java----JSON
JSON:
注意事项
解析的JSON对象必须有默认构造器
FastJson
pom
<dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.32</version> </dependency>
使用
解析简单xui JSON.toJSONString(jwtUser) JSON.parseObject("jsonString",JwtUser.class)
GSON
pom
<dependency> <groupId>com.google.code.gson</groupId> <artifactId>gson</artifactId> <version>2.6.2</version> </dependency>
使用
- 解析嵌套json
class Teacher{ private String name; private Stu stu; public Teacher(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Stu getStu() { return stu; } public void setStu(Stu stu) { this.stu = stu; } } class Stu{ private String name; public Stu(String name){ this.name=name; } public String getName() { return name; } public void setName(String name) { this.name = name; } } public class Test { public static void main(String[] args) { Gson gson = new Gson(); Teacher teacher = new Teacher("1"); Stu stu = new Stu("1"); stu.setName("stu"); teacher.setStu(stu); teacher.setName("teacher"); String s = gson.toJson(teacher); System.out.println(s); Teacher jwtUser1 = gson.fromJson(s, Teacher.class); System.out.println(jwtUser1); } }
下载组件 GSON jar 包
https://mvnrepository.com/artifact/com.google.code.gson/gson
创建JSON
import com.google.gson.JsonArray; import com.google.gson.JsonObject; import java.io.*; import java.util.ArrayList; public class Demo { public static void main(String[] args) throws IOException { createJson(); } public static void createJson(){ ArrayList<Person> list = new ArrayList<>(); list.add(new Person("花花",10)); list.add(new Person("哈哈",12)); JsonArray jsonElements = new JsonArray(); for (int i = 0; i < list.size(); i++) { JsonObject jsonObject = new JsonObject(); jsonObject.addProperty("name",list.get(i).getName()); jsonObject.addProperty("age",list.get(i).getAge()); jsonElements.add(jsonObject); } // System.out.println(jsonElements.toString()); try { BufferedWriter bw = new BufferedWriter(new FileWriter("a.json")); bw.write(jsonElements.toString()); bw.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } class Person{ private String name; private int age; public Person(String name, int age) { this.name = name; this.age = age; } public Person() { } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; } }
解析json数据(适合解析复杂的json数据)
必须严格准守解析流程,中途如果出现错误,就会发生解析失败
[] : beginArray;
{} : beginObject;
import com.google.gson.stream.JsonReader; import com.google.gson.stream.JsonToken; import java.io.*; import java.util.ArrayList; public class Demo { public static void main(String[] args){ jsonParse(); } public static void jsonParse(){ try { InputStream resourceAsStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("json\\person_json.json"); InputStreamReader inputStreamReader = new InputStreamReader(resourceAsStream); //json解释工具a JsonReader jsonReader = new JsonReader(inputStreamReader); ArrayList<Person> nameList = new ArrayList<>(); //开始解析数组 jsonReader.beginArray(); while (jsonReader.hasNext()){ nameList.add(parsePerson(jsonReader)); } //结束解析数组 jsonReader.endArray(); nameList.forEach((p)-> System.out.println(p)); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } private static Person parsePerson(JsonReader jsonReader) throws IOException { Person person = new Person(); jsonReader.beginObject(); while (jsonReader.hasNext()){ String name = jsonReader.nextName(); if ("name".equals(name)&&jsonReader.peek()!=JsonToken.NUMBER){ person.setName(jsonReader.nextString()); }else if("age".equals(name)){ person.setAge(Integer.parseInt(jsonReader.nextString())); }else{ //表示当所有都不成立的时候,就跳过该字段;解析下一个 jsonReader.skipValue(); } } jsonReader.endObject(); return person; } } class Person{ private String name; private int age; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; } }
json数据
[{"name":"花花","age":"10"},{"name":"哈哈","age":"10"}]
补充:
{"name":null}
while (jsonReader.hasNext()){ String name = jsonReader.nextName(); if ("name".equals(name)&&jsonReader.peek()!=JsonToken.NULL){ person.setName(jsonReader.nextString());//表示如果name为空,就不设置值,此时默认情况下,就为空 }else{ //跳过该字段 jsonReader.skipValue() } }
JsonReader.peek():看看值:没有真正的读取;(即光标没有移动)
JsonToken.STRING :值是否为字符串
JsonToken.NUMBER:值是否为数字
jsonReader.nextString():读取字符串;
JsongReader.nextInt():读取int数据
jsonReader.nextDouble():读取数组:
使用GSON工具解析json数据为单个对象
将一个java对象转换为json字符串,或者将json字符串解析并创建java对象
注意:只能是一个对象;
import com.google.gson.Gson; import java.io.*; public class Demo { public static void main(String[] args) { Mygson(); } private static void Mygson() { Gson gson = new Gson(); InputStream resourceAsStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("json\\person_json.json"); InputStreamReader inputStreamReader = new InputStreamReader(resourceAsStream); Person person = gson.fromJson(inputStreamReader, Person.class); System.out.println(person); } } class Person{ private String name; private int age; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; } }
json数据
{"name":"花花","age":10}
把一组JSON数据转换为java对象集合,或者把一个java对象集合转换为Json字符串
import com.google.gson.Gson; import com.google.gson.reflect.TypeToken; import java.io.*; import java.util.List; public class Demo { public static void main(String[] args) { Mygson(); } private static void Mygson() { Gson gson = new Gson(); InputStream resourceAsStream = Thread.currentThread().getContextClassLoader().getResourceAsStream("json" + "\\person_json.json"); InputStreamReader inputStreamReader = new InputStreamReader(resourceAsStream); TypeToken<List<Person>> listTypeToken = new TypeToken<List<Person>>() { }; List<Person> list = gson.fromJson(inputStreamReader, listTypeToken.getType()); System.out.println(list); System.out.println("---------------------------------------------------------"); //将list对象转换json字符串 String s = gson.toJson(list, listTypeToken.getType()); System.out.println(s); } } class Person { private String name; private int age; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Person{" + "name='" + name + '\'' + ", age=" + age + '}'; } }
json数据
[{"name":"花花","age":"10"},{"name":"哈哈","age":"10"}]
MapperUtils
import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.DeserializationFeature; import com.fasterxml.jackson.databind.JavaType; import com.fasterxml.jackson.databind.ObjectMapper; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; public class MapperUtils { private final static ObjectMapper objectMapper = new ObjectMapper(); public static ObjectMapper getInstance() { return objectMapper; } /** * 转换为 JSON 字符串 * * @param obj * @return * @throws Exception */ public static String obj2json(Object obj) throws Exception { return objectMapper.writeValueAsString(obj); } /** * 转换为 JSON 字符串,忽略空值 * * @param obj * @return * @throws Exception */ public static String obj2jsonIgnoreNull(Object obj) throws Exception { ObjectMapper mapper = new ObjectMapper(); mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL); return mapper.writeValueAsString(obj); } /** * 转换为 JavaBean * * @param jsonString * @param clazz * @return * @throws Exception */ public static <T> T json2pojo(String jsonString, Class<T> clazz) throws Exception { objectMapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true); return objectMapper.readValue(jsonString, clazz); } /** * 字符串转换为 Map<String, Object> * * @param jsonString * @return * @throws Exception */ public static <T> Map<String, Object> json2map(String jsonString) throws Exception { ObjectMapper mapper = new ObjectMapper(); mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL); return mapper.readValue(jsonString, Map.class); } /** * 字符串转换为 Map<String, T> */ public static <T> Map<String, T> json2map(String jsonString, Class<T> clazz) throws Exception { Map<String, Map<String, Object>> map = objectMapper.readValue(jsonString, new TypeReference<Map<String, T>>() { }); Map<String, T> result = new HashMap<String, T>(); for (Map.Entry<String, Map<String, Object>> entry : map.entrySet()) { result.put(entry.getKey(), map2pojo(entry.getValue(), clazz)); } return result; } /** * 深度转换 JSON 成 Map * * @param json * @return */ public static Map<String, Object> json2mapDeeply(String json) throws Exception { return json2MapRecursion(json, objectMapper); } /** * 把 JSON 解析成 List,如果 List 内部的元素存在 jsonString,继续解析 * * @param json * @param mapper 解析工具 * @return * @throws Exception */ private static List<Object> json2ListRecursion(String json, ObjectMapper mapper) throws Exception { if (json == null) { return null; } List<Object> list = mapper.readValue(json, List.class); for (Object obj : list) { if (obj != null && obj instanceof String) { String str = (String) obj; if (str.startsWith("[")) { obj = json2ListRecursion(str, mapper); } else if (obj.toString().startsWith("{")) { obj = json2MapRecursion(str, mapper); } } } return list; } /** * 把 JSON 解析成 Map,如果 Map 内部的 Value 存在 jsonString,继续解析 * * @param json * @param mapper * @return * @throws Exception */ private static Map<String, Object> json2MapRecursion(String json, ObjectMapper mapper) throws Exception { if (json == null) { return null; } Map<String, Object> map = mapper.readValue(json, Map.class); for (Map.Entry<String, Object> entry : map.entrySet()) { Object obj = entry.getValue(); if (obj != null && obj instanceof String) { String str = ((String) obj); if (str.startsWith("[")) { List<?> list = json2ListRecursion(str, mapper); map.put(entry.getKey(), list); } else if (str.startsWith("{")) { Map<String, Object> mapRecursion = json2MapRecursion(str, mapper); map.put(entry.getKey(), mapRecursion); } } } return map; } /** * 将 JSON 数组转换为集合 * * @param jsonArrayStr * @param clazz * @return * @throws Exception */ public static <T> List<T> json2list(String jsonArrayStr, Class<T> clazz) throws Exception { JavaType javaType = getCollectionType(ArrayList.class, clazz); List<T> list = (List<T>) objectMapper.readValue(jsonArrayStr, javaType); return list; } /** * 获取泛型的 Collection Type * * @param collectionClass 泛型的Collection * @param elementClasses 元素类 * @return JavaType Java类型 * @since 1.0 */ public static JavaType getCollectionType(Class<?> collectionClass, Class<?>... elementClasses) { return objectMapper.getTypeFactory().constructParametricType(collectionClass, elementClasses); } /** * 将 Map 转换为 JavaBean * * @param map * @param clazz * @return */ public static <T> T map2pojo(Map map, Class<T> clazz) { return objectMapper.convertValue(map, clazz); } /** * 将 Map 转换为 JSON * * @param map * @return */ public static String mapToJson(Map map) { try { return objectMapper.writeValueAsString(map); } catch (Exception e) { e.printStackTrace(); } return ""; } /** * 将 JSON 对象转换为 JavaBean * * @param obj * @param clazz * @return */ public static <T> T obj2pojo(Object obj, Class<T> clazz) { return objectMapper.convertValue(obj, clazz); } }
使用
ObjectMapper instance = MapperUtils.getInstance(); JsonNode jsonNode = instance.readTree(data); //封装的json字符串 JsonNode data1 = jsonNode.findPath("data"); //找到key为data的数据 String s = data1.toString(); //data1转换为String List<TbContent> tbContentDtos = MapperUtils.json2list(s, TbContent.class); //json数据变成java对象
使用 Jackson 处理 JSON 数据
Jackson 简介
Jackson 是一个简单基于 Java 应用库,Jackson 可以轻松的将 Java 对象转换成 json 对象和 xml 文档,同样也可以将 json、xml 转换成 Java 对象。Jackson 所依赖的 jar 包较少,简单易用并且性能也要相对高些,并且 Jackson 社区相对比较活跃,更新速度也比较快。
Jackson 特点
- 容易使用 - jackson API 提供了一个高层次外观,以简化常用的用例。
- 无需创建映射 - API提供了默认的映射大部分对象序列化。
- 性能高 - 快速,低内存占用,适合大型对象图表或系统。
- 干净的 JSON - jackson 创建一个干净和紧凑的 JSON 结果,这是让人很容易阅读。
- 不依赖 - 库不需要任何其他的库,除了 JDK。
- 开源代码 - jackson 是开源的,可以免费使用。
Jackson 注解
Jackson 类库包含了很多注解,可以让我们快速建立 Java 类与 JSON 之间的关系。
@JsonProperty
@JsonProperty
注解指定一个属性用于 JSON 映射,默认情况下映射的 JSON 属性与注解的属性名称相同,不过可以使用该注解的 value
值修改 JSON 属性名,该注解还有一个 index
属性指定生成 JSON 属性的顺序,如果有必要的话。
@JsonIgnore
@JsonIgnore
注解用于排除某个属性,这样该属性就不会被 Jackson 序列化和反序列化。
@JsonIgnoreProperties
@JsonIgnoreProperties
注解是类注解。在序列化为 JSON 的时候,@JsonIgnoreProperties({"prop1", "prop2"})
会忽略 pro1
和 pro2
两个属性。在从 JSON 反序列化为 Java 类的时候,@JsonIgnoreProperties(ignoreUnknown=true)
会忽略所有没有 Getter
和 Setter
的属性。该注解在 Java 类和 JSON 不完全匹配的时候很有用。
@JsonIgnoreType
@JsonIgnoreType
也是类注解,会排除所有指定类型的属性。
@JsonPropertyOrder
@JsonPropertyOrder
和 @JsonProperty
的 index
属性类似,指定属性序列化时的顺序。
@JsonRootName
@JsonRootName
注解用于指定 JSON 根属性的名称。
Jackson 使用实例
pom添加依赖(版本自己去maven仓库中查看最新版)
<!-- Json Begin --> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-core</artifactId> <version>${jackson-core.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>${jackson-databind.version}</version> </dependency> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-annotations</artifactId> <version>${jackson-core.version}</version> </dependency> <!-- Json End -->
对象的序列化与反序列化
package com.funtl.hello.httpclient; import com.fasterxml.jackson.core.JsonParseException; import com.fasterxml.jackson.databind.JsonMappingException; import com.fasterxml.jackson.databind.ObjectMapper; import java.io.IOException; public class JsonTester { public static void main(String[] args) { // 创建 ObjectMapper 对象 ObjectMapper mapper = new ObjectMapper(); String jsonString = "{\"name\":\"Mahesh\", \"age\":21}"; try { // 反序列化 JSON 到对象 Student student = mapper.readValue(jsonString, Student.class); System.out.println(student); // 序列化对象到 JSON String json = mapper.writeValueAsString(student); System.out.println(json); } catch (JsonParseException e) { e.printStackTrace(); } catch (JsonMappingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } class Student { private String name; private int age; }
集合的序列化与反序列化
package com.funtl.hello.httpclient; import com.fasterxml.jackson.databind.JavaType; import com.fasterxml.jackson.databind.JsonNode; import com.fasterxml.jackson.databind.ObjectMapper; import java.io.IOException; import java.util.ArrayList; import java.util.List; public class JsonTester { public static void main(String[] args) { // 创建 ObjectMapper 对象 ObjectMapper mapper = new ObjectMapper(); String jsonString = "{\"draw\":1,\"recordsTotal\":1,\"recordsFiltered\":1,\"data\":[{\"id\":33,\"title\":\"ad1\",\"subTitle\":\"ad1\",\"titleDesc\":\"ad1\",\"url\":\"https://sale.jd.com/act/XkCzhoisOMSW.html\",\"pic\":\"https://m.360buyimg.com/babel/jfs/t20164/187/1771326168/92964/b42fade7/5b359ab2N93be3a65.jpg\",\"pic2\":\"\",\"content\":\"<p><br></p>\"}],\"error\":null}"; try { // 反序列化 JSON 到树 JsonNode jsonNode = mapper.readTree(jsonString); // 从树中读取 data 节点 JsonNode jsonData = jsonNode.findPath("data"); System.out.println(jsonData); //获取的是一个数组(集合) // 反序列化 JSON 到集合 JavaType javaType = mapper.getTypeFactory().constructParametricType(ArrayList.class, TbContent.class); List<TbContent> tbContents = mapper.readValue(jsonData.toString(), javaType); for (TbContent tbContent : tbContents) { System.out.println(tbContent); } // 序列化集合到 JSON String json = mapper.writeValueAsString(tbContents); System.out.println(json); } catch (IOException e) { e.printStackTrace(); } } } class TbContent { private Long id; private String title; private String subTitle; private String titleDesc; private String url; private String pic; private String pic2; private String content; }
jackson工具类
package com.lusifer.leeshop.server.commons.utils; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.core.type.TypeReference; import com.fasterxml.jackson.databind.DeserializationFeature; import com.fasterxml.jackson.databind.JavaType; import com.fasterxml.jackson.databind.ObjectMapper; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * Jackson 工具类 * <p>Title: MapperUtils</p> * <p>Description: </p> * * @author Lusifer * @version 1.0.0 * @date 2018/3/4 21:50 */ public class MapperUtils { private final static ObjectMapper objectMapper = new ObjectMapper(); public static ObjectMapper getInstance() { return objectMapper; } /** * 转换为 JSON 字符串 * * @param obj * @return * @throws Exception */ public static String obj2json(Object obj) throws Exception { return objectMapper.writeValueAsString(obj); } /** * 转换为 JSON 字符串,忽略空值 * * @param obj * @return * @throws Exception */ public static String obj2jsonIgnoreNull(Object obj) throws Exception { ObjectMapper mapper = new ObjectMapper(); mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL); return mapper.writeValueAsString(obj); } /** * 转换为 JavaBean * * @param jsonString * @param clazz * @return * @throws Exception */ public static <T> T json2pojo(String jsonString, Class<T> clazz) throws Exception { objectMapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true); return objectMapper.readValue(jsonString, clazz); } /** * 字符串转换为 Map<String, Object> * * @param jsonString * @return * @throws Exception */ public static <T> Map<String, Object> json2map(String jsonString) throws Exception { ObjectMapper mapper = new ObjectMapper(); mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL); return mapper.readValue(jsonString, Map.class); } /** * 字符串转换为 Map<String, T> */ public static <T> Map<String, T> json2map(String jsonString, Class<T> clazz) throws Exception { Map<String, Map<String, Object>> map = objectMapper.readValue(jsonString, new TypeReference<Map<String, T>>() { }); Map<String, T> result = new HashMap<String, T>(); for (Map.Entry<String, Map<String, Object>> entry : map.entrySet()) { result.put(entry.getKey(), map2pojo(entry.getValue(), clazz)); } return result; } /** * 深度转换 JSON 成 Map * * @param json * @return */ public static Map<String, Object> json2mapDeeply(String json) throws Exception { return json2MapRecursion(json, objectMapper); } /** * 把 JSON 解析成 List,如果 List 内部的元素存在 jsonString,继续解析 * * @param json * @param mapper 解析工具 * @return * @throws Exception */ private static List<Object> json2ListRecursion(String json, ObjectMapper mapper) throws Exception { if (json == null) { return null; } List<Object> list = mapper.readValue(json, List.class); for (Object obj : list) { if (obj != null && obj instanceof String) { String str = (String) obj; if (str.startsWith("[")) { obj = json2ListRecursion(str, mapper); } else if (obj.toString().startsWith("{")) { obj = json2MapRecursion(str, mapper); } } } return list; } /** * 把 JSON 解析成 Map,如果 Map 内部的 Value 存在 jsonString,继续解析 * * @param json * @param mapper * @return * @throws Exception */ private static Map<String, Object> json2MapRecursion(String json, ObjectMapper mapper) throws Exception { if (json == null) { return null; } Map<String, Object> map = mapper.readValue(json, Map.class); for (Map.Entry<String, Object> entry : map.entrySet()) { Object obj = entry.getValue(); if (obj != null && obj instanceof String) { String str = ((String) obj); if (str.startsWith("[")) { List<?> list = json2ListRecursion(str, mapper); map.put(entry.getKey(), list); } else if (str.startsWith("{")) { Map<String, Object> mapRecursion = json2MapRecursion(str, mapper); map.put(entry.getKey(), mapRecursion); } } } return map; } /** * 将 JSON 数组转换为集合 * * @param jsonArrayStr * @param clazz * @return * @throws Exception */ public static <T> List<T> json2list(String jsonArrayStr, Class<T> clazz) throws Exception { JavaType javaType = getCollectionType(ArrayList.class, clazz); List<T> list = (List<T>) objectMapper.readValue(jsonArrayStr, javaType); return list; } /** * 获取泛型的 Collection Type * * @param collectionClass 泛型的Collection * @param elementClasses 元素类 * @return JavaType Java类型 * @since 1.0 */ public static JavaType getCollectionType(Class<?> collectionClass, Class<?>... elementClasses) { return objectMapper.getTypeFactory().constructParametricType(collectionClass, elementClasses); } /** * 将 Map 转换为 JavaBean * * @param map * @param clazz * @return */ public static <T> T map2pojo(Map map, Class<T> clazz) { return objectMapper.convertValue(map, clazz); } /** * 将 Map 转换为 JSON * * @param map * @return */ public static String mapToJson(Map map) { try { return objectMapper.writeValueAsString(map); } catch (Exception e) { e.printStackTrace(); } return ""; } /** * 将 JSON 对象转换为 JavaBean * * @param obj * @param clazz * @return */ public static <T> T obj2pojo(Object obj, Class<T> clazz) { return objectMapper.convertValue(obj, clazz); } }
JSON数组转成LIST<Bean>
jar包:json-lib-2.1-jdk15.jar
前台
var gridjson = JSON.stringify([{a:b,c:d},{},{}]);
后台解析
import net.sf.json.JSONArray; import net.sf.json.JSONObject; String gridjson = request.getParameter("gridjson"); JSONArray jsonArray = JSONArray.fromObject(gridjson); List objectList = new ArrayList(); for (Iterator iter = jsonArray.iterator(); iter.hasNext();) { JSONObject jsonObject = (JSONObject) iter.next(); objectList.add(JSONObject.toBean(jsonObject, entityClass)); } return objectList;
BeanUtils
自己创建utils
public static <T> String beanToString(T value) { if (value == null) { return null; } Class<?> clazz = value.getClass(); if (clazz == int.class || clazz == Integer.class) { return String.valueOf(value); } else if (clazz == long.class || clazz == Long.class) { return String.valueOf(value); } else if (clazz == String.class) { return (String) value; } else { return JSON.toJSONString(value); } } public static <T> T stringToBean(String str, Class<T> clazz) { if (str == null || str.length() <= 0 || clazz == null) { return null; } if (clazz == int.class || clazz == Integer.class) { return (T) Integer.valueOf(str); } else if (clazz == long.class || clazz == Long.class) { return (T) Long.valueOf(str); } else if (clazz == String.class) { return (T) str; } else { return JSON.toJavaObject(JSON.parseObject(str), clazz); } }