Servlet返回字符串或JSON内容

电玩女神 2021-09-30 11:30 502阅读 0赞

在项目开发中，有时候我们需要Servlet类返回字符串、JSON或者页面HTML内容。

# 1、Servlet返回字符串 #

**示例：**创建CharacterServlet类，实现Servlet类返回字符串。

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;
    
    /**
     * 输出字符串Servlet类
     * @author pan_junbiao
     */
    @WebServlet(name="CharacterServlet",urlPatterns = "/Servlet/CharacterServlet")
    public class CharacterServlet extends HttpServlet
    {
        @Override
        public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
        {
            String result = "您好，欢迎访问 pan_junbiao的博客！";
    
            //返回结果
            response.setContentType("text/html");
            response.setCharacterEncoding("UTF-8");
            // 获取PrintWriter对象
            PrintWriter out = response.getWriter();
            out.print(result);
            // 释放PrintWriter对象
            out.flush();
            out.close();
        }
    }

**执行结果：**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Bhbl9qdW5iaWFv_size_16_color_FFFFFF_t_70][]

# 2、Servlet返回JSON内容 #

**示例：**创建JsonServlet类，实现Servlet类返回JSON内容。

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;
    
    /**
     * 输出JSON内容Servlet类
     * @author pan_junbiao
     */
    @WebServlet(name="JsonServlet",urlPatterns = "/Servlet/JsonServlet")
    public class JsonServlet extends HttpServlet
    {
        @Override
        public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
        {
            String json = "{\n" +
                    "\t\"userId\": 1,\n" +
                    "\t\"userName\": \"pan_junbiao的博客\",\n" +
                    "\t\"blogUrl\": \" https: //blog.csdn.net/pan_junbiao\",\n" +
                    "\t\"sex\": \"男\"\n" +
                    "}";
    
            //返回结果
            response.setContentType("application/json");
            response.setCharacterEncoding("UTF-8");
            // 获取PrintWriter对象
            PrintWriter out = response.getWriter();
            out.print(json);
            // 释放PrintWriter对象
            out.flush();
            out.close();
        }
    }

**执行结果：**

**![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Bhbl9qdW5iaWFv_size_16_color_FFFFFF_t_70 1][]**

# 3、Servlet返回页面HTML内容 #

**示例：**创建PageServlet类，实现Servlet类返回页面HTML内容。

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;
    
    /**
     * 输出页面HTML内容Servlet类
     * @author pan_junbiao
     */
    @WebServlet(name="PageServlet",urlPatterns = "/Servlet/PageServlet")
    public class PageServlet extends HttpServlet
    {
        @Override
        public void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
        {
            response.setContentType("text/html");
            response.setCharacterEncoding("UTF-8");
            PrintWriter out = response.getWriter();
            out.println("<HTML>");
            out.println("<HEAD><TITLE>Servlet 实例</TITLE></HEAD>");
            out.println("<BODY>");
            out.println("您好，欢迎访问 pan_junbiao的博客！");
            out.println("<br/>博客地址：https://blog.csdn.net/pan_junbiao");
            out.println("<br/>Servlet实例：");
            out.println(this.getClass());
            out.println("</BODY>");
            out.println("</HTML>");
            out.flush();
            out.close();
        }
    }

**执行结果：**

**![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Bhbl9qdW5iaWFv_size_16_color_FFFFFF_t_70 2][]**

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Bhbl9qdW5iaWFv_size_16_color_FFFFFF_t_70]: /images/20210724/b0a66b737c6d4980b942a157d530ebe8.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Bhbl9qdW5iaWFv_size_16_color_FFFFFF_t_70 1]: /images/20210724/d1dc45c438a34830bac38d199b6874bc.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Bhbl9qdW5iaWFv_size_16_color_FFFFFF_t_70 2]: /images/20210724/d087d261ff604843936ed2142cd40e75.png