2. 一个示例

来一个简单示例感受一下（所有代码可在源码包src\test\java\xyz\calvinwilliams\okjson里找到）

2.1. 编写JSON文件

demo.json

{
    "userName" : "Calvin" ,
    "email" : "calvinwilliams@163.com" ,
    "userExtInfo" : {
        "gender" : "M" ,
        "age" : 30 ,
        "address" : "I won't tell you"
    } ,
    "interestGroupList" : [
        "Programing", "Playing game", "Reading", "Sleeping"
    ] ,
    "borrowDetailList" : [
        {
            "bookName" : "Thinking in JAVA" ,
            "author" : "Bruce Eckel" ,
            "borrowDate" : "2014-01-02" ,
            "borrowTime" : "17:30:00"
        } ,
        {
            "bookName" : "Thinking in C++" ,
            "author" : "Bruce Eckel too" ,
            "borrowDate" : "2014-02-04" ,
            "borrowTime" : "17:35:00"
        } ,
        {
            "bookName" : "Thinking in okjson" ,
            "author" : "It's me !!!" ,
            "borrowDate" : "2014-03-06" ,
            "borrowTime" : "17:40:00"
        }
    ]
}

2.2. 编写实体类

DemoUserClass.java

package xyz.calvinwilliams.okjson;
import java.time.LocalDate;
import java.time.LocalTime;
import java.util.LinkedList;
public class DemoUserClass {
    String                userName ;
    String                email ;
    UserExtInfo            userExtInfo ;
    LinkedList<String>            interestGroupList ;
    LinkedList<BorrowDetail>    borrowDetailList ;
}
class UserExtInfo {
    String                gender ;
    int                    age ;
    String                address ;
}
class BorrowDetail {
    String                bookName ;
    String                author ;
    @OkJsonDateTimeFormatter(format="yyyy-MM-dd")
    LocalDate            borrowDate ;
    @OkJsonDateTimeFormatter(format="HH:mm:ss")
    LocalTime            borrowTime ;
}

2.3. 编写示例代码

读入JSON文件，映射所有字段数据到实体类属性中去

package xyz.calvinwilliams.okjson;
import java.time.format.DateTimeFormatter;
public class Demo {
    public static void printDemoUser( DemoUserClass demoUser ) {
        ...
    }
    public static void main(String[] args) {
        DemoUserClass    demoUser = new DemoUserClass() ;
        System.out.println( "OKJSON.stringToObject ..." );
        demoUser = OKJSON.fileToObject( "demo.json", DemoUserClass.class, OKJSON.OKJSON_OTIONS_DIRECT_ACCESS_PROPERTY_ENABLE ) ;
        if( demoUser == null ) {
            System.out.println( "OKJSON.stringToObject failed["+OKJSON.getErrorCode()+"]["+OKJSON.getErrorDesc()+"]" );
            return;
        } else {
            System.out.println( "OKJSON.stringToObject ok" );
            printDemoUser( demoUser );
        }
    }
}

调用一个静态方法就能把JSON所有字段数据都映射到实体类属性中去，是不是很简单。

我的其它开源产品都用它装载配置文件，小巧、高效、灵活。