使用gson转换bo对象与json字符串

所需jar包 gson-2.2.1.jar .

sample1： json字符串转换bo对象

工具类

import java.io.IOException;import java.io.StringReader;import java.lang.reflect.Type;import java.util.Iterator;import java.util.LinkedList;import com.google.gson.Gson;import com.google.gson.stream.JsonReader;import com.google.gson.reflect.TypeToken;public class JsonUtils {        public void parseJson(String jsonData){            // 解析JSON数据，首先要创建一个JsonReader对象            JsonReader reader = new JsonReader(new StringReader(jsonData));            try {                // 开始解析JSON数组                reader.beginArray();                // 循环读取JSON中的数组                while(reader.hasNext()){                    // 开始解析JSON数组里的对象                    reader.beginObject();                    // 循环读取JSON数组中的对象                    while(reader.hasNext()){                        String tagName = reader.nextName();                        if(tagName.equals("name")){                            System.out.println("name---->" + reader.nextString());                        }                        else if(tagName.equals("age")){                            System.out.println("age---->" + reader.nextInt());                        }                    }                    reader.endObject();                }                reader.endArray();            } catch (IOException e) {                e.printStackTrace();            }           }        public void parseUserFromJson(String jsonData){            // 解析json对象并赋值给User对象            Gson gson = new Gson();            User user = gson.fromJson(jsonData, User.class);            System.out.println("name---->" + user.getName());            System.out.println("age---->" + user.getAge());        }        // 解析JSON数组并赋值给User对象        public void parseUserArrayFromJson(String jsonData){            // 取得该类型的实体            Type listType = new TypeToken<LinkedList<User>>(){}.getType();            Gson gson = new Gson();            LinkedList<User> users = gson.fromJson(jsonData, listType);            for(Iterator<User> iterator = users.iterator(); iterator.hasNext();){                User user = (User)iterator.next();                System.out.println("name---->" + user.getName());                System.out.println("age---->" + user.getAge());            }        }    }   

bo类

public class User {private String name;private String age;public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}}

main：

public class Test {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubJsonUtils j = new JsonUtils();String jsondata = "[{\"name\":\"kevin\",\"age\":25},{\"name\":\"cissy\",\"age\":24}]";String jsondata2 = "{\"name\":\"kevin\",\"age\":25}";//System.out.println("----------------------------1");//j.parseJson(jsondata);//System.out.println("----------------------------2");//j.parseUserFromJson(jsondata2);//System.out.println("----------------------------3");j.parseUserArrayFromJson(jsondata);}}

output：

name---->kevin
age---->25
name---->cissy
age---->24

sample2：bo转json

package com.wonders.stpt.util;import java.io.BufferedInputStream;import java.io.IOException;import java.io.OutputStream;import java.io.Writer;import javax.servlet.http.HttpServletResponse;import com.google.gson.Gson;import com.google.gson.GsonBuilder;public class ActionWriter {private HttpServletResponse response;private Gson gsonAnnotation = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();private Gson gson = new Gson();public ActionWriter(HttpServletResponse response){this.response = response;}/**JSON输出(ajax) * @param response * @param obj */public void writeJsonWithAnnotation(Object obj){if(response==null) return;Writer w = null;try {response.setContentType("text/html");response.setCharacterEncoding("UTF-8");w = response.getWriter();String ret = gsonAnnotation.toJson(obj);w.write(ret);w.flush();} catch (IOException e) {e.printStackTrace();}finally{if(w!=null){try {w.close();} catch (IOException e) {e.printStackTrace();}}}}public void writeJson(Object obj){if(response==null) return;Writer w = null;try {response.setContentType("text/html");response.setCharacterEncoding("UTF-8");w = response.getWriter();String ret = gson.toJson(obj);w.write(ret);w.flush();} catch (IOException e) {e.printStackTrace();}finally{if(w!=null){try {w.close();} catch (IOException e) {e.printStackTrace();}}}}/**字符串输出(ajax) * @param response * @param str */public void writeAjax(String str){if(response==null) return;Writer w = null;try {response.setContentType("text/html");response.setCharacterEncoding("UTF-8");w = response.getWriter();w.write(str);w.flush();} catch (IOException e) {e.printStackTrace();}finally{if(w!=null){try {w.close();} catch (IOException e) {e.printStackTrace();}}}}public void writeJpeg(BufferedInputStream bis){if(response==null) return;OutputStream output = null;try {response.setContentType("image/jpeg");        response.setHeader("Pragma","No-cache");        response.setHeader("Cache-Control","no-cache");        response.setDateHeader("Expires", 0);        output = response.getOutputStream();        byte[] bytes = new byte[100];        int len;        while ((len = bis.read(bytes)) > 0) {        output.write(bytes, 0, len);        }        bis.close();        output.flush();        output.close();        } catch (IOException e) {e.printStackTrace();}finally{if(output!=null){try {output.close();} catch (IOException e) {e.printStackTrace();}}}}}

调用writeJson 返回结果为：

[
{"createTime":"2012-06-04","title":"上海地铁第四届公共安全宣传周总结","picUrl":"","memo":"","SJ_ID":"25","moreUrl":"/node281/node25/index.htm","seq":"","copyTitle":"上海地铁第四届公共安全宣传周总结","partId":"0","copyMemo":"","url":"/node281/node25/201206/con1024263"},
{"createTime":"2011-04-29","title":"第二届“上海地铁公共安全宣传周”活动回顾","picUrl":"","memo":"","SJ_ID":"25","moreUrl":"/node281/node25/index.htm","seq":"","copyTitle":"第二届“上海地铁公共安全宣传周”活动回顾","partId":"0","copyMemo":"","url":"/node281/node25/201104/con1011596"}
]