javaservlet POST示例
时间：2020-02-23 14:37:15 来源:igfitidea点击:
此示例演示如何使用Servlet的doPost()方法处理POST请求
在前面的Javaservlet教程示例中，我演示了doGet()方法的用法。现在，将介绍如何使用doPost()方法处理表单提交。javaservlets可以处理各种类型的请求。下面的列表显示了所有方法及其用途
项目结构
在我们的项目中，我们确实需要三个文件。pom.xml文件–设置Maven依赖项和构建属性，web.xml文件–将Servlet和Servlet本身配置为java类
Servlet POST示例项目结构
马文pom.xml文件文件
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>net.theitroad.tutorials</groupId>
<artifactId>ServletPOSTExample</artifactId>
<version>1</version>
<packaging>war</packaging>
<name>Servlet POST Example</name>
<url>https://theitroad.local</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
</dependencies>
<build>
<finalName>servletpost</finalName>
<sourceDirectory>src/main/java</sourceDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.3</version>
<configuration>
<warSourceDirectory>src/main/webapp</warSourceDirectory>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
与上一个教程一样，我们使用依赖关系
javax.servlet-api
对于我们的Servlet和
maven-war-plugin
构建web应用程序
将Servlet映射到web.xml文件文件
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" version="3.1"> <display-name>Simple Servlet Application</display-name> <servlet> <servlet-name>servletPost</servlet-name> <servlet-class>net.theitroad.tutorials.ServletPOST</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>servletPost</servlet-name> <url-pattern>/welcome</url-pattern> </servlet-mapping> </web-app>
servlet被命名为“servletPost”，它指向java类servletPost
在servlet映射中，我们将url“/welcome”分配给servlet
Servlet类
package net.theitroad.tutorials;
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 ServletPOST extends HttpServlet {
private static final long serialVersionUID = -1641096228274971485L;
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//set response headers
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8");
//create HTML form
PrintWriter writer = response.getWriter();
writer.append("<!DOCTYPE html>\r\n")
.append("<html>\r\n")
.append(" <head>\r\n")
.append(" <title>Form input</title>\r\n")
.append(" </head>\r\n")
.append(" <body>\r\n")
.append(" <form action=\"welcome\" method=\"POST\">\r\n")
.append(" Enter your name: \r\n")
.append(" <input type=\"text\" name=\"user\" \r\n")
.append(" <input type=\"submit\" value=\"Submit\" \r\n")
.append(" </form>\r\n")
.append(" </body>\r\n")
.append("</html>\r\n");
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String user = request.getParameter("user");
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8");
//create HTML response
PrintWriter writer = response.getWriter();
writer.append("<!DOCTYPE html>\r\n")
.append("<html>\r\n")
.append(" <head>\r\n")
.append(" <title>Welcome message</title>\r\n")
.append(" </head>\r\n")
.append(" <body>\r\n");
if (user != null && !user.trim().isEmpty()) {
writer.append(" Welcome " + user + ".\r\n");
writer.append(" You successfully completed this theitroad.local example.\r\n");
} else {
writer.append(" You did not entered a name!\r\n");
}
writer.append(" </body>\r\n")
.append("</html>\r\n");
}
}
在上面的代码中， doGet()方法用于显示表单。客户端(浏览器)调用urlhttp://yoururl.com：8080/servletpost/welcome with GET request它看到下面的表格
输入表单
servlet在客户端浏览器中呈现为HTML，如下所示：
<!DOCTYPE html> <html> <head> <title>Form input</title> </head> <body> <form action="welcome" method="POST"> Enter your name: <input type="text" name="user" <input type="submit" value="Submit" </form> </body> </html>
提交后，调用servlet中的 doPost()方法。其中我们根据用户的输入构建一个响应。如果名称字段填写正确，则用户将收到一条问候消息
