java方式的将java对象以及list或者map转化为json数据,json转换为object或者map

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学会了在j2ee中使用ajax后,有时候从服务器返回客户端的数据是对象，自己手动拼凑
json字符串容易出错，通过谷歌知道了json-lib这个类库，方便的支持java中对象到json字符串的转化。
看source-forge的json-lib介绍说，需要
jakarta commons-lang 2.4
jakarta commons-beanutils 1.7.0
jakarta commons-collections 3.2
jakarta commons-logging 1.1.1
ezmorph 1.0.6

这些jar包的支持，下载下来试了一把，挺好用的，写出来，与大家分享。
代码如下：

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

public class Test {
public static void main(String[] args) {
//当是对象的时候
Student student = new Student();
student.setAge(18);
student.setName("zhangsan");
student.setSex("male");
JSONObject jsonObject = JSONObject.fromObject(student);
System.out.println(jsonObject);//输出{"age":18,"name":"zhangsan","sex":"male"}
//当是数组或list的时候
Student[] stus = new Student[5];
List<Student> stuList = new ArrayList<Student>();
for (int i = 0; i < stus.length; i++) {
stus[i] = new Student();
stus[i].setAge(i*10+8);
stus[i].setName("zhang"+i);
stus[i].setSex("male");
//添加到list,一会儿用
stuList.add(stus[i]);
}
JSONArray jsonArray = JSONArray.fromObject(stus);
System.out.println(jsonArray);//和下面打印的结果相同
//结果：[{"age":8,"name":"zhang0","sex":"male"},{"age":18,"name":"zhang1","sex":"male"},{"age":28,"name":"zhang2","sex":"male"},{"age":38,"name":"zhang3","sex":"male"},{"age":48,"name":"zhang4","sex":"male"}]
JSONArray jsonArrayFromList = JSONArray.fromObject(stuList);
System.out.println(jsonArrayFromList);//和上面打印的结果相同
//当既有对象又有数组的时候
Map<String,Object> map = new HashMap<String,Object>();
Teacher teacher = new Teacher();
teacher.setAge(30);
teacher.setName("laoshi");
teacher.setSex("male");
map.put("teacher", teacher);
map.put("student", stuList);
JSONObject jsonObjectFromMap = JSONObject.fromObject(map);
System.out.println(jsonObjectFromMap);
//结果：
//{"student":[{"age":8,"name":"zhang0","sex":"male"},{"age":18,"name":"zhang1","sex":"male"},{"age":28,"name":"zhang2","sex":"male"},{"age":38,"name":"zhang3","sex":"male"},{"age":48,"name":"zhang4","sex":"male"}],"teacher":{"age":30,"name":"laoshi","sex":"male"}}
}
}

把json转换为map或者object类型

1.转换为map :

String s = "{\"a1\":\"v1\",\"a2\":\"v2\"}";
Object obj = JSONObject.toBean(JSONObject.fromObject(s),HashMap.class);
System.out.println(((HashMap<String, String>) obj).get("a1"));

2.转换为object

public static void main(String[] args) {
Map map=new HashMap();
map.put("我","妹");
map.put("擦","哇");
map.put("你","呀");
JSONObject json = JSONObject.fromObject(map);
System.out.println(json);
}

輸出的結果 {"我":"妹","擦":"哇","你":"呀"}

toBean();

首先一个javabean对象
public class Student {

private int id ;
private String name;
private int age;

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

public String toString(){
return this.id + ", " + this.name + ", " + this.age;
}
}

然后测试toBean方法的类
import net.sf.json.JSONObject;

public class ToBeanTest {

public static void main(String[] args) {

String json = "{id:'1001',name:'张三',age:'22'}";
Student stu = new Student();
JSONObject obj = JSONObject.fromObject(json);
stu = (Student)JSONObject.toBean(obj, Student.class);
System.out.println(stu);
}

}
输出结果为1001, 张三, 22
然后我们在修改修改
import net.sf.json.JSONObject;

public class ToBeanTest {

public static void main(String[] args) {

String json = "{id:'1001',name:'张三'}";
Student stu = new Student();
JSONObject obj = JSONObject.fromObject(json);
stu = (Student)JSONObject.toBean(obj, Student.class);
System.out.println(stu);
}

}
把年龄给去掉age为int型，输出结果为：1001, 张三, 0
然后再做小小改动
import net.sf.json.JSONObject;

public class ToBeanTest {

public static void main(String[] args) {

String json = "{id:'1001',age:'22'}";
Student stu = new Student();
JSONObject obj = JSONObject.fromObject(json);
stu = (Student)JSONObject.toBean(obj, Student.class);
System.out.println(stu);
}

}
把姓名给去掉name为String型，输出结果为：1001, null, 22
再改动一下：
import net.sf.json.JSONObject;

public class ToBeanTest {

public static void main(String[] args) {

String json = "{id:'1001',name:'张三',age:'nn'}";
Student stu = new Student();
JSONObject obj = JSONObject.fromObject(json);
stu = (Student)JSONObject.toBean(obj, Student.class);
System.out.println(stu);
}

}
把age改成非整形，输出结果为：
1001, 张三, 0

再改动一下：
import net.sf.json.JSONObject;

public class ToBeanTest {

public static void main(String[] args) {

String json = "{id:'1001',name:'张三',age:'22',sex:'男'}";
Student stu = new Student();
JSONObject obj = JSONObject.fromObject(json);
stu = (Student)JSONObject.toBean(obj, Student.class);
System.out.println(stu);
}

}
加了一个sex:'男'的一对键值，输出结果为：
1001, 张三, 22

JSON与JAVA数据的转换

Posted on 2008-10-31 02:47 xcp 阅读(62639)评论(8) 编辑收藏

关键字: json java

JSON-lib这个Java类包用于把bean,map和XML转换成JSON并能够把JSON转回成bean和DynaBean。

下载地址:http://json-lib.sourceforge.net/
还要需要的第3方包:
org.apache.commons(3.2以上版本)
org.apache.oro
net.sf.ezmorph(ezmorph-1.0.4.jar)
nu.xom

1、List

Java代码

boolean[] boolArray =newboolean[]{true,false,true};
JSONArray jsonArray1 = JSONArray.fromObject( boolArray );
System.out.println( jsonArray1 );
// prints [true,false,true]
List list = new ArrayList();
list.add( "first" );
list.add( "second" );
JSONArray jsonArray2 = JSONArray.fromObject( list );
System.out.println( jsonArray2 );
// prints ["first","second"]
JSONArray jsonArray3 = JSONArray.fromObject( "['json','is','easy']" );
System.out.println( jsonArray3 );
// prints ["json","is","easy"]

2、Map

Java代码

Map map = new HashMap();
map.put( "name","json" );
map.put( "bool", Boolean.TRUE );
map.put( "int",new Integer(1) );
map.put( "arr",new String[]{"a","b"} );
map.put( "func","function(i){ return this.arr[i]; }" );
JSONObject json = JSONObject.fromObject( map );
System.out.println( json );
//{"func":function(i){ return this.arr[i]; },"arr":["a","b"],"int":1,"name":"json","bool":true}

3、BEAN

Java代码

/**
* Bean.java
private String name = "json";
private int pojoId = 1;
private char[] options = new char[]{'a','f'};
private String func1 = "function(i){ return this.options[i]; }";
private JSONFunction func2 = new JSONFunction(new String[]{"i"},"return this.options[i];");
*/
JSONObject jsonObject = JSONObject.fromObject( new JsonBean() );
System.out.println( jsonObject );
//{"func1":function(i){ return this.options[i]; },"pojoId":1,"name":"json","options":["a","f"],"func2":function(i){ return this.options[i]; }}

4、BEANS

Java代码

/**
* private int row ;
private int col ;
private String value ;
*
*/
List list = new ArrayList();
JsonBean2 jb1 = new JsonBean2();
jb1.setCol(1);
jb1.setRow(1);
jb1.setValue("xx");
JsonBean2 jb2 = new JsonBean2();
jb2.setCol(2);
jb2.setRow(2);
jb2.setValue("");
list.add(jb1);
list.add(jb2);
JSONArray ja = JSONArray.fromObject(list);
System.out.println( ja.toString() );
//[{"value":"xx","row":1,"col":1},{"value":"","row":2,"col":2}]

5、String to bean

Java代码

String json = "{name=\"json\",bool:true,int:1,double:2.2,func:function(a){ return a; },array:[1,2]}";
JSONObject jsonObject = JSONObject.fromString(json);
Object bean = JSONObject.toBean( jsonObject );
assertEquals( jsonObject.get( "name" ), PropertyUtils.getProperty( bean,"name" ) );
assertEquals( jsonObject.get( "bool" ), PropertyUtils.getProperty( bean,"bool" ) );
assertEquals( jsonObject.get( "int" ), PropertyUtils.getProperty( bean,"int" ) );
assertEquals( jsonObject.get( "double" ), PropertyUtils.getProperty( bean,"double" ) );
assertEquals( jsonObject.get( "func" ), PropertyUtils.getProperty( bean,"func" ) );
List expected = JSONArray.toList( jsonObject.getJSONArray( "array" ) );
assertEquals( expected, (List) PropertyUtils.getProperty( bean, "array" ) );

Java代码

String json = "{\"value\":\"xx\",\"row\":1,\"col\":1}";
JSONObject jsonObject = JSONObject.fromString(json);
JsonBean2 bean = (JsonBean2) JSONObject.toBean( jsonObject, JsonBean2.class );
assertEquals( jsonObject.get( "col" ),new Integer( bean.getCol()) );
assertEquals( jsonObject.get( "row" ),new Integer( bean.getRow() ) );
assertEquals( jsonObject.get( "value" ), bean.getValue() );

6 json to xml
1)
JSONObject json = new JSONObject( true );
String xml = XMLSerializer.write( json );

<o class="object" null="true">

2)
JSONObject json = JSONObject.fromObject("{\"name\":\"json\",\"bool\":true,\"int\":1}");
String xml = XMLSerializer.write( json );
<o class="object">
<name type="string">json</name>
<bool type="boolean">true</bool>
<int type="number">1</int>
</o>
<o class="object">
<name type="string">json</name>
<bool type="boolean">true</bool>
<int type="number">1</int>
</o>
3)
JSONArray json = JSONArray.fromObject("[1,2,3]");
String xml = XMLSerializer.write( json );
<a class="array">
<e type="number">1</e>
<e type="number">2</e>
<e type="number">3</e>
</a>

7 、xml to json
<a class="array">
<e type="function" params="i,j">
return matrix[i][j];
</e>
</a>
<a class="array">
<e type="function" params="i,j">
return matrix[i][j];
</e>
</a>

JSONArray json = (JSONArray) XMLSerializer.read( xml );
System.out.println( json );
// prints [function(i,j){ return matrix[i][j]; }]