class JsonUtils {
private static String beanToJson(Object bean) {
StringBuilder json = new StringBuilder();
json.append("{");
PropertyDescriptor[] props = null;
try {
props = Introspector.getBeanInfo(bean.getClass(), Object.class)
.getPropertyDescriptors();
} catch (IntrospectionException e) {
}
if (props != null) {
for (int i = 0; i < props.length; i++) {
try {
String name = objToJson(props[i].getName());
String value = objToJson(props[i].getReadMethod()
.invoke(bean));
json.append(name);
json.append(":");
json.append(value);
json.append(",");
} catch (Exception e) {
}
}
json.setCharAt(json.length() - 1, '}');
} else {
json.append("}");
}
return json.toString();
}
private static String listToJson(List list) {
StringBuilder json = new StringBuilder();
json.append("[");
if (list != null && list.size() > 0) {
for (Object obj : list) {
json.append(objToJson(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
private static String arrayToJson(Object[] array) {
StringBuilder json = new StringBuilder();
json.append("[");
if (array != null && array.length > 0) {
for (Object obj : array) {
json.append(objToJson(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
private static String mapToJson(Map map) {
StringBuilder json = new StringBuilder();
json.append("{");
if (map != null && map.size() > 0) {
for (Object key : map.keySet()) {
json.append(objToJson(key));
json.append(":");
json.append(objToJson(map.get(key)));
json.append(",");
}
json.setCharAt(json.length() - 1, '}');
} else {
json.append("}");
}
return json.toString();
}
private static String setToJson(Set set) {
StringBuilder json = new StringBuilder();
json.append("[");
if (set != null && set.size() > 0) {
for (Object obj : set) {
json.append(objToJson(obj));
json.append(",");
}
json.setCharAt(json.length() - 1, ']');
} else {
json.append("]");
}
return json.toString();
}
private static String stringToJson(String s) {
if (s == null) {
return "";
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
char ch = s.charAt(i);
switch (ch) {
case '"':
sb.append("\"");
break;
case '\':
sb.append("\\");
break;
case 'b':
sb.append("\b");
break;
case 'f':
sb.append("\f");
break;
case 'n':
sb.append("\n");
break;
case 'r':
sb.append("\r");
break;
case 't':
sb.append("\t");
break;
case '/':
sb.append("\/");
break;
default:
if (ch >= 'u0000' && ch <= 'u001F') {
String ss = Integer.toHexString(ch);
sb.append("\u");
for (int k = 0; k < 4 - ss.length(); k++) {
sb.append('0');
}
sb.append(ss.toUpperCase());
} else {
sb.append(ch);
}
}
}
return sb.toString();
}
public static String objToJson(Object obj) {
StringBuilder json = new StringBuilder();
if (obj == null) {
json.append("""");
} else if (obj instanceof Number) {
Number num = (Number)obj;
json.append(num.toString());
} else if (obj instanceof Boolean) {
Boolean bl = (Boolean)obj;
json.append(bl.toString());
} else if (obj instanceof String) {
json.append(""").append(stringToJson(obj.toString())).append(""");
} else if (obj instanceof Object[]) {
json.append(arrayToJson((Object[]) obj));
} else if (obj instanceof List) {
json.append(listToJson((List) obj));
} else if (obj instanceof Map) {
json.append(mapToJson((Map) obj));
} else if (obj instanceof Set) {
json.append(setToJson((Set) obj));
} else {
json.append(beanToJson(obj));
}
return json.toString();
}
@SuppressWarnings("unchecked")
public static Map json2Map(String jsonString) {
Map map = new HashMap();
try {
if(null != jsonString && !"".equals(jsonString)){
JSonObject jsonObject = new JSonObject(jsonString);
Iterator keyIter = jsonObject.keys();
String key = "";
Object value = null;
while (keyIter.hasNext()) {
key = (String) keyIter.next();
value = jsonObject.get(key);
map.put(key, value);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return map;
}
//测试方法
public static void main(String[] args) {
Map params = new HashMap();
params.put("callId123", Integer.valueOf(1000));
Map retMap = new HashMap();
retMap.put("params", params);
retMap.put("result", true);
List ls = new ArrayList();
ls.add(new HashMap());
ls.add("hello world!!");
ls.add(new String[4]);
retMap.put("list", ls);
String[] strArray = new String[10];
strArray[1]="first";
strArray[2]="2";
strArray[3]="3";
System.out.println("Boolean:"+JsonUtils.objToJson(true));
System.out.println("Number:"+JsonUtils.objToJson(23.3));
System.out.println("String:"+JsonUtils.objToJson("sdhfsjdgksdlkjfk"sd,!#%$^&*#(*@&*%&*$fsdfsdfsdf"));
System.out.println("Map :"+JsonUtils.objToJson(retMap));
System.out.println("List:"+JsonUtils.objToJson(ls));
System.out.println("Array:"+JsonUtils.objToJson(strArray));
String json = JsonUtils.objToJson(retMap);
Map r = JsonUtils.json2Map(json);
System.out.println(r.get("callId123"));
}
}
再来聊聊net.sf.json.JSONObject这个JSONObject，代码如下
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.linkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.TimeZone;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.util.CycleDetectionStrategy;
import net.sf.json.util.PropertyFilter;
import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
public class JsonUtil {
private static ObjectMapper objectMapper = null;
static {
objectMapper = new ObjectMapper();
//设置为中国上海时区
objectMapper.setTimeZone(TimeZone.getTimeZone("GMT+8"));
//空值不序列化
objectMapper.setSerializationInclusion(Include.NON_NULL);
//反序列化时，属性不存在的兼容处理
objectMapper.getDeserializationConfig().withoutFeatures(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
//序列化时，日期的统一格式
objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}
public static String convertObjectToJson(Object obj) {
if (obj == null) {
// throw new IllegalArgumentException("对象参数不能为空。");
return null;
}
try {
return objectMapper.writevalueAsString(obj);
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
public static T parseJsonToObject(String jsonString, Class valueType) {
if(jsonString == null || "".equals((jsonString))){
return null;
}
try {
return objectMapper.readValue(jsonString, valueType);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
@SuppressWarnings("unchecked")
public static List parseJsonToList(String jsonString,Class valueType) {
if(jsonString == null || "".equals((jsonString))){
return null;
}
List result = new ArrayList();
try {
List> list = objectMapper.readValue(jsonString, List.class);
for (linkedHashMap map : list) {
String jsonStr = convertObjectToJson(map);
T t = parseJsonToObject(jsonStr, valueType);
result.add(t);
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
public static JSonObject getJsonObject(Object obj) {
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);
jsonConfig.setJsonPropertyFilter(new PropertyFilter() {
@Override
public boolean apply(Object source, String name, Object value) {
if(value==null){
return true;
}
return false;
}
});
return JSONObject.fromObject(obj, jsonConfig);
}
public static JSonArray getJsonArray(Object obj) {
JsonConfig jsonConfig = new JsonConfig();
jsonConfig.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);
return JSONArray.fromObject(obj, jsonConfig);
}
public static Map parseJsonStr(String jsonStr) {
Map result = new HashMap();
JSonObject jsonObj = JsonUtil.getJsonObject(jsonStr);
for (Object key : jsonObj.keySet()) {
result.put((String) key, jsonObj.get(key));
}
return result;
}
}
总结：net.sf.json.JSONObject这个属于json-lib这个老牌的系列，依赖的包超级多，commons的lang、logging、beanutils、collections等组件都有。
而org.json则相对来说依赖的包少一些，速度和性能方面没有怎么进行测试。
以上这篇基于JSON和java对象的互转方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持考高分网。
