JSON-lib使用手册
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。
相关的Jar包：
-
json-lib-2.3-jdk15.jar
-
commons-beanutils-1.8.0.jar
-
commons-collections-3.1.jar
-
commons-lang-2.4.jar
-
commons-logging-1.1.1.jar
-
ezmorph-1.0.6.jar
备注：我们这里用的Struts-2.3.3版本中Json-lib包。
官方网站：http://json-lib.sourceforge.net/
下表中是Java与JavaScript类型对应关系。
| JSON |
Java |
|
| string |
<=> |
java.lang.String, java.lang.Character, char |
| number |
<=> |
java.lang.Number, byte, short, int, long, float, double |
| true|false |
<=> |
java.lang.Boolean, boolean |
| null |
<=> |
null |
| function |
<=> |
net.sf.json.JSONFunction |
| array |
<=> |
net.sf.json.JSONArray (object, string, number, boolean, function) |
| object |
<=> |
net.sf.json.JSONObject |
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';
}
}