fastjson 是一个性能很好的 Java 语言实现的 JSON 解析器和生成器，它可以操作任何 Java 对象，即使是一些预先存在的没有源码的对象。那fastjson如何下载更新?下面来我们就来给大家讲解一下。
你可以在 maven 中央仓库中直接下载：
https://repo1.maven.org/maven2/com/alibaba/fastjson/
或者配置 maven 依赖:
<dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>x.x.x</version></dependency>
fastjson怎么使用?
java对象与JSON字符串的互转
User测试类
/**
* User测试类
* @author dmego
*/
public class User
{
private String username;
private String password;
public User()
{}
public User(String username, String password)
{
this.username = username;
this.password = password;
}
public String getUsername()
{
return username;
}
public void setUsername(String username)
{
this.username = username;
}
public String getPassword()
{
return password;
}
public void setPassword(String password)
{
this.password = password;
}
@Override
public String toString()
{
return "User [username=" + username + ", password=" + password + "]";
}
}UserGroup测试类
import java.util.ArrayList;
import java.util.List;
/**
* 用户组测试类
* @author dmego
*
*/
public class UserGroup
{
private String name;
private List < User > users = new ArrayList < User > ();
public UserGroup()
{}
public UserGroup(String name, List < User > users)
{
this.name = name;
this.users = users;
}
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;
}
@Override
public String toString()
{
return "UserGroup [name=" + name + ", users=" + users + "]";
}
}fastJson测试类
package demo;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;
import com.alibaba.fastjson.JSON;
/**
* fastJson测试类
* @author dmego
*
*/
public class TestFastJosn
{
/**
* java对象转 json字符串
*/
@Test
public void objectTOJson()
{
//简单java类转json字符串
User user = new User("dmego", "123456");
String UserJson = JSON.toJSONString(user);
System.out.println("简单java类转json字符串:" + UserJson);
//List<Object>转json字符串
User user1 = new User("zhangsan", "123123");
User user2 = new User("lisi", "321321");
List < User > users = new ArrayList < User > ();
users.add(user1);
users.add(user2);
String ListUserJson = JSON.toJSONString(users);
System.out.println("List<Object>转json字符串:" + ListUserJson);
//复杂java类转json字符串
UserGroup userGroup = new UserGroup("userGroup", users);
String userGroupJson = JSON.toJSONString(userGroup);
System.out.println("复杂java类转json字符串:" + userGroupJson);
}
/**
* json字符串转java对象
* 注：字符串中使用双引号需要转义 (" --> \"),这里使用的是单引号
*/
@Test
public void JsonTOObject()
{
/* json字符串转简单java对象
* 字符串：{"password":"123456","username":"dmego"}*/
String jsonStr1 = "{'password':'123456','username':'dmego'}";
User user = JSON.parseObject(jsonStr1, User.class);
System.out.println("json字符串转简单java对象:" + user.toString());
/*
* json字符串转List<Object>对象
* 字符串：[{"password":"123123","username":"zhangsan"},{"password":"321321","username":"lisi"}]
*/
String jsonStr2 = "[{'password':'123123','username':'zhangsan'},{'password':'321321','username':'lisi'}]";
List < User > users = JSON.parseArray(jsonStr2, User.class);
System.out.println("json字符串转List<Object>对象:" + users.toString());
/*json字符串转复杂java对象
* 字符串：{"name":"userGroup","users":[{"password":"123123","username":"zhangsan"},{"password":"321321","username":"lisi"}]}
* */
String jsonStr3 = "{'name':'userGroup','users':[{'password':'123123','username':'zhangsan'},{'password':'321321','username':'lisi'}]}";
UserGroup userGroup = JSON.parseObject(jsonStr3, UserGroup.class);
System.out.println("json字符串转复杂java对象:" + userGroup);
}
}输出结果
简单java类转json字符串:
{
"password": "123456"
, "username": "dmego"
}
List转json字符串: [
{
"password": "123123"
, "username": "zhangsan"
}
, {
"password": "321321"
, "username": "lisi"
}]
复杂java类转json字符串:
{
"name": "userGroup"
, "users": [
{
"password": "123123"
, "username": "zhangsan"
}
, {
"password": "321321"
, "username": "lisi"
}]
}
json字符串转简单java对象: User[username = dmego, password = 123456]
json字符串转List对象: [User[username = zhangsan, password = 123123], User[username = lisi, password = 321321]]
json字符串转复杂java对象: UserGroup[name = userGroup, users = [User[username = zhangsan, password = 123123], User[username = lisi, password = 321321]]]总之，Fastjson 是一个 Java 库，可以将 Java 对象转换为 JSON 格式，当然它也可以将 JSON 字符串转换为 Java 对象。最后大家如果想要了解更多json相关知识，敬请关注奇Q工具网。
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