个人博客原文：Json 工具类 代码：JsonUtil.java

摘要：文中使用了阿里的Json转换工具fastjson来做封装，实现了对象和Json互转，对象数组和Json互转，list和Json互转，Map和Json互转。在项目中可以直接使用该工具类来做Json和其他对象的转换。

maven

<!-- fastjson --> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.30</version> </dependency>

工具类代码：

JsonUtil.java

package com.example.util.json; import com.alibaba.fastjson.JSON; import com.alibaba.fastjson.JSONObject; import com.alibaba.fastjson.serializer.JSONLibDataFormatSerializer; import com.alibaba.fastjson.serializer.SerializeConfig; import com.alibaba.fastjson.serializer.SerializerFeature; import java.util.List; import java.util.Map; import java.util.Objects; /** * @author James-CSH * @since 17-3-29 下午10:41 */ public class JsonUtil { private static final SerializeConfig config; static { config = new SerializeConfig(); // compatible with the java.util.Date and the java.sql.Date config.put(java.util.Date.class, new JSONLibDataFormatSerializer()); config.put(java.sql.Date.class, new JSONLibDataFormatSerializer()); } /** * set the default value of the object which the value is null */ private static final SerializerFeature[] features = { SerializerFeature.WriteMapNullValue, SerializerFeature.WriteNullListAsEmpty, SerializerFeature.WriteNullBooleanAsFalse, SerializerFeature.WriteNullStringAsEmpty, }; /** * list to json * * @param list * the list that will transform to json string * @return * the json string of list transform */ public static String list2json(List list) { return JSON.toJSONString(list); } /** * map to json * @param map * the map that will transform to json string * @return * the json string of map transform */ public static String map2json(Map map) { return JSONObject.toJSONString(map); } /** * object array to json * * @param objects * the object array that will transform to json string * @return * the json string of array transform */ public static String array2json(Object[] objects) { return JSON.toJSONString(objects); } /** * object to json * * @param object * the object that will transform to json string * @return * the json string of object */ public static String object2json(Object object) { return JSON.toJSONString(object, config, features); } /** * json to list * * @param json * the json string that will transform to list * @param clazz * the class of the list's element * @param <T> * the generic of the class * @return * the list that json string transform */ public static <T> List<T> json2list(String json, Class<T> clazz) { return JSON.parseArray(json, clazz); } /** * json to map * * @param json * json string that will transform to map * @return * the map fo json string */ public static Map json2map(String json) { return JSONObject.parseObject(json); } /** * json string to object array * * @param json * the json string will transform to object array * @param clazz * the class of the json will transform * @param ts * the real object array * @param <T> * the real object * @return * the object array of the json string * * @param json * @param clazz * @param ts * @param <T> * @return */ public static <T> T[] json2array(String json, Class<T> clazz, T[] ts) { return JSON.parseArray(json, clazz).toArray(ts); } /** * json string to object * * @param json * the json string that will transform to object * @param clazz * the class that json will transform * @param <T> * the object class * @return * the object of json string */ public static <T> Object json2object(String json, Class<T> clazz) { return JSON.parseObject(json, clazz); } }

测试代码：

TestJsonUtil.java

package com.example.util.json; import org.junit.Test; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; /** * @author James-CSH * @since 17-3-31 下午10:47 */ public class TestJsonUtil { @Test public void testObject() { Person person = new Person(); person.setId(1); person.setName("James陈"); person.setAge(23); person.setGender(1); Person child = new Person(); child.setId(2); child.setName("James陈 儿子"); child.setAge(2); child.setGender(1); List<Person> children = new ArrayList<Person>(); children.add(child); person.setChildren(children); String personsJson = JsonUtil.object2json(person); System.out.println(personsJson); //{"age":23,"children":[{"age":2,"children":[],"gender":1,"id":2,"name":"James陈 儿子"}],"gender":1,"id":1,"name":"James陈"} Person person2 = (Person) JsonUtil.json2object(personsJson, Person.class); System.out.println(person2.toString()); //Person{id=1, name='James陈', age=23, gender=1, children=[Person{id=2, name='James陈 儿子', age=2, gender=1, children=[]}]} } @Test public void testArray() { Person[] persons = new Person[10]; Person person; Person child; for (int i=0; i<persons.length; i++) { person = new Person(); person.setId(i); person.setName("James陈" + i); person.setAge(20 + i); person.setGender(i > 5 ? 1 : 0); child = new Person(); child.setId(100 + i); child.setName("James陈 " + i + "儿子"); child.setAge(i); child.setGender(i < 5 ? 1 : 0); List<Person> children = new ArrayList<Person>(1); children.add(child); person.setChildren(children); persons[i] = person; } String personsJson = JsonUtil.array2json(persons); System.out.println(personsJson); //[{"age":20,"children":[{"age":0,"gender":1,"id":100,"name":"James陈 0儿子"}],"gender":0,"id":0,"name":"James陈0"},{"age":21,"children":[{"age":1,"gender":1,"id":101,"name":"James陈 1儿子"}],"gender":0,"id":1,"name":"James陈1"},{"age":22,"children":[{"age":2,"gender":1,"id":102,"name":"James陈 2儿子"}],"gender":0,"id":2,"name":"James陈2"},{"age":23,"children":[{"age":3,"gender":1,"id":103,"name":"James陈 3儿子"}],"gender":0,"id":3,"name":"James陈3"},{"age":24,"children":[{"age":4,"gender":1,"id":104,"name":"James陈 4儿子"}],"gender":0,"id":4,"name":"James陈4"},{"age":25,"children":[{"age":5,"gender":0,"id":105,"name":"James陈 5儿子"}],"gender":0,"id":5,"name":"James陈5"},{"age":26,"children":[{"age":6,"gender":0,"id":106,"name":"James陈 6儿子"}],"gender":1,"id":6,"name":"James陈6"},{"age":27,"children":[{"age":7,"gender":0,"id":107,"name":"James陈 7儿子"}],"gender":1,"id":7,"name":"James陈7"},{"age":28,"children":[{"age":8,"gender":0,"id":108,"name":"James陈 8儿子"}],"gender":1,"id":8,"name":"James陈8"},{"age":29,"children":[{"age":9,"gender":0,"id":109,"name":"James陈 9儿子"}],"gender":1,"id":9,"name":"James陈9"}] Person[] persons2 = new Person[]{}; persons2 = JsonUtil.json2array(personsJson, Person.class, persons2); for (int i=0; i<persons2.length; i++) { System.out.println(persons2[i].toString()); /* Person{id=0, name='James陈0', age=20, gender=0, children=[Person{id=100, name='James陈 0儿子', age=0, gender=1, children=null}]} Person{id=1, name='James陈1', age=21, gender=0, children=[Person{id=101, name='James陈 1儿子', age=1, gender=1, children=null}]} Person{id=2, name='James陈2', age=22, gender=0, children=[Person{id=102, name='James陈 2儿子', age=2, gender=1, children=null}]} Person{id=3, name='James陈3', age=23, gender=0, children=[Person{id=103, name='James陈 3儿子', age=3, gender=1, children=null}]} Person{id=4, name='James陈4', age=24, gender=0, children=[Person{id=104, name='James陈 4儿子', age=4, gender=1, children=null}]} Person{id=5, name='James陈5', age=25, gender=0, children=[Person{id=105, name='James陈 5儿子', age=5, gender=0, children=null}]} Person{id=6, name='James陈6', age=26, gender=1, children=[Person{id=106, name='James陈 6儿子', age=6, gender=0, children=null}]} Person{id=7, name='James陈7', age=27, gender=1, children=[Person{id=107, name='James陈 7儿子', age=7, gender=0, children=null}]} Person{id=8, name='James陈8', age=28, gender=1, children=[Person{id=108, name='James陈 8儿子', age=8, gender=0, children=null}]} Person{id=9, name='James陈9', age=29, gender=1, children=[Person{id=109, name='James陈 9儿子', age=9, gender=0, children=null}]} */ } } @Test public void testList() { List<Person> persons = new ArrayList<Person>(10); Person person; Person child; for (int i=0; i<10; i++) { person = new Person(); person.setId(i); person.setName("James陈" + i); person.setAge(20 + i); person.setGender(i > 5 ? 1 : 0); child = new Person(); child.setId(100 + i); child.setName("James陈 " + i + "儿子"); child.setAge(i); child.setGender(i < 5 ? 1 : 0); List<Person> children = new ArrayList<Person>(1); children.add(child); person.setChildren(children); persons.add(person); } String personsJson = JsonUtil.list2json(persons); System.out.println(personsJson); //[{"age":20,"children":[{"age":0,"gender":1,"id":100,"name":"James陈 0儿子"}],"gender":0,"id":0,"name":"James陈0"},{"age":21,"children":[{"age":1,"gender":1,"id":101,"name":"James陈 1儿子"}],"gender":0,"id":1,"name":"James陈1"},{"age":22,"children":[{"age":2,"gender":1,"id":102,"name":"James陈 2儿子"}],"gender":0,"id":2,"name":"James陈2"},{"age":23,"children":[{"age":3,"gender":1,"id":103,"name":"James陈 3儿子"}],"gender":0,"id":3,"name":"James陈3"},{"age":24,"children":[{"age":4,"gender":1,"id":104,"name":"James陈 4儿子"}],"gender":0,"id":4,"name":"James陈4"},{"age":25,"children":[{"age":5,"gender":0,"id":105,"name":"James陈 5儿子"}],"gender":0,"id":5,"name":"James陈5"},{"age":26,"children":[{"age":6,"gender":0,"id":106,"name":"James陈 6儿子"}],"gender":1,"id":6,"name":"James陈6"},{"age":27,"children":[{"age":7,"gender":0,"id":107,"name":"James陈 7儿子"}],"gender":1,"id":7,"name":"James陈7"},{"age":28,"children":[{"age":8,"gender":0,"id":108,"name":"James陈 8儿子"}],"gender":1,"id":8,"name":"James陈8"},{"age":29,"children":[{"age":9,"gender":0,"id":109,"name":"James陈 9儿子"}],"gender":1,"id":9,"name":"James陈9"}] List<Person> persons2 = JsonUtil.json2list(personsJson, Person.class); for (int i=0; i<persons2.size(); i++) { System.out.println(persons2.get(i).toString()); /* Person{id=0, name='James陈0', age=20, gender=0, children=[Person{id=100, name='James陈 0儿子', age=0, gender=1, children=null}]} Person{id=1, name='James陈1', age=21, gender=0, children=[Person{id=101, name='James陈 1儿子', age=1, gender=1, children=null}]} Person{id=2, name='James陈2', age=22, gender=0, children=[Person{id=102, name='James陈 2儿子', age=2, gender=1, children=null}]} Person{id=3, name='James陈3', age=23, gender=0, children=[Person{id=103, name='James陈 3儿子', age=3, gender=1, children=null}]} Person{id=4, name='James陈4', age=24, gender=0, children=[Person{id=104, name='James陈 4儿子', age=4, gender=1, children=null}]} Person{id=5, name='James陈5', age=25, gender=0, children=[Person{id=105, name='James陈 5儿子', age=5, gender=0, children=null}]} Person{id=6, name='James陈6', age=26, gender=1, children=[Person{id=106, name='James陈 6儿子', age=6, gender=0, children=null}]} Person{id=7, name='James陈7', age=27, gender=1, children=[Person{id=107, name='James陈 7儿子', age=7, gender=0, children=null}]} Person{id=8, name='James陈8', age=28, gender=1, children=[Person{id=108, name='James陈 8儿子', age=8, gender=0, children=null}]} Person{id=9, name='James陈9', age=29, gender=1, children=[Person{id=109, name='James陈 9儿子', age=9, gender=0, children=null}]} */ } } @Test public void testMap() { Person person = new Person(); person.setId(1); person.setName("James陈"); person.setAge(23); person.setGender(1); Person child = new Person(); child.setId(2); child.setName("James陈 儿子"); child.setAge(2); child.setGender(1); List<Person> children = new ArrayList<Person>(); children.add(child); person.setChildren(children); Map<String, Person> map1 = new HashMap<String, Person>(); map1.put("key1", person); String personJson = JsonUtil.map2json(map1); System.out.println(personJson); //{"key1":{"age":23,"children":[{"age":2,"gender":1,"id":2,"name":"James陈 儿子"}],"gender":1,"id":1,"name":"James陈"}} Map map2 = JsonUtil.json2map(personJson); System.out.println(map2.get("key1")); //{"gender":1,"children":[{"gender":1,"name":"James陈 儿子","id":2,"age":2}],"name":"James陈","id":1,"age":23} } }