Servlet 返回Json数据格式

其实就是把数据库中的数据查询出来拼接成一个Json数据

import dao.UserDao;
import endy.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

@WebServlet("/Json")
public class Json extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        UserDao ud=new UserDao();
        List<User> users=ud.FandAll();
        response.setCharacterEncoding("utf-8");
        response.setContentType("application/json;charset=utf-8");
        PrintWriter out=response.getWriter();
        String[] keys={"id","name","pwd","phone","img"};//属性名称
        StringBuffer json=new StringBuffer("[");
        for (int i=0;i<users.size();i++){
            json.append("{");
            User u=users.get(i);
            Object[] values=u.toarry();
            for (int j=0;j<keys.length;j++){
                json.append("""+keys[j]+"":""+values[j]+""");
                if (j<keys.length-1) json.append(",");
            }
            json.append("}");
            if (i<users.size()-1) json.append(",");
        }
        json.append("]");
        out.write(json.toString());
        out.close();
    }
}

 这里是后台直接拼成json字符串

26         StringBuffer json=new StringBuffer("[");
27         for (int i=0;i<users.size();i++){
28             json.append("{");
29             User u=users.get(i);
30             Object[] values=u.toarry();
31             for (int j=0;j<keys.length;j++){
32                 json.append("""+keys[j]+"":""+values[j]+""");
33                 if (j<keys.length-1) json.append(",");
34             }
35             json.append("}");
36             if (i<users.size()-1) json.append(",");
37         }
38         json.append("]");