JSON-lib基本使用说明（新手必看）

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1、JsonLib简介

Json-lib包是一个Java类库，提供将Java对象（包括：beans，maps，collections，java arrays 和 XML等）和JSON互相转换的功能。

2、JsonLib使用

2.1 准备工作

我们这里使用JUnit4.0进行测试实验，下面是测试中使用中的类。

【测试实体——Student】

package com.hebut.jsonlib;

public class Student {
    private String userName;
    private String sex;
    private int age;

    public Student() {
    }

    public Student(String userName, String sex, int age) {
        this.userName = userName;
        this.sex = sex;
        this.age = age;
    }

    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
}

【测试实体——Class】

package com.hebut.jsonlib;

import java.util.Date;
import java.util.List;

public class Class {
    private String name;
    private Date date;
    private List<Student> students;

    public Class() {
    }

    public Class(String name, Date date, List<Student> students) {
        this.name = name;
        this.date = date;
        this.students = students;
    }

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Date getDate() {
        return date;
    }
    public void setDate(Date date) {
        this.date = date;
    }
    public List<Student> getStudents() {
        return students;
    }
    public void setStudents(List<Student> students) {
        this.students = students;
    }
}

2.2 处理ArraysToJson

【示例代码】

package com.hebut.jsonlib;

import java.util.ArrayList;
import java.util.List;
import net.sf.json.JSONArray;
import org.junit.Test;

public class JsonLib {

    @Test
    public void array2json() {
        int[] intArray = new int[]{1,4,5};
        JSONArray jsonArray1 = JSONArray.fromObject(intArray);
        System.out.println("int[] intArray");
        System.out.println(jsonArray1);

        boolean[] boolArray = new boolean[]{true,false,true};
        System.out.println("boolean[] boolArray");
        JSONArray jsonArray2 = JSONArray.fromObject(boolArray);
        System.out.println(jsonArray2);

        int[][] int2Array = new int[][]{{1,2},{3,4}};
        JSONArray jsonArray3 = JSONArray.fromObject(int2Array);
        System.out.println("int[][] int2Array");
        System.out.println(jsonArray3);

        float[] floatArray = new float[]{0.1f,0.2f,0.3f};
        JSONArray jsonArray4 = JSONArray.fromObject(floatArray);
        System.out.println("float[] floatArray");
        System.out.println(jsonArray4);

        String[] strArray = new String[]{"hello","hebut","xiapi"};
        JSONArray jsonArray5 = JSONArray.fromObject(strArray);
        System.out.println("String[] strArray");
        System.out.println(jsonArray5);
    }
}

【运行结果】

int[] intArray
[1,4,5]
boolean[] boolArray
[true,false,true]
int[][] int2Array
[[1,2],[3,4]]
float[] floatArray
[0.1,0.2,0.3]
String[] strArray
["hello","hebut","xiapi"]

2.3 处理CollectionsToJson

【示例代码】

package com.hebut.jsonlib;

import java.util.ArrayList;
import java.util.List;
import net.sf.json.JSONArray;
import org.junit.Test;

public class JsonLib {

    @Test
    public void collections2json(){
        List list1 = new ArrayList();
        list1.add("first");
        list1.add("second");
        JSONArray jsonArray1 = JSONArray.fromObject(list1);
        System.out.println("List list1");
        System.out.println(jsonArray1);

        List<Student> list2 = new ArrayList<Student>();
        list2.add(new Student("xiapi1","男",10));
        list2.add(new Student("xiapi2","女",11));
        list2.add(new Student("xiapi3","男",12));
        JSONArray jsonArray2 = JSONArray.fromObject(list2);
        System.out.println("List<Student> list2");
        System.out.println(jsonArray2);
    }
}

【运行结果】

List list1
["first","second"]
List<Student> list2
[{"age":10,"sex":"男","userName":"xiapi1"},{"age":11,"sex":"女","userName":"xiapi2"},{"age":12,"sex":"男","userName":"xiapi3"}]

2.4 处理MapToJson

【示例代码】

package com.hebut.jsonlib;

import java.util.HashMap;
import java.util.Map;
import net.sf.json.JSONObject;
import org.junit.Test;

public class JsonLib {

    @Test
    public void map2json(){
        Map map1 = new HashMap();
        map1.put("name","json");
        map1.put("bool",Boolean.TRUE);
        map1.put("int",new Integer(1));
        map1.put("arr",new String[]{"a","b"});
        map1.put("func","function(i){ return this.arr[i]; }");
        JSONObject jsonObject1 = JSONObject.fromObject(map1);
        System.out.println("Map map1");
        System.out.println(jsonObject1);

        Map<String,Student> map2 = new HashMap<String,Student>();
        map2.put("k1", new Student("xiapi1","男",10));
        map2.put("k2", new Student("xiapi2","女",12));
        map2.put("k3", new Student("xiapi3","男",13));
        JSONObject jsonObject2 = JSONObject.fromObject(map2);
        System.out.println("Map<String,Student> map2");
        System.out.println(jsonObject2);
    }
}

【运行结果】

Map map1
{"arr":["a","b"],"int":1,"name":"json","func":function(i){ return this.arr[i]; },"bool":true}
Map<String,Student> map2
{"k3":{"age":13,"sex":"男","userName":"xiapi3"},"k1":{"age":10,"sex":"男","userName":"xiapi1"},"k2":{"age":12,"sex":"女","userName":"xiapi2"}}

2.5 处理BeanToJson

【示例代码】

package com.hebut.jsonlib;

import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import net.sf.json.JSON;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;
import net.sf.json.util.CycleDetectionStrategy;
import org.junit.Test;

public class JsonLib {

    @Test
    public void bean2json(){
        Student s1 = new Student("xiapi","男",22);
        JSONObject jsonObject1 = JSONObject.fromObject(s1);
        System.out.println("Student s1");
        System.out.println(jsonObject1);

        Class c1 = new Class();
        c1.setName("计算机应用1班");
        c1.setDate(new Date());
        JsonConfig config=new JsonConfig();
        //设置循环策略为忽略
        config.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);
        //设置 json转换的处理器用来处理日期类型
        //凡是反序列化Date类型的对象，都会经过该处理器进行处理
        config.registerJsonValueProcessor(Date.class,
                                    new JsonValueProcessor() {
            //参数1 ：属性名参数2：json对象的值参数3：jsonConfig对象
            public Object processObjectValue(String arg0, Object arg1,JsonConfig arg2) {
                SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                Date d=(Date) arg1;
                return sdf.format(d);
            }
            public Object processArrayValue(Object arg0, JsonConfig arg1) {
                return null;
            }
        });
        List<Student> students = new ArrayList<Student>();
        students.add(new Student("xiapi1","男",10));
        students.add(new Student("xiapi2","女",11));
        students.add(new Student("xiapi3","男",12));
        c1.setStudents(students);
        JSONObject jsonObject2 = JSONObject.fromObject(c1,config);
        System.out.println("Class c1");
        System.out.println(jsonObject2);
    }
}

【运行结果】

Student s1
{"age":22,"sex":"男","userName":"xiapi"}
Class c1
{"date":"2012-05-21 19:19:31","name":"计算机应用1班","students":[{"age":10,"sex":"男","userName":"xiapi1"},{"age":11,"sex":"女","userName":"xiapi2"},{"age":12,"sex":"男","userName":"xiapi3"}]}

2.6 处理XmlToJson

在处理XML时，需要另添加"xom-1.2.8.jar"包。

下载地址：http://www.xom.nu/

【示例代码】

package com.hebut.jsonlib;

import net.sf.json.JSON;
import net.sf.json.xml.XMLSerializer;
import org.junit.Test;

public class JsonLib {

    @Test
    public void xml2json(){
        String s="<student>
                        <name id='n1'>xiapi</name>
                        <sex class='s1'>男</sex>
                        <age>20</age>
                    </student>";
        XMLSerializer x =new XMLSerializer();
        JSON json = x.read(s);
        System.out.println("XmlToJson");
        System.out.println(json.toString());
    }
}

【运行结果】

2012-5-21 19:01:03 net.sf.json.xml.XMLSerializer getType
信息: Using default type string
XmlToJson
{"name":{"@id":"n1","#text":"xiapi"},"sex":{"@id":"s1","#text":"男"},"age":"20"}

2.7 处理JsonToArrays

【示例代码】

package com.hebut.jsonlib;

import net.sf.ezmorph.test.ArrayAssertions;
import net.sf.json.JSONArray;
import net.sf.json.JSONSerializer;
import net.sf.json.JsonConfig;

import org.junit.Test;

public class JsonLib {

    @Test
    public void json2arrays(){
        String json1 = "['first','second']";
        JSONArray jsonArray1 = (JSONArray) JSONSerializer.toJSON(json1);
        JsonConfig jsonConfig = new JsonConfig();
        jsonConfig.setArrayMode(JsonConfig.MODE_OBJECT_ARRAY);
        Object[] output1 = (Object[]) JSONSerializer.toJava(jsonArray1, jsonConfig);
        Object[] expected = new Object[] { "first", "second" };
        ArrayAssertions.assertEquals(expected, output1);
        System.out.println("Object[]");
        System.out.println(output1.length);
        System.out.println(output1[1]);

        String json2 ="[[1,2],[3,4]]";
        JSONArray jsonArray2 = JSONArray.fromObject(json2);
        Object[][] output2 = (Object[][])JSONArray.toArray(jsonArray2);
        System.out.println("Object[][]");
        System.out.println(output2.length);
        System.out.println(output2[0][0]);
    }
}

【运行结果】

Object[]
2
second
Object[][]
2
1

2.8 处理JsonToCollections

【示例代码】

package com.hebut.jsonlib;

import java.util.List;
import net.sf.json.JSONArray;
import net.sf.json.JSONSerializer;
import org.junit.Test;

public class JsonLib {

    @Test
    public void json2collections(){
        String json1 = "['first','second']";
        JSONArray jsonArray1 = (JSONArray) JSONSerializer.toJSON(json1);
        List output1 = (List) JSONSerializer.toJava(jsonArray1);
        System.out.println("List");
        System.out.println(output1.get(0));

        String json2 = "[{'age':10,'sex':'男','userName':'xiapi1'},
                        {'age':11,'sex':'女','userName':'xiapi2'}]";
        JSONArray jsonArray2 = JSONArray.fromObject(json2);
        List<Student> output2 = JSONArray.toList(jsonArray2,Student.class);
        System.out.println("List<Student>");
        System.out.println(output2.size());
        System.out.println(output2.get(0));
        System.out.println(output2.get(0).getUserName());
    }
}

【运行结果】

List
first
List<Student>
2
com.hebut.jsonlib.Student@16f144c
xiapi1

2.9 处理JsonToMap

【示例代码】

package com.hebut.jsonlib;

import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import net.sf.ezmorph.Morpher;
import net.sf.ezmorph.MorpherRegistry;
import net.sf.ezmorph.bean.BeanMorpher;
import net.sf.ezmorph.test.ArrayAssertions;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;
import net.sf.json.util.JSONUtils;
import net.sf.json.xml.XMLSerializer;

import org.junit.Test;

public class JsonLib {

    @Test
    public void json2map(){
        String json1 ="{'arr':['a','b'],'int':1,
                        'name':'json','bool':true}";
        JSONObject jsonObject1 = JSONObject.fromObject(json1);
        Map typeMap1 = new HashMap();
        typeMap1.put("arr", String[].class);
        typeMap1.put("int", Integer.class);
        typeMap1.put("name", String.class);
        typeMap1.put("bool", Boolean.class);
        Map output1 = (Map)JSONObject.toBean(jsonObject1, Map.class,typeMap1);
        System.out.println("Map");
        System.out.println(output1.size());
        System.out.println(output1.get("name"));
        System.out.println(output1.get("arr"));

        String json2 ="{'k1':{'age':10,'sex':'男','userName':'xiapi1'},
                        'k2':{'age':12,'sex':'女','userName':'xiapi2'}}";
        JSONObject jsonObject2 = JSONObject.fromObject(json2);
        Map<String,Class<?>> typeMap2 =new HashMap<String,Class<?>>();
        Map<String,Student> output2 = (Map<String,Student>)JSONObject.toBean(jsonObject2,Map.class,typeMap2);
        System.out.println("Map<String,Student>");
        System.out.println(output2.size());
        System.out.println(output2.get("k1"));

        //先往注册器中注册变换器，需要用到ezmorph包中的类
　　　　MorpherRegistry morpherRegistry = JSONUtils.getMorpherRegistry();
　　　　Morpher dynaMorpher = new BeanMorpher(Student.class,morpherRegistry);
　　　　morpherRegistry.registerMorpher(dynaMorpher);

        System.out.println(((Student)morpherRegistry.morph(Student.class,output2.get("k2"))).getUserName());
    }
}

【运行结果】

Map
4
json
[a, b]
Map<String,Student>
2
net.sf.ezmorph.bean.MorphDynaBean@5b8827[
{sex=男, age=10, userName=xiapi1}
]
xiapi2

2.10 处理JsonToBean

【示例代码】

package com.hebut.jsonlib;

import net.sf.ezmorph.Morpher;
import net.sf.ezmorph.MorpherRegistry;
import net.sf.ezmorph.bean.BeanMorpher;
import net.sf.ezmorph.object.DateMorpher;
import net.sf.json.JSONObject;
import net.sf.json.JSONSerializer;
import net.sf.json.util.JSONUtils;

import org.junit.Test;

public class JsonLib {

    @Test
    public void json2bean(){
        //简单对象
        String json1 = "{'age':22,'sex':'男','userName':'xiapi'}";
        JSONObject jsonObject1 = JSONObject.fromObject(json1);
        Student output1 = (Student)JSONObject.toBean(jsonObject1,Student.class);
        System.out.println("Student");
        System.out.println(output1.getUserName());

        //复杂对象
        String json2 = "{'date':'2012-05-21 13:03:11',
                            'name':'计算机应用1班',
                'students':[{'age':10,'sex':'男','userName':'xiapi1'},
                            {'age':11,'sex':'女','userName':'xiapi2'}]}";
        //转为日期
        String[] DATE_FORMAT = { "yyyy-MM-dd HH:mm:ss" };
        MorpherRegistry morpherRegistry = JSONUtils.getMorpherRegistry();
        morpherRegistry.registerMorpher(new DateMorpher(DATE_FORMAT));
        JSONObject jsonObject2 = JSONObject.fromObject(json2);
        Map typeMap1 = new HashMap();
        typeMap1.put("date", Date.class);
        typeMap1.put("name",String.class);
        typeMap1.put("students", Student.class);
        Class output2 = (Class)JSONObject.toBean(jsonObject2,Class.class,typeMap1);
        System.out.println("Class");
        System.out.println(output2.getName());
        System.out.println(output2.getDate());
        System.out.println(output2.getStudents().get(0).getUserName());
    }
}

【运行结果】

Student
xiapi
Class
计算机应用1班
Mon May 21 13:03:11 CST 2012
xiapi1

2.11 处理JsonToXml

【示例代码】

package com.hebut.jsonlib;

import net.sf.json.JSONObject;
import net.sf.json.xml.XMLSerializer;
import org.junit.Test;

public class JsonLib {

    @Test
    public void json2xml(){
        String json1 = "{'age':22,'sex':'男','userName':'xiapi'}";
        JSONObject jsonObj = JSONObject.fromObject(json1);
　　　　XMLSerializer x = new XMLSerializer();
　　　　String xml = x.write(jsonObj);
　　　　System.out.println("XML");
　　　　System.out.println(xml);
    }
}

【运行结果】

XML
<?xml version="1.0" encoding="UTF-8"?>
<o><age type="number">22</age><sex type="string">男</sex><userName type="string">xiapi</userName></o>

2.12 对象JSONArray

【示例代码】

package com.hebut.jsonlib;

import net.sf.json.JSONArray;
import org.junit.Test;

public class JsonLib2 {

    @Test
    public void testJSONArray() {
        JSONArray jsonArray = new JSONArray();
        jsonArray.add(0,"第一个值");
        jsonArray.add(1,"第二个值");
        jsonArray.add(2,"第三个值");
        System.out.print(jsonArray.toString());
    }
}

【运行结果】

["第一个值","第二个值","第三个值"]

2.13 对象JSONObject

【示例代码】

package com.hebut.jsonlib;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

import org.junit.Test;

public class JsonLib2 {

    @Test
    public void testJSONObject() {
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("name", "xiapi");
        jsonObject.put("age", 20);
        jsonObject.put("sex", "男");
        JSONArray jsonArray = new JSONArray();
        jsonArray.add("唱歌");
        jsonArray.add("摄影");
        jsonArray.add("象棋");
        jsonObject.element("hobby",jsonArray);
        System.out.println(jsonObject);
    }
}

【运行结果】

{"name":"xiapi","age":20,"sex":"男","hobby":["唱歌","摄影","象棋"]}

3、日期转换

　　json-lib转换出来的日期类型格式：

"birthday":{"date":1,"day":0,"hours":0,"minutes":0,"month":7,"nanos":0,"seconds":0,"time":1280592000000,"timezoneOffset":-480,"year":110}

　　那么我们如果想要"yyyy-MM-dd HH:mm:ss "这种格式的怎么办呢？

3.1 三种解决方案

　　都必须使用jsonConfig对象进行处理

　　（1）使用jsonConfig的setExcludes的方法进行过滤，将所需要过滤的字段名传入setExcludes方法。

    public void objectToJson(){
        //创建对象
        Emp emp= new Emp(****);
        //创建jsonConfig对象
        JsonConfig config=new JsonConfig();
        //设置过滤字段
        config.setExcludes(new String[]{"dept"});
        String s=JSONObject.fromObject(emp,config).toString();
        System.out.println(s);
    }

　　（2）使用jsonConfig的setJsonPropertyFilter进行属性过滤，过滤器中返回true表示过滤该字段，返回false表示可以转换该字段。

    public void objectToJson(){
        //创建对象
        Emp emp= new Emp(****);
        //创建jsonConfig对象
        JsonConfig config=new JsonConfig();
        //设置过滤字段
        config.setJsonPropertyFilter(new PropertyFilter() {
            public boolean apply(Object arg0, String arg1, Object arg2) {
                if("dept".equals(arg1)){
                    return true;
                }
                return false;
            }
        });
        String s=JSONObject.fromObject(emp,config).toString();
        System.out.println(s);
    }

　　上述两种解决方案可以解决部分问题，但是json-lib使用代理进行反射，所以如果想要部门表的信息，而去过滤部门表的员工对象，这样还是解决不了。这样可以使用更简单有效的方案

　　（3）使用jsonConfig的setCycleDetectionStrategy()方法进行忽略死循环。

使用jsonConfig的registerJsonValueProcessor()进行属性转换设置。

    public void objectToJson(){
        //创建对象
        Emp emp= new Emp(****);
        //创建jsonConfig对象
        JsonConfig config=new JsonConfig();
        //设置循环策略为忽略解决json最头疼的问题死循环
        config.setCycleDetectionStrategy(CycleDetectionStrategy.LENIENT);
        //设置 json转换的处理器用来处理日期类型
        //凡是反序列化Date类型的对象，都会经过该处理器进行处理
        config.registerJsonValueProcessor(Date.class, new JsonValueProcessor() {
            //参数1 ：属性名参数2：json对象的值参数3：jsonConfig对象
            public Object processObjectValue(String arg0, Object arg1, JsonConfig arg2) {
                SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
                Date d=(Date) arg1;
                return sdf.format(d);
            }
            public Object processArrayValue(Object arg0, JsonConfig arg1) {
                return null;
            }
        });
        String s=JSONObject.fromObject(emp,config).toString();
        System.out.println(s);
    }

　　这种方案可以解决死循环问题和日期格式化的问题。

　　结果：

{"birthday":"2010-08-01 00:00:00","dept":{"depid":1,"depname":"开发部","emps":[{"birthday":"2009-08-01 00:00:00","dept":null,"empid":30,"empname":"田七"},null]},"empid":27,"empname":"王五"}

3.2 封装函数方案

public static String convert2Json2(Object object) {
    JsonConfig jsonConfig = new JsonConfig();
    jsonConfig.registerJsonValueProcessor(java.util.Date.class,
            new JsonValueProcessor() {
                private final String format = "yyyy-MM-dd hh:mm:ss";

                public Object processArrayValue(Object object,
                        JsonConfig jsonConfig) {
                    return null;
                }

                public Object processObjectValue(String string,
                        Object object, JsonConfig jsonConfig) {
                    if (null == object) {
                        return "";
                    } else {
                        if (object instanceof java.util.Date) {
                            SimpleDateFormat simpleDateFormat = new
                                SimpleDateFormat(format);
                            String dateStr = simpleDateFormat
                                    .format(object);
                            return dateStr;
                        }
                    }

                    return object.toString();
                }
            });

    if (object instanceof String)
        return object.toString();
    if ((object instanceof Object[]) || (object instanceof List)) {
        JSONArray jsonObject = JSONArray.fromObject(object, jsonConfig);
        return jsonObject.toString() + '\n';
    } else {
        JSONObject jsonObject = JSONObject.fromObject(object, jsonConfig);
        return jsonObject.toString() + '\n';
    }
}

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