json使用时需要导入的包

使用json之前需要导入如下的包：

json-lib-2.3-jdk15.jar
commons-beanutils-1.7.0.jar
commons-httpclient-3.1.jar
commons-lang-2.3.jar
commons-logging-1.0.4.jar
commons-collections-3.1.jar
ezmorph-1.0.3.jar

这些包可以从一下地方下载：
http://commons.apache.org/index.html
http://json-lib.sourceforge.net/
http://ezmorph.sourceforge.net/
http://www.docjar.com/
如果不关联这些包，则会出现以下错误：
java.lang.NoClassDefFoundError: net/sf/ezmorph/Morpher
java.lang.NoClassDefFoundError: org/apache/commons/collections/map/ListOrderedMap
java.lang.NoClassDefFoundError: org/apache/commons/beanutils/DynaBean
java.lang.NoClassDefFoundError: org/apache/commons/codec/DecoderException
java.lang.NoClassDefFoundError: org/apache/commons/lang/exception/NestableRuntimeException
java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory


package com.json;        
       
public class User {        
    String username;        
    String password;        
    public String getUsername() {        
        return username;        
    }        
    public void setUsername(String username) {        
        this.username = username;        
    }        
    public String getPassword() {        
        return password;        
    }        
    public void setPassword(String password) {        
        this.password = password;        
    }        
            
} 


package com.json;        
       
import java.io.IOException;        
import java.io.PrintWriter;        
import java.util.ArrayList;        
import java.util.List;        
       
import javax.servlet.ServletException;        
import javax.servlet.http.HttpServlet;        
import javax.servlet.http.HttpServletRequest;        
import javax.servlet.http.HttpServletResponse;        
       
import net.sf.json.JSONArray;        
       
public class TestJson extends HttpServlet {        
       
    public void doGet(HttpServletRequest request, HttpServletResponse response)        
            throws ServletException, IOException {        
           doPost(request,response);        
    }        
    public void doPost(HttpServletRequest request, HttpServletResponse response)        
            throws ServletException, IOException {        
       
        response.setContentType("text/html");           
    String str= request.getParameter("name");//得到ajax传递过来的paramater        
        System.out.print(str);        
        PrintWriter out = response.getWriter();        
        List list = new ArrayList();//传递List        
                  Map m=new HashMap();//传递Map            
        User u1=new User();        
        u1.setUsername("zah");        
        u1.setPassword("123");        
        User u2=new User();        
        u2.setUsername("ztf");        
        u2.setPassword("456");          
        list.add(u1); //添加User对象              
         list.add(u2);     //添加User对象          
              
          m.put("u1", u1);        
         m.put("u2", u2);           
       
   JSONArray jsonArray2 = JSONArray.fromObject( list );        
       //把java数组转化成转化成json对象         
   JSONObject jo=JSONObject.fromObject(m);//转化Map对象        
        out.print(jsonArray2);//返给ajax请求        
       out.print(jo);//返给ajax请求        
    }        
} 

<script type="text/javascript" src="js/jquery.js"></script>        
<script type="text/javascript">        
     function test(){        
         $.ajax({         
                type:"POST", //请求方式        
                url:"testjson", //请求路径        
                cache: false,           
                data:"name=zah",  //传参        
                dataType: 'json',   //返回值类型        
               success:function(json){              
                    alert(json[0].username+" " json[0].password);    //弹出返回过来的List对象        
                   }        
                });        
      }        
</script>        
  </head>        
  <body>        
    <input type="button" name="b" value="测试" onclick=test()>        
  </body>