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什么是JSON?
JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式。 易于人阅读和编写。同时也易于机器解析和生成。 它基于javascript Programming Language, Standard ECMA-262 3rd Edition – December 1999的一个子集。 JSON采用完全独立于语言的文本格式，但是也使用了类似于C语言家族的习惯（包括C, C++, C#, Java, JavaScript, Perl, Python等）。 这些特性使JSON成为理想的数据交换语言。
现在我们就来研究一下fastJson。
Fastjson是国内著名的电子商务互联网公司阿里巴巴内部开发的用于java后台处理json格式数据的一个工具包，包括“序列化”和“反序列化”两部分，它具备如下特征
1. 速度最快，测试表明，fastjson具有极快的性能，超越任其他的java json parser。包括自称最快的jackson。
2. 功能强大，完全支持java bean、集合、Map、日期、Enum，支持范型，支持自省。
3. 无依赖，能够直接运行在Java SE 5.0以上版本
4. 支持Android。
5. 这是fastJson的网址：http://code.alibabatech.com/wiki/display/FastJSON/Overview其中包含了json数据处理的教程，jar下载地址，example样例等
JSONObject 与JSONArray
- JSONObject
json对象，就是一个键对应一个值，使用的是大括号{ }，如：{key:value}
- JSONArray
json数组，使用中括号[ ],只不过数组里面的项也是json键值对格式的
Json对象中是添加的键值对,JSONArray中添加的是Json对象
例子
/** * Created by wanggs on 2017/7/27. */
public class JsonTest {
public static void main(String[] args) {
// Json对象中是添加的键值对,JSONArray中添加的是Json对象
JSONObject jsonObject = new JSONObject();
JSONObject jsonObject1 = new JSONObject();
JSONArray jsonArray = new JSONArray();
jsonObject1.put("001","tom");
// JSONObject 对象中添加键值对
jsonObject.put("key","value");
// 将JSONObject对象添加到json数组中
jsonArray.add(jsonObject);
jsonArray.add(jsonObject1);
System.out.println(jsonArray.toString());
// 输出结果: [{"key":"value"},{"001":"tom"}]
}
}先来个官方例子
package com.wanggs.com.wanggs.json.fastjson;
import java.util.List;
/** * Created by wanggs on 2017/7/27. */
public class Group {
private int id;
private String name;
List<User> users;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<User> getUsers() {
return users;
}
public void setUsers(List<User> users) {
this.users = users;
}
}
class User{
private int id;
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
package com.wanggs.com.wanggs.json.fastjson;
import com.alibaba.fastjson.JSON;
import java.util.ArrayList;
import java.util.List;
/** * Created by wanggs on 2017/7/27. */
public class FastJsonTest {
public static void main(String[] args) {
Group group = new Group();
group.setId(0);
group.setName("admin");
User user = new User();
user.setId(001);
user.setName("guest");
User user1 = new User();
user1.setId(002);
user1.setName("root");
List<User> users = new ArrayList<User>();
users.add(user);
users.add(user1);
group.setUsers(users);
String json = JSON.toJSONString(group);
System.out.println(json);
// 输出: {
"id":0,"name":"admin","users":[{
"id":1,"name":"guest"},{
"id":2,"name":"root"}]}
}
}
下面给出fastJson处理json数据格式的代码样例：
package test.com.wanggs.com.wanggs.json.fastjson;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.serializer.SerializerFeature;
import com.wanggs.com.wanggs.json.fastjson.People;
import org.junit.Test;
import static org.junit.Assert.*;
/** * Created by wanggs on 2017/7/27. */
public class FastJsonTestTest {
/** * 序列化 */
@Test
public void toJsonString() {
People people = new People("001","tom",12);
String text = JSON.toJSONString(people);
System.out.println(text);
// 输出结果: {"age":12,"id":"001","name":"tom"}
}
/** * 反序列为Json对象 */
@Test
public void parseJsonObject(){
String text = "{\"age\":12,\"id\":\"001\",\"name\":\"tom\"}";
People people = (People) JSON.parseObject(text,People.class);
System.out.println("parseBeanObject()方法：people==" + people.getId() + "," + people.getName() + "," + people.getAge());
// 输出结果为: parseBeanObject()方法：people==001,tom,12
}
/** * 将javaBean转化为json对象 */
@Test
public void bean2Json(){
People people = new People("002","jack",23);
JSONObject jsonObject = (JSONObject) JSON.toJSON(people);
System.out.println("bean2Json()方法：jsonObject==" + jsonObject);
// 输出结果: bean2Json()方法：jsonObject=={"name":"jack","id":"002","age":23}
}
/** * 全序列化 直接把java bean序列化为json文本之后，能够按照原来的类型反序列化回来。支持全序列化，需要打开SerializerFeature.WriteClassName特性 */
@Test
public void parseJSONAndBeanEachother(){
People people = new People("002","jack",23);
SerializerFeature[] featureArr = { SerializerFeature.WriteClassName };
String text = JSON.toJSONString(people, featureArr);
System.out.println("parseJSONAndBeanEachother()方法：text==" + text);
// 输出结果：parseJSONAndBeanEachother()方法：text=={"@type":"com.wanggs.com.wanggs.json.fastjson.People","age":23,"id":"002","name":"jack"}
People people1 = (People) JSON.parse(text);
System.out.println("parseJSONAndBeanEachother()方法：People==" + people1.getId() + "," + people1.getName() + "," + people1.getAge());
// 输出结果：userObj==testFastJson001,maks,105
}
}附：javaBean类People.java
package com.wanggs.com.wanggs.json.fastjson;
/** * Created by wanggs on 2017/7/27. */
public class People {
private String id;
private String name;
private int age;
public People() {
}
public People(String id, String name, int age) {
this.id = id;
this.name = name;
this.age = age;
}
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 int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
}
在深入Json
package test.com.wanggs.com.wanggs.json.fastjson;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.wanggs.com.wanggs.json.fastjson.Address;
import com.wanggs.com.wanggs.json.fastjson.People;
import org.junit.Test;
import java.util.*;
import static org.junit.Assert.*;
/** * Created by wanggs on 2017/7/27. */
public class FastJsonTest1Test {
/** * 数组转json字符串 */
@Test
public void array2Json() {
String[] arr = {
"bill", "green", "maks", "jim"};
String jsonText = JSON.toJSONString(arr);
System.out.println("array2Json()方法：jsonText==" + jsonText);
// 输出结果：jsonText==["bill","green","maks","jim"]
}
/** * json格式字符串转数组 */
@Test
public void json2Array() {
String jsonText = "[\"bill\",\"green\",\"maks\",\"jim\"]";
JSONArray jsonArray = JSON.parseArray(jsonText);
System.out.println("json2Array()方法：jsonArray==" + jsonArray);
// 输出结果：jsonArray==["bill","green","maks","jim"]
}
/** * 数组转json格式字符串 */
@Test
public void array2Json2() {
People people = new People("001", "tom", 12);
People people1 = new People("002", "jack", 23);
People people2 = new People("003", "mair", 22);
People[] peoples = new People[]{people, people1, people2};
String jsonText = JSON.toJSONString(peoples);
System.out.println("array2Json2()方法：jsonText==" + jsonText);
//输出结果：array2Json2()方法：jsonText==[{
"age":12,"id":"001","name":"tom"},{
"age":23,"id":"002","name":"jack"},{
"age":22,"id":"003","name":"mair"}]
}
/** * json格式字符串转数组 */
@Test
public void json2Array2() {
String jsonText = "[{\"age\":12,\"id\":\"001\",\"name\":\"tom\"},{\"age\":23,\"id\":\"002\",\"name\":\"jack\"},{\"age\":22,\"id\":\"003\",\"name\":\"mair\"}]";
JSONArray jsonArr = JSON.parseArray(jsonText);
System.out.println("json2Array2()方法：jsonArr==" + jsonArr);
// 输出结果：json2Array2()方法：jsonArr==[{
"name":"tom","id":"001","age":12},{
"name":"jack","id":"002","age":23},{
"name":"mair","id":"003","age":22}]
}
/** * list集合转json格式字符串 */
@Test
public void list2Json() {
List<People> list = new ArrayList<People>();
list.add(new People("001", "tom", 12));
list.add(new People("002", "jack", 23));
list.add(new People("003", "mair", 22));
String jsonText = JSON.toJSONString(list);
System.out.println("list2Json()方法：jsonText==" + jsonText);
// 输出的结果为: [{
"age":12,"id":"001","name":"tom"},{
"age":23,"id":"002","name":"jack"},{
"age":22,"id":"003","name":"mair"}]
}
/** * map转json格式字符串 */
@Test
public void map2Json() {
Map map = new HashMap();
Address address1 = new Address("广东省","深圳市","科苑南路","580053");
map.put("address1", address1);
Address address2 = new Address("江西省","南昌市","阳明路","330004");
map.put("address2", address2);
Address address3 = new Address("陕西省","西安市","长安南路","710114");
map.put("address3", address3);
String jsonText = JSON.toJSONString(map, true);
System.out.println("map2Json()方法：jsonText=="+jsonText);
//输出结果：jsonText=={
"address1":{
"city":"深圳市","post":"580053","province":"广东省","street":"科苑南路"},"address2":{
"city":"南昌市","post":"330004","province":"江西省","street":"阳明路"},"address3":{
"city":"西安市","post":"710114","province":"陕西省","street":"长安南路"}}
}
/** * json转map */
@Test
public void json2Map(){
String text = "{\"age\":12,\"id\":\"001\",\"name\":\"tom\"}";
Map<String,Object> map = JSON.parseObject(text);
System.out.println("json2Map()方法：map=="+map);
//输出结果：{
"name":"tom","id":"001","age":12}
Set<String> set = map.keySet();
for(String key : set){
System.out.println(key+"--->"+map.get(key));
}
}
}技巧
package com.wanggs.com.wanggs.json.fastjson;
import com.alibaba.fastjson.JSON;
/** * Created by wanggs on 2017/7/27. */
public class CustomText {
/** * touser : OPENID * msgtype : text * text : {"content":"Hello World"} */
//{"msgtype":"text","text":{"content":"Hello World"},"touser":"OPENID"}
private String touser;
private String msgtype;
private TextBean text;
public static class TextBean {
/** * content : Hello World */
private String content;
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
}
public String getTouser() {
return touser;
}
public void setTouser(String touser) {
this.touser = touser;
}
public String getMsgtype() {
return msgtype;
}
public void setMsgtype(String msgtype) {
this.msgtype = msgtype;
}
public TextBean getText() {
return text;
}
public void setText(TextBean text) {
this.text = text;
}
}
class Test{
public static void main(String[] args) {
CustomText customText = new CustomText();
customText.setTouser("OPENID");
customText.setMsgtype("text");
CustomText.TextBean textBean = new CustomText.TextBean();
textBean.setContent("Hello World");
customText.setText(textBean);
String json = JSON.toJSONString(customText);
System.out.println(json);
//{"msgtype":"text","text":{"content":"Hello World"},"touser":"OPENID"}
}
/** * { "touser":"OPENID", "msgtype":"text", "text": { "content":"Hello World" } } */
}
归纳六种方式json转map
package com.wanggs.com.wanggs.json.fastjson;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import java.util.Map;
import java.util.Set;
/** * Created by wanggs on 2017/7/27. */
public class FastJsonTest1 {
public static void main(String[] args) {
String str = "{\"0\":\"zhangsan\",\"1\":\"lisi\",\"2\":\"wangwu\",\"3\":\"maliu\"}";
//第一种方式
Map maps = (Map)JSON.parse(str);
System.out.println("这个是用JSON类来解析JSON字符串!!!");
for (Object map : maps.entrySet()){
System.out.println(((Map.Entry)map).getKey()+" " + ((Map.Entry)map).getValue());
}
//第二种方式
Map mapTypes = JSON.parseObject(str);
System.out.println("这个是用JSON类的parseObject来解析JSON字符串!!!");
for (Object obj : mapTypes.keySet()){
System.out.println("key为："+obj+"值为："+mapTypes.get(obj));
}
//第三种方式
Map mapType = JSON.parseObject(str,Map.class);
System.out.println("这个是用JSON类,指定解析类型，来解析JSON字符串!!!");
for (Object obj : mapType.keySet()){
System.out.println("key为："+obj+"值为："+mapType.get(obj));
}
//第四种方式
/** * JSONObject是Map接口的一个实现类 */
Map json = (Map) JSONObject.parse(str);
System.out.println("这个是用JSONObject类的parse方法来解析JSON字符串!!!");
for (Object map : json.entrySet()){
System.out.println(((Map.Entry)map).getKey()+" "+((Map.Entry)map).getValue());
}
//第五种方式
/** * JSONObject是Map接口的一个实现类 */
JSONObject jsonObject = JSONObject.parseObject(str);
System.out.println("这个是用JSONObject的parseObject方法来解析JSON字符串!!!");
for (Object map : json.entrySet()){
System.out.println(((Map.Entry)map).getKey()+" "+((Map.Entry)map).getValue());
}
//第六种方式
/** * JSONObject是Map接口的一个实现类 */
Map mapObj = JSONObject.parseObject(str,Map.class);
System.out.println("这个是用JSONObject的parseObject方法并执行返回类型来解析JSON字符串!!!");
for (Object map: json.entrySet()){
System.out.println(((Map.Entry)map).getKey()+" "+((Map.Entry)map).getValue());
}
String strArr = "{
{\"0\":\"zhangsan\",\"1\":\"lisi\",\"2\":\"wangwu\",\"3\":\"maliu\"}," +
"{\"00\":\"zhangsan\",\"11\":\"lisi\",\"22\":\"wangwu\",\"33\":\"maliu\"}}";
// JSONArray.parse()
System.out.println(json);
}
}
package com.wanggs.com.wanggs.json.fastjson;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import java.util.*;
/** * Created by wanggs on 2017/7/27. */
public class FastJsonTest {
public static void main(String[] args) {
String json = "[{\"id\":1,\"type\":\"cycle\",\"attribute\":{\"center\":\"(10.4, 123.345)\", \"radius\":67.4}},{\"id\":2,\"type\":\"polygon\",\"attribute\":[{\"vertex\":\"(10.4, 133.345)\"}, {\"vertex\":\"(10.4, 143.345)\"}]}]";
JSONArray array = JSON.parseArray(json);
System.out.println(array.getJSONObject(0).getJSONObject("attribute").get("center"));
System.out.println(array.getJSONObject(1).getJSONArray("attribute").getJSONObject(1).get("vertex"));
// 输出结果为: (10.4, 123.345) (10.4, 143.345)
}
}
方法总结
java和js中JSONObject,JSONArray,Map,String之间转换——持续更新中
4.JSONObject、JSONArray，Map转String
JSONObject——String：
System.out.println(myJsonObject);//可直接输出JSONObject的内容
myJsonObject.toString();
JSONArray——String：
System.out.println(myJsonArray);//可直接输出myJsonArray的内容
myJsonArray.toString();
Map——String:
System.out.println(map);//可直接输出map的内容
map.toString();5.JSONObject转JSONArray
JSONObject myJson = JSONObject.fromObject(jsonString);
Map m = myJson;
7.JSONArray转JSONObject
for(int i=0 ; i < myJsonArray.length() ;i++)
{
//获取每一个JsonObject对象
JSONObject myjObject = myJsonArray.getJSONObject(i);
}
8.JSONArray转Map
9.Map转JSONObject
JSONObject json = JSONObject.fromObject( map );10.Map转JSONArray
JSONArray.fromObject(map);11.List转JSONArray
JSONArray jsonArray2 = JSONArray.fromObject( list );
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