Json建构于两种结构:
1、“名称/值”对的集合(A collection of name/value pairs)。不同的语言中,它被理解为对象(object),纪录(record),结构(struct),字典(dictionary),哈希表(hash table),有键列表(keyed list),或者关联数组 (associative array)。 如:
{
“name”:”jackson”,
“age”:100
}
2、值的有序列表(An ordered list of values)。在大部分语言中,它被理解为数组(array)如:
{
“students”:
[
{“name”:”jackson”,“age”:100},
{“name”:”michael”,”age”:51}
]
}
二、java解析JSON步骤
A、服务器端将数据转换成json字符串
首先、服务器端项目要导入json的jar包和json所依赖的jar包至builtPath路径下(这些可以到JSON-lib官网下载:http://json-lib.sourceforge.net/)
然后将数据转为json字符串,核心函数是:
public static String createJsonString(String key, Object value)
{
JSONObject jsonObject = new JSONObject()
jsonObject.put(key, value)
return jsonObject.toString()
}
B、客户端将json字符串转换为相应的javaBean
1、客户端获取json字符串(因为android项目中已经集成了json的jar包所以这里无需导入)
public class HttpUtil
{
public static String getJsonContent(String urlStr)
{
try
{// 获取HttpURLConnection连接对象
URL url = new URL(urlStr)
HttpURLConnection httpConn = (HttpURLConnection) url
.openConnection()
// 设置连接属性
httpConn.setConnectTimeout(3000)
httpConn.setDoInput(true)
httpConn.setRequestMethod("GET")
// 获取相应码
int respCode = httpConn.getResponseCode()
if (respCode == 200)
{
return ConvertStream2Json(httpConn.getInputStream())
}
}
catch (MalformedURLException e)
{
// TODO Auto-generated catch block
e.printStackTrace()
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace()
}
return ""
}
private static String ConvertStream2Json(InputStream inputStream)
{
String jsonStr = ""
// ByteArrayOutputStream相当于内存输出流
ByteArrayOutputStream out = new ByteArrayOutputStream()
byte[] buffer = new byte[1024]
int len = 0
// 将输入流转移到内存输出流中
try
{
while ((len = inputStream.read(buffer, 0, buffer.length)) != -1)
{
out.write(buffer, 0, len)
}
// 将内存流转换为字符串
jsonStr = new String(out.toByteArray())
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace()
}
return jsonStr
}
}
2、获取javaBean
public static Person getPerson(String jsonStr)
{
Person person = new Person()
try
{// 将json字符串转换为json对象
JSONObject jsonObj = new JSONObject(jsonStr)
// 得到指定json key对象的value对象
JSONObject personObj = jsonObj.getJSONObject("person")
// 获取之对象的所有属性
person.setId(personObj.getInt("id"))
person.setName(personObj.getString("name"))
person.setAddress(personObj.getString("address"))
}
catch (JSONException e)
{
// TODO Auto-generated catch block
e.printStackTrace()
}
return person
}
public static List<Person>getPersons(String jsonStr)
{
List<Person>list = new ArrayList<Person>()
JSONObject jsonObj
try
{// 将json字符串转换为json对象
jsonObj = new JSONObject(jsonStr)
// 得到指定json key对象的value对象
JSONArray personList = jsonObj.getJSONArray("persons")
// 遍历jsonArray
for (int i = 0i <personList.length()i++)
{
// 获取每一个json对象
JSONObject jsonItem = personList.getJSONObject(i)
// 获取每一个json对象的值
Person person = new Person()
person.setId(jsonItem.getInt("id"))
person.setName(jsonItem.getString("name"))
person.setAddress(jsonItem.getString("address"))
list.add(person)
}
}
catch (JSONException e)
{
// TODO Auto-generated catch block
e.printStackTrace()
}
return list
}
public static void main(String[] args){
String temp="{'data':{'a':[{'b1':'bb1','c1':'cc1'},{'b2':'bb2','c2':'cc2'}]}}"
JSONObject jodata =JSONObject.fromObject(temp)
JSONObject joa =JSONObject.fromObject(jodata.get("data").toString())
JSONArray ja=JSONArray.fromObject(joa.get("a"))
for(int i=0i<ja.size()i++){
JSONObject o=ja.getJSONObject(i)
if(o.get("b1")!=null){
System.out.println(o.get("b1"))
}
if(o.get("c1")!=null){
System.out.println(o.get("c1"))
}
if(o.get("b2")!=null){
System.out.println(o.get("b2"))
}
if(o.get("c2")!=null){
System.out.println(o.get("c2"))
}
}
}
注:要包含两个jar包ezmorph-1.0.6.jar和json-lib-2.2.2-jdk15.jar,jar包在附件中
java解析json格式文件,再保存在数据库的方法:1:定义一个实体类
2:用json lib将json字符串转为Java对象
3:用jdbc或hibernate将java对象存入数据库
直接读写文件,再把读出来的文件内容格式化成json,再用JDBC、Mybatis或者其他框架将json数据存入数据库。
假设实体类是这样的:
public class ElectSet {public String xueqi
public String xuenian
public String startTime
public String endTime
public int menshu
public String isReadDB
//{"xueqi":,"xuenian":,"startTime":,"endTime":,"renshu":,"isReadDB":}
public String getXueqi() {
return xueqi
}
public void setXueqi(String xueqi) {
this.xueqi = xueqi
}
public String getXuenian() {
return xuenian
}
public void setXuenian(String xuenian) {
this.xuenian = xuenian
}
public String getStartTime() {
return startTime
}
public void setStartTime(String startTime) {
this.startTime = startTime
}
public String getEndTime() {
return endTime
}
public void setEndTime(String endTime) {
this.endTime = endTime
}
public int getMenshu() {
return menshu
}
public void setMenshu(int menshu) {
this.menshu = menshu
}
public String getIsReadDB() {
return isReadDB
}
public void setIsReadDB(String isReadDB) {
this.isReadDB = isReadDB
}
}
有一个json格式的文件,存的信息如下:
Sets.json:
{"xuenian":"2007-2008","xueqi":"1","startTime":"2009-07-19 08:30","endTime":"2009-07-22 18:00","menshu":"10","isReadDB":"Y"}
具体操作:
/*
* 取出文件内容,填充对象
*/
public ElectSet findElectSet(String path){
ElectSet electset=new ElectSet()
String sets=ReadFile(path)//获得json文件的内容
JSONObject jo=JSONObject.fromObject(sets)//格式化成json对象
//System.out.println("------------" jo)
//String name = jo.getString("xuenian")
//System.out.println(name)
electset.setXueqi(jo.getString("xueqi"))
electset.setXuenian(jo.getString("xuenian"))
electset.setStartTime(jo.getString("startTime"))
electset.setEndTime(jo.getString("endTime"))
electset.setMenshu(jo.getInt("menshu"))
electset.setIsReadDB(jo.getString("isReadDB"))
return electset
}
//设置属性,并保存
public boolean setElect(String path,String sets){
try {
writeFile(path,sets)
return true
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace()
return false
}
}
//读文件,返回字符串
public String ReadFile(String path){
File file = new File(path)
BufferedReader reader = null
String laststr = ""
try {
//System.out.println("以行为单位读取文件内容,一次读一整行:")
reader = new BufferedReader(new FileReader(file))
String tempString = null
int line = 1
//一次读入一行,直到读入null为文件结束
while ((tempString = reader.readLine()) != null) {
//显示行号
System.out.println("line " line ": " tempString)
laststr = laststr tempString
line
}
reader.close()
} catch (IOException e) {
e.printStackTrace()
} finally {
if (reader != null) {
try {
reader.close()
} catch (IOException e1) {
}
}
}
return laststr
}
将获取到的字符串,入库即可。