json文件中的数据读入数组
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发布时间：2022-04-25 20:39
共2个回答
热心网友
时间：2022-04-22 23:35
Java 读写json格式的文件方法详解
一、要解决这个问题首先要知道json格式是什么？
JSON格式：
比如学生有学号，姓名，性别等。
用json表示则为：
{"studno":"11111","studname":"wwww","studsex":"男"}(各个字段都是字符型）
这代表一个学生的信息。
如果多个呢？
[{"studno":"122222","studname":"wwww","studsex":"男"},
{"studno":"11111","studname":"xxxx","studsex":"男"},
{"studno":"33333","studname":"ssss","studsex":"男"}]
这就是json格式。
二、那如何操作json格式的文件呢？
这个更简单了，说白了就是直接读写文件，再把读出来的文件内容格式化成json就可以了。
三、具体操作。
1.我有一个实体类，如下：
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;
}
}
2.有一个json格式的文件，存的就是他的信息，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"}
3.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;
}
//把json格式的字符串写到文件
public void writeFile(String filePath, String sets) throws IOException {
FileWriter fw = new FileWriter(filePath);
PrintWriter out = new PrintWriter(fw);
out.write(sets);
out.println();
fw.close();
out.close();
}
4.调用，使用（在网站的controller里调用的）
//取出json对象
public void GetElectSettings(HttpServletRequest request,
HttpServletResponse response) throws Exception {
ElectSet electset=new ElectSet();
String absPath = request.getRealPath("\");
String filePath = absPath "public\sets\electSets.json";
electset=businessService.findElectSets(filePath);//这里是调用，大家自己改改，我调用的业务层 的。
JSONArray jsonItems = new JSONArray();
jsonItems.add(electset);
JSONObject jo=new JSONObject();
jo.put("data", jsonItems);
System.out.println(jo);
request.setCharacterEncoding("utf-8");
response.setContentType("application/json;charset=utf-8");
PrintWriter out = response.getWriter();
out.print(jo);
}
//修改json文件
public void ChangeElectSet(HttpServletRequest request,
HttpServletResponse response) throws Exception {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/json;charset=utf-8");
log.info("reach ChangeElectSet");
String json = (String) request.getParameter("json").trim();
log.info("Change ElectSet");
log.info(json);
ElectSet sets = new ElectSet();
JSONObject jsonObject = JSONObject.fromObject(json);
sets = (ElectSet) JSONObject.toBean(jsonObject, ElectSet.class);
if(sets.getIsReadDB()=="false"){
sets.setIsReadDB("否");
}
else{
sets.setIsReadDB("是");
}
String changes="{"xuenian":"";//因为json的属性要用引号，所以要用"转义一下
changes =sets.getXuenian() "","xueqi":"" sets.getXueqi() "","startTime":"" sets.getStartTime() "","endTime":"" sets.getEndTime() "","menshu":"" sets.getMenshu() "","isReadDB":"" sets.getIsReadDB() ""}";
System.out.println(changes);
String absPath = request.getRealPath("\");
String filePath = absPath "public\sets\electSets.json";
热心网友
时间：2022-04-23 00:53
String[] arrStr = {(String)jsonArray.getJSONObject(0),(String)jsonArray.getJSONObject(1),(String)jsonArray.getJSONObject(2)};
追问你好，读入文件怎么写，还有test.json中如果有多条，怎么遍历读出
