通过反射解析json，无需依赖三方

package com.example.jsontools;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.lang.reflect.ParameterizedType;import java.lang.reflect.Type;import java.lang.reflect.TypeVariable;import java.util.ArrayList;import java.util.Collection;import java.util.List;import java.util.Map;import java.util.Set;import org.json.JSONArray;import org.json.JSONException;import org.json.JSONObject;import android.util.Log;/** * @author wly * @date 2016-07-22 */public class JsonUtil {/** * 解析字符串  */public static String getString(String jsonStr, String key){if(isEmpty(jsonStr) || isEmpty(key))return null;try {JSONObject obj = new JSONObject(jsonStr);String content = obj.optString(key);if(isEmpty(content))//统一将所有的空值状态返回为""return "";return content;} catch (JSONException e) {Log.e("JsonUtil", e.getMessage());}return null;}/** * 无数据或解析异常时返回int最小值 */public static int getInt(String jsonStr, String key){if(isEmpty(jsonStr) || isEmpty(key))return Integer.MIN_VALUE;try {JSONObject obj = new JSONObject(jsonStr);int content = obj.optInt(key);return content;} catch (JSONException e) {return Integer.MIN_VALUE;}}/** * 无数据或解析异常时返回long最小值 */public static long getLong(String jsonStr, String key){if(isEmpty(jsonStr) || isEmpty(key))return Long.MIN_VALUE;try{JSONObject obj = new JSONObject(jsonStr);long l = obj.optLong(key);return l;} catch (JSONException e){return Long.MIN_VALUE;}}/** * 无数据或解析异常时返回Double最小值 */public static double getDouble(String jsonStr, String key){if(isEmpty(jsonStr) || isEmpty(key))return Double.MIN_VALUE;try{JSONObject obj = new JSONObject(jsonStr);double d = obj.optDouble(key);return d;} catch (JSONException e){return Double.MIN_VALUE;}}/** * 将json转换为List<Bean> */public static <T> List<T> json2BeanList(String jsonStr, Class<T> clazz){if(isEmpty(jsonStr))return null;try{List<T> beans = new ArrayList<T>();JSONArray arr = new JSONArray(jsonStr);for(int i = 0; i < arr.length(); i++)beans.add(json2Bean(arr.optJSONObject(i).toString(), clazz));return beans;} catch (Exception e) {Log.e("JsonUtil", e.getMessage());}return null;}/** * 将json转换为Bean */public static <T> T json2Bean(String jsonStr, Class<T> clazz){if(isEmpty(jsonStr))return null;try {JSONObject obj = new JSONObject(jsonStr);T bean = json2BeanByAttr(clazz, obj);return bean;} catch (InstantiationException e) {Log.e("JsonUtil", e.getMessage());} catch (IllegalAccessException e) {// 说明访问到了私有的属性，表示该javaBean是private的try {JSONObject obj = new JSONObject(jsonStr);T bean = json2BeanByMethod(clazz, obj);return bean;} catch (JSONException e1) {Log.e("JsonUtil", e1.getMessage());} catch (InstantiationException e1) {Log.e("JsonUtil", e1.getMessage());} catch (IllegalAccessException e1) {Log.e("JsonUtil", e1.getMessage());} catch (IllegalArgumentException e1) {Log.e("JsonUtil", e1.getMessage());} catch (InvocationTargetException e1) {Log.e("JsonUtil", e1.getMessage());}} catch (JSONException e) {Log.e("JsonUtil", e.getMessage());}return null;}/** * 当javaBean属性为private修饰时通过set方法设置属性值 */private static <T> T json2BeanByMethod(Class<T> clazz, JSONObject obj) throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{T bean = clazz.newInstance();Method[] methods = clazz.getMethods();Field[] fds = clazz.getDeclaredFields();for(Field fd : fds){List<T> datas = null;if(beanContainsCollection(fd)) {JSONArray arr = obj.optJSONArray(fd.getName());for (int j = 0; j < methods.length; j++) {if(methods[j].getName().equalsIgnoreCase("get" + fd.getName())){Type fc = fd.getGenericType();if(fc == null) continue;              if(fc instanceof ParameterizedType){              // 如果是泛型参数的类型                   ParameterizedType pt = (ParameterizedType) fc;                  Class<T> genericClazz = (Class<T>) pt.getActualTypeArguments()[0]; // 得到泛型里的class类型对象。                  datas = json2BeanList(arr.toString(), genericClazz);;            }   }}}for (int i = 0; i < methods.length; i++) {if(methods[i].getName().equalsIgnoreCase("set" + fd.getName()))//拼接方法名if(datas != null && datas.size() > 0)methods[i].invoke(bean, datas);//执行方法elsemethods[i].invoke(bean, obj.opt(fd.getName()));//执行方法}}return bean;}/** * 当javaBean属性为public修饰时直接设置属性值 */private static <T> T json2BeanByAttr(Class<T> clazz, JSONObject obj) throws InstantiationException, IllegalAccessException{T bean = clazz.newInstance();Field[] fds = clazz.getDeclaredFields();for(Field fd : fds)            fd.set(bean, obj.opt(fd.getName()));//设置属性return bean;}/** * 集合对象转json */public static <T> String beanList2Json(/*Class<T> bean,*/ List<T> infos){if(infos == null || infos.size() == 0)return null;StringBuffer buffer = new StringBuffer();buffer.append("[");for (int i = 0; i < infos.size(); i++) buffer.append(bean2Json((Class<T>) infos.get(i).getClass(), infos.get(i)) + ((i == infos.size() - 1) ? "" : "," ));return buffer.append("]").toString();}/** * Map<T, T>集合嵌套转换为json */public static <T> String beanMap2Json(Map<T, T> maps){if(maps.size() == 0 || maps == null)return null;StringBuffer buffer = new StringBuffer();//buffer.apped("{");Set<T> keys = maps.keySet();for(T key : keys){if(maps.get(key).getClass().toString().contains("Map"))return "\"" + key + "\":" + beanMap2Json((Map<T, T>)maps.get(key)); else if(maps.get(key).getClass().toString().contains("List"))return "\"" + key + "\":" + beanList2Json((List<T>)maps.get(key));String bean2Json = bean2Json((Class<T>)maps.get(key).getClass(), maps.get(key));buffer.append("\"" + key + "\":[{").append(bean2Json.substring(1, bean2Json.length() - 1)).append("}],");}return buffer.substring(0, buffer.length() - 1);}/** * Map<T, List<T>>集合嵌套转换为json */public static <T> String beanListMap2Json(/*Class<T> bean, */Map<T, List<T>> maps){if(maps.size() == 0 || maps == null)return null;StringBuffer buffer = new StringBuffer();buffer.append("{");Set<T> keys = maps.keySet();for(T key : keys)buffer.append("\"" + key + "\":").append(beanList2Json(/*bean, */maps.get(key))).append(",");return buffer.substring(0, buffer.length() - 1) + "}";}/** * 对象转json */public static <T> String bean2Json(Class<T> clazz, T info){try {String json = bean2JsonByAttr(clazz, info);return json;} catch (IllegalAccessException e) {// 说明访问到了私有的属性，表示该javaBean是private的try {String json = bean2JsonByMethod(/*clazz, */info);return json;} catch (Exception e1) {Log.e("JsonUtil", e1.getMessage());}}return null;}private static <T> String bean2JsonByAttr(Class<T> clazz, T info) throws IllegalAccessException{StringBuffer buffer = new StringBuffer();Field[] fds = clazz.getDeclaredFields();buffer.append("{");for(Field fd : fds){if(beanContainsCollection(/*clazz, */fd/*, info*/)){String jsonBean = beanType(/*clazz,*/ fd, info);buffer.append(jsonBean + ",");continue;}String name = fd.getName();Object value = fd.get(info);try{if(fd.getType().newInstance() instanceof String)buffer.append("\"" + name + "\":\"" + value + "\",");elsebuffer.append("\"" + name + "\":" + value + ",");} catch (InstantiationException e) {buffer.append("\"" + name + "\":" + value + ",");}}return buffer.substring(0, buffer.length() - 1) + "}";}private static <T> String bean2JsonByMethod(/*Class<T> clazz, */T info) throws IllegalAccessException, IllegalArgumentException, InvocationTargetException{StringBuffer buffer = new StringBuffer();Method[] methods = info.getClass().getMethods();Field[] fds = info.getClass().getDeclaredFields();buffer.append("{");for(Field fd : fds){if(beanContainsCollection(/*clazz, */fd/*, info*/)){String jsonBean = beanType(/*clazz,*/ fd, info);buffer.append(jsonBean + ",");continue;}for (int i = 0; i < methods.length; i++) {if(methods[i].getName().equalsIgnoreCase("get" + fd.getName())){Object value = methods[i].invoke(info);//执行方法String name = fd.getName();try{if(fd.getType().newInstance() instanceof String)buffer.append("\"" + name + "\":\"" + value + "\",");elsebuffer.append("\"" + name + "\":" + value + ",");} catch (InstantiationException e) {buffer.append("\"" + name + "\":" + value + ",");}}}}return buffer.substring(0, buffer.length() - 1) + "}";}/** * 对象中如果包含有集合<对象>的处理方法 * @throws IllegalArgumentException  * @throws IllegalAccessException  * @throws InstantiationException  */private static <T> String beanType(/*Class<T> clazz, */Field fd, T info){try {Object instance = fd.getType().newInstance();} catch (Exception e) {// 判断该属性是否是集合if(e.getMessage().contains("Map"))try {return beanMap2Json(/*clazz, */(Map<T, T>)fd.get(info));} catch (IllegalAccessException e1) {// 被private 修饰，调用get方法获取参数return beanTypeByMethod(/*clazz, */fd, info, "map");} catch (IllegalArgumentException e1) {Log.e("JsonUtil", e1.getMessage());}if(e.getMessage().contains("List"))try {return beanList2Json(/*clazz, */(List<T>)fd.get(info));} catch (IllegalAccessException e1) {// 被private 修饰，调用get方法获取参数return beanTypeByMethod(/*clazz, */fd, info, "list");} catch (IllegalArgumentException e1) {Log.e("JsonUtil", e1.getMessage());}}//// 判断属性为哪种集合//if(instance instanceof Map) //return beanListMap2Json(clazz, (Map<T, List<T>>)fd.get(info));//if(instance instanceof List)//return beanList2Json(clazz, (List<T>)fd.get(info));return null;}private static <T> String beanTypeByMethod(/*Class<T> clazz, */Field fd, T info, String type) {Method[] methods = info.getClass().getMethods();for (int i = 0; i < methods.length; i++) {if(methods[i].getName().equalsIgnoreCase("get" + fd.getName())){try {Object value = methods[i].invoke(info);if(type.equals("list"))return "\"" + fd.getName() + "\":" + beanList2Json(/*clazz, */(List<T>)value);elsereturn beanMap2Json(/*clazz, */(Map<T, T>)value);} catch (IllegalAccessException e2) {Log.e("JsonUtil", e2.getMessage());} catch (IllegalArgumentException e2) {Log.e("JsonUtil", e2.getMessage());} catch (InvocationTargetException e2) {Log.e("JsonUtil", e2.getMessage());}}}return null;}/** * 判断对象中是否包含集合 */private static <T> boolean beanContainsCollection(/*Class<T> clazz, */Field fd/*, T info*/){try {Object instance = fd.getType().newInstance();// 判断该属性是否是集合//if(instance instanceof  Collection || instance instanceof Map)//return true;} catch (Exception e) {// 判断该属性是否是集合if(e.getMessage().contains("Map") || e.getMessage().contains("List"))return true;}return false;}/** * 验证非空 */private static boolean isEmpty(String str){if(str == null || "".equals(str) || "null".equals(str))return true;return false;}}

相对于上一篇博客，这里的方法更为全面一些，新增功能：将Map<T, T>  Map<T , List<T>>转换为Json字符串，以及解析json时解析到对象中的List<Bean>的解析，如果有什么问题，请及时指正，欢迎留言