Java Web的第一个程序(Hello World!)

# JJU_干干

Tomcat配置

1. 下载：https://tomcat.apache.org/

2. 打开eclipse，在windows选项 / Server / Runtime Environment / Add ，添加下载后解压好的的Tomcat文件夹

方法一：.java + .xml

1. 创建一个Java Web 项目

　　（1）选中 project:

　　（2）创建动态web项目：

　　（3）点击next，命名项目名；再连续点击next，勾选生成xml文件选项

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2. 代码：java+xml

.java：

package case_01;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HelloWorld extends HttpServlet{
    public void service(HttpServletRequest req, HttpServletResponse res) throws
        IOException,ServletException{
    PrintWriter out = res.getWriter();
    out.print("Hellow World!");
    }
}

.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>Servlet_01</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
      <servlet-name>hello</servlet-name> 
      <!--包名.类名-->
      <servlet-class>case_01.HelloWorld</servlet-class>
  </servlet>
  
  <servlet-mapping>
      <servlet-name>hello</servlet-name>  <!--这里的servlet-name一定要和上面的一样-->
      <url-pattern>/hello</url-pattern> <!-- 这里一定要加左斜杠，且这里的名字可以任意，不是非得是hello，但习惯保持一样 -->
  </servlet-mapping>
</web-app>

xml位置：

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3. 运行：

在 .java中鼠标右键，选择Run as 中的 Run on Server

选择Tomcat容器，点击finish

4. 运行结果：

方法二：使用注解方式配置Sevrlet：直接创建一个servlet项目，自动生成一个模板

代码：

package case_01;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class HelloWorld_02
 */
@WebServlet("/HelloWorld_02")
public class HelloWorld_02 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public HelloWorld_02() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        // 以下两条语句防止输入中文出现乱码
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset = utf-8");
        
        response.getWriter().append("Served at: ").append(request.getContextPath());
        PrintWriter out = response.getWriter();
        out.print("Hellow World! I'm 干干");
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

运行结果：