本部分内容：实现博客列表页；web程序问题的分析方法；实现博客详情页；

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该部分的代码如下：

@WebServlet("/blog")
public class BlogServlet extends HttpServlet {
    //Jackson ObjectMapper类(com.fasterxml.jackson.databind.ObjectMapper)解析JSON工具
    //
    //序列化：      Java对象生成Json
    //
    //反序列化：  Json解析为Java对象
    private ObjectMapper objectMapper=new ObjectMapper();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        BlogDao blogDao=new BlogDao();
        List<Blog> blogs =blogDao.getblogs();
        String respJson=objectMapper.writeValueAsString(blogs);
        resp.setContentType("application/json;charset=utf8");
        resp.getWriter().write(respJson);
    }

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上述过程中的一些疑问

这部分的运行效果图如下：

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修改后的BlogServlet.java代码如下：

package api;

import Dao.Blog;
import Dao.BlogDao;
import com.fasterxml.jackson.databind.ObjectMapper;

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.util.List;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: Home-pc
 * Date: 2023-10-28
 * Time: 16:56
 */
@WebServlet("/blog")
public class BlogServlet extends HttpServlet {
    //Jackson ObjectMapper类(com.fasterxml.jackson.databind.ObjectMapper)解析JSON工具
    //
    //序列化：      Java对象生成Json
    //
    //反序列化：  Json解析为Java对象
    private ObjectMapper objectMapper=new ObjectMapper();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        BlogDao blogDao=new BlogDao();
        //尝试获取blogId这个参数，根据是否能获取到这个参数，将其进行分支
        String blogId=req.getParameter("blogId");
        if(blogId==null){
            //说明此处是需要获取博客列表
            List<Blog> blogs =blogDao.getblogs();
            String respJson=objectMapper.writeValueAsString(blogs);
            resp.setContentType("application/json;charset=utf8");
            resp.getWriter().write(respJson);
        }else{
            //说明此处要获得某篇博客的详情页 获取一篇博客
            Blog blog=blogDao.getblog(Integer.parseInt(blogId));
            //如果该篇博客不存在，那么此时的blog==null
            if(blog==null){
                blog=new Blog();
            }
            String respJson=objectMapper.writeValueAsString(blog);
            resp.setContentType("application/json;charset=utf8");
            resp.getWriter().write(respJson);
        }
    }
}