当前位置: 代码迷 >> JavaScript >> 施用JSON 需要的jar包
  详细解决方案

施用JSON 需要的jar包

热度:193   发布时间:2012-09-03 09:48:39.0
使用JSON 需要的jar包
需要导入这些包
commons-beanutils-1.7.0.jar  
commons-lang-2.1.jar 
ezmorph-1.0.2.jar 
json-lib-1.1-jdk15.jar




一、JSON介绍


JSON(JavaScript Object Notation),类似于XML,是一种数据交换格式,比如JAVA产生了一个数据想要给JavaScript,则除了利用XML外,还可以利用JSON;

JSON相比XML的优势是表达起来很简单;

官网:http://www.json.org/

JSON是AJAX中的X(就是可以取代XML);          ------出自JSON创始人;




注意:JSON并不是一个文档格式,没有*.json的文档,一般JSON格式的文档存在txt中,而XML可以是一个标准;




二、JSON数据结构


JSON有两种数据结构:

(1)Map,也称为对象;{....}

(2)Array;[......]

也就是说所有的JSON对象都是要以这些形式表示;




1.Map


简单的说就是Java中的Map,名称-值对的形式给出,名称和值之间用“:”隔开,两个Map之间用“,”隔开,一般表示形式如下:

{'key1':'value1','key2':'value2'}

以下为官网的图:







2.Array


就是普通意义上的数组,一般形式如下:

['arr1','arr2','arr3'];

以下为官网的图:









图中的value可以是:














总结:

(1)JSON的数据结构只有两种;

(2)可以嵌套表示,比如Array中可以嵌套Object等;

(3)记住:Object是以{}表示,Array是以[  ]表示;



三、JSON与XML互转示例


前面提到任何的XML都能够转换成JSON包;




1.简单XML


XML格式:


view plaincopy to clipboardprint?<person> 
    <name>xiazdong</name> 
    <age>20</age> 
</person> 
<person>
<name>xiazdong</name>
<age>20</age>
</person>

JSON格式:


view plaincopy to clipboardprint?{ 
    "name":"xiazdong", 
    "age":20 

{
"name":"xiazdong",
"age":20
}







2.复杂XML


XML格式:


view plaincopy to clipboardprint?<section> 
    <title>BOOK</title> 
    <signing> 
        <author name="author-1"/> 
        <book title="book1" price="$11"/> 
    </signing> 
    <signing> 
        <author name="author-2"/> 
        <book title="book2" price="$22"/> 
    </signing> 
</section> 
<section>
<title>BOOK</title>
<signing>
<author name="author-1"/>
<book title="book1" price="$11"/>
</signing>
<signing>
<author name="author-2"/>
<book title="book2" price="$22"/>
</signing>
</section>
JSON格式:


view plaincopy to clipboardprint?"section":{ 
        "title":"BOOK", 
        "signing":[ 
        { 
    <span style="white-space:pre">    </span>   "author": 
            { 
                "name":"author-1" 
            }, 
            "book": 
            { 
                "title":"book1", 
                "price":"$11" 
            } 
        }, 
        { 
            "author": 
            { 
                "name":"author-2" 
            }, 
            "book": 
            { 
                "title":"book2", 
                "price":"$22" 
            } 
        }    
<span style="white-space:pre">    </span>   ]} 
    } 
"section":{
"title":"BOOK",
"signing":[
{
<span style="white-space:pre"> </span> "author":
{
"name":"author-1"
},
"book":
{
"title":"book1",
"price":"$11"
}
},
{
"author":
{
"name":"author-2"
},
"book":
{
"title":"book2",
"price":"$22"
}
}
<span style="white-space:pre"> </span> ]}
}
注意:XML中的属性也是通过JSON的Map表示;




四、JSON包


如果我们想要使用JSON包,则可以下载JSON包的源代码,并将这些代码添加进Eclipse工程中,即可调用;

如果想要看API文档,可以参见:http://www.JSON.org/java/index.html

JSON包中最常用的两个类就是JSONObject和JSONArray,分别表示两种数据结构;




1.JSONObject代码实例



view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import weibo4j.org.json.JSONArray; 
import weibo4j.org.json.JSONObject; 
 
public class Test { 
 
    public static void main(String[] args) throws Exception{ 
        JSONObject jsonobj = new JSONObject("{'name':'xiazdong','age':20}"); 
        String name = jsonobj.getString("name"); 
        int age = jsonobj.getInt("age"); 
        System.out.println(name+":"+age);    
         
    } 

package com.xiazdong.json;

import weibo4j.org.json.JSONArray;
import weibo4j.org.json.JSONObject;

public class Test {

public static void main(String[] args) throws Exception{
JSONObject jsonobj = new JSONObject("{'name':'xiazdong','age':20}");
String name = jsonobj.getString("name");
int age = jsonobj.getInt("age");
System.out.println(name+":"+age);

}
}



2.JSONArray代码实例




view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import weibo4j.org.json.JSONArray; 
import weibo4j.org.json.JSONObject; 
 
public class Test { 
 
    public static void main(String[] args) throws Exception{ 
             
        JSONArray jsonarray = new JSONArray("[{'name':'xiazdong','age':20},{'name':'xzdong','age':15}]"); 
        for(int i=0;i<jsonarray.length();i++){ 
            String name = jsonarray.getJSONObject(i).getString("name"); 
            int age = jsonarray.getJSONObject(i).getInt("age"); 
            System.out.println("name="+name); 
            System.out.println("age="+age); 
        } 
         
    } 

package com.xiazdong.json;

import weibo4j.org.json.JSONArray;
import weibo4j.org.json.JSONObject;

public class Test {

public static void main(String[] args) throws Exception{

JSONArray jsonarray = new JSONArray("[{'name':'xiazdong','age':20},{'name':'xzdong','age':15}]");
for(int i=0;i<jsonarray.length();i++){
String name = jsonarray.getJSONObject(i).getString("name");
int age = jsonarray.getJSONObject(i).getInt("age");
System.out.println("name="+name);
System.out.println("age="+age);
}

}
}



3.嵌套JSONObject和JSONArray代码实例




view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import weibo4j.org.json.JSONArray; 
import weibo4j.org.json.JSONObject; 
 
public class Test { 
 
    public static void main(String[] args) throws Exception{ 
 
        String str = "{'name':'xiazdong','age':20,'book':['book1','book2']"; 
        JSONObject obj = new JSONObject(str); 
        System.out.println(obj.getJSONArray("book").getString(0)); 
    } 

package com.xiazdong.json;

import weibo4j.org.json.JSONArray;
import weibo4j.org.json.JSONObject;

public class Test {

public static void main(String[] args) throws Exception{

String str = "{'name':'xiazdong','age':20,'book':['book1','book2']";
JSONObject obj = new JSONObject(str);
System.out.println(obj.getJSONArray("book").getString(0));
}
}





4.JSONStringer代码示例


JSONStringer可以用来快速构建一个JSON格式的文本,并转换成String,可以写入文件;

JSONStringer是JSONWriter的子类;

JSONStringer一般通过object().key().value().key().value().endObject()进行构造;

object()表明开始一个对象,即添加{  ;

endObject()表明结束一个对象,即添加 } ;

array()表明开始一个数组,即添加一个 [ ;

endArray()表明结束一个数组,即添加一个 ] ;

key()表示添加一个key;

value()表示添加一个value;


view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import weibo4j.org.json.JSONStringer; 
 
public class JsonStringerDemo { 
 
    public static void main(String[] args) throws Exception{ 
        JSONStringer stringer = new JSONStringer(); 
        String str = stringer.object().key("name").value("xiazdong").key("age").value(20).endObject().toString(); 
        System.out.println(str); 
    } 
 

package com.xiazdong.json;

import weibo4j.org.json.JSONStringer;

public class JsonStringerDemo {

public static void main(String[] args) throws Exception{
JSONStringer stringer = new JSONStringer();
String str = stringer.object().key("name").value("xiazdong").key("age").value(20).endObject().toString();
System.out.println(str);
}

}

复杂JSON格式写入
view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import java.io.File; 
import java.io.FileReader; 
 
import weibo4j.org.json.JSONArray; 
import weibo4j.org.json.JSONObject; 
import weibo4j.org.json.JSONStringer; 
import weibo4j.org.json.JSONTokener; 
 
public class JsonStringerDemo { 
 
    public static void main(String[] args) throws Exception{ 
         
        JSONStringer js = new JSONStringer(); 
        JSONObject obj2 = new JSONObject(); 
        JSONObject obj3 = new JSONObject(); 
        JSONObject obj4 = new JSONObject(); 
        obj4.put("title", "book1").put("price", "$11"); 
        obj3.put("book", obj4); 
        obj3.put("author", new JSONObject().put("name", "author-1")); 
         
        JSONObject obj5 = new JSONObject(); 
        JSONObject obj6 = new JSONObject(); 
        obj6.put("title", "book2").put("price", "$22"); 
        obj5.put("book", obj6); 
        obj5.put("author", new JSONObject().put("name", "author-2")); 
         
        JSONArray obj7 = new JSONArray(); 
        obj7.put(obj3).put(obj5); 
         
         
         
        obj2.put("title","BOOK"); 
        obj2.put("signing", obj7); 
         
        js.object().key("session").value(obj2).endObject(); 
         
        System.out.println(js.toString()); 
         
        PrintWriter out = new PrintWriter(new FileOutputStream(1.txt)); 
        out.println(js.toString()); 
         
     
    } 
 

package com.xiazdong.json;

import java.io.File;
import java.io.FileReader;

import weibo4j.org.json.JSONArray;
import weibo4j.org.json.JSONObject;
import weibo4j.org.json.JSONStringer;
import weibo4j.org.json.JSONTokener;

public class JsonStringerDemo {

public static void main(String[] args) throws Exception{

JSONStringer js = new JSONStringer();
JSONObject obj2 = new JSONObject();
JSONObject obj3 = new JSONObject();
JSONObject obj4 = new JSONObject();
obj4.put("title", "book1").put("price", "$11");
obj3.put("book", obj4);
obj3.put("author", new JSONObject().put("name", "author-1"));

JSONObject obj5 = new JSONObject();
JSONObject obj6 = new JSONObject();
obj6.put("title", "book2").put("price", "$22");
obj5.put("book", obj6);
obj5.put("author", new JSONObject().put("name", "author-2"));

JSONArray obj7 = new JSONArray();
obj7.put(obj3).put(obj5);



obj2.put("title","BOOK");
obj2.put("signing", obj7);

js.object().key("session").value(obj2).endObject();

System.out.println(js.toString());

PrintWriter out = new PrintWriter(new FileOutputStream(1.txt));
out.println(js.toString());


}

}


以上代码生成了如下JSON格式:
view plaincopy to clipboardprint?{"section":{ 
        "title":"BOOK", 
        "signing":[ 
        { 
            "author": 
            { 
                "name":"author-1" 
            }, 
            "book": 
            { 
                "title":"book1", 
                "price":"$11" 
            } 
        }, 
        { 
            "author": 
            { 
                "name":"author-2" 
            }, 
            "book": 
            { 
                "title":"book2", 
                "price":"$22" 
            } 
        }    
        ]} 
    } 

{"section":{
"title":"BOOK",
"signing":[
{
"author":
{
"name":"author-1"
},
"book":
{
"title":"book1",
"price":"$11"
}
},
{
"author":
{
"name":"author-2"
},
"book":
{
"title":"book2",
"price":"$22"
}
}
]}
}
}


5.JSONTokener代码示例



JSONTokener是用来读取JSON格式的文件;

JSONObject obj = new JSONObject( new JSONTokener(java.io.Reader));可以从文件中读取一个JSONObject;

JSONArray obj = new JSONArray( new JSONTokener(java.io.Reader)); 可以从文件中读取一个JSONArray;


1.txt


view plaincopy to clipboardprint?{ 
    'name':'xiazdong', 
    'book':['book1','book2'] 

{
'name':'xiazdong',
'book':['book1','book2']
}




view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import java.io.File; 
import java.io.FileReader; 
 
import weibo4j.org.json.JSONObject; 
import weibo4j.org.json.JSONTokener; 
 
public class JsonStringerDemo { 
 
    public static void main(String[] args) throws Exception{ 
        JSONObject obj = new JSONObject(new JSONTokener(new FileReader(new File("1.txt")))); 
        System.out.println(obj.getJSONArray("book").getString(1)); //可以读取book2  
    } 
 

package com.xiazdong.json;

import java.io.File;
import java.io.FileReader;

import weibo4j.org.json.JSONObject;
import weibo4j.org.json.JSONTokener;

public class JsonStringerDemo {

public static void main(String[] args) throws Exception{
JSONObject obj = new JSONObject(new JSONTokener(new FileReader(new File("1.txt"))));
System.out.println(obj.getJSONArray("book").getString(1)); //可以读取book2
}

}


复杂JSON格式的读取代码:

1.txt


view plaincopy to clipboardprint?{"section":{ 
        "title":"BOOK", 
        "signing":[ 
        { 
            "author": 
            { 
                "name":"author-1" 
            }, 
            "book": 
            { 
                "title":"book1", 
                "price":"$11" 
            } 
        }, 
        { 
            "author": 
            { 
                "name":"author-2" 
            }, 
            "book": 
            { 
                "title":"book2", 
                "price":"$22" 
            } 
        }    
        ]} 
    } 

{"section":{
"title":"BOOK",
"signing":[
{
"author":
{
"name":"author-1"
},
"book":
{
"title":"book1",
"price":"$11"
}
},
{
"author":
{
"name":"author-2"
},
"book":
{
"title":"book2",
"price":"$22"
}
}
]}
}
}
view plaincopy to clipboardprint?package com.xiazdong.json; 
 
import java.io.File; 
import java.io.FileReader; 
 
import weibo4j.org.json.JSONObject; 
import weibo4j.org.json.JSONTokener; 
 
public class JsonStringerDemo { 
 
    public static void main(String[] args) throws Exception{ 
        JSONObject obj = new JSONObject(new JSONTokener(new FileReader(new File("1.txt")))); 
        System.out.println(obj.getJSONObject("section").getJSONArray("signing").getJSONObject(0).getJSONObject("author").getString("name")); <span style="white-space:pre">       </span>//获取author-1  
    } 
 

package com.xiazdong.json;

import java.io.File;
import java.io.FileReader;

import weibo4j.org.json.JSONObject;
import weibo4j.org.json.JSONTokener;

public class JsonStringerDemo {

public static void main(String[] args) throws Exception{
JSONObject obj = new JSONObject(new JSONTokener(new FileReader(new File("1.txt"))));
System.out.println(obj.getJSONObject("section").getJSONArray("signing").getJSONObject(0).getJSONObject("author").getString("name")); <span style="white-space:pre"> </span>//获取author-1
}

}



总结:


1在Java中JSON格式的String最好用单引号表示;

2.利用JSONObject+JSONTokener能够读取JSON格式文件对象;

3.利用PrintWriter+JSONStringer可以写入JSON文件;

注:由于原本想要试图用JSONWriter写入,但是没有成功;所以只能利用JSONStringer+PrintWriter写入;

  相关解决方案