alibaba的架包FastJson可以对json字符串进行快捷的类型转换。下面是一些各种类型转换的使用例子。
一、下载FastJson的架包，并导入项目中，如下：
Maven项目pom.xml配置如下：
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.32</version>
</dependency>
二、附上代码例子，如下：
1、创建2个实体类，供后面例子使用，如下：
public class School {
private String id;
private String name;
List<User> students = new ArrayList<User>();
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<User> getStudents() {
return students;
}
public void setStudents(List<User> students) {
this.students = students;
}
}
public class User {
private String id;
private String name;
public User(){
}
public User(String id, String name){
this.id = id;
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
2、Json字符串与Map、List、object之间的相互转换例子，如下：
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map; import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject; public class TestFastJson { public static void main(String[] args){
json2JsonObject();//将Json字符串转换为JSONObject对象
json2JavaBean();//将Json字符串转换为JavaBean对象
json2JsonArray();//将Json字符串转换为JSONArray对象
json2JavaBeanList();//将Json字符串转换为JavaBean的集合
javaBean2Json();//将JavaBean转换为Json格式的数据
javaBean2JsonObject();//将JavaBean转换为JSONObject对象
json2ListInMap();//从Json字符串的Map中获取List对象
list2JsonInMap();//将含list的Map对象转换为Json字符串
} private static void json2JsonObject() {
String s = "{\"name\":\"peter\"}";
JSONObject object = JSON.parseObject(s);
System.out.println(object.get("name"));
} private static void json2JavaBean() {
String s = "{\"id\":\"17051801\",\"name\":\"lucy\"}";
User user = JSON.parseObject(s, User.class);
System.out.println(user.getId());
System.out.println(user.getName());
} private static void json2JsonArray() {
String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
JSONArray array = JSON.parseArray(s);
for (int i = 0; i < array.size(); i++) {
//JSONArray中的数据转换为String类型需要在外边加"";不然会报出类型强转异常！
String str = array.get(i)+"";
JSONObject object = JSON.parseObject(str);
System.out.println(object.get("name"));
}
} private static void json2JavaBeanList() {
String s = "[{\"id\":\"17051801\",\"name\":\"lucy\"},{\"id\":\"17051802\",\"name\":\"peter\"}]";
List<User> list = JSON.parseArray(s, User.class);
for (User user : list) {
System.out.println(user.getName());
}
} private static void javaBean2Json() {
User user = new User("17051801", "lucy");
String string = JSON.toJSONString(user);
System.out.println(string);
} private static void javaBean2JsonObject() {
User user = new User("17051801", "lucy");
JSONObject json = (JSONObject) JSON.toJSON(user);
System.out.println(json.get("id"));
} private static void json2ListInMap() {
String s = "{json:[{id:\"17051801\",\"name\":\"lucy\"},{id:\"17051802\",\"name\":\"peter\"},"
+ "{id:\"17051803\",\"name\":\"tom\"},{id:\"17051804\",\"name\":\"lily\"}]}";
//将Json字符串转换为JSONObject对象,并取出list对象的值
JSONObject object = JSON.parseObject(s);
Object objArray = object.get("json");
String str = objArray+"";
//方式1:转换成JSONArray对象形式
JSONArray array = JSON.parseArray(str);
for (int i = 0; i < array.size(); i++) {
JSONObject obj = JSON.parseObject(array.get(i)+"");
System.out.println(obj.get("name"));
}
//方式2:转换成List<JavaBean>形式
List<User> list = JSON.parseArray(str, User.class);
for (User user : list) {
System.out.println(user.getName());
}
} private static void list2JsonInMap() {
//方式1:构建一个带有list的JavaBean对象
School school = new School();
school.setId("1");
school.setName("schoolA"); User user1 = new User();
user1.setId("17051801");
user1.setName("lucy");
User user2 = new User();
user2.setId("17051802");
user2.setName("peter"); school.getStudents().add(user1);
school.getStudents().add(user2);
//将JavaBean对象转换成Json字符串
String string1 = JSON.toJSONString(school);
System.out.println(string1); //方式2:构建一个带有list的Map对象
Map<String, Object> map1 = new HashMap<String,Object>();
map1.put("id", "17051801");
map1.put("name", "lucy"); Map<String, Object> map2 = new HashMap<String,Object>();
map2.put("id", "17051802");
map2.put("name", "peter"); List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
list.add(map1);
list.add(map2); Map<String, Object> map = new HashMap<String,Object>();
map.put("id", "1");
map.put("name", "schoolA");
map.put("students", list);
//将map对象转换成Json字符串
String string2 = JSON.toJSONString(map);
System.out.println(string2);
}
}