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angular-tree-component组件中实现特定节点自动展开

罗蓁蓁 2024-01-20 阅读 9

在前后端的交互中,前端通过以下三种方式来与后端进行交互🌟

下面我们将书写这三种方式的后端代码并进行讲解

1、Query String

QueryString即在url中写入键值对,一般用doGet方法进行交互

代码如下 

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;

@WebServlet("/getParameter")
public class GetParameterServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");

        System.out.println(username);
        System.out.println(password);

        resp.getWriter().write("ok");
    }
}

用postman验证

 

2、form表单

 form表单一般用doPost方法进行交互

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;

@WebServlet("/postParameter")
public class postParameterServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String username = req.getParameter("username");
        String password = req.getParameter("password");

        System.out.println(username);
        System.out.println(password);

        resp.getWriter().write("ok");
    }
}

3、Jason字符串

 (1)关于Jason

Jason是什么

要在Servlet中实现Jason相关操作,我们使用Jackson解析器

(2)jackson的配置

怎样配置Jackson呢?🧐

在中央仓库搜索Jackson,选中Jackson Databind👆

 点击进去之后,选择2.15.0版本👆

(Jackson2.15.0对应Tomcat8、对应Servlet3.1.0)

进去后,点击复制下面这段代码📃

<!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.15.0</version>
</dependency>

粘贴到pom.xml文件中

之后会出现Maven的按钮,点击进行下载 

下载完成后,原本出现的红字报错消失

(3)使用json字符串进行前后端交互

 在配置好json的解析器后,我们书写代码进行前后端交互

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;

//定一个Request类
class Request{
    public String username;
    public String password;
}

class Response{
    public Boolean ok;
}

@WebServlet("/json")
public class JsonParameterSerlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        ObjectMapper mapper = new ObjectMapper();
        Request request = mapper.readValue(req.getInputStream(),Request.class);
        //把json字符串映射成Request类的java对象
        System.out.println("username:" + request.username);
        System.out.println("password:" + request.password);
        Response response = new Response();
        response.ok = true;
        //将Response类的java对象映射成json字符串
        String respjson = mapper.writeValueAsString(response);
        resp.setContentType("applicaton/json;charset=utf8");
        resp.getWriter().write(respjson);
    }
}

使用postman进行验证 ​​​​​​​

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